Astronomy Archives

January 9, 2017January 16, 2017 by Tammy Plotner

Messier 31 – Observing Andromeda (M31)

Messier 31 (the Andromeda Galaxy), along with Messier 32 and Messier 110. Credit: Wikisky

Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at the Andromeda Galaxy, also known as Messier 31. Enjoy!

During 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 them so that others would not make the same mistake he did. In time, this list (known as the Messier Catalog) would come to include 100 of the most fabulous objects in the night sky.

One of these objects is the famed Andromeda Galaxy, the closest spiral galaxy to the Milky Way which is named for the area of the sky it appears in (in the vicinity of the Andromeda constellation). It is the largest galaxy in the Local Group, and has the distinction of being one of the few objects that is actually getting closer to the Milky Way (and is expected to merge with us in a few billion years!).

Description:

Approaching us at roughly 300 kilometers per second, our massive galactic neighbor has been the object of studies of spiral structure, globular and open clusters, interstellar matter, planetary nebulae, supernova remnants, galactic nucleus, companion galaxies, and more for as long as we’ve been peering its way with a telescope. It’s part of our Local Group of galaxies and its two easily visible companions are only part of the eleven others that swarm around it.

One day, this galaxy will collide with our own, much as it is now consuming its neighbor – M32. However, this won’t come to pass for several billions years, so don’t go worrying about the immense gravitational disturbances just yet! And not surprisingly, a giant galaxy like Andromeda doesn’t get to be so big by keeping to itself. How many times now has the Great Andromeda Galaxy consumed another? More than once!

In 1993, the Hubble Space Telescope revealed that M31 has a double nucleus – a ‘leftover’ from another meal! As NASA and the ESA stated about the discovery at the time:

“Each of the two light-peaks contains a few million densely packed stars. The brighter object is the “classic” nucleus as studied from the ground. However, HST reveals that the true center of the galaxy is really the dimmer component. One possible explanation is that the brighter cluster is the leftover remnant of a galaxy cannibalized by M31. Another idea is that the true center of the galaxy has been divided in two by deep dust absorption across the middle, creating the illusion of two peaks. This green-light image was taken with HST’s Wide Field and Planetary Camera (WF/PC), in high resolution mode, on July 6, 1991. The two peaks are separated by 5 light-years. The Hubble image is 40 light-years across.”

Perhaps one of the most fascinating discovery recent years in Messier 31 was made by the orbiting Chandra X-Ray Observatory. The X-ray image below, made with the Chandra X-Ray Astronomy Center’s Advanced CCD Imaging Spectrometer (ACIS), shows the central portion of the Andromeda Galaxy. The Chandra X-ray Observatory is part of NASA’s fleet of “Great Observatories” along with the Hubble Space Telescope.

*The Andromeda galaxy as seen in optical light, and Chandra’s X-ray vision of the changing supermassive black hole in Andromeda’s heart. Credit: X-Ray NASA/CXC/SAO/Li et al.), Optical (DSS)*

The blue dot in the center of the image is a “cool” million degree X-ray source where Andromeda’s massive central object, with the mass of 30 million suns, is located, which many astronomers consider to be a supermassive black hole. Most of these are probably due to X-ray binary systems, in which a neutron star (or perhaps a stellar black hole) is in a close orbit around a normal star.”

Over the years our studies have advanced even more with the discovery of an eclipsing binary star in Messier 31. As Ignasi Ribas (et al) put it in a 2005:

“We present the first detailed spectroscopic and photometric analysis of an eclipsing binary in the Andromeda Galaxy (M31). This is a 19.3 mag semidetached system with late O and early B spectral type components. From the light and radial velocity curves we have carried out an accurate determination of the masses and radii of the components. Their effective temperatures have been estimated by modeling the absorption-line spectra. The analysis yields an essentially complete picture of the properties of the system, and hence an accurate distance determination to M31.”

In 2005, we discovered more. At that time, Scott Chapman of Caltech, Rodrigo Ibata of the Observatoire de Strasbourg, and their colleagues conducted detailed studies on the motions and metals of nearly 10,000 stars in Andromeda, which that the galaxy’s stellar halo is “metal-poor.” Essentially, this indicated that the stars lying in the outer bounds of the galaxy are lacking in elements heavier than hydrogen.

*Image of the Andromeda Galaxy, showing Messier 32 to the lower left, which is currently merging with Andromeda. Credit: Wikipedia Commons/Torben Hansen*

According to Chapman, this was surprising since one of the key differences thought to exist between Andromeda and the Milky Way was that the former’s stellar halo was metal-rich and the latter’s was metal-poor. If both galaxies are metal-poor, then they must have had very similar evolutions. As Chapman explained:

“Probably, both galaxies got started within a half billion years of the Big Bang, and over the next three to four billion years, both were building up in the same way by protogalactic fragments containing smaller groups of stars falling into the two dark-matter haloes.”

While no one yet knows what dark matter is made of, its existence is well established because of the mass that must exist in galaxies for their stars to orbit the galactic centers. In fact, current theories of galactic evolution assume that dark-matter wells acted as a sort of “seed” for today’s galaxies, with the dark matter pulling in smaller groups of stars as they passed nearby.

What’s more, galaxies like Andromeda and the Milky Way have each probably gobbled up about 200 smaller galaxies and protogalactic fragments over the last 12 billion years. Chapman and his colleagues arrived at the conclusion about the metal-poor Andromeda halo by obtaining careful measurements of the speed at which individual stars are coming directly toward or moving directly away from Earth.

*The Andromeda Galaxy, viewed using conventional optics and IR. Credit: Kitt Peak National Observatory*

This measure is called the radial velocity, and can be determined very accurately with the spectrographs of major instruments such as the 10-meter Keck-II telescope, which was used in the study. Of the approximately 10,000 Andromeda stars for which the researchers have obtained radial velocities, about 1,000 turned out to be stars in the giant stellar halo that extends outward by more than 500,000 light-years.

These stars, because of their lack of metals, are thought to have formed quite early, at a time when the massive dark-matter halo had captured its first protogalactic fragments. The stars that dominate closer to the center of the galaxy, by contrast, are those that formed and merged later, and contain heavier elements due to stellar evolution processes.In addition to being metal-poor, the stars of the halo follow random orbits and are not in rotation.

By contrast, the stars of Andromeda’s visible disk are rotating at speeds upwards of 200 kilometers per second.According to Ibata, the study could lead to new insights on the nature of dark matter. “This is the first time we’ve been able to obtain a panoramic view of the motions of stars in the halo of a galaxy,” says Ibata. “These stars allow us to weigh the dark matter, and determine how it decreases with distance.”

History of Observation:

Andromeda was known as the “Little Cloud” to Persian astronomer Abd-al-Rahman Al-Sufi, who described and depicted it in 964 AD in his Book of Fixed Stars. This wonderful galaxy was also cataloged by Giovanni Batista Hodierna in 1654, Edmund Halley in 1716, by Bullialdus 1664, and again by Charles Messier in 1764.

*The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years away in the constellation Andromeda. Credit: Wikipedia Commons/Adam Evans*

Like most of the objects he added to the Messier Catalog, he mistook the galaxy initially for a nebulous object. As he wrote of the object in his notes:

“The sky has been very good in the night of August 3 to 4, 1764; and the constellation Andromeda was near the Meridian, I have examined with attention the beautiful nebula in the girdle of Andromeda, which was discovered in 1612 by Simon Marius, and which has been observed since with great care by different astronomers, and at last by M. le Gentil who has given a very ample and detailed description in the volume of the Memoirs of the Academy for 1759, page 453, with a drawing of its appearance. I will not report here what I have written in my Journal: I have employed different instruments for examining that nebula, and above all an excellent Gregorian telescope of 30 pouces focal length, the large mirror having 6 pouces in diameter, and magnifying 104 times these objects: the middle of that nebula appeared rather bright with this instrument, without any appearance of stars; the light went diminishing up to extinguishing; it resembles two cones or pyramids of light, opposed at their bases, of which the axis was in the direction form North-West to South-East; the two points of light or the two summits are about 40 minutes of arc apart; I say about, because of the difficulty to recognize these two extremities. The common base of the two pyramids is 15 minutes: these measures have been made with a Newtonian telescope of 4 feet and a half focal length, equipped with a micrometer of silk wires. With the same instrument I have compared the middle of the summits of the two cones of light with the star Gamma Andromedae of fourth magnitude which is very near to it, and little distant from its parallel. From these observations, I have concluded the right ascension of the middle of this nebula as 7d 26′ 32″, and its declination as 39d 9′ 32″ north. Since fifteen years during which I viewed and observed this nebula, I have not noticed any change in its appearances; having always perceived it in the same shape.”

A great many astronomers would observe the Andromeda Galaxy over the years, each colorfully describing it. However, as we know from history, it would be quite some time before its true nature as an external galaxy would be discovered. Here is where we must give the utmost respect to Sir William Herschel, who knew way ahead of everyone else, that there was something very, very different about Messier’s Object 31!

*Composite Infrared/visble light image of the Andromeda Galaxy, taken by NASA’s Wide-field Infrared Survey Explorer (WISE). Credit: NASA/JPL-Caltech/WISE Team*

Although he never publicly published his observing notes on another astronomer’s discoveries, it’s a shame he did not for this is what he had to say:

“.. But when an object is of such a construction, or at such a distance from us, that the highest power of penetration, which hitherto has been applied to it, leaves it undetermined whether it belongs to the class of nebulae or of stars, it may be called ambiguous. As there is, however, a considerable difference in the ambiguity of such objects, I have arranged 71 of them into the following four collections. The first contains seven objects that may be supposed to consist of stars, but where the observations hitherto made, of either their appearance or form, leave it undecided into which class they should be placed. Connoiss. 31 [M31] is: A large nucleus with very extensive nebulous branches, but the nucleus is very gradually joined to them. The stars which are scattered over it appear to be behind it, and seem to lose part of their lustre in the passage of their light through the nebulosity; there are not more of them scattered over the immediate neighborhood. I examined it in the meridian with a mirror of 24 inches in diameter, and saw it in high perfection; but its nature remains mysterious. Its light, instead of appearing resolvable with this aperture, seemed to be more milky. The objects in this collection must at present remain ambiguous.”

Locating Messier 31:

Even under moderately light polluted skies the Great Andromeda Galaxy, located in the Andromeda constellation, can be easily be found with the unaided eye – if you know where to look. Seasoned amateur astronomers can literally point to the sky and show you the location of M31, but perhaps you have never tried to find it. Believe it or not, this is an easy galaxy to spot even under the moonlight.

Simply identify the large diamond-shaped pattern of stars that is the Great Square of Pegasus. The northernmost star is Alpha, and it is here we will begin our hop. Stay with the northern chain of stars and look four finger widths away from Alpha for an easily seen star. The next along the chain is about three more finger widths away. Two more finger widths to the north and you will see a dimmer star that looks like it has something smudgy nearby.

*The location of Messier 31, in the Andromeda constellation (from which it takes its name). Credit: IAU/Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)*

Point your binoculars there, because that’s no cloud – it’s the Andromeda Galaxy! Now aim your binoculars or small telescope its way… Perhaps one of the most outstanding of all galaxies to the novice observer, M31 spans so much sky that it takes up several fields of view in a larger telescope, and even contains its own clusters and nebulae with New General Catalog designations.

If you have a slightly larger telescope, you may also be able to pick up M31’s two companions – M32 and M110. Even with no scope or binoculars, it’s pretty amazing that we can see something – anything! – that is over two million light-years away!

Enjoy this wonderful and mysterious galaxy at any and every opportunity! Even the most modest of optical aids will reveal it for what it is… Another island universe!

And here are ye’ ole’ quick facts. Enjoy!

Object Name: Messier 31
Alternative Designations: M31, NGC 224, Andromeda Galaxy
Object Type: Type Sb Galaxy
Constellation: Andromeda
Right Ascension: 00 : 42.7 (h:m)
Declination: +41 : 16 (deg:m)
Distance: 2900 (kly)
Visual Brightness: 3.4 (mag)
Apparent Dimension: 178×63 (arc min)

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:

January 9, 2017 by Matt Williams

Exploding Binary Stars Will Light Up the Sky in 2022

Artist’s impression of the VFTS 352 star system, the hottest and most massive double star system to date where the two components are in contact and sharing material. Credit: ESO/L. Calçada

Stellar collisions are an amazingly rare thing. According to our best estimates, such events only occur in our galaxy (within globular clusters) once every 10,000 years. It’s only been recently, thanks to ongoing improvements in instrumentation and technology, that astronomers have been able to observe such mergers taking place. As of yet, no one has ever witnessed this phenomena in action – but that may be about to change!

According to study from a team of researchers from Calvin College in Grand Rapids, Michigan, a binary star system that will likely merge and explode in 2022. This is an historic find, since it will allow astronomers to witness a stellar merger and explosion for the first time in history. What’s more, they claim, this explosion will be visible with the naked-eye to observers here on Earth.

The findings were presented last week at the 229th Meeting of the American Astronomical Society (AAS). In a presentation titled “A Precise Prediction of a Stellar Merger and Red Nova Outburst“, Professor Lawrence Molnar and his team shared findings that indicate how this binary pair will merge in about six years time. This event, they claim, will cause an outburst of light so bright that it will become the brightest object in the night sky.

*Professor Lawrence Molnar of the Calvin College’s Dept. of Physics and Astronomy. He predicts KIC 9832227 will collide and explode in 2022. Credit: calvin.edu*

This binary star system, which is known as KIC 9832227, is one that Prof. Molnar and his colleagues – which includes students from the Apache Point Observatory and the University of Wyoming – have been monitoring since 2013. His interest in the star was piqued during a conference in 2013 when Karen Kinemuchi (an astronomers with the Apache Point Observatory) presented findings about brightness changes in the star.

This led to questions about the nature of this star system – specifically, whether it was a pulsar or a binary pair. After conducting their own observations using the Calvin observatory, Prof. Molnar and his colleagues concluded that the star was a contact binary – a class of binary star where the two stars are close enough to share an atmosphere. This brought to mind similar research in the past about another binary star system known as V1309 Scorpii.

This binary pair also had a shared atmosphere; and over time, their orbital period kept decreasing until (in 2008) they unexpectedly collided and exploded. Believing that KIC 9832227 would undergo a similar fate, they began conducting tests to see if the star system was exhibiting the same behavior. The first step was to make spectroscopic observations to see if their observations could be explained by the presence of a companion star.

As Cara Alexander, a Calvin College student and one of the co-authors on the team’s research paper, explained in a college press release:

“We had to rule out the possibility of a third star. That would have been a pedestrian, boring explanation. I was processing data from two telescopes and obtained images that showed a signature of our star and no sign of a third star. Then we knew we were looking at the right thing. It took most of the summer to analyze the data, but it was so exciting. To be a part of this research, I don’t know any other place where I would get an opportunity like that; Calvin is an amazing place.”

*Diagram showing the summer constellations of Cygnus and Lyra and the position of KIC 9832227 (shown with a red circle). Credit: calvin.edu*

The next step was to measure the pair’s orbital period, to see it was in fact getting shorter over time – which would indicate that the stars were moving closer to each other. By 2015, Prof. Molnar and his team determined that the stars would eventually collide, resulting in a kind of stellar explosion known as a “Red Nova”. Initially, they estimated this would take place between 2018 and 2020, but have since placed the date at 2022.

In addition, they predict that the burst of light it will cause will be bright enough to be seen from Earth. The star will be visible as part of the constellation Cygnus, and it appear as an addition star in the familiar Northern Cross star pattern (see above). This is an historic case, since no astronomer has ever been able to accurately predict when and where a stellar collision would take place in the past.

What’s more, this discovery is immensely significant because it represents a break with the traditional discovery process. Not only have small research institutions and universities not been the ones to take the lead on these sorts of discoveries in the past, but student-and-teacher teams have also not been the ones who got to make them. As Molnar explained it:

“Most big scientific projects are done in enormous groups with thousands of people and billions of dollars. This project is just the opposite. It’s been done using a small telescope, with one professor and a few students looking for something that is not likely. Nobody has ever predicted a nova explosion before. Why pay someone to do something that almost certainly won’t succeed? It’s a high-risk proposal. But at Calvin it’s only my risk, and I can use my work on interesting, open-ended questions to bring extra excitement into my classroom. Some projects still have an advantage when you don’t have as much time or money.”

*The model Prof. Molnar and his team constructed of the double star system KIC 9832227, which is a contact binary (i.e. two stars that are touching). Credit: calvin.edu.*

Over the course of the next year, Molnar and his colleagues will be monitoring KIC 9832227 carefully, and in multiple wavelengths. This will be done with the help of the NROA’s Very Large Array (VLA), NASA’s Infrared Telescope Facility at Mauna Kea, and the ESA’s XMM-Newton spacecraft. These observatories will study the star’s radio, infrared and X-ray emissions, respectively.

Molnar also expects that amateur astronomers will be able to monitor the pair’s orbital timing and variations in brightness. And if he and his team’s predictions are correct, every student and stargazer in the northern hemisphere – not to mention people who just happen to be out for a walk – will be privy to the amazing light show. This is sure to be a once-in-a-lifetime event, so stay tuned for more information!

Interestingly enough, this historic discovery is also the subject of a documentary film. Titled “Luminous“, the documentary – which is directed by Sam Smartt, a Calvin professor of communication arts and sciences – chronicles the process that led Prof. Molnar and his team to make this unprecedented discovery. The documentary will also include footage of the Red Nova as it happens in 2022, and is expected to be released sometime in 2023.

Check out the trailer below:

Further Reading: Calvin College, Science Mag

January 6, 2017January 6, 2017 by Matt Williams

Hubble Spots Possible Exocomets in Nearby Star System

Artist's impression of comets plunging into the star HD 172555, which was observed using the Hubble Space Telescope. Credit: hubblesite.org

The Hubble Space Telescope is a workhorse which, despite its advanced years, keeps on producing valuable scientific data. In addition to determining the rate at which the Universe is expanding, spotting very distant galaxies, and probing the early history of the Universe, it has also observed some truly interesting things happening in nearby star systems.

For example, Hubble recently spotted some unusual activity in HD 172555, a star system located about 95 light-years from Earth. Here, Hubble obtained spectral information that indicated the presence of comets that appeared to be falling into the star. This could prove useful to scientists who are looking to understand how comets behaved during the early history of the Solar System.

These findings were presented at the 229th Meeting of the American Astronomical Society (AAS), which has been taking place this past week in Grapevine, Texas. During the course of the presentation, Dr. Carol Grady of Eureka Scientific Inc. and NASA’s Goddard Space Flight Center, shared Hubble data that hinted at the presence of infalling comets, a finding which could bolster theories about what is known as “gravitational stirring”.

*Artist’s concept of a collision that is believed to have taken place in the HD 172555 star system between a moon-sized object and a Mercury-sized planet. Credit: NASA/JPL-Caltech*

Basically, this theory states that the presence of a Jupiter-size planet in a star system will lead to comets being deflected by its massive gravity, thus sending them into the star. This phenomena is associated with younger stars, and is believed to have taken place in our own Solar System billions of years ago – which also led to number of comets being diverted towards Earth.

The detection of infalling comets in this system (and the way it bolsters the theory of gravitational stirring) is of imminence significant, since it is believed that it was this very mechanism that transported water to Earth when it was quite young. By observing how comets behave around young stars like HD 172555, which is estimated to be around 40 million years old, astronomers are able to see just how this mechanism could work.

As Carol Grady explained in a Hubble press release:

“Seeing these sun-grazing comets in our solar system and in three extrasolar systems means that this activity may be common in young star systems. This activity at its peak represents a star’s active teenage years. Watching these events gives us insight into what probably went on in the early days of our solar system, when comets were pelting the inner solar system bodies, including Earth. In fact, these star-grazing comets may make life possible, because they carry water and other life-forming elements, such as carbon, to terrestrial planets.”

And while exocomets are far too small to be observed directly, the research team – which included members from the European Space Agency, the Kapteyn Institute, NASA Goddard Space Flight Center, and the University of Colorado – were able to discern their presence in 2015 using data obtained by Hubble’s Space Telescope Imaging Spectrograph (STIS) and the Cosmic Origins Spectrograph (COS).

*Artist’s concept of circumstellar disk of debris, which the HD 172555 star system is known to have. Credit: NASA*

Over the course of six days of observation, Hubble’s instruments detected silicon and carbon gas in the ultraviolet wavelength. The source of these gases also appeared to be moving at a speed of over 579,360 km (360,000 mph) across the face of the star. The only viable explanation for this was that they were spotting trails of gas as they evaporated from comets as they made their way across the system’s debris disk and closer to the star.

This is not the first time that exocomets have been seen transiting HD 172555. In 2004 and 2011, similar detections were made by the European Southern Observatory’s High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph. On those occasions, HARPS detected spectra that indicated the presence of calcium, which was seen as evidence that comet-like objects were falling into the star.

Dr. Grady and her team followed up on this by conducting their own spectral analysis of the system. By viewing HD 172555 and its debris disk in ultraviolet light, they were able to discern the presence of silicon and carbon. This was made easier thanks to the fact that HD 172555’s debris disk is viewed close to edge-on, which gives the telescope a clear view of any comet activity taking place within it.

Dr. Grady admits that there are still some uncertainties with their study. For instance, it is not entirely clear whether the objects they observed were comets or asteroids. Though the behavior is consistent with comets, more data on their particular compositions will be needed before they can be sure.

But in the meantime, it is compelling evidence for how comets behaved during the early history of the Solar System. And it may lend weight to the debate about how water originated on Earth, which is also central to determining how and where life may emerge in other parts of the Universe.

Further Reading: Hubble Space Telescope

January 5, 2017 by Matt Williams

Could Garnet Planets be Habitable?

A new study based on data from Sloan Digital Sky Survey (SDSS) shows how certain exoplanets are dominated by minerals like olivine and garnet. Credit: NASA

The hunt for exoplanet has revealed some very interesting things about our Universe. In addition to the many gas giants and “Super-Jupiters” discovered by mission like Kepler, there have also been the many exoplanet candidate that comparable in size and structure to Earth. But while these bodies may be terrestrial (i.e. composed of minerals and rocky material) this does not mean that they are “Earth-like”.

For example, what kind of minerals go into a rocky planet? And what could these particular compositions mean for the planet’s geological activity, which is intrinsic to planetary evolution? According to new study produced by a team of astronomers and geophysicists, the composition of an exoplanet depends on the chemical composition of its star – which can have serious implications for its habitability.

The findings of this study were presented at the 229th Meeting of the American Astronomical Society (AAS), which will be taking place from Jan. 3rd to Jan. 7th. During an afternoon presentation – titled “Between a Rock and a Hard Place: Can Garnet Planets Be Habitable?” – Johanna Teske (an astronomer from the Carnegie Institute of Science) showed how different types of stars can produce vastly different types of planets.

*The Apache Point Observatory Galactic Evolution Experiment (APOGEE), which collects spectrographic information on distant stars. Credit: astronomy.as.virginia.edu*

Using the Apache Point Observatory Galactic Evolution Experiment (APOGEE), which is part of the Sloan Digital Sky Survey (SDSS) Telescope at Apache Point Observatory, they examined spectrographic information obtained from 90 star systems – which were also observed by the Kepler Mission. These systems are of particular interest to exoplanet hunters because they have been shown to contain rocky planets.

As Teske explained during the course of the presentation, this information could help scientists to place further constraints on what it takes for a planet to be habitable. “[O]ur study combines new observations of stars with new models of planetary interiors,” she said. “We want to better understand the diversity of small, rocky exoplanet composition and structure — how likely are they to have plate tectonics or magnetic fields?”

Focusing on two star systems in particular – Kepler 102 and Kepler 407 – Teske demonstrated how the composition of a planet has a great deal to do with the composition of its star. Whereas Kepler 102 has five known planets, Kepler 407, has two different planets – one gaseous and the other terrestrial. And while Kepler 102 is quite similar to our Sun (slightly less luminous), Kepler 407 has close to the same mass (but a lot more silicon).

In order to understand what consequences these differences could have for planetary formation, the SDSS team turned to a team of geophysicists. Led by Cayman Unterborn from Arizona State University, this team ran computer models to see what kinds of planets each system would have. As Unterborn explained:

“We took the star compositions found by APOGEE and modeled how the elements condensed into planets in our models. We found that the planet around Kepler 407, which we called ‘Janet,” would likely be rich in the mineral garnet. The planet around Kepler 102, which we called ‘Olive,’ is probably rich in olivine, like Earth.”

*Artist rendition of interior compositions of planets around the stars Kepler 102 and Kepler 407. Credit: Robin Dienel/Carnegie DTM*

This difference would have considerable impact on planetary tectonics. For one, garnet is lot more rigid than olivine, which would mean “Janet” would experience less in the way of long-term plate tectonics. This in turn would mean that processes that are believed to be essential to life on Earth – like volcanic activity, atmospheric recycling, and mineral exchanges between the crust and mantle – would be less common.

This raises additional questions about the habitability of “Earth-like” planets in other star systems. In addition to being rocky and having strong magnetic fields and viable atmospheres, it seems that exoplanets also need to have the right mix of minerals in order to support life – life as we know it, at any rate. What’s more, this kind of research also helps us to understand how life came to emerge on Earth in the first place.

Looking forward, the research team hopes to extend their study to include all the 200,000 stars surveyed by APOGEE to see which could host terrestrial planets. This will allow astronomers to determine the mineral composition of more rocky worlds, thus helping them to determine which rocky exoplanets are “Earth-like”, and which are just “Earth-sized”.

Further Reading: SDSS

January 5, 2017 by Matt Williams

Chandra Spots Two Cosmic Heavy-Hitters at Once

Composite view of the collision between galaxy clusters Abell 3411 and Abell 3412 . Credit: X-ray: NASA/CXC/SAO/R. van Weeren et al./NAOJ/Subaru

This week, the 229th Meeting of the American Astronomical Society (AAS) kicked off in Grapevine, Texas. Between Monday and Friday (January 3rd to January 7th), attendees will be hearing presentations by researchers and scientists from several different fields as they share the latest discoveries in astronomy and Earth science.

One of the highlights so far this week was a presentation from NASA’s Chandra X-ray Observatory, which took place on the morning of Wednesday, January 5th. In the course of the presentation, an international research team showed some stunning images of two of the most powerful cosmic forces seen together for the first time – a supermassive black hole and two massive galaxy clusters colliding.

The galaxy clusters are known as Abell 3411 and Abell 3412, which are located about two billion light years from Earth. Both of these clusters are quite massive, each possessing the equivalent of about a quadrillion times the mass of our Sun. Needless to say, the collision of these objects produced quite the shockwave, which included the release of hot gas and energetic particles.

*X-ray image of the collision between Abell 3411 and Abell 3412. Credit: NASA/CXC/SAO/R. van Weeren et al.*

This was made all the more impressive thanks to the presence of a supermassive black hole (SMBH) at the center of one of the galaxy clusters. As the team described in their paper – titled “The Case for Electron Re-Acceleration at Galaxy Cluster Shocks” – the galactic collision produced a nebulous outburst of x-rays (shown above), which were produced when hot clouds of gas from one cluster plowed through the hot gas clouds of the other.

Meanwhile, the inflowing gas was accelerated outward into a jet-like stream, thanks to the powerful electromagnetic fields of the SMBH. These particles were accelerated even further when they got swept up by the shock waves produced by the collision of the galactic clusters and their massive gas clouds. These streams were detected thanks to the burst of radio waves they released as a result.

By seeing these two major events happening at the same time in the same place, the research team effectively witnessed a cosmic “double whammy”. As Felipe Andrade-Santos of the Harvard-Smithsonian Center for Astrophysics (CfA), and co-author of the paper, described it in a Chandra press release:

“It’s almost like launching a rocket into low-Earth orbit and then getting shot out of the Solar System by a second rocket blast. These particles are among the most energetic particles observed in the Universe, thanks to the double injection of energy.”

*Image of radio waves produce by the collision between Abell 3411 and Abell 3412. Credit: NASA/CXC/SAO/R. van Weeren et al.*

Relying on data obtained from the Chandra X-ray Observatory, the Giant Metrewave Radio Telescope (GMRT) in India, the Karl G. Jansky Very Large Array, the Keck Observatory, and Japan’s Subaru Telescope, the team was able to capture this event in the optical, x-ray, and radio wave wavelengths. This not only led to some stunning images, but shed some light on a long-standing mystery in galaxy research.

In the past, astronomers have detected radio emissions coming from Abell 3411 and Abell 3412 using the GMRT. But the origins of these emissions, which reached for millions of light years, was the subject of speculation and debate. Relying on the data they obtained, the research team was able to determine that they are the result of energetic particles (produced by the clouds of hot gas colliding) being further accelerated by galactic shock waves.

Or as co-author William Dawson, of the Lawrence Livermore National Lab in Livermore, California, put it:

“This result shows that a remarkable combination of powerful events generate these particle acceleration factories, which are the largest and most powerful in the Universe. It is a bit poetic that it took a combination of the world’s biggest observatories to understand this.”

Many interesting finds have been shared since the 229th Meeting of the AAS began – like the hunt for the source of a Fast Radio Burst – and many more are expected before it wraps up at the end of the week. These will include the latest results from the Sloan Digital Sky Survey (SDSS), and new and exciting research on black holes, exoplanets, and other astronomical phenomena.

And be sure to check out this podcast from Chandra as well, which talks about the collision between Abell 3411 and 3412 and the cosmic forces it unleashed.

Further Reading: Chandra X-ray Observatory

January 4, 2017January 4, 2017 by Matt Williams

NASA Announces Missions to Explore Early Solar System

An artist’s conception of the Lucy spacecraft (left) flying by the Trojan Eurybates, and Psyche (Right) Psyche, the first mission to the metal world 16 Psyche. Credits: SwRI and SSL/Peter Rubin

It’s a New Year, with new challenges and new opportunities! And NASA, looking to kick things off, has announced the two new missions that will be launching in the coming decade. These robotic missions, named Lucy and Psyche, are intended to help us understand the history of the early Solar System, and will deploy starting in 2021 and 2023, respectively.

While Lucy’s mission is to explore one of Jupiter’s Trojan asteroids, Psyche will explore a metal asteroid known as 16 Psyche. And between the two of them, it is hoped that they will answer some enduring questions about planetary formation and how the Solar System came to be. More than that, these mission represent historic firsts for NASA and human space exploration.

NASA’s Discovery Program, of which Lucy and Psyche are part, was created in 1992 to compliment their larger “flagship” programs. By bringing scientists and engineers together to design missions, the Discovery Program’s focus has been to maximize scientific research by creating many smaller missions that have shorter development periods and require less in the way of operational resources.

*Artist’s concept of the Lucy spacecraft flying by Eurybates, one of the six diverse and scientifically important Trojans it will study. Credit: SwRI*

The Lucy mission is scheduled to launch in October of 2021, and is expected to arrive at its first destination (a Main Belt asteroid) in 2025. It will then set course for Jupiter’s Trojans, a group of asteroids that are trapped by Jupiter’s gravity and share its orbit. These asteroids are thought to be relics of the early Solar System; and between 2027 and 2033, Lucy will study six of them.

In addition to being the first mission to explore Jupiter’s Trojan population, Lucy is also of historic importance because of the number of asteroids it will visit. Throughout the course of its mission, it is will investigate six Trojans, which is the total number of Main Belt asteroids that have been studied to date. The nature of these six asteroids is also expected to tell us much about the early history of the Solar System.

As Harold F. Levison – the principal investigator of the Lucy mission from the Southwest Research Institute (SwRI) in Boulder, Colorado – explained during a NASA call-in briefing:

“One of the surprising aspects of this population is their diversity. If we look at them through telescopes on the Earth, we see that they are very different from one other in their color, in their spectra. And so, we believe that’s telling us something about how the Solar System formed and evolved… This diversity in these objects, we believe, are due to the fact that they actually formed in very different regions of the Solar System, with very different physical characteristics. And something occurred in the history of the Solar System where these objects started off at very different distances, but during the formation and evolution of the Solar System, they got moved around and placed in these stable reservoirs near Jupiter’s orbit.”

*Illustration of the Lucy spacecraft’s orbit around Jupiter, which will allow it to study its Trojan population. Credit: SwRI*

The six Trojans that Lucy is intended investigate were selected because the diversity of their physical characteristics show that they are from different locations throughout the Solar System. As Levison put it, “These small bodies really are the fossils of planet formation, and that’s why we named Lucy after the human ancestor known as Lucy.”

In addition, Lucy will build on the success of missions like New Horizons and OSIRIS-REx., which includes using updated versions of instruments they used to explore Pluto, the Kuiper Belt, and the asteroid Bennu -i.e. the RALPH and LORRI instruments and the OTES instrument. In addition, several members of the New Horizons and OSIRIS-REx science teams will be lending their expertise to the Lucy mission.

Similarly, the Psyche mission will of be immense scientific value since it will visit the only metal asteroid known to exist. This asteroid measures about 210 km (130 mi) in diameter and is believed to be composed entirely of iron and nickel. In this respect, it is similar to Earth’s metallic core, as well as the cores of every terrestrial planet in the Solar System.

It is for this reason why scientists believe it may be the exposed core of a Mars-sized planet. According to this theory, 16 Psyche experienced several major collisions during the early history of the Solar System, which caused it to shed its rocky mantle. The robotic probe will launch in 2023 and is expected to arrive by 2030 – after receiving an Earth gravity-assist maneuver in 2024 and a Mars flyby in 2025.

By measuring its composition, magnetic field, and mapping its surface features, Lucy’s science team hopes to learn more about the history of planetary formation. As Lindy Elkins-Tanton – the Principal Investigator of Psyche and the Director of the School of Earth and Space Exploration at Arizona State University – said during the NASA call-in briefing:

“Humankind has visited rocky worlds and icy worlds and worlds made of gas. But we have never seen a metal world. Psyche has never been visited or had a picture taken that was more than a point of light. And so, its appearance remains a mystery. This mission will be true exploration and discovery. We think that Psyche is the metal core of a small planet that was destroyed in the high-energy, high-speed, first one-one-hundredth of the age of our Solar System. By visiting Psyche we can literally visit a planetary core the only way humanity can… Psyche let’s us visit inner space by visiting outer space.”

Not only are planetary cores thought to be where magnetic fields originate (which are necessary for the emergence of life), but they are entirely inaccessible to us. The very edge of Earth’s outer core is roughly 2,890 km (1790 mi) from our planet’s surface. But the deepest humanity has ever dug has been to a depth of 12 km (7.5 mi), which took place at the Kola Superdeep Borehole, in Russia.

In addition, within the Earth’s core, temperature and pressure conditions are estimated to reach 5700 K (5400 °C; 9752 °F) and 330 to 360 gigapascals (over three million times normal air pressure). This makes exploring the core of our planet (or any other planet in the Solar System, for that matter) completely impractical. Hence why a robotic mission to a world like Pysche is such an opportunity.

And since Psyche is the only rounded body of metal that is known to exist in the Solar System, the asteroid is as improbably as it is unique. And since no missions have ever taken place to explore its surface, and no pictures exist that can tell us what its surface features would look like, the Psyche mission is sure to shed some serious light on what a metal world looks like.

“What do we think it might look like?” asked Tanton. “Does it have surface sulfur lava flows on its surface? Is it covered with towering cliffs created when solidifying metal shrank and the exterior of the body broke into fault? Is its surface a combination of iron metal and green mineral crystal as iron meteorites are? And what does an impact crater in metal look like? Could its edges or its metal flashes become frozen in the cold of space before they fell back on the surface. We don’t know.”

Jim Green, NASA’s Planetary Science Director, expressed enthusiasm for the Discovery 13 and 14 missions in a recent NASA press release:

“These are true missions of discovery that integrate into NASA’s larger strategy of investigating how the solar system formed and evolved. We’ve explored terrestrial planets, gas giants, and a range of other bodies orbiting the sun. Lucy will observe primitive remnants from farther out in the solar system, while Psyche will directly observe the interior of a planetary body. These additional pieces of the puzzle will help us understand how the sun and its family of planets formed, changed over time, and became places where life could develop and be sustained – and what the future may hold.”

Lucy and Psyche were chosen from five finalists that were selected for further development back in September 2015. These in turn were chosen from 27 mission concepts that were submitted back in November of 2014. Examples of past and present Discovery missions include the Kepler space probe, the Dawn spacecraft, the Mars Pathfinder, and the InSight lander (which is scheduled to launch in 2018).

Further Reading: NASA

January 3, 2017January 3, 2017 by Matt Williams

What is the Closest Galaxy to the Milky Way?

Image showing nearly 50,000 galaxies in the nearby universe detected by the Two Micron All Sky Survey (2MASS) in infrared light. Credit: 2MASS/ T. H. Jarrett/J. Carpenter/R. Hurt

Scientists have known for some time that the Milky Way Galaxy is not alone in the Universe. In addition to our galaxy being part of the Local Group – a collection of 54 galaxies and dwarf galaxies – we are also part of the larger formation known as the Virgo Supercluster. So you could say the Milky Way has a lot of neighbors.

Of these, most people consider the Andromeda Galaxy to be our closest galactic cohabitant. But in truth, Andromeda is the closest spiral galaxy, and not the closest galaxy by a long shot. This distinction falls to a formation that is actually within the Milky Way itself, a dwarf galaxy that we’ve only known about for a little over a decade.

Closest Galaxy:

At present, the closet known galaxy to the Milky Way is the Canis Major Dwarf Galaxy – aka. the Canis Major Overdensity. This stellar formation is about 42,000 light years from the galactic center, and a mere 25,000 light years from our Solar System. This puts it closer to us than the center of our own galaxy, which is 30,000 light years away from the Solar System.

Illustration of the Canis Dwarf Dwarf Galaxy, Credit: R. Ibata (Strasbourg Observatory, ULP) et al./2MASS/NASA — *Illustration of the Canis Dwarf Galaxy and its associated tidal (shown in red) in relation to our Milky Way. Credit: R. Ibata (Strasbourg Observatory, ULP) et al./2MASS/NASA*

Characteristics:

The Canis Major Dwarf Galaxy Dwarf Galaxy is believed to contain one billion stars in all, a relatively high-percentage of which are in the Red Giant Branch phase of their lifetimes. It has a roughly elliptical shape and is thought to contain as many stars as the Sagittarius Dwarf Elliptical Galaxy, the previous contender for closest galaxy to our location in the Milky Way.

In addition to the dwarf galaxy itself, a long filament of stars is visible trailing behind it. This complex, ringlike structure – which is sometimes referred to as the Monoceros Ring – wraps around the galaxy three times. The stream was first discovered in the early 21st century by astronomers conducting the Sloan Digital Sky Survey (SDSS).

It was in the course of investigating this ring of stars, and a closely spaced group of globular clusters similar to those associated with the Sagittarius Dwarf Elliptical Galaxy, that the Canis Major Dwarf Galaxy was first discovered. The current theory is that this galaxy was accreted (or swallowed up) by the Milky Way Galaxy.

Other globular clusters that orbit the center of our Milky Way as a satellite – i.e. NGC 1851, NGC 1904, NGC 2298 and NGC 2808 – are thought to have been part of the Canis Major Dwarf Galaxy before its accretion. It also has associated open clusters, which are thought to have formed as a result of the dwarf galaxy’s gravity perturbing material in the galactic disk and stimulating star formation.

*Images of a few examples of merging galaxies taken by the Hubble Space Telescope. Credit: NASA/ESA/STScI/A. Evans/NRAO/Caltech*

Discovery:

Prior to its discovery, astronomers believed that the Sagittarius Dwarf Galaxy was the closest galactic formation to our own. At 70,000 light years from Earth, this galaxy was determined in 1994 to be closer to us than the Large Magellanic Cloud (LMC), the irregular dwarf galaxy that is located 180,000 light years from Earth, and which previously held the title of the closest galaxy to the Milky Way.

All of that changed in 2003 when The Canis Major Dwarf Galaxy was discovered by the Two Micron All-Sky Survey (2MASS). This collaborative astronomical mission, which took place between 1997 and 2001, relied on data obtained by the Mt. Hopkins Observatory in Arizona (for the Northern Hemisphere) and the Cerro Tololo Inter-American Observatory in Chile (for the southern hemisphere).

From this data, astronomers were able to conduct a survey of 70% of the sky, detecting about 5,700 celestial sources of infrared radiation. Infrared astronomy takes advantage of advances in astronomy that see more of the Universe, since infrared light is not blocked by gas and dust to the same extent as visible light.

Because of this technique, the astronomers were able to detect a very significant over-density of class M giant stars in a part of the sky occupied by the Canis Major constellation, along with several other related structures composed of this type of star, two of which form broad, faint arcs (as seen in the image close to the top).

*An artist depicts the incredibly powerful flare that erupted from the red dwarf star EV Lacertae. Credit: Casey Reed/NASA*

The prevalence of M-class stars is what made the formation easy to detect. These cool, “Red Dwarfs” are not very luminous compared to other classes of stars, and cannot even be seen with the naked eye. However, they shine very brightly in the infrared, and appeared in great numbers.

The discovery of this galaxy, and subsequent analysis of the stars associated with it, has provided some support for the current theory that galaxies may grow in size by swallowing their smaller neighbors. The Milky Way became the size it is now by eating up other galaxies like Canis Major, and it continues to do so today. And since stars from the Canis Major Dwarf Galaxy are technically already part of the Milky Way, it is by definition the nearest galaxy to us.

As already noted, it was the Sagittarius Dwarf Elliptical Galaxy that held the position of closest galaxy to our own prior to 2003. At 75,000 light years away. This dwarf galaxy, which consists of four globular clusters that measure some 10,000 light-years in diameter, was discovered in 1994. Prior to that, the Large Magellanic Cloud was thought to be our closest neighbor.

The Andromeda Galaxy (M31) is the closest spiral galaxy to us, and though it’s gravitationally bound to the Milky Way, it’s not the closest galaxy by far – being 2 million light years away. Andromeda is currently approaching our galaxy at a speed of about 110 kilometers per second. In roughly 4 billion years, the Andromeda Galaxy is expected to merge with out own, forming a single, super-galaxy.

Future of the Canis Major Dwarf Galaxy:

Astronomers also believe that the Canis Major Dwarf Galaxy is in the process of being pulled apart by the gravitational field of the more massive Milky Way Galaxy. The main body of the galaxy is already extremely degraded, a process which will continue as it travels around and through our Galaxy.

In time, the accretion process will likely culminate with the Canis Major Dwarf Galaxy merging entirely with the Milky Way, thus depositing its 1 billion stars to the 200 t0 400 billion that are already part of our galaxy.

We have written many interesting articles on galaxies here at Universe Today. Here’s Closest Galaxy Discovered, How did the Milky Way Form?, How Many Galaxies are there in the Universe?, What is the Milky Way Collision, Spiral Galaxies Could eat Dwarfs all over the Universe and The Canis Major Constellation.

For more information, check out this article from the Spitzer Space Telescope‘s website about the galaxies that are closest to the Milky Way Galaxy. And here is a video by the same author on the subject.

Astronomy Cast has some interesting episodes on the subject. Here’s Episode 97: Galaxies and Episode 99: The Milky Way.

Sources:

January 2, 2017January 2, 2017 by Tammy Plotner

Messier 30 – The NGC 7099 Globular Cluster

The Messier 30 globular cluster, in proximigy to other deep sky objects in the direction of the Capricornus constellation. Credit: Wikisky

Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at the globular cluster known as Messier 30. Enjoy!

One of these objects is Messier 30, a globular cluster located in the southern constellation of Capricornus. Owing to its retrograde orbit through the inner galactic halo, it is believed that this cluster was acquired from a satellite galaxy in the past. Though it is invisible to the naked eye, this cluster can be viewed using little more than binoculars, and is most visible during the summer months.

Description:

Messier measures about 93 light years across and lies at a distance of about 26,000 light years from Earth, and approaching us at a speed of about 182 kilometers per second. While it looks harmless enough, its tidal influence covers an enormous 139 light years – far greater than its apparent size.

Half of its mass is so concentrated that literally thousands of stars could be compressed in an area that spans no further than the distance between our solar system and Sirius! However, inside this density only 12 variable stars have been found and very little evidence of any stellar collisions, although a dwarf nova has been recorded!

So what’s so special about this little globular? Try a collapsed core – and one that’s even been resolved by Earth-bound telescopes. According to Bruce Jones Sams III, an astrophysicists at Harvard University:

“The globular cluster NGC 7099 is a prototypical collapsed core cluster. Through a series of instrumental, observational, and theoretical observations, I have resolved its core structure using a ground based telescope. The core has a radius of 2.15 arcsec when imaged with a V band spatial resolution of 0.35 arcsec. Initial attempts at speckle imaging produced images of inadequate signal to noise and resolution. To explain these results, a new, fully general signal-to-noise model has been developed. It properly accounts for all sources of noise in a speckle observation, including aliasing of high spatial frequencies by inadequate sampling of the image plane. The model, called Full Speckle Noise (FSN), can be used to predict the outcome of any speckle imaging experiment. A new high resolution imaging technique called ACT (Atmospheric Correlation with a Template) was developed to create sharper astronomical images. ACT compensates for image motion due to atmospheric turbulence.”

Photography is an important tool for astronomers to work with – both land and space-based. By combining results, we can learn far more than just from the results of one telescope observation alone. As Justin H. Howell wrote in a 1999 study:

“It has long been known that the post-core-collapse globular cluster M30 (NGC 7099) has a bluer-inward color gradient, and recent work suggests that the central deficiency of bright red giant stars does not fully account for this gradient. This study uses Hubble Space Telescope Wide Field Planetary Camera 2 images in the F439W and F555W bands, along with ground-based CCD images with a wider field of view for normalization of the noncluster background contribution. The quoted uncertainty accounts for Poisson fluctuations in the small number of bright evolved stars that dominate the cluster light. We explore various algorithms for artificially redistributing the light of bright red giants and horizontal-branch stars uniformly across the cluster. The traditional method of redistribution in proportion to the cluster brightness profile is shown to be inaccurate. There is no significant residual color gradient in M30 after proper uniform redistribution of all bright evolved stars; thus, the color gradient in M30’s central region appears to be caused entirely by post-main-sequence stars.”

*Image of Messier 30 (M 30, NGC 7099) was taken by Hubble’s Advanced Camera for Surveys (ACS). Credit: NASA/ESA*

So what happens when you dig even deeper with a different type of photography? Just ask the folks from Chandra – like Phyllis M. Lugger, who wrote in her study, “Chandra X-ray Sources in the Collapsed-Core Globular Cluster M30 (NGC 7099)“:

“We report the detection of six discrete, low-luminosity X-ray sources, located within 12” of the center of the collapsed-core globular cluster M30 (NGC 7099), and a total of 13 sources within the half-mass radius, from a 50 ks Chandra ACIS-S exposure. Three sources lie within the very small upper limit of 1.9” on the core radius. The brightest of the three core sources has a blackbody-like soft X-ray spectrum, which is consistent with it being a quiescent low-mass X-ray binary (qLMXB). We have identified optical counterparts to four of the six central sources and a number of the outlying sources, using deep Hubble Space Telescope and ground-based imaging. While the two proposed counterparts that lie within the core may represent chance superpositions, the two identified central sources that lie outside of the core have X-ray and optical properties consistent with being cataclysmic variables (CVs). Two additional sources outside of the core have possible active binary counterparts.”

History of Observation:

When Charles Messier first encountered this globular cluster in 1764, he was unable to resolve individual stars, and mistakenly believed it to be a nebula. As he wrote in his notes at the time:

“In the night of August 3 to 4, 1764, I have discovered a nebula below the great tail of Capricornus, and very near the star of sixth magnitude, the 41st of that constellation, according to Flamsteed: one sees that nebula with difficulty in an ordinary [non-achromatic] refractor of 3 feet; it is round, and I have not seen any star: having examined it with a good Gregorian telescope which magnifies 104 times, it could have a diameter of 2 minutes of arc. I have compared the center with the star Zeta Capricorni, and I have determined its position in right ascension as 321d 46′ 18″, and its declination as 24d 19′ 4″ south. This nebula is marked in the chart of the famous Comet of Halley which I observed at its return in 1759.”

*Image of the core region of Messier 30 by the Hubble Space Telescope. Credit: NASA*

However, we cannot fault Messier, for his job was to hunt comets and we thank him for logging this object for further study. Perhaps the first clue to M30’s underlying potential came from Sir William Herschel, who often studied Messier’s objects, but did not report his findings formally. In his personal notes he wrote:

“A brilliant cluster, the stars of which are gradually more compressed in the middle. It is insulated, that is, none of the stars in the neighborhood are likely to be connected with it. Its diameter is from 2’40” to 3’30”. The figure is irregularly round. The stars about the centre are so much compressed as to appear to run together. Towards the north, are two rows of bright stars 4 or 5 in a line. In this accumulation of stars, we plainly see the exertion of a central clustering power, which may reside in a central mass, or, what is more probable, in the compound energy of the stars about the centre. The lines of bright stars, although by a drawing made at the time of observation, one of them seems to pass through the cluster, are probably not connected with it.”

So, as telescopes progressed and resolution improved, so did our way of thinking about what we were seeing… By Admiral Smyth’s time, things had improved even more and so had the art of understanding more:

“A fine pale white cluster, under the creature’s caudal fin, and about 20 deg west-north-west of Fomalhaut, where it precedes 41 Capricorni, a star of 5th magnitude, within a degree. This object is bright, and from the straggling streams of stars on its northern verge, has an elliptical aspect, with a central blaze; and there are but few other stars, or outliers, in the field.

“When Messier discovered this, in 1764, he remarked that it was easily seen with a 3 1/2-foot telescope, that it was a nebula, unaccompanied by any star, and that its form was circular. But in 1783 it was attacked by WH [William Herschel] with both his 20-foot Newtonians, and forthwith resolved into a brilliant cluster, with two rows pf stars, four or five in a line, which probably belong to it; and therefore he deemed it insulated. Independently of this opinion, it is situated in a blankish space, one of those chasmata which Lalande termed d’espaces vuides, wherein he could not perceive a star of the 9th magnitude in the achromatic telescope of sixty-seven millimetres aperture. By a modification of his very ingenious gauging process, Sir William considered the profundity of this cluster to be of the 344th order.

“Here are materials for thinking! What an immensity of space is indicated! Can such an arrangement be intended, as a bungling spouter of the hour insists, for a mere appendage to the speck of a world on which we dwell, to soften the darkness of its petty midnight? This is impeaching the intelligence of Infinite Wisdom and Power, in adapting such grand means to so disproportionate an end. No imagination can fill up the picture of which the visual organs afford the dim outline; and he who confidently probes the Eternal Design cannot be many removes from lunacy. It was such a consideration that made the inspired writer claim, “How unsearchable are His operations, and His ways past finding out!”

Throughout all historic observing notes, you’ll find notations like “remarkable” and even Dreyer’s famous exclamation points. Even though M30 may not be the easiest to find, nor the brightest of the Messier objects, it is still quite worthy of your time and attention!

*The location of Messier 30, in the direction of the Scorpius constellation. Credit: IAU/Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)*

Locating Messier 30:

Finding M30 is not an easy task, unless you’re using a GoTo telescope. In any other case, it’s a starhop process, which must begin with identifying the the big grin-shape of the constellation of Capricornus. Once you’ve separated out this constellation, you’ll begin to notice that many of its primary asterism stars are paired – which is a good thing! The northeastern most pair are Gamma and Delta, which is where binocular-users should start.

As you move slowly south and slightly west, you’ll encounter your next wide pair – Chi and Epsilon. The next southwestern set is 36 Cap and Zeta. Now, from here you have two options! You can find Messier 30 a little more than a finger width east(ish) of Zeta (about half a binocular field)… or, you can return to Epsilon and look about one binocular field south (about 3 degrees) for star 41 which will appear just east of Messier 30 in the same field of view.

For the finderscope, star 41 is a critical giveaway to the globular cluster’s position! It won’t be visible to the unaided eye, but even a little magnification will reveal its presence. Using binoculars or a very small telescope, Messier 30 will appear as only a small, faded gray ball of light with a small star beside it. However, with telescope apertures as small as 4″ you’ll begin some resolution on this overlooked globular cluster and larger apertures will resolve it nicely.

And here are the quick facts on Messier 30 to help you get started:

Object Name: Messier 30
Alternative Designations: M30, NGC 7099
Object Type: Class V Globular Cluster
Constellation: Capricornus
Right Ascension: 21 : 40.4 (h:m)
Declination: -23 : 11 (deg:m
Distance: 26.1 (kly)
Visual Brightness: 7.2 (mag)
Apparent Dimension: 12.0 (arc min)

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

Sources:

January 1, 2017 by Bob King

Start the Year With Spark: See the Quadrantid Meteor Shower

The Quadrantid meteor shower, named for the obsolete constellation Quadran Muralis, will appear to stream from a point in the sky called the radiant (yellow star), located below the end of the Big Dipper’s handle and across from the bright, orange-red star Arcturus. The map shows the sky around 4 a.m. local time Tuesday, Jan. 3. The shower will be best between 4 a.m. and 6 a.m., the start of dawn. Map: Bob King, Source: Stellarium

If one of your New Year’s resolutions is to spend more time under the stars in 2017, you’ll have motivation to do so as soon as Tuesday. That morning, the Quadrantid (kwah-DRAN-tid) meteor shower will peak between 4 to about 6 a.m. local time just before the start of dawn. This annual shower can be a rich one with up to 120 meteors flying by an hour — under perfect conditions.

Those include no moon, a light-pollution free sky and most importantly, for the time of maximum meteor activity to coincide with the time the radiant is highest in the pre-dawn sky. Timing is everything with the “Quads” because the shower is so brief. Meteor showers occur when Earth passes through either a stream of dusty debris left by a comet or asteroid. With the Quads, asteroid 2003 EH1 provides the raw material — bits of crumbled rock flaked off the 2-mile-wide (~3-4 km) object during its 5.5 year orbit around the sun.

A Quadrantid fireball flares to the left of the Hyades star cluster and Jupiter in 2013. As Earth travels across the debris stream, bits and pieces of asteroid 2003 EH1 strike the atmosphere at nearly 100,000 mph (43 km/second) and vaporize while creating a glowing dash of light called a meteor. Credit: Jimmy Westlake via NASA

Only thing is, the debris path is narrow and Earth tears through it perpendicularly, so we’re in and out in a hurry. Just a few hours, tops. This year’s peak happens around 14 hours UT or 8 a.m. Central time (9 a.m. Eastern, 7 a.m. Mountain and 6 a.m. Pacific), not bad for the U.S. and Canada. The timing is rather good for West Coast skywatchers and ideal if you live in Alaska. Alaska gets an additional boost because the radiant, located in the northeastern sky, is considerably higher up and better placed than it is from the southern U.S. states.

Another Quadrantid fireball. Credit: NASA

The Quads will appear to radiate from a point in the sky below the Big Dipper’s handle, which stands high in the northeastern sky at the time. This area was once home to the now defunct constellation Quadrans Muralis (mural quadrant), the origin of the shower’s name. As with all meteor showers, you’ll see meteors all over the sky, but all will appear to point back to the radiant. Meteors that point back to other directions don’t belong to the Quads are called sporadic or random meteors.

The long-obsolete constellation Quadrans Muralis represents the wall quadrant, a instrument once used to measure star positions. It was created by French astronomer Jerome Lalande in 1795. Credit: Johann Bode atlas

Off-peak observers can expect at least a decent shower with up to 25 meteors an hour visible from a reasonably dark sky. Peak observers could see at least 60 per hour. Tropical latitude skywatchers will miss most of the the show because the radiant is located at or below the horizon, but they should be on the lookout for Earthgrazers, meteors that climb up from below the horizon and make long trails as they skirt through the upper atmosphere.

Set your clock for 4 or 5 a.m. Tuesday, put on a few layers of clothing, tuck hand warmers in your boots and gloves, face east and have at it! The Quads are known for their fireballs, brilliant meteors famous for taking one’s breath away. Each time you see one chalk its way across the sky, you’re witnessing the fiery end of an asteroid shard. As the crumble burns out, you might be fulfilling another resolution: burning away those calories while huddling outside to see the show.

December 31, 2016January 5, 2017 by Fraser Cain

Our Free Book: 101 Astronomical Events in 2017

Let’s forget all about 2016, and instead look forward to the amazing 2017 we all know we’re going to have. And to help you celebrate this amazing year in space, we’re pleased to publish an entire book on what you can observe in the upcoming year: 101 Astronomical Events in 2017.

This totally free ebook was written by our own David Dickinson and contains all the predictable events coming up: the occultations, the eclipses, the meteor showers, the equinoxes, the super-moons and mini-moons. Every significant event coming up in 2017.

In addition, a few amateur astronomers like Cory Schmitz from PhotographingSpace and the Upside Down Astronomer Paul Stewart provided some of the beautiful photographs to inspire you to get outside.

Once again, this book is totally free. There’s no cost to purchase it, there are no advertisements in it. All we ask is that you get out there, enjoy the night sky with your friends and family, and take amazing pictures to share with us and the rest of astronomy community.

Well, it would also really help if you shared the book with your friends, family, astronomy club, and forums.

This is an experiment. Will you download and actually use it? If so, then expect us to release a new edition every year. If not, then, we’ll go back to the regular blog post version.

Thanks again to David for putting in an enormous amount of work 6 months ago to think through an entire year of observing, and to the readers and photographers who helped doublecheck the math to make sure it’s accurate.

Click here to download a copy in PDF format, or click here to download a copy in EPUB format.

Also, here’s a great Google Calendar link to all 101 events courtesy of Christopher Becke (@BeckePhysics)… thanks Chris!

Fraser Cain
Publisher, Universe Today