Astronomy Archives

August 8, 2016August 8, 2016 by Tammy Plotner

Messier 22 – The Sagittarius Nebula

The Sagittarius Cluster, aka. Messier 22. Credit: Wikipedia Commons/Hewholooks

Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at the Sagittarius Cluster (aka. Messier 22). Enjoy!

Back in the 18th century, famed French astronomer Charles Messier noted the presence of several “nebulous objects” in the night sky. Having originally mistaken them for comets, he began compiling a list of these objects so that others wouldn’t make the same mistake. Consisting of 100 objects, this “Messier Catalog” would come to be viewed by posterity as a major milestone in the study of Deep Space Objects.

One of these objects is the Sagittarius Cluster, otherwise known as Messier 22 (and NGC 6656). This elliptical globular cluster, is located in the constellation Sagittarius, near the Galactic bulge region. It is one of the brightest globulars visible in the night sky, and was therefore one of the first of its kind to be discovered and later studied.

Description:

Located around 10,400 light years from our Solar System, in the direction of Sagittarius, M22 occupied a volume of space that is 200 light years in diameter and is receding away from us at 149 kilometers per second. M22 has a lot in common with many other clusters of its type, which includes being a gravitationally bound sphere of stars, and that most of its stars are all about the same age – about 12 billion years old.

Messier 22, showing its proximity to Messier 28 and Kaus Borealis. Credit: Wikisky

It is part of our galactic halo, and may once have been part of a galaxy that our Milky Way cannibalized. But it’s there that the similarities end. For example, it consists of at least 70,000 individual stars, only 32 of which are variable stars. It also spans an incredible 32 arc minutes in the sky and ranks as the fourth brightness of all the known globular clusters in our galaxy.

And four must be its lucky number, because it is also one of only four globular clusters known to contain a planetary nebula. Recent Hubble Space Telescope investigations of Messier 22 have led to the discovery of an astonishing discovery. For starters, in 1999, astronomers discovered six planet-sized objects floating around inside the cluster that were about 80 times the mass of Earth!

Using a technique known as microlensing, which measures the way gravity bends the light of the background stars, the Hubble Space Telescope was able to determine the existence of the gas giant. Even though the Hubble can’t resolve them because the angle at which the light bends is about 100 times smaller than the telescope’s angular resolution, scientist know they are there because the gravity “powers up” the starlight, making it brighter each time a body passes in front of it.

Because a microlensing event is very rare and totally unpredictable, the Hubble team needed to monitor 83,000 stars every three days for nearly four months. Luckily, a sharp peak in brightness was all the proof they needed that they were on the right track.

*The center of the globular cluster Messier 22, also known as M22, as observed by the NASA/ESA Hubble Space Telescope. Credit: ESA/HST/NASA*

Said Kailash Sahu, of the Space Telescope Science Institute, Baltimore, MD, of the discovery in 2007: “Hubble’s excellent sharpness allowed us to make this remarkable new type of observation, successfully demonstrating our ability to see very small objects. This holds tremendous potential for further searches for dark, low-mass objects.”

During their study time, the Hubble team caught six microlensing events that lasted less than 20 hours and one which endured for 18 days. By calculating the times of the eclipses and the spikes in brightness, astronomers could then estimate the mass of the object passing in front of the star. These wandering rogues might be planets torn away from their parent stars by the huge amounts of gravitational influence from so many closely packed suns – or (in the case of the long event) simply a smaller mass star passing in front of another.

They could be brown dwarfs, or even a totally new type of object. As co-investigator Nino Panagia of the European Space Agency and Space Telescope Science Institute said: “Since we know that globular clusters like M22 are very old, this result opens new and exciting opportunities for the discovery and study of planet-like objects that formed in the early universe,”

Two black holes were also discovered in M22 and confirmed by the Chandra X-ray telescope in 2012. The objects have between 10 and 20 solar masses, and their discovery suggests that there may be 5 to 100 black holes within the cluster (and maybe some multiple black holes as well). The presence of black holes and their interaction with the stars of M22 could explain the cluster’s unusually large central region.

These are optical images of M22 and the candidate companion stars to the radio sources M22-VLA1 and M22-VLA2: the globular cluster M22, on the left, and the location of the radio sources on archival Hubble images. Credit: Doug Matthews/Adam Block/NOA/AURA/NSF/HST/NASA/ESA — *Optical images of M22 and the candidate companion stars to the radio sources M22-VLA1 and M22-VLA2. Credit: Doug Matthews/Adam Block/NOA/AURA/NSF/HST/NASA/ESA*

Other objects of interesting include two black holes – M22-VLA1 and M22-VLA2 – both of which are part of binary star systems. Each has a companion star and is pulling matter from it. This gas and dust, in turn, forms an accretion disk around each black hole, creating emissions that scientists used to confirm their existence.

Messier 22 is one of only four known globular clusters that contain a planetary nebula. This nebula – catalogued as GJJC1 or IRAS 18333-2357 – is rather small and young, being only 3 arcseconds in diameter and 6,000 years old. It was discovered in 1986 using the infrared satellite IRAS, and identified as a planetary nebula in 1989.

History of Observation:

Chances are, magnificent Messier 22 was probably the first globular cluster to ever be recorded in the history of astronomy, most likely by Abraham Ihle in 1665. Over the years it has been included in many historic observations, including Edmund Halley’s list of 6 objects published 1715, and observed by De Chéseaux (his Number 17) and Le Gentil, as well as by Abbe Nicholas Louis de la Caille, who included it in his catalog of southern objects (as Lacaille I.12).

Atlas image mosaic of Messier 22 obtained as part of the Two Micron All Sky Survey (2MASS), a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology. Credit: NASA/NSF — *Atlas image mosaic of Messier 22 obtained as part of the Two Micron All Sky Survey (2MASS). Credit:UoM/IPAC/Caltech/NASA/NSF*

However, it was Charles Messier who made it famous when he cataloged it as M22 on June 5th, 1764. As he said of the object at the time:

“I have observed a nebula situated a bit below the ecliptic, between the head and the bow of Sagittarius, near the star of seventh magnitude, the twenty-fifth of that constellation, according to the catalog of Flamsteed. That nebula didn’t appear to me to contain any star, although I have examined it with a good Gregorian telescope which magnified 104 times: it is round, and one sees it very well with an ordinary refractor of 3 feet and a half; its diameter is about 6 minutes of arc. I have determined its position by comparing with the star Lambda Sagittarii: its right ascension has been concluded as 275d 28′ 39″, and its declination as 24d 6′ 11”. It was Abraham Ihle, a German, who discovered this nebula in 1665, when observing Saturn. M. le Gentil has examined it also, and he has made an engraving of the configuration in the volume of the Memoirs of the Academy, for the year 1759, page 470. He observed it on August 29, 1747, under good weather, with a refractor of 18 feet length: He also observed it on July 17, and on other days. “It always appeared to me,” he says, “very irregular in its figure, hair and distributing in space of rays of light all over its diameter.”

While Messier’s description is a wonder, let us remember that he was a comet hunter by profession. Once more, it was the observer Admiral Smythto whom we are indebted for the most detailed and vivid description of the cluster:

“A fine globular cluster, outlying that astral stream, the Via Lactea [Milky Way], in the space between the Archer’s head and bow, not far from the point of the winter solstice, and midway between Mu and Sigma Sagittarii. It consists of very minute and thickly condensed particles of light, with a group of small stars preceding by 3m, somewhat in a crucial form. Halley ascribes the discovery of this in 1665, to Abraham Ihle, the German; but it has been thought this name should have been Abraham Hill, who was one of the first council of the Royal Society, and was wont to dabble with astronomy. Hevelius, however, appears to have noticed it previous to 1665, so that neither Ihle nor Hill can be supported.

“In August, 1747, it was carefully drawn by Le Gentil, as seen with an 18-foot telescope, which drawing appears in the Mémoires de l’Académie for 1759. In this figure three stars accompany the cluster, and he remarks that two years afterwards he did not see the preceding and central one: I, however, saw it very plainly in 1835. In the description he says, “Elle m’a toujours parue tres-irrégulière dans sa figure, chevelue, et rependant des espèces de rayons de lumière tout autout de son diamètre.” This passage, I quote, “as in duty bound;” but from familiarity with the object itself, I cannot say that I clearly understand how or why his telescope exhibited these “espèces de rayons.” Messier, who registered it in 1764, says nothing about them, merely observing that it is a nebula without a star, of a round form; and Sir William Herschel, who first resolved it, merely describes it as a circular cluster, with an estimated profundity of the 344th order. Sir John Herschel recommends it as a capital test for trying the space-penetrating power of a telescope.

“This object is a fine specimen of the compression on which the nebula-theory is built. The globular systems of stars appear thicker in the middle than they would do if these stars were all at equal distances from each other; they must, therefore, be condensed toward the centre. That the stars should be accidentally disposed is too improbable a supposition to be admitted; whence Sir William Herschel supposes that they are thus brought together by their mutual attractions, and that the gradual condensation towards the centre must be received as proof of a central power of such kind.”

Messier 22 location. Image: IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg) — *The location of Messier 22 in the night sky. Credit: IAU/Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)*

Locating Messier 22:

From its position almost on the ecliptic plane, bright globular cluster M22 is easy to find in optics of all sizes. The most important clue is simply identifying the Sagittarius “teapot” shape. Once you’ve located it, just choose the “lid” star, Lambda (Kaus Borealis) and look about a fingerwidth (2 degrees) due northeast. In binoculars, if you center on Lambda, M22 will appear in the 10:00 region of your field of view.

In a finderscope, you will need to hop from Lambda northeast to 24 Sagittari and you’ll see it as a faint fuzzy nearby also to the northeast. From a dark sky location, Messier Object 22 can also sometimes be spotted with the unaided eye! No matter what size optics you use, this large, very luminous ball of stars is quite appealing. A joy to binocular users and an exercise in resolution to telescopes.

And here are the quick facts to help you get started:

Object Name: Messier 22
Alternative Designations: M22, NGC 6656
Object Type: Class VII Globular Star Cluster
Constellation: Sagittarius
Right Ascension: 18 : 36.4 (h:m)
Declination: -23 : 54 (deg:m)
Distance: 10.4 (kly)
Visual Brightness: 5.1 (mag)
Apparent Dimension: 32.0 (arc min)

Go on… Magnificent Messier 22 is waiting for you to appreciate it!

We have written many interesting articles about Messier Objects here at Universe Today. Here’s Tammy Plotner’s Introduction to the Messier Objects, , M1 – The Crab Nebula, M8 – The Lagoon Nebula, and David Dickison’s articles on the 2013 and 2014 Messier Marathons.

Be to sure to check out our complete Messier Catalog. And for more information, check out the SEDS Messier Database.

Sources:

August 8, 2016September 26, 2016 by Matt Williams

The Hype Machine Deflates After CERN Data Shows No New Particle

Image of the results obtained by colliding lead ions in the ALICE detector. Credit: CERN

This summer in Chicago, from August 3rd until the 10th, theorists and experimental physicists from around the world will be participating in the International Conference of High Energy Physics (ICHEP). One of the highlights of this conference comes from CERN Laboratories, where particle physicists are showcasing the wealth of new data that the Large Hadron Collider (LHC) has produced so far this year.

But amidst all the excitement that comes from being able to peer into the more than 100 latest results, some bad news also had to be shared. Thanks to all the new data provided by the LHC, the chance that a new elementary particle was discovered – a possibility that had begun to appear likely eight months ago – has now faded. Too bad, because the existence of this new particle would have been groundbreaking!

The indications of this particle first appeared back in December of 2015, when teams of physicists using two of CERN’s particle detectors (ATLAS and CMS) noted that the collisions performed by the LHC were producing more pairs of photons than expected, and with a combined energy of 750 gigaelectronvolts. While the most likely explanation was a statistical fluke, there was another tantalizing possibility – that they were seeing evidence of a new particle.

The ATLAS detector, one of two general-purpose detectors at the Large Hadron Collider (LHC). Credit: CERN — *The ATLAS instrument, one of two general-purpose detectors at the Large Hadron Collider (LHC). Credit: CERN*

If this particle were in fact real, then it was likely to be a heavier version of the Higgs boson. This particle, which gives other elementary particles their mass, had been discovered in 2012 by researchers at CERN. But whereas the discover of the Higgs boson confirmed the Standard Model of Particle Physics (which has been the scientific convention for the past 50 years), the possible existence of this particle was inconsistent with it.

Another, perhaps even more exciting, theory was that the particle was the long-sought-after gravitron, the theoretical particle that acts as the “force carrier” for gravity. If indeed it was this particle, then scientists would finally have a way for explaining how General Relativity and Quantum Mechanics go together – something that has eluded them for decades and inhibited the development of a Theory of Everything (ToE).

For this reason, there has been a fair degree of excitement in the scientific community, with over 500 scientific papers produced on the subject. However, thanks to the massive amounts of data provided in the past few months, the CERN researchers were forced to announce on Friday at ICEP 2016 that there was no new evidence of a particle to be had.

The results were presented by representatives of the teams that first noticed the unusual data last December. Representing CERN’s ATLAS detector, which first noted the photon pairs, was Bruno Lenzi. Meanwhile, Chiara Rovelli representing the competing team that uses the Compact Muon Solenoid (CMS), which confirmed the readings.

The Compact Muon Solenoid (CMS) is a general-purpose detector at the Large Hadron Collider. Credit: CERN

As they showed, the readings which indicated a bump in photon pairs last December have since gone into the flatline, removing any doubt as to whether or not it was a fluke. However, as Tiziano Campores – a spokesman for C.M.S. – was quoted by the New York Times as saying on the eve of the announcement, the teams had always been clear about this not being a likely possibility:

“We don’t see anything. In fact, there is even a small deficit exactly at that point. It’s disappointing because so much hype has been made about it. [But] we have always been very cool about it.”

These results were also stated in a paper submitted to CERN by the C.M.S. team on the same day. And CERN Laboratories echoed these statement in a recent press release which addressed the latest data-haul being presented at ICEP 2016:

“In particular, the intriguing hint of a possible resonance at 750 GeV decaying into photon pairs, which caused considerable interest from the 2015 data, has not reappeared in the much larger 2016 data set and thus appears to be a statistical fluctuation.”

This was all disappointing news, since the discovery of a new particle could have shed some light on the many questions arising out of the discovery of the Higgs boson. Ever since it was first observed in 2012, and later confirmed, scientists have been struggling to understand how it is that the very thing that gives other particles their mass could be so “light”.

The Large Hadron Collider - destined to deliver fabulous science data, but uncertain if these will include an evidence basis for quantum gravity theories. Credit: CERN. — *The Large Hadron Collider – which discovered the Higgs Boson in 2012 – appears to have confirmed the Standard Model yet again. Credit: CERN*

Despite being the heaviest elementary particle – with a mass of 125 billion electron volts – quantum theory predicted that the Higgs boson had to be trillions of times heavier. In order to explain this, theoretical physicists have been wondering if in fact there are some other forces at work that keep the Higgs boson’s mass at bay – i.e. some new particles. While no new exotic particles have been discovered just yet, the results so far have still been encouraging.

For instance, they showed that LHC experiments have already recorded about five times more data in the past eight months than they did in all of last year. They also offered scientists a glimpse of how subatomic particles behave at energies of 13 trillion electronvolts (13 TeV), a new level that was reached last year. This energy level has been made possible from the upgrades performed on the LHC during its two-year hiatus; prior to which, it was functioning at only half-power.

Another thing worth bragging about was the fact that the LHC surpassed all previous performance records this past June, reaching a peak luminosity of 1 billion collisions per second. Being able to conduct experiments at this energy level, and involving this many collisions, has provided LHC researchers with a large enough data set that they are able to conduct more precise measurements of Standard Model processes.

In particular, they will be able to look for anomalous particle interactions at high mass, which constitutes an indirect test for physics beyond the Standard Model – specifically new particles predicted by the theory of Supersymmetry and others. And while they have yet to discover any new exotic particles, the results so far have still been encouraging, mainly because they show that the LHC is producing more results than ever.

This is the signature of one of 100s of trillions of particle collisions detected at the Large Hadron Collider. The combined analysis lead to the discovery of the Higgs Boson. This article describes one team in dissension with the results. (Photo Credit: CERN) — *Data representation from the CMS experiment, showing the decay of protons into two photons (dashed yellow lines and green towers). Credit: CERN*

And while discovering something that could explain the questions arising from the discovery of the Higgs bosons would have been a major breakthrough, many agree that it was simply too soon to get our hopes up. As Fabiola Gianotti, the Director-General at CERN, said:

“We’re just at the beginning of the journey. The superb performance of the LHC accelerator, experiments and computing bodes extremely well for a detailed and comprehensive exploration of the several TeV energy scale, and significant progress in our understanding of fundamental physics.”

For the time being, it seems we are all going to have to be patient and wait on more scientific results to be produced. And we can all take solace in the fact that, at least for now, the Standard Model still appears to be the correct one. Clearly, there are no short cuts when it comes to figuring out how the Universe works and how all its fundamental forces fit together.

Further Reading: CERN

August 5, 2016September 26, 2016 by Matt Williams

North Korea Aims To Place Its Flag On The Moon

North Koreans dance under a flashcard display of a satellite during the Arirang Mass Games celebrations in Pyonyang, July 26, 2013. Credit: AP Photo/Wong Maye-E

Space exploration was once considered the province of two superpowers, with only tertiary participation from other nations. But since the turn of the century, more and more nations are joining in. China and India, for example, have placed landers on the Moon, satellites around Mars, and are even working on a space station. And as if that weren’t enough, private industry is also making its presence felt, largely through SpaceX and Blue Origins‘ development of reusable rockets.

But in the latest announcement to come out of the world’s last Stalinist regime, it seems that North Korea also hopes to join the 100 mile-high club (the space race, not the other thing!) In a recent interview with the Associated Press, a North Korean official indicated that the country is busy working on a five year plan that will put more satellites into orbit by 2020, and mount a mission to the moon within 10 years time.

According to the official – Hyon Kwang Il, the director of the scientific research department of North Korea’s National Aerospace Development Administration – the 5-year plan is focused on the deployment of more Earth observations satellites, as well as what will be the country’s first geostationary communications satellite.

*Visitors takes photos of an illuminated model of a globe at the Sci-Tech Complex in Pyongyang, North Korea. Credit: Kim Kwang Hyon/AP*

He further indicated that universities in North Korea are expanding their programs to train rocket scientists, with the ultimate purpose of mounting an unmanned Moon mission sometime in the 2020s. If this statement is to be believed, then this plan would constitute significant steps being taken by the isolated regime to establish a foothold in space.

As Hyon indicated in an interview with AP on July 28th, this will all be taking place despite the ongoing embargo and attempts to stifle North Korea’s technological ambitions:

“Even though the U.S. and its allies try to block our space development, our aerospace scientists will conquer space and definitely plant the flag of the DPRK on the moon… We are planning to develop the Earth observation satellites and to solve communications problems by developing geostationary satellites. All of this work will be the basis for the flight to the moon.”

Considering the announcements to come out of this isolated, totalitarian state in the past – i.e. having a cure for HIV, Ebola and cancer, finding a unicorn lair, and having invisible phones – you might be asking yourself, “how seriously should I take this?” The answer: with cautious skepticism. Granted, North Korea’s state-controlled media frequently releases propaganda statements that are so outlandish that they make us laugh out loud.

Still, this latest claim does not seem so farfetched. Already, North Korea has deployed two Earth observation satellites as part of its Kwangmyongsong program, which began in earnest in 1998. Back in February, the fifth satellite in this program (Kwangmyongsong-5) was successfully launched into orbit. And while this was only the second successful launch, it does show that country is developing a certain degree of competency when it comes to space technology.

Image released by the Korean Central News Agency (KCNA) of the rocket said to be carrying North Korea's Kwangmyongsong-4 satellite, Feb.7, 2016. Credit: AP — *Image released by the Korean Central News Agency (KCNA) of the rocket said to be carrying North Korea’s Kwangmyongsong-4 satellite, Feb. 7, 2016. Credit: AP*

The Unha rockets that were used to deliver the satellites into orbit are also considered to be capable. An expandable carrier rocket, the Unha relies on a delivery system that is similar to the Taepodong-2 long-range ballistic missile (which is a modified version of the Russian Scud). What’s more, recent satellite images of the Sohae Satellite Launching Station (located in the northeastern North Pyongan Province) has revealed that an enlarged launch tower is under construction.

This could be an indication that an enlarged version (Unha-X) might be under development, which is consistent with propaganda posters that are also advertising the new rocket. And this past Wednesday, the country test-fired what was believed to be a medium-range ballistic missile into the seas off Japan, which is the fourth reported weapons launch to take place in the past two weeks. Clearly, the regime is working to develop its rocket capabilities, which is essential to any space program.

Beyond that, the success other nations have had in recent years conducting unmanned mission to the Moon – like China’s Chang’e program – could serve as an indication that the North Korean regime is entirely serious about planting a flag there as well. “Our country has started to accomplish our plan and we have started to gain a lot of successes,” said Hyon. “No matter what anyone thinks, our country will launch more satellites.”

Seriousness or not, whether or not North Korea can actually achieve their more ambitious goal of reaching the Moon in a decade remains to be seen. And it will only come with a whole lot of time, effort, and the country burning through another significant chunk of its GDP (as with its nuclear tests). In the meantime, we better get used to the idea of Low-Earth Orbit getting a bit more crowded!

And in the meantime, be sure to enjoy this video from the Onion, which presents what is only a semi-satirical take on the regime’s space plans:

Further Reading: Associated Press

August 5, 2016September 19, 2022 by Tammy Plotner

The Constellation Camelopardalis

The large but faint northern Camelopardalis constellation (aka. "the giraffe"). Credit: astronoo.com

Welcome back to Constellation Friday! Today, in honor of our dear friend and contributor, Tammy Plotner, we examine the Caelum constellation. Enjoy!

In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of the then-known 48 constellations. Until the development of modern astronomy, his treatise (known as the Almagest) would serve as the authoritative source on astronomy. This list has since come to be expanded to include the 88 constellations that are recognized by the International Astronomical Union (IAU) today.

One of these modern additions is Camelopardalis, otherwise known as “the giraffe”. Located in the northern sky, this large but faint constellation is the eighteenth largest in the night sky. It belongs to the Ursa Major family of constellations and is bordered by Draco, Ursa Minor, Cepheus, Cassiopeia, Perseus, Auriga, Lynx, and Ursa Major and should be considered circumpolar.

Name and Meaning:

There is no real mythology connected to Camelopardalis since it is considered a “modern” constellation. Due to the faintness of the stars associated with it, the early Greeks considered this area of the sky to be empty – or a desert. But based on its Latin name, it could be considered to be a long-necked animal with the neck of a camel and the spots of a panther – connected to the twelve labors of Hercules.

Camelopardalis as depicted in Urania's Mirror, a set of constellation cards published in London c.1825. Above it are shown the now-abandoned constellations of Tarandus and Custos Messium. Credit: Sidney Hall/Library of Congress — *Camelopardalis as depicted in Urania’s Mirror, a set of constellation cards published in London c.1825. Credit: Sidney Hall/Library of Congress*

The true nature of the “giraffe,” unfortunately, remains unclear. However, the name could be a reference to the book of Genesis in the Bible. a theory that is based on the fact that when Jacob Bartsch included Camelopardalis on his star map of 1624, he described the constellation as a camel on which Rebecca rode into Canaan. But since Camelopardalis represents a giraffe, not a camel, this explanation is not considered likely.

Notable Features:

Beta Camelopardalis is the brightest star in this constellation. It is a binary star with a yellow G-type supergiant as the primary and is located approximately 1,000 light years from Earth. Beta Cam is also an X-ray source, which suggests that it undergoes some kind of solar-like magnetic behavior (which accounts for its periodic flashes).

Camelopardalis’ second brightest star is CS Camelopardalis, another binary located approximately 3,000 light years away. It consists of a blue-white B-type supergiant that exhibits non-radial pulsations (which means that some portions of the star’s surface expand while others contract). It has a magnitude 8.7 companion located 2.9 arcseconds away, and the entire system is located in the reflection nebula vdB 14.

Then there’s Sigma 1694 Camelopardalis (aka. Struve 1694), which represents the “head’ of the giraffe. This binary star is composed of a white A-type subgiant located 300 light years from Earth, and a spectroscopic binary that consists of two A-type main sequence stars. Then there’s VZ Camelopardalis, a semi-regular variable M-type red giant located approximately 470 light years from Earth.

*The asterism Kemble’s Cascade, located in the Camelopardalis constellation. Credit & Copyright: Noel Carboni/Greg Parker/New Forest Observatory/NASA*

Camelopardalis is home to the asterism known as Kemble’s Cascade. Named after Father Lucian J. Kemble, a Franciscan Friar who discovered it, this asterism is formed by more than 20 stars that vary between magnitude 5 and 10 and form a straight line in the sky. After describing it to Walter Scott Houston (of Sky and Telescope magazine), Houston named it after Father Kemble and included it in his “Deep Sky Wonders” column in 1980.

Since Camelopardalis faces away from the galactic plane, a number of Deep Sky Objects are visible within its borders. These include NGC 2403, an intermediate spiral galaxy located approximately 12 million light years away. It was first discovered in the 18th century by William Herschel while he was working in England.

Then there’s NGC 1569, an irregular dwarf galaxy that is approximately 11 million light years away. This galaxy is known for the super star clusters it contains, both of which experience a considerable amount of star-forming activity. Then there’s NGC 1502, an open star cluster that is associated with Kemble’s Cascade and is located around 3,000 light years from Earth. NGC 1501, a planetary nebula, is located 1.4 degrees south of NGC 1502.

Camelopardalis is also home to IC 342, another intermediate spiral galaxy that is approximately 10.7 million light years away. It is one of the two brightest galaxies in the IC 342/Maffei Group (the nearest group of galaxies to the Local Group) and was discovered in 1895 by the British astronomer William Frederick Denning.

*The spiral galaxy IC 342, located in the Camelopardalis constellation. Credit & Copyright: Stephen Leshin/NASA*

History of Observation:

Camelopardalis was first recorded by Jakob Bartsch in 1624 but was most likely created by Petrus Plancius in 1613. Camelopardalis is the eighteenth largest constellation in the night sky, and its brightest stars are of the fourth magnitude. It was German astronomer Johannes Hevelius who gave it the official name of “Camelopardus” (alternately “Camelopardalis”) because he saw the constellation’s many faint stars as the spots of a giraffe.

Some of the stars in this constellation were used by William Croswell to form the constellation Sciurus Volans in 1810. However, this did not catch on with later cartographers. Today, Camelopardalis is one of the 88 constellations used by the IAU.

Finding Camelopardalis:

Located Camelopardalis is not too difficult a task, given its proximity to several major constellations. However, it is quite faint compared to its immediate neighbors, so good viewing conditions (low light pollution) are a plus. One of the easiest ways is to locate the Big Dipper (Ursa Major) in the night sky, then tracing from the tip of the “spoon” directly outwards towards the head of the bear.

Next, locate Cassiopeia on the other side of the night sky – easily identified by its characteristic W shape. Camelopardalis is directly between them and is identifiable by the three stars (alpha, beta, gamma) that form the “neck” of the giraffe. For those who know its coordinates, it is located in the second quadrant of the northern hemisphere (NQ2) and can be seen at latitudes between +90° and -10°.

With 36 stars that have Bayer/Flamsteed designations, Camelopardalis provides many opportunities for star gazing. Using binoculars, Alpha Cam can be spotted. This rare, blue-white class O super giant may very well be a runaway star that originated from the associated cluster NGC 1502. It appears faint because it is dimmed by nearly a full magnitude by intervening interstellar dust, and its true luminosity might be as much as 530,000 times that of our Sun.

Now take a look at slightly brighter Beta. At 40 million years old and about 1000 light years from our solar system, Beta has a mass of about 7 times greater than our Sun. But lying just over an arc minute away is a companion star which is in itself a double star that takes at least a million years to orbit the super giant parent star! According to Jim Kaler, Beta Cam is also a double mystery, one which is most likely making the transition from a hydrogen-fusing dwarf (of hot class B) to a larger helium-fusing red giant.

Whatever its status, it falls into a zone of temperature and luminosity in which stars become unstable and pulsate as Cepheid variable stars. Beta Cam, however, does not vary, though some multiple pulsations are present with periods of tens of days. During aircraft observations of meteors in 1967, Beta Cam was seen suddenly to flash, brightening by about a full magnitude over the course of a quarter of a second. So keep your eye on it… If you can find it!

For larger binoculars and small telescopes, check out NGC 1502. This small open cluster of approximately 45 stars is made even better by its proximity to an asterism known as “Kemble’s Cascade”. To find it, simply look around Polaris in a counterclockwise rotation moving outward by a field twice. It is two full binocular fields from Alpha and Beta. The cluster itself is very attractive, but look closely in the telescope, and you will see it also contains two double stars – Struve 484 and Struve 485!

Larger binoculars and small telescopes will also have no problem picking up NGC 2403 from a dark sky location. NGC 2403 is a spiral galaxy discovered by William Herschel that belongs to the M81 galaxy group. At around 8 million light-years from Earth, larger telescopes will notice the northern spiral arm connects to NGC 2404 in a satellite galaxy interaction. Allan Sandage detected Cepheid variables in NGC 2403 using the Hale telescope, making it the first galaxy beyond our local group to have Cepheids found in it. As of late 2004, there had been two reported supernovae in the galaxy.

For larger telescopes and an observing challenge, try planetary nebula NGC 1501. Discovered in 1787 by Sir William Herschel and located about 4,890 light years away, this irregular disc has a great 14th magnitude central star hidden inside the dimpled structure, which gives rise to its popular moniker – the “Oyster Nebula.” Find the pearl!

For a dim fuzzy, hunt down NGC 2715. At magnitude 13.6, this small barred spiral galaxy may have recently experienced a galaxy merger, and as many as three supernovae events have been detected recently. For a true test of your observing skills and equipment, try IC 342. IC 342 is a nearby giant spiral that has a significant dust light extinction. It averages about magnitude 9, and it’s quite large (20′).

Once you’ve found it, see if you can spot its very stellar nucleus. While the exact size and mass of this galaxy are still the subject of controversy, there are strong indications that in many respects, IC 342 resembles a giant spiral (similar to our own Galaxy) and competes with two other near giant spirals – the Milky Way and Andromeda (M 31) – for the gravitational influence in the Local Volume.

There is one meteor shower associated with the constellation of Camelopardalis – the March Camelopardalids. They occur on or about March 22nd with no definite peak, and the fall rate averages only about one per hour. They are the slowest known meteors at 7 kps.

We have written many interesting articles about the constellation here at Universe Today. Here is What Are The Constellations?, What Is The Zodiac?, and Zodiac Signs And Their Dates.

Be sure to check out The Messier Catalog while you’re at it!

For more information, check out the IAUs list of Constellations.

Sources:

August 4, 2016September 26, 2016 by Matt Williams

New Poll Shows 2-1 Margin Of Support From Hawaiians For Thirty Meter Telescope

Artist's impression of the top view of the proposed Thirty Meter Telescope complex. Credit: tmt.org

Ever since it was approved for construction, the Thirty Meter Telescope has been the subject of controversy. A proposed astronomical observatory that is planned to be built on Mauna Kea – Hawaii’s famous dormant volcano and the home of the Mauna Kea Observatories – the construction of this facility has been delayed multiple times due to resistance from the local community.

Stressing the impact the facility will have on local wild life, the associated noise and traffic, and the fact that the proposed site is on land sacred to Hawaii’s indigenous people, there are many locals who have protested the facility’s construction. But after multiple delays, and the cancellation of the facility’s building permits, it appears that public support may be firmly behind the creation of the TMT.

Planning for the Thirty Meter Telescope began in 2000, when astronomers began considering the construction of telescopes that measured more than 20 meters in diameter. In time, the University of California and Caltech began conducting a series of studies, which would eventually culminate in the plans for the TMT. Site proposals also began to be considered by the TMT board, which led to the selection of Mauna Kea in 2009.

*Mauna Kea summit as seen from the northeast. Credit: University of Hawaii.*

However, after opposition and protests halted construction on three occasions – on Oct. 14th, 2014, then again on April 2th and June 24th of 2015 – the State Supreme Court of Hawaii invalidated the TMT’s building permits. Since that time, multiple polls have been conducted to gauge public support for the project. Whereas a previous one, which was conducting in Oct. 2015, indicated that 59% of Big Island residents supported it (and 39% opposed it) the most recent poll yielded different results.

This poll, which was conducted in July of 2016 by Honolulu-based Ward Research, Inc. shows that 60% of Big Island residents now support moving ahead with construction, while 31% remain opposed. While not a huge change, it does indicate that support for the project now outweighs opposition by a 2 to 1 margin since the last time residents were asked, roughly nine months ago.

The first poll surveyed 613 Hawaii Big Island residents, aged 18 years and older and from a variety of backgrounds. The most recent poll surveyed 404 Hawaii residents at least 18 years old via both cellphone and landline (with a margin of error of plus or minus 4.9 percent).

The recent poll also indicated that the majority of respondents, ranging from 66% to 76%, believe that TMT will provide economic and educational opportunities, and that not moving forward would be bad for the island and its residents. Also of interest was the fact that support for TMT’s construction was split among Indigenous Hawaiians, with 46 percent of those polled in support and 45 percent opposed.

*Artists concept of the Thirty Meter Telescope Observatory. Credit: TMT*

As Ed Stone, the TMT Executive Director, said of the results in a recent press release:

“It was important for us to understand how Hawaii Island residents feel about the project, and the latest poll results demonstrate that opposition to TMT on Hawaii Island is decreasing. That’s significant and we are most grateful that the community’s support of the project remains high. The findings also show that the general public on Hawaii Island understands the benefits TMT will bring in terms of Hawaii’s economy and education, both of which are very important to TMT.”

What is perhaps most relevant is the fact that while this most-recent poll shows virtually no change in the amount of support, it does show that opposition has decreased. The reason for this is not clear, but according to Kealoha Pisciotta of the Mauna Kea Hui – which is litigating against TMT’s construction – the change is attributable to the PR efforts of TMT, which hired Honolulu-based PR firm to promote their agenda.

Pisciotta also stressed that the state Constitution of Hawaii protects the cultural and traditional practices that will be affected by this massive project, which is something residents don’t appear to understand. Faced with the promise of benefits – which includes TMT’s annual $1 million contribution to The Hawaii Island New Knowledge (THINK) Fund, which provides for STEM education.

This is not to say that those polled rejected the concerns of those advocating for protection of Hawaiian heritage and culture. In fact, 89% of respondents – the largest return in the poll – indicated that “there should be a way for science and Hawaiian culture to co-exist”. While this is easier said than done, it does show that compromise is the most popular option, and could present a mutually-satisfactory way of moving forward.

What’s more, this is hardly the first time that Mauna Kea has been at the center of controversy. Ever since construction began on the Astronomy Precinct in 1967, there has been opposition from environmentalists and the Indigenous community. Not only is the Precinct located on land protected by the Historical Preservation Act of 1966 due to its significance to Hawaiian culture, it is also the habitat of an endangered species of bird (the Palila).

Nevertheless, Mauna Kea remains the preferred choice for the location of the TMT, though the board is evaluating alternative sites in case the project cannot move forward. Stone and his colleagues hope to resume construction of the TMT facility by April of 2018, and begin gathering images of the cosmos in the near-ultraviolet to mid-infrared by the 2020s.

Further Reading: tmt.org

August 4, 2016September 26, 2016 by Matt Williams

Focusing On ‘Second-Earth’ Candidates In The Kepler Catalog

Artist’s impression of how an an Earth-like exoplanet might look. Credit: ESO.

The ongoing hunt for exoplanets has yielded some very interesting returns in recent years. All told, the Kepler mission has discovered more than 4000 candidates since it began its mission in March of 2009. Amidst the many “Super-Jupiters” and assorted gas giants (which account for the majority of Kepler’s discoveries) astronomers have been particularly interested in those exoplanets which resemble Earth.

And now, an international team of scientists has finished perusing the Kepler catalog in an effort to determine just how many of these planets are in fact “Earth-like”. Their study, titled “A Catalog of Kepler Habitable Zone Exoplanet Candidates” (which will be published soon in the Astrophysical Journal), explains how the team discovered 216 planets that are both terrestrial and located within their parent star’s “habitable zone” (HZ).

The international team was made up of researchers from NASA, San Francisco State University, Arizona State University, Caltech, University of Hawaii-Manoa, the University of Bordeaux, Cornell University and the Harvard-Smithsonian Center for Astrophysics. Having spent the past three years looking over the more than 4000 entries, they have determined that 20 of the candidates are most like Earth (i.e. likely habitable).

This figure shows the habitable zone for stars of different temperatures, as well as the location of terrestrial size planetary candidates and confirmed Kepler planets described in new research from SF State astronomer Stephen Kane. Some of the Solar System terrestrial planets are also shown for comparison. Credit: Chester Harman Read more at: http://phys.org/news/2016-08-team-second-earth-candidates.html#jCp — *Figure showing the habitable zone for different types of stars, as well as the location of terrestrial size Kepler candidates. Credit: Chester Harman*

As Stephen Kane, an associate professor of physics and astronomy at San Fransisco University and lead author of the study, explained in a recent statement:

“This is the complete catalog of all of the Kepler discoveries that are in the habitable zone of their host stars. That means we can focus in on the planets in this paper and perform follow-up studies to learn more about them, including if they are indeed habitable.”

In addition to isolating 216 terrestrial planets from the Kepler catalog, they also devised a system of four categories to determine which of these were most like Earth. These included “Recent Venus”, where conditions are like that of Venus (i.e. extremely hot); “Runaway Greenhouse”, where planets are undergoing serious heating; “Maximum Greenhouse”, where planets are within their star’s HZ; and “Recent Mars”, where conditions approximate those of Mars.

From this, they determined that of the Kepler candidates, 20 had radii less than twice that of Earth (i.e. on the smaller end of the Super-Earth category) and existed within their star’s HZ. In other words, of all the planets discovered in our local Universe, they were able to isolate those where liquid water can exist on the surface, and the gravity would likely be comparable to Earth’s and not crushing!

*Earlier today, NASA announced that Kepler had confirmed the existence of 1,284 new exoplanets, the most announced at any given time. Credit: NASA*

This is certainly exciting news, since one of the most important aspects of exoplanet hunting has been finding worlds that could support life. Naturally, it might sound a bit anthropocentric or naive to assume that planets which have similar conditions to our own would be the most likely places for it to emerge. But this is what is known as the “low-hanging fruit” approach, where scientists seek out conditions which they know can lead to life.

“There are a lot of planetary candidates out there, and there is a limited amount of telescope time in which we can study them,” said Kane. “This study is a really big milestone toward answering the key questions of how common is life in the universe and how common are planets like the Earth.”

Professor Kane is renowned for being one of the world’s leading “planet-hunters”. In addition to discovering several hundred exoplanets (using data obtained by the Kepler mission) he is also a contributor to two upcoming satellite missions – the NASA Transiting Exoplanet Survey Satellite (TESS) and the European Space Agency’s Characterizing ExOPLanet Satellite (CHEOPS).

These next-generation exoplanet hunters will pick up where Kepler left off, and are likely to benefit greatly from this recent study.

Further Reading: arXiv

August 3, 2016April 4, 2023 by Matt Williams

How Do We Settle on Mercury?

Planet Mercury as seen from the MESSENGER spacecraft in 2008. Credit: NASA/JPL

Welcome back to the first in our series on Settling the Solar System! First up, we take a look at that hot, hellish place located closest to the Sun – the planet Mercury!

Humanity has long dreamed of establishing itself on other worlds, even before we started going into space. We’ve talked about colonizing the Moon, Mars, and even establishing ourselves on exoplanets in distant star systems. But what about the other planets in our own backyard? When it comes to the Solar System, there is a lot of potential real estate out there that we don’t really consider.

Well, consider Mercury. While most people wouldn’t suspect it, the closest planet to our Sun is actually a potential candidate for settlement. Whereas it experiences extremes in temperature – gravitating between heat that could instantly cook a human being to cold that could flash-freeze flesh in seconds – it actually has potential as a starter colony.

Examples in Fiction:

The idea of colonizing Mercury has been explored by science fiction writers for almost a century. However, it has only been since the mid-20th century that colonization has been dealt with in a scientific fashion. Some of the earliest known examples of this include the short stories of Leigh Brackett and Isaac Asimov during the 1940s and 50s.

In the former’s work, Mercury is a tidally-locked planet (which was what astronomers believed at the time) that has a “Twilight Belt” characterized by extremes in heat, cold, and solar storms. Some of Asimov’s early work included short stories where a similarly tidally-locked Mercury was the setting, or characters came from a colony located on the planet.

Mercury, as imaged by the MESSENGER spacecraft, revealing parts of the never seen by human eyes. Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington — *Mercury, as imaged by the MESSENGER spacecraft, revealing parts of the never seen by human eyes. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington*

These included “Runaround” (written in 1942, and later included in I, Robot), which centers on a robot that is specifically designed to cope with the intense radiation of Mercury. In Asimov’s murder-mystery story “The Dying Night” (1956) – in which the three suspects hail from Mercury, the Moon, and Ceres – the conditions of each location are key to finding out who the murderer is.

In 1946, Ray Bradbury published “Frost and Fire”, a short story that takes place on a planet described as being next to the sun. The conditions on this world allude to Mercury, where the days are extremely hot, the nights extremely cold, and humans live for only eight days. Arthur C. Clarke’s Islands in the Sky (1952) contains a description of a creature that lives on what was believed at the time to be Mercury’s permanently dark side and occasionally visits the twilight region.

In his later novel, Rendezvous with Rama (1973), Clarke describes a colonized Solar System which includes the Hermians, a toughened branch of humanity that lives on Mercury and thrives off the export of metals and energy. The same setting and planetary identities are used in his 1976 novel Imperial Earth.

In Kurt Vonnegut’s novel The Sirens of Titan (1959), a section of the story is set in caves located on the dark side of the planet. Larry Niven’s short story “The Coldest Place” (1964) teases the reader by presenting a world that is said to be the coldest location in the Solar System, only to reveal that it is the dark side of Mercury (and not Pluto, as is generally assumed).

"Lava Falls on Mercury", cover art by Ken Fagg for If magazine, June 1954 — *“Lava Falls on Mercury” (by Ken Fagg) for If magazine, June 1954. Credit: Public Domain*

Mercury also serves as a location in many of Kim Stanley Robinson’s novels and short stories. These include The Memory of Whiteness (1985), Blue Mars (1996), and 2312 (2012), in which Mercury is the home to a vast city called Terminator. To avoid the harmful radiation and heat, the city rolls around the planet’s equator on tracks, keeping pace with the planet’s rotation so that it stays ahead of the Sun.

In 2005, Ben Bova published Mercury (part of his Grand Tour series) that deals with the exploration of Mercury and colonizing it for the sake of harnessing solar energy. Charles Stross’ 2008 novel Saturn’s Children involves a similar concept to Robinson’s 2312, where a city called Terminator traverses the surface on rails, keeping pace with the planet’s rotation.

Proposed Methods:

A number of possibilities exist for a colony on Mercury, owing to the nature of its rotation, orbit, composition, and geological history. For example, Mercury’s slow rotational period means that one side of the planet is facing towards the Sun for extended periods of time – reaching temperatures highs of up to 427 °C (800 °F) – while the side facing away experiences extreme cold (-193 °C; -315 °F).

In addition, the planet’s rapid orbital period of 88 days, combined with its sidereal rotation period of 58.6 days, means that it takes roughly 176 Earth days for the Sun to return to the same place in the sky (i.e. a solar day). Essentially, this means that a single day on Mercury lasts as long as two of its years. So if a city were placed on the night-side, and had tracks wheels so it could keep moving to stay ahead of the Sun, people could live without fear of burning up.

Images of Mercury's northern polar region, provided by MESSENGER. Credit: NASA/JPL — *Images of Mercury’s northern polar region, provided by MESSENGER. Credit: NASA/JPL*

In addition, Mercury’s very low axial tilt (0.034°) means that its polar regions are permanently shaded and cold enough to contain water ice. In the northern region, a number of craters were observed by NASA’s MESSENGER probe in 2012 which confirmed the existence of water ice and organic molecules. Scientists believe that Mercury’s southern pole may also have ice, and claim that an estimated 100 billion to 1 trillion tons of water ice could exist at both poles, which could be up to 20 meters thick in places.

In these regions, a colony could be built using a process called “paraterraforming” – a concept invented by British mathematician Richard Taylor in 1992. In a paper titled “Paraterraforming – The Worldhouse Concept”, Taylor described how a pressurized enclosure could be placed over the usable area of a planet to create a self-contained atmosphere. Over time, the ecology inside this dome could be altered to meet human needs.

In the case of Mercury, this would include pumping in a breathable atmosphere, and then melting the ice to create water vapor and natural irrigation. Eventually, the region inside the dome would become a livable habitat, complete with its own water cycle and carbon cycle. Alternately, the water could be evaporated, and oxygen gas created by subjecting it to solar radiation (a process known as photolysis).

Another possibility would be to build underground. For years, NASA has been toying with the idea of building colonies in stable, underground lava tubes that are known to exist on the Moon. And geological data obtained by the MESSENGER probe during flybys it conducted between 2008 and 2012 led to speculation that stable lava tubes might exist on Mercury as well.

*A previous MESSENGER image of hollows inside Tyagaraja crater. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington*

This includes information obtained during the probe’s 2009 flyby of Mercury, which revealed that the planet was a lot more geologically active in the past than previously thought. In addition, MESSENGER began spotting strange Swiss cheese-like features on the surface in 2011. These holes, which are known as “hollows”, could be an indication that underground tubes exist on Mercury as well.

Colonies built inside stable lava tubes would be naturally shielded to cosmic and solar radiation, extremes in temperature, and could be pressurized to create breathable atmospheres. In addition, at this depth, Mercury experiences far less in the way of temperature variations and would be warm enough to be habitable.

Potential Benefits:

At a glance, Mercury looks similar to the Earth’s Moon, so settling it would rely on many of the same strategies for establishing a moon base. It also has abundant minerals to offer, which could help move humanity towards a post-scarcity economy. Like Earth, it is a terrestrial planet, which means it is made up of silicate rocks and metals that are differentiated between an iron core and silicate crust and mantle.

However, Mercury is composed of 70% metals whereas’ Earth’s composition is 40% metal. What’s more, Mercury has a particular large core of iron and nickel, and which accounts for 42% of its volume. By comparison, Earth’s core accounts for only 17% of its volume. As a result, if Mercury were to be mined, enough minerals could be produced to last humanity indefinitely.

The different colors in this MESSENGER image of Mercury indicate the chemical, mineralogical, and physical differences between the rocks that make up the planet’s surface. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington. — The different colors in this MESSENGER image of Mercury indicate the planet’s chemical, mineralogical, and physical differences. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.

Its proximity to the Sun also means that it could harness a tremendous amount of energy. This could be gathered by orbital solar arrays, which would be able to harness energy constantly and beam it to the surface. This energy could then be beamed to other planets in the Solar System using a series of transfer stations positioned at Lagrange Points.

Also, there’s the matter of Mercury’s gravity, which is 38% percent of Earth’s gravity. This is over twice what the Moon experiences, which means colonists would have an easier time adjusting to it. At the same time, it is also low enough to present benefits as far as exporting minerals is concerned, since ships departing from the surface would need less energy to achieve escape velocity.

Lastly, there is the distance to Mercury itself. At an average distance of about 93 million km (58 million mi), Mercury ranges between being 77.3 million km (48 million mi) to 222 million km (138 million mi) away from the Earth. This puts it a lot closer than other possible resource-rich areas like the Asteroid Belt (329 – 478 million km distant), Jupiter and its system of moons (628.7 – 928 million km), or Saturn’s (1.2 – 1.67 billion km).

Also, Mercury achieves inferior conjunction – the point where it is at its closest point to Earth – every 116 days, which is significantly shorter than either Venus’ or Mars’. Basically, missions destined for Mercury could launch almost every four months, whereas launch windows to Venus and Mars would have to take place every 1.6 years and 26 months, respectively.

The MESSENGER spacecraft has been in orbit around Mercury since March 2011 – but its days are numbered. Image credit: NASA/JHUAPL/Carnegie Institution of Washington — *The MESSENGER spacecraft has been in orbit around Mercury since March 2011 – but its days are numbered. Credit: NASA/JHUAPL/Carnegie Institution of Washington*

In terms of travel time, several missions have been mounted to Mercury that can give us a ballpark estimate of how long it might take. For instance, the first spacecraft to travel to Mercury, NASA’s Mariner 10 spacecraft (which launched in 1973), took about 147 days to get there.

More recently, NASA’s MESSENGER spacecraft launched on August 3^rd, 2004 to study Mercury in orbit, and made its first flyby on January 14th, 2008. That’s a total of 1,260 days to get from Earth to Mercury. The extended travel time was due to engineers seeking to place the probe in orbit around the planet, so it needed to proceed at a slower velocity.

Challenges:

Of course, a colony on Mercury would still be a huge challenge, both economically and technologically. The cost of establishing a colony anywhere on the planet would be tremendous and would require abundant materials to be shipped from Earth, or mined on site. Either way, such an operation would require a large fleet of spaceships capable of making the journey in a respectable amount of time.

Such a fleet does not yet exist, and the cost of developing it (and the associated infrastructure for getting all the necessary resources and supplies to Mercury) would be tremendous. Relying on robots and in-situ resource utilization (ISRU) would certainly cut costs and reduce the amount of materials that would need to be shipped. But these robots and their operations would need to be shielded from radiation and solar flares until they got the job done.

Enhanced-color image of Munch, Sander and Poe craters amid volcanic plains (orange) near Caloris Basin NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington — Enhanced-color image of Munch, Sander, and Poe craters amid volcanic plains (orange) near Caloris Basin. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Basically, the situation is like trying to establish a shelter in the middle of a thunderstorm. Once it is complete, you can take shelter. But in the meantime, you’re likely to get wet and dirty! And even once the colony was complete, the colonists themselves would have to deal with the ever-present hazards of radiation exposure, decompression, and extremes in heat and cold.

As such, if a colony was established on Mercury, it would be heavily dependent on its technology (which would have to be rather advanced). Also, until such time as the colony became self-sufficient, those living there would be dependent on supply shipments that would have to come regularly from Earth (again, shipping costs!)

Still, once the necessary technology was developed, and we could figure out a cost-effective way to create one or more settlements and ship to Mercury, we could look forward to having a colony that could provide us with limitless energy and minerals. And we would have a group of human neighbors known as Hermians!

As with everything else pertaining to colonization and terraforming, once we’ve established that it is in fact possible, the only remaining question is “how much are we willing to spend?”

We have written many interesting articles on colonization here at Universe Today. Here’s Why Colonize the Moon First?, Colonizing Venus with Floating Cities, Will We Ever Colonize Mars?, and The Definitive Guide to Terraforming.

Astronomy Cast also has some interesting episodes on the subject. Check out Episode 95: Humans to Mars, Part 2 – Colonists, Episode 115: The Moon, Part 3 – Return to the Moon, Episode 381: Hollowing Asteroids in Science Fiction.

Sources:

August 3, 2016September 26, 2016 by Matt Williams

The Closest Supernova Since 1604 Is Hissing At Us

Artist’s impression of the supernova flare seen in the Large Magellanic Cloud on February 23rd, 1987. Credit: CAASTRO / Mats Björklund (Magipics).

Thirty years ago, a star that went by the designation of SN 1987A collapsed spectacularly, creating a supernova that was visible from Earth. This was the largest supernova to be visible to the naked eye since Kepler’s Supernova in 1604. Today, this supernova remnant (which is located approximately 168,000 light-years away) is being used by astronomers in the Australian Outback to help refine our understanding of stellar explosions.

Led by a student from the University of Sydney, this international research team is observing the remnant at the lowest-ever radio frequencies. Previously, astronomers knew much about the star’s immediate past by studying the effect the star’s collapse had on the neighboring Large Magellanic Cloud. But by detecting the star’s faintest hisses of radio static, the team was able to observe a great deal more of its history.

The team’s findings, which were published yesterday in the journal Monthly Notices of the Royal Astronomical Society, detail how the astronomers were able to look millions of years farther back in time. Prior to this, astronomers could only observe a tiny fraction of the star’s life cycle before it exploded – 20,000 years (or 0.1%) of its multi-million year life span.

*Artist’s impression of the star in its multi-million year long and previously unobservable phase as a large, red supergiant. Credit: CAASTRO / Mats Björklund (Magipics)*

As such, they were only able to see the star when it was in its final, blue supergiant phase. But with the help of the Murchison Widefield Array (MWA) – a low-frequency radio telescope located at the Murchison Radio-astronomy Observatory (MRO) in the West Australian desert – the radio astronomers were able to see all the way back to when the star was still in its long-lasting red supergiant phase.

In so doing, they were able to observe some interesting things about how this star behaved leading up to the final phase in its life. For instance, they found that SN 1987A lost its matter at a slower rate during its red supergiant phase than was previously assumed. They also observed that it generated slower than expected winds during this period, which pushed into its surrounding environment.

Joseph Callingham, a PhD candidate with the University of Sydney and the ARC Center of Excellence for All-Sky Astrophysics (CAASTRO), is the leader of this research effort. As he stated in a recent RAS press release:

“Just like excavating and studying ancient ruins that teach us about the life of a past civilization, my colleagues and I have used low-frequency radio observations as a window into the star’s life. Our new data improves our knowledge of the composition of space in the region of SN 1987A; we can now go back to our simulations and tweak them, to better reconstruct the physics of supernova explosions.”

*Aerial photograph of the core region of the MWA telescope. Credit: mwatelescope.org*

The key to finding this new information was the quiet and (some would say) temperamental conditions that the MWA requires to do its thing. Like all radio telescopes, the MWA is located in a remote area to avoid interference from local radio sources, not to mention a dry and elevated area to avoid interference from atmospheric water vapor.

As Professor Gaensler – the former CAASTRO Director and the supervisor of the project – explained, such methods allow for impressive new views of the Universe. “Nobody knew what was happening at low radio frequencies,” he said, “because the signals from our own earthbound FM radio drown out the faint signals from space. Now, by studying the strength of the radio signal, astronomers for the first time can calculate how dense the surrounding gas is, and thus understand the environment of the star before it died.”

These findings will likely help astronomers to understand the life cycle of stars better, which will come in handy when trying to determine what our Sun has in store for us down the road. Further applications will include the hunt for extra-terrestrial life, with astronomers being able to make more accurate estimates on how stellar evolution could effect the odds of life forming in different star systems.

In addition to being home to the MWA, the Murchison Radio-astronomy Observatory (MRO) is also the planned site of the future Square Kilometer Array (SKA). The MWA is one of three telescopes – along with the South African MeerKAT array and the Australian SKA Pathfinder (ASKAP) array – that are designated as a Precursor for the SKA.

Further Reading: Royal Astronomical Society

August 3, 2016April 14, 2020 by Matt Williams

Did We Arrive Early To The Universe’s Life Party?

Artist's impression of an exoplanet orbiting a low-mass star. Credit: ESO/L. Calçada

The Fermi Paradox essentially states that given the age of the Universe, and the sheer number of stars in it, there really ought to be evidence of intelligent life out there. This argument is based in part on the fact that there is a large gap between the age of the Universe (13.8 billion years) and the age of our Solar System (4.5 billion years ago). Surely, in that intervening 9.3 billion years, life has had plenty of time to evolve in other star system!

August 1, 2016August 1, 2016 by Tammy Plotner

Messier 21 (M21) – The NGC 6531 Open Star Cluster

The Messier 21 open star cluster and the Trifid Nebula. Credit: Wikisky

Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at the Messier 21 open star cluster. Enjoy!

Back in the 18th century, famed French astronomer Charles Messier noted the presence of several “nebulous objects” in the night sky. Having originally mistaken them for comets, he began compiling a list of these objects so that other astronomers wouldn’t make the same mistake. Consisting of 100 objects, the Messier Catalog has come to be viewed as a major milestone in the study of Deep Space Objects.

One of these objects is Messier 21 (aka. NGC 6531), an open star cluster located in the Sagittarius constellation. A relatively young cluster that is tightly packed, this object is not visible to the naked eye. Hence why it was not discovered until 1764 by Charles Messier himself. It is now one of the over 100 Deep Sky Objects listed in the Messier Catalog.

Description:

At a distance of 4,250 light years from Earth, this group of 57 various magnitude stars all started life together about 4.6 million years ago as part of the Sagittarius OB1 stellar association. What makes this fairly loose collection of stars rather prized is its youth as a cluster, and the variation of age in its stellar members. Main sequence stars are easy enough to distinguish in a group, but low mass stars are a different story when it comes to separating them from older cluster members.

Messier 21 (NGC 6531). Atlas Image mosaic obtained as part of the Two Micron All Sky Survey (2MASS), a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. — *Atlas mosaic image of Messier 21 (NGC 6531) obtained as part of the Two Micron All Sky Survey (2MASS). Credit: 2MASS/UofM/IPAC/Catech/NASA/NSF*

As Byeong Park of the Korean Astronomy Observatory said in a 2001 study of the object:

“In the case of a young open cluster, low-mass stars are still in the contraction phase and their positions in the photometric diagrams are usually crowded with foreground red stars and reddened background stars. The young open cluster NGC 6531 (M21) is located in the Galactic disk near the Sagittarius star forming region. The cluster is near to the nebula NGC 6514 (the Trifid nebula), but it is known that it is not associated with any nebulosity and the interstellar reddening is low and homogeneous. Although the cluster is relatively near, and has many early B-type stars, it has not been studied in detail.”

But study it in detail they did, finding 56 main sequence members, 7 pre-main sequence stars and 6 pre-main sequence candidates. But why did this cluster… you know, cluster in the way it did? As Didier Raboud, an astronomer from the Geneva Observatory, explained in his 1998 study “Mass segregation in very young open clusters“:

“The study of the very young open cluster NGC 6231 clearly shows the presence of a mass segregation for the most massive stars. These observations, combined with those concerning other young objects and very recent numerical simulations, strongly support the hypothesis of an initial origin for the mass segregation of the most massive stars. These results led to the conclusion that massive stars form near the center of clusters. They are strong constraints for scenarii of star and stellar cluster formation.” say Raboud, “In the context of massive star formation in the center of clusters, it is worth noting that we observe numerous examples of multiple systems of O-stars in the center of very young OCs. In the case of NGC 6231, 8 stars among the 10 brightest are spectroscopic binaries with periods shorter than 6 days.”

*Achernar, the flattest star known, is classified as be star. Credit: earthsky.org*

But are there any other surprises hidden inside? You bet! Try Be-stars, a class of rapidly rotating stars that end up becoming flattened at the poles. As Virginia McSwain of Yale University’s Department of Astronomy wrote in a 2005 study, “The Evolutionary Status of Be Stars: Results from a Photometric Study of Southern Open Clusters“:

“Be stars are a class of rapidly rotating B stars with circumstellar disks that cause Balmer and other line emission. There are three possible reasons for the rapid rotation of Be stars: they may have been born as rapid rotators, spun up by binary mass transfer, or spun up during the main-sequence (MS) evolution of B stars. To test the various formation scenarios, we have conducted a photometric survey of 55 open clusters in the southern sky. We use our results to examine the age and evolutionary dependence of the Be phenomenon. We find an overall increase in the fraction of Be stars with age until 100 Myr, and Be stars are most common among the brightest, most massive B-type stars above the zero-age main sequence (ZAMS). We show that a spin-up phase at the terminal-age main sequence (TAMS) cannot produce the observed distribution of Be stars, but up to 73% of the Be stars detected may have been spun-up by binary mass transfer. Most of the remaining Be stars were likely rapid rotators at birth. Previous studies have suggested that low metallicity and high cluster density may also favor Be star formation.”

History of Observation:

Charles Messier discovered this object on June 5th, 1764. As he wrote in his notes on the occassion:

“In the same night I have determined the position of two clusters of stars which are close to each other, a bit above the Ecliptic, between the bow of Sagittarius and the right foot of Ophiuchus: the known star closest to these two clusters is the 11th of the constellation Sagittarius, of seventh magnitude, after the catalog of Flamsteed: the stars of these clusters are, from the eighth to the ninth magnitude, environed with nebulosities. I have determined their positions. The right ascension of the first cluster, 267d 4′ 5″, its declination 22d 59′ 10″ south. The right ascension of the second, 267d 31′ 35″; its declination, 22d 31′ 25″ south.”

Messier 21. Credit: Wikisky — *Close up of the Messier 21 star cluster. Credit: Wikisky*

While Messier did separate the two star clusters, he assumed the nebulosity of M20 was also involved with M21. In this circumstance, we cannot fault him. After all, his job was to locate comets, and the purpose of his catalog was to identify those objects that were not. In later years, Messier 21 would be revisited again by Admiral Smyth, who would describe it as follows:

“A coarse cluster of telescopic stars, in a rich gathering galaxy region, near the upper part of the Archer’s bow; and about the middle is the conspicuous pair above registered, – A being 9, yellowish, and B 10, ash coloured. This was discovered by Messier in 1764, who seems to have included some bright outliers in his description, and what he mentions as nebulosity, must have been the grouping of the minute stars in view. Though this was in the power of the meridian instruments, its mean apparent place was obtained by differentiation from Mu Sagittarii, the bright star about 2 deg 1/4 to the north-east of it.”

Locating Messier 21:

Once you have become familiar with the Sagittarius region, finding Messier 21 is easy. It’s located just two and a half degrees northwest of Messier 8 – the “Lagoon Nebula” – and about a half a degree northeast of Messier 20 – the “Trifid Nebula“. If you are just beginning to astronomy, try starting at the teapot’s tip star (Lambda) “Al Nasl”, and starhopping in the finderscope northwest to the Lagoon.

Credit IAU/Sky & Telescope magazineRoger Sinnott & Rick Fienberg — *The location of M21 in the Sagittarius constellation. Credit: IAU/Sky & Telescope magazineRoger Sinnott & Rick Fienberg*

While the nebulosity might not show in your finder, optical double 7 Sagittari, will. From there you will spot a bright cluster of stars two degrees due north. These are the stars embedded withing the Trifid Nebula, and the small, compressed area of stars to its northeast is the open star cluster M21. It will show well in binoculars under most sky conditions as a small, fairly bright concentration and resolve well for all telescope sizes.

And here are the quick facts, for your convenience:

Object Name: Messier 21
Alternative Designations: M21, NGC 6531
Object Type: Open Star Cluster
Constellation: Sagittarius
Right Ascension: 18 : 04.6 (h:m)
Declination: -22 : 30 (deg:m)
Distance: 4.25 (kly)
Visual Brightness: 6.5 (mag)
Apparent Dimension: 13.0 (arc min)

Be to sure to check out our complete Messier Catalog. And for more information, check out the SEDS Messier Database.

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