What will Curious George grow up to be? Being curious, then George will ask a lot of questions. And if lucky then physics will be George’s destiny, for physics seems to have so many answers. From the biggest to the smallest, that’s its purview. And for Delia Perlov and Alex Vilenkin in their book “Cosmology for the Curious” aim to answer a great many of those questions. Or at least those questions pertaining to mankind’s place in space.
Cosmology is all about space and time. Which means that this book begins by traveling back in time. Traveling to the time of the Greeks. Hundreds of years b.c.e. Apparently the Greek philosophers did a lot of pondering about the smallest of things they called atoms. And the largest, they called planetary epicycles. From this baseline the book very quickly progresses through the traditional growth of knowledge with some choice descriptions.
As an example it proposes energy as nature’s ultimate currency. And it allows the reader to wonder. Wonder why the sky is black at night. And ask questions. As in “why is the speed of light the same as the Earth travels about the Sun?”
Most of the descriptions rely on Newtonian mechanics for explanation but it is only a slight passing for the book quickly raises Einstein’s field equations, particularly emphasizing inertial frames of reference. With this, the reader is accorded a pleasant view of Lorentz transforms, a somewhat abstract view of the Sun being flung out of the solar system by a very large golf club and a realization of how the GPS navigation system incorporates gravitational time dilation. Still all this is simply the cosmological baseline for the reader.
Now the neat thing about cosmology is that there is simply no first hand observation. Most everything of interest happened a long time ago and in a somewhat different relative location. And this is the book’s next and most rewarding destination. Through many arguments or thought experiments, it associates the cosmic microwave background with redshifts and the changing spatial dimensions.
Later, postulated dark matter and dark energy refocus the reader’s attention on the very beginning of the universe in a big bang. Or perhaps a multiverse of many shapes and various physical laws. Which of course leads to considerations about what’s next. How will our universe continue? Will it go to a quiet heat death or will we be gobbled up by another bubble universe? We can’t determine from our vantage point on Earth. But this book does provide its own vantage point.
Helping this book along are a number of pleasant additions. For one, often when an accomplished researcher is mentioned, there’s an accompanying, quite complementary photograph. And equations are liberally spread throughout as if teasing the reader to explore more. But the book has very little math. And best of all are the questions at the end of each chapter. Now these questions aren’t your typical textbook questions. For example, consider “Inflation is almost certainly eternal to the future. Is it eternal to the past too? Why/why not?” Isn’t this a great question? And one that you really can’t get wrong.
Which of course begs the question “Why aren’t you as curious as George?” There’s a whole universe out there waiting for us to explore and understand. Let’s not take it for granted. Let’s satisfy our curiosity perhaps with reading the marvellous book “Cosmology for the Curious” by Delia Perlov and Alex Vilenkin. After all you don’t want to be upstaged by George, do you?
On October 19th, 2017, the Panoramic Survey Telescope and Rapid Response System-1 (Pan-STARRS-1) telescope in Hawaii picked up the first interstellar asteroid, named 1I/2017 U1 (aka. `Oumuamua). After originally being mistaken for a comet, observations performed by the European Southern Observatory (ESO) and other astronomers indicated that it was actually an asteroid that measures about 400 meters (1312 ft) long.
Thanks to data obtained by the ESO’s Very Large Telescope (VLT) at the Paranal Observatory in Chile, the brightness, color and orbit of this asteroid have been precisely determined. And according to a new study led by Dr. Karen Meech of the Institute for Astronomy in Hawaii, `Oumuamua is unlike any other asteroid we’ve ever seen, in that its shape is highly elongated (i.e. very long and thin).
The VLT was intrinsic to the combined effort to characterize the fast-moving asteroid rapidly, as it needed to be observed before it passed back into interstellar space again. Based on initial calculations of `Oumuamua’s orbit, astronomers had determined that it had already passed the closest point in its orbit to the Sun in September of 2017. Together with other large telescopes, the VLT captured images of the asteroid using its FORS instrument.
What these revealed was that `Oumuamua varies dramatically in terms of brightness (by a factor of ten) as it spins on its axis every 7.3 hours. As Dr. Meech explained in an ESO press release, this was both surprising and highly significant:
“This unusually large variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape. We also found that it has a dark red colour, similar to objects in the outer Solar System, and confirmed that it is completely inert, without the faintest hint of dust around it.”
These observations also allowed Dr. Meech and her team to constrain Oumuamua’s composition and basic properties. Essentially, the asteroid is now believed to be a dense and rocky asteroid with a high metal content and little in the way of water ice. It’s dark and reddened surface is also an indication of tholins, which are the result of organic molecules (like methane) being irradiated by cosmic rays for millions of years.
Unlike other asteroids that have been studied in Near-Earth space and the Solar System at large, `Oumuamua is unique in that it is not bound by the Sun’s gravity. In addition to originating outside of our Solar System, its hyperbolic orbit – which has an eccentricity of 1.2 – means that it will head back out into interstellar space after its brief encounter with our Solar System.
Based on preliminary calculations of its orbit, astronomers have deduced that it came from the general direction of Vega, the brightest star in the northern constellation of Lyra. Traveling at a whopping speed of 95,000 km/hour (59,000 mph), `Oumuamua would have left the Vega system about 300,000 years ago. However, it is also possible that the asteroid may have originated somewhere else entirely, wandering the Milky Way for millions of years.
Astronomers estimate that interstellar asteroids like `Oumuamua pass through the inner Solar System at a rate of about once a year. But until now, they have been too faint and difficult to detect in visible light, and have therefore gone unnoticed. It is only recently that survey telescopes like Pan-STARRS have been powerful enough to have a chance at detecting them.
Hence what makes this discovery so significant in the first place. As the first asteroid of its kind to be detected, further improvements in our instruments will it make it easier to spot the others that are sure to be on the way. And as Olivier Hainaut – a researcher with the ESO and a co-author on the study – indicated, there’s plenty more to be learned from `Oumuamua as well:
“We are continuing to observe this unique object, and we hope to more accurately pin down where it came from and where it is going next on its tour of the galaxy,” he said. “And now that we have found the first interstellar rock, we are getting ready for the next ones!”
And be sure to enjoy this ESOcast video about `Oumuamua, courtesy of the ESO:
If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!
Welcome back to Messier Monday! Today, we continue in our tribute to our dear friend, Tammy Plotner, by looking at the elliptical galaxy known as Messier 60.
In the 18th century, while searching the night sky for comets, French astronomer Charles Messier kept noting the presence of fixed, diffuse objects he initially mistook for comets. In time, he would come to compile a list of approximately 100 of these objects, hoping to prevent other astronomers from making the same mistake. This list – known as the Messier Catalog – would go on to become one of the most influential catalogs of Deep Sky Objects.
One of the notable objects in this catalog is Messier 60, an elliptical galaxy located approximately 55 million light-years away in the Virgo constellation. Measuring some 60,000 light years across, this galaxy is only about half as large as the Milky Way. However, it still manages to pack in an estimated 400 billion stars which, depending on which estimates you go by, is between four times and the same amount as our own.
What You Are Looking At:
Located about 60 million light years away and spanning about 120 million light years of space, M60 is the third brightest elliptical in the Virgo group and and is the dominant member of a subcluster of four galaxies, which is the closest-known isolated compact group of galaxies. In larger telescopes, you’ll see another nearby galaxy – NGC 4647 – which might first be taken for a interactor, but may very well lay at a different distance since there is no tidal evidence so far found.
As L.M. Young (et al.) explained in their 2006 study:
“We present matched-resolution maps of H I and CO emission in the Virgo Cluster spiral NGC 4647. The galaxy shows a mild kinematic disturbance in which one side of the rotation curve flattens but the other side continues to rise. This kinematic asymmetry is coupled with a dramatic asymmetry in the molecular gas distribution but not in the atomic gas. An analysis of the gas column densities and the interstellar pressure suggests that the H2/H I surface density ratio on the east side of the galaxy is 3 times higher than expected from the hydrostatic pressure contributed by the mass of the stellar disk. We discuss the probable effects of ram pressure, gravitational interactions, and asymmetric potentials on the interstellar medium and suggest it is likely that a m = 1 perturbation in the gravitational potential could be responsible for all of the galaxy’s features. Kinematic disturbances of the type seen here are common, but the curious thing about NGC 4647 is that the molecular distribution appears more disturbed than the H I distribution. Thus, it is the combination of the two gas phases that provides such interesting insight into the galaxy’s history and into models of the interstellar medium.”
Although a search for young optical pulsars turned up negative after a recent supernova event, astronomer’s did discover something rather exciting… a supermassive black hole! As Philip J. Humphrey (et al) indicated in their 2008 study:
“We present a Chandra study of the hot ISM in the giant elliptical galaxy NGC4649. In common with other group-centred ellipticals, its temperature profile rises with radius in the outer parts of the galaxy. Under the assumption of hydrostatic equilibrium, we demonstrate that the central temperature spike arises due to the gravitational influence of a quiescent central super-massive black hole. This is the first direct measurement of MBH based on studies of hydrostatic X-ray emitting gas, which are sensitive to the most massive black holes, and is a crucial validation of both mass-determination techniques. This agreement clearly demonstrates the gas must be close to hydrostatic, even in the very centre of the galaxy, which is consistent with the lack of morphological disturbances in the X-ray image. NGC4649 is now one of only a handful of galaxies for which MBH has been measured by more than one method.”
History of Observation:
Both M59 and neighboring M60 were discovered on April 11, 1779 by Johann Gottfried Koehler who wrote: “Two very small nebulae, hardly visible in a 3-foot telescope: The one above the other.” It was independently found one day later by Barnabus Oriani, who missed M59, and four days later, on April 15, 1779, by Charles Messier, who also found nearby M58. In his notes Messier writes:
“Nebula in Virgo, a little more distinct than the two preceding [M58 and M59], on the same parallel as Epsilon [Virginis], which has served for its [position] determination. M. Messier reported it on the Chart of the Comet of 1779. He discovered these three nebulae while observing this Comet which passed very close to them. The latter passed so near on April 13 and 14 that the one and the other were both in the same field of the refractor, and he could not see it; it was not until the 15th, while looking for the Comet, that he perceived the nebula. These three nebulae don’t appear to contain any star.”
William Herschel would later perceive it as a double nebula and so would son John, calling it “A very fine and curious object.” However, it was Admiral Smyth who must have finally had a clear viewing night a took a look at what was all around!
“The hypothesis of Sir John Herschel, upon double nebulae, is new and attracting. They may be stellar systems each revolving round the other: each a universe, according to ancient notions. But as these revolutionary principles of those vast and distant firmamental clusters connot for ages yet be established, the mind lingers in admiration, rather than comprehension of such mysterious collocations. Meantime our clear duty is, so industriously to collect facts, that much of what is now unintelligible, may become plain to our successors, and a portion of the grand mechanism now beyond our conception, revealed. ‘How much,’ exclaims Sir John Herschel, ‘how much is escaping us! How unworthy is it in them who call themselves philosophers, to let these great phenomena of nature, these slow but majestic manifestations of power and the glory of God, glide unnoticed, and drop out of memory beyond the reach of recovery, because we will not take the pains to note them in their unobstrusive and furtive passage, because we see them in their every-day dress, and mark no sudden change, and conclude that all is dead, because we will not look for signs of life; and that all is uninteresting, because we are not impressed and dazzled.’ ….. ‘To say, indeed, that every individual star in the Milky Way, to the amount of eight or ten millions, is to have its place determined, and its motion watched, would be extravagant; but at least let samples be taken, at least let monographs of parts be made with powerful telescopes and refined instruments, that we may know what is going on in that abyss of stars, where at present imagination wanders without a guide!” Such is the enthusiastic call of one, whose father cleared the road by which we are introduced to the grandest phenomena of the stellar universe.'”
Locating Messier 58:
M59 is a telescopic only object and requires patience to find. Because the Virgo Galaxy field contains so many galaxies which can easily be mis-identified, it is sometimes easier to “hop” from one galaxy to the next! In this case, we need to start by locating bright Vindemiatrix (Epsilon Virginis) almost due east of Denebola.
Let’s starhop four and a half degrees west and a shade north of Epsilon to locate one of the largest elliptical galaxies presently known – M60. At a little brighter than magnitude 9, this galaxy could be spotted with binoculars, but stick with your telescope. In the same low power field (depending on aperture size) you may also note faint NGC 4647 which only appears to be interacting with M60.
In a smaller telescope, do not expect to see much. What will appear at low power is a tiny egg-shaped patch of contrast change with a brighter center. As aperture increases, a sharper nucleus will begin to appear as you move into the 4-6″ size range at dark sky locations, but elliptical galaxies do not show details. As with all galaxies, dark skies are a must!
Enjoy your own observations of the Virgo galaxy fields….
And here are the quick facts on this Messier Object to help you get started:
Object Name: Messier 60 Alternative Designations: M60, NGC 4649 Object Type: E2 Galaxy Constellation: Virgo Right Ascension: 12 : 43.7 (h:m) Declination: +11 : 33 (deg:m) Distance: 60000 (kly) Visual Brightness: 8.8 (mag) Apparent Dimension: 7×6 (arc min)
The Orbital ATK Cygnus spacecraft was christened the S.S. Gene Cernan and named in honor of NASA’s Apollo 17 lunar landing commander; Gene Cernan.
Among the goodies delivered by the newly arrived S.S. Gene Cernan Cygnus OA-8 supply run to resident the crew of six astronauts and cosmonauts from the US, Russia and Italy are ice cream, pizza and presents for the holidays. They are enjoying the fruits of the earthy labor of thousands of space workers celebrating the mission’s success.
The journey began with the flawless liftoff of the two stage Antares rocket shortly after sunrise Sunday at 7:19 a.m. EST, Nov. 12, rocket from Pad-0A at NASA’s Wallops Flight Facility in Virginia.
Check out the expanding gallery of launch imagery and videos captured by this author and several space colleagues of Antares prelaunch activities around the launch pad and through Sunday’s stunningly beautiful sunrise blastoff.
After a carefully choreographed series of intricate thruster firings to raise its orbit in an orbital pursuit over the next two days, the Cygnus spacecraft on the OA-8 resupply mission for NASA arrived in the vicinity of the orbiting research laboratory.
Expedition 53 Flight Engineer Paolo Nespoli of ESA (European Space Agency) assisted by NASA astronaut Randy Bresnik then deftly maneuvered the International Space Station’s 57.7-foot-long (17.6 meter-long) Canadarm2 robotic arm to grapple and successfully capture the Cygnus cargo freighter at 5:04 a.m., Tuesday Nov. 14.
The station was orbiting 260 statute miles over the South Indian Ocean at the moment Nespoli grappled the S.S. Gene Cernan Cygnus spacecraft with the Canadian-built robotic arm.
Ground controllers at NASA’s Mission Control at the Johnson Space Center in Texas, then maneuvered the arm and robotic hand grappling Cygnus towards the exterior hull and berthed the cargo ship at the Earth-facing port of the stations Unity module.
The berthing operation was completed at 7:15 a.m. after all 16 bolts were driven home for hard mating as the station was flying 252 miles over the North Pacific in orbital night.
The Cygnus spacecraft dubbed OA-8 is Orbital ATK’s eighth contracted cargo resupply mission with NASA to the International Space Station under the unmanned Commercial Resupply Services (CRS) program to stock the station with supplies on a continuing and reliable basis.
Altogether over 7,400 pounds of science and research, crew supplies and vehicle hardware launched to the orbital laboratory and its crew of six for investigations that will occur during Expeditions 53 and 54.
The S.S. Gene Cernan manifest includes equipment and samples for dozens of scientific investigations including those that will study communication and navigation, microbiology, animal biology and plant biology. The ISS science program supports over 300 ongoing research investigations.
Apollo 17 was NASA’s final lunar landing mission. Gere Cernan was the last man to walk on the Moon.
Among the experiments flying aboard Cygnus are the coli AntiMicrobial Satellite (EcAMSat) mission, which will investigate the effect of microgravity on the antibiotic resistance of E. coli, the Optical Communications and Sensor Demonstration (OCSD) project, which will study high-speed optical transmission of data and small spacecraft proximity operations, the Rodent Research 6 habitat for mousetronauts who will fly on a future SpaceX cargo Dragon.
Cygnus will remain at the space station until Dec. 4, when the spacecraft will depart the station and release 14 CubeSats using a NanoRacks deployer, a record number for the spacecraft.
It will then be commanded to fire its main engine to lower its orbit and carry out a fiery and destructive re-entry into Earth’s atmosphere over the Pacific Ocean as it disposes of several tons of trash.
The Cygnus OA-8 manifest includes:
Crew Supplies 2,734.1 lbs. / 1,240 kg
Science Investigations 1631.42 lbs. / 740 kg
Spacewalk Equipment 291.0 lbs. / 132 kg
Vehicle Hardware 1,875.2 lbs. / 851 kg
Computer Resources 75.0 lbs. / 34 kg
Total Cargo: 7,359.0 lbs. / 3,338 kg
Total Pressurized Cargo with Packaging: 7,118.7 lbs. / 3,229 kg
Unpressurized Cargo (NanoRacks Deployer): 240.3 lbs. / 109 kg
Under the Commercial Resupply Services-1 (CRS-1) contract with NASA, Orbital ATK will deliver approximately 66,000 pounds (30,000 kilograms) of cargo to the space station. OA-8 is the eighth of these missions.
The Cygnus OA-8 spacecraft is Orbital ATK’s eighth contracted cargo resupply mission with NASA to the International Space Station under the unmanned Commercial Resupply Services (CRS) program to stock the station with supplies on a continuing basis.
Beginning in 2019, the company will carry out a minimum of six cargo missions under NASA’s CRS-2 contract using a more advanced version of Cygnus.
Watch for Ken’s continuing Antares/Cygnus mission and launch reporting from on site at NASA’s Wallops Flight Facility, VA during the launch campaign.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
KENNEDY SPACE CENTER, FL – Liftoff of the clandestine spy satellite codenamed ‘Zuma’ on a SpaceX Falcon 9 rocket has been postponed indefinitely to resolve a lingering issue with the testing of a payload fairing for another customer.
SpaceX announced today, Friday, Nov 17, that they will ‘stand down’ to allow engineers the additional time needed to carefully scrutinize all the pertinent data before proceeding with the top secret Zuma launch.
“We have decided to stand down and take a closer look at data from recent fairing testing for another customer,” said SpaceX spokesman John Taylor.
The super secret ‘Zuma’ spysat is a complete mystery and it has not been claimed by any U.S. government entity – not even the elusive NRO spy agency ! The NRO does claim ownership of a vast fleet of covert and hugely capable orbiting surveillance assets supporting US national security.
Zuma’s goals are veiled in virtually complete darkness. And as far as the taxpaying public is concerned its ownerless.
Originally scheduled for Wednesday evening at 8 p.m. EST Nov 15, the Zuma launch from the Florida Space Coast had already been postponed twice this week before today’s decision to called it off indefinitely.
The initial 24 hour delay to Thursday was to deal with unspecified ‘mission assurance’ issues.
The second days delay to Friday was pinned more specifically on the payload fairing or nose cone.
“Though we have preserved the range opportunity for tomorrow, we will take the time we need to complete the data review and will then confirm a new launch date,” Taylor stated.
Just exactly what the fairing problem is has not been disclosed. Its also not known if the two delays are related or not.
The fairing is jettisoned three minutes after liftoff. Any failure to deploy would result in a total loss of the mission.
Zuma was to roar off seaside Launch Complex 39A at NASA’s Kennedy Space Center in Florida during a lengthy two hour launch window that extended from 8 to 10 p.m. each targeted day this week.
The Eastern range had been reserved by SpaceX for a potential Saturday launch opportunity as well.
However all mention of the Zuma launch has now been deleted from the website of the 45th Space Wing at Patrick Air Force Base, FL.
Forecast weather conditions in central Florida were near perfect over the past few days and spectators would have witnessed a dazzling sky show as the two stage 229-foot-tall (70-meter-tall) Falcon 9 soared to orbit.
One of the few tidbits we can confirm is that the launch contract was arranged as a commercial enterprise under the auspices of Northrop Grumman Corporation – as a means to significantly slash launch costs for whatever U.S government entity is responsible for Zuma.
That goal is completely in line with SpaceX founder and CEO Elon Musk’s entire company-wide goal in developing the Falcon and Dragon family of rockets and spaceships.
“The U.S. Government assigned Northrop Grumman the responsibility of acquiring launch services for this mission,” Lon Rains, Northrop Grumman Director of Communications, told Universe Today.
“We have procured the Falcon 9 launch service from SpaceX.”
But the launch was only publicly announced 1 month ago in mid October and it suddenly appeared on the SpaceX launch manifest after an FAA launch license was granted.
We don’t know anything about the ‘Zuma’ payloads characteristics and vital statistics – despite the seemingly endless leaks streaming out of Washington these days.
“The Zuma payload is a restricted payload,” Rains told me.
“Northrop Grumman is proud to be a part of the Zuma launch,” Rains added. “This event represents a cost effective approach to space access for government missions.”
The only clue to its goals to be revealed is the intended orbit.
“It will be launched into Low Earth Orbit,” Rains informed me.
Low Earth Orbit extends to roughly 1200 miles altitude and includes the ISS orbit for example at approx. 250 miles.
“As a company, Northrop Grumman realizes this is a monumental responsibility and we have taken great care to ensure the most affordable and lowest risk scenario for Zuma.”
On Friday evening the rocket was lowered to the horizontal position on the transporter erector on pad 39A. It will be rolled back to the processing hangar outside the perimeter fence for further engineering evaluation.
Whenever the launch is rescheduled SpaceX will attempt to recover the 16 story tall first stage booster with a soft landing on the ground back at Cape Canaveral Air Force Station. So expect some extremely loud sonic booms to rock the space coast region about eight minutes after liftoff.
Watch for Ken’s continuing onsite coverage of SpaceX Zuma, KoreaSat-5A & SES-11, ULA NROL-52 and NASA and space mission reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station, Florida.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
The super-Earth 55 Cancri e (aka. Janssen) is somewhat famous, as exoplanet go. Originally discovered in 2004, this world was one of the few whose discovery predated the Kepler mission. By 2016, it was also the first exoplanet to have its atmosphere successfully characterized. Over the years, several studies have been conducted on this planet that revealed some rather interesting things about its composition and structure.
For example, scientists believed at one time that 55 Cancri e was a “diamond planet“, whereas more recent work based on data from the Spitzer Space Telescope concluded that its surface was covered in lakes of hot lava. However, a new study conducted by scientists from NASA’s Jet Propulsion Laboratory indicates that despite its intense surface heat, 55 Cancri e has an atmosphere that is comparable to Earth’s, only much hotter!
The study, titled “A Case for an Atmosphere on Super-Earth 55 Cancri e“, recently appeared in The Astrophysical Journal. Led by Isabel Angelo (a physics major with UC Berkeley) with the assistance of Renyu Hu – a astronomer and Hubble Fellow with JPL and Caltech – the pair conducted a more detailed analysis of the Spitzer data to determine the likelihood and composition of an atmosphere around 55 Cancri e.
Previous studies of the planet noted that this super-Earth (which is twice as large as our planet), orbits very close to its star. As a result, it has a very short orbital period of about 17 hours and 40 minutes and is tidally locked (with one side constantly facing towards the star). Between June and July of 2013, Spitzer observed 55 Cancri e and obtained temperature data using its special infrared camera.
Initially, the temperature data was seen as being an indication that large deposits of lava existed on the surface. However, after re-analyzing this data and combining it with a new model previously develop by Hu, the team began to doubt this explanation. According to their findings, the planet must have a thick atmosphere, since lava lakes exposed to space would create hots spots of high temperatures.
What’s more, they also noted that the temperature differences between the day and night side were not as significant as previously thought – another indication of an atmosphere. By comparing changes in the planet’s brightness to energy flow models, the team concluded that an atmosphere with volatile materials was the best explanation for the high temperatures. As Renyu Hu explained in a recent NASA press statement:
“If there is lava on this planet, it would need to cover the entire surface. But the lava would be hidden from our view by the thick atmosphere. Scientists have been debating whether this planet has an atmosphere like Earth and Venus, or just a rocky core and no atmosphere, like Mercury. The case for an atmosphere is now stronger than ever.”
Using Hu’s improved model of how heat would flow throughout the planet and radiate back into space, they found that temperatures on the day side would average about 2573 K (2,300 °C; 4,200 °F). Meanwhile, temperatures on the “cold” side would average about 1573 – 1673 K (1,300 – 1,400 °C; 2,400 – to 2,600 °F). If the planet had no atmosphere, the differences in temperature would be far more extreme.
As for the composition of this atmosphere, Angelo and Hu revealed that it is likely similar to Earth’s – containing nitrogen, water and even oxygen. While much hotter, the atmospheric density also appeared to be similar to that of Earth, which suggests the planet is most likely rocky (aka. terrestrial) in composition. On the downside, the temperatures are far too hot for the surface to maintain liquid water, which makes habitability a non-starter.
Ultimately, this study was made possible thanks to Hu’s development of a method that makes the study exoplanet atmospheres and surfaces easier. Angelo, who led the study, worked on it as part of her internship with JPL and adapted Hu’s model to 55 Cancri e. Previously, this model had only been applied to mass gas giants that orbit close to their respective suns (aka. “Hot Jupiters”).
Naturally, there are unresolved questions that this study helps to raise, such as how 55 Cancri e has avoided losing its atmosphere to space. Given how close the planet orbits to its star, and the fact that it’s tidally locked, it would be subject to intense amounts of radiation. Further studies may help to reveal how this is the case, and will help advance our understanding of large, rocky planets.
The application of this model to a Super-Earth is the perfect example of how exoplanet research has been evolving in recent years. Initially, scientists were restricted to studying gas giants that orbit close to their stars (as well as their respective atmospheres) since these are the easiest to spot and characterize. But thanks to improvements in instrumentation and methods, the range of planets we are capable of studying is growing.
Welcome to another edition of Constellation Friday! Today, in honor of the late and great Tammy Plotner, we take a look at “the Dolphin” – the Delphinus constellation. Enjoy!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of all the then-known 48 constellations. This treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come, effectively becoming astrological and astronomical canon until the early Modern Age.
One of these is the northern constellation of Delphinus, which translates to “the Dolphin” in Latin. This constellation is located close to the celestial equator and is bordered by Vulpecula, Sagitta, Aquila, Aquarius, Equuleus, and Pegasus. Today, Delphinus is one of the 88 modern constellations recognized by the International Astronomical Union (IAU).
Name and Meaning:
According to classical Greek mythology, Delphinus represented a Dolphin. Once you “see” Delphinus, it is not hard to picture a small dolphin leaping from the waters of the Milky Way. According to Greek legend, Poseidon wanted to marry Amphitrite, a Nereid – or sea nymph. However, she hid from him. Poseidon sent out searchers, one of whom was named Delphinus.
Can you guess who found Amphitrite and talked her into marrying? You got it. In gratitude, Poseidon placed Delphinus’ image among the stars. Not a bad call since the Nereids were known to live in the silvery caves of the deep and the silvery Milky Way is so nearby!
In the other version of the myth, it was Apollo – the god of poetry and music – who placed the dolphin among the constellations for saving the life of Arion, a famed poet and musician. Arion was born on the island of Lesbos and his skill with the lyre made him famous in the 7th century BC.
History of Observation:
The small constellation of Delphinus was one of the original 48 constellations complied by Ptolemy in the Almagest in the 2nd century CE. In Chinese astronomy, the stars of Delphinus are located within the Black Tortoise of the North (Bei Fang Xuán Wu) – one of the four symbols associated with the Chinese constellations. Delphinus was also recognized by some cultures in Polynesia – particularly the people of Pukapuka and the Tuamotu Islands.
Notable Objects:
Located very near the celestial equator, this kite-like asterism is comprised of 5 main stars and contains 19 stellar members with Bayer/Flamsteed designations. It’s primary star, Alpha Delphini (aka. Sualocin), is a multiple star system located 240 light years from Earth which consists of an aging subgiant of 2.82 Solar masses, and a companion that cannot be discerned because it is too close to its primary and too faint.
Next is Beta Delphini (aka. Rotanev), a pair of stars located approximately 101 light years from Earth. This system is comprised of a F5 III class blue-white giant and a F5 IV blue-white subgiant. If you don’t think astronomers have a sense of humor, then you better think again! Sualocin and Rotanev were both named by Italian astronomer Nicolaus Cacciatore, who simply spelled the Latin form of name (Nicolaus Venator) backwards as a practical joke!
Epsilon Delphini (aka. Deneb Dulfim) is a spectral class B6 III blue-white giant star located about 358 light years from Earth. It’s traditional name comes from the Arabic ðanab ad-dulf?n, meaning “tail of the Dolphin”. Then there’s Rho Aquilae (aka. Tso Ke), a main sequence A2V white dwarf that is 154 light years distant. The star’s traditional name means “the left flag” in Mandarin, which refers to an asterism formed by Rho Aquilae and several stars in the constellation Sagittarius.
Delphinus is also home to numerous Deep Sky Objects, like the relatively large globular cluster NGC 6934. Located near Epsilon Delphini, this cluster is roughly 50,000 light years from Earth and was discovered by William Herschel on September 24th, 1785. Another globular cluster, known as NGC 7006, can be found near Gamma Delphini, roughly 137,000 light-years from Earth.
Delphinus is also home to the small planetary nebulas of NGC 6891 and NGC 6905 (the “Blue Flash Nebula”). Whereas the former is located near Rho Aquilae about 7,200 light years from Earth, the more notable Blue Flash Nebula (named because of its blue coloring) is located between 5,545 and 7,500 light-years from Earth.
Finding Delphinus:
Delphinus is bordered by the constellations of Vulpecula, Sagitta, Aquila, Aquarius, Equuleus and Pegasus. It is visible to all viewers at latitudes between +90° and -70° and is best seen at culmination during the month of September. Are you ready to start exploring Delphinus with binoculars? Then we’ll star with Alpha Delphini, whose name is Sualocin.
Sualocin has seven components: A and G, a physical binary, and B, C, D, E, and F, which are optical and have no physical association with A and G. The primary is another rapid rotator star, whipping around at about 160 kilometers per second at its equator – or about 70 times faster than our Sun.
What it’s classification is, is confusing as well. It might a hydrogen-fusing main sequence star, and it subgiant that might just be starting to evolve. Wherever Suolocin lay in the scheme of things, there’s no use trying to resolve out the companion star, because it’s only a fraction of a second of arc away. However, Alpha’s nearby star, still makes for an interesting binocular view!
Now let’s look at Beta Delphini. Are you still ready for a smile? Good old Cacciatore wasn’t done yet. Beta’s name is Rotanev, which is a reversal of his Latinized family name, Venator. Here again we have a multiple star system. Rotanev has five components. Stars A and B are are a true physical binary star, while the others are simply optical companions. This time it’s cool to get out the telescope and split them!
Beta Delphini is a fine target for testing quality optics. At 97 light years from Earth, Rotanev’s components are only separated by about one stellar magnitude and 0.65 seconds of arc. By the way, in case you were wondering…. Nicolaus Venator was the assistant of the one and only Giuseppe Piazzi!
Are you ready for a look at Gamma Delphini? It’s the Y shape on the map. Here we have a binary star very worthy of even a small telescope. Located about a 101 light-years away from Earth, Gamma is one of the best known double stars in the night sky. The primary is a yellow-white dwarf star, a the secondary is an orange subgiant star. Both are separated by about one stellar magnitude and a very comfortable 9.2 seconds of arc apart.
Regardless of their spectral class, take a look at how differently their colors appear in the telescope. While Gamma 1 (to the west) should by all rights be white, it often appears pale yellow orange, while Gamma 2 can appear yellow, green, or blue.
Before we put our binoculars away, let’s have a look at Delta Delphini – the figure “8” on our chart. Delta has no given name, but it has a partner. That’s right, it’s also a binary star. Its identical members are too close together to see separately and only by studying them spectroscopically were astronomers able to detect their 40.58 day orbital period.
Although Delta is officially classed as a type A (A7) giant star, it has a very strange low stellar temperature and an even stranger metal abundance. So what’s going on here? Chances are the Delta pair are really class F subgiants that have just ended core hydrogen fusion and both slightly variable. Do they orbit close to one another? You bet. So close, in fact, there orbit is only about the same distance as Mercury is from our Sun!
Now let’s take out the telescopes and have a look at NGC 7006 (RA 21h 1m 29.4 Dec +16 11′ 14.4) just a few arc minutes due east of Gamma. At magnitude 10, this small and powerful globular cluster might be mistaken for a stellar point in small telescopes at low power, for a very good reason… it’s very, very far away.
It is thought to be about 125 thousand light years from the galaxy’s core and over 135 thousand light years from us – far, far beyond the galaxy’s halo where it belongs. Even though it is a Class 1 globular, the most star dense in the Shapely?Sawyer classification system, and many observers comment that it looks more planetary nebula than it does a globular cluster!
Try NGC 6934 instead (RA 20 : 34.2 Dec +07 : 24) . This 50,000 light year distant globular cluster is much brighter and larger, though at Class VIII it doesn’t even come close to having as much stellar concentration. Discovered by Sir William Herschel on September 24, 1785, you’ll enjoy this one just for the rich star field that accompanies it. For larger telescope, you’ll enjoy the resolution and the study in contrasts between these two pairs.
Now let’s take a look at 12th magnitude planetary nebula, NGC 6891 (RA 20 : 15.2 Dec +12 : 42). Here we have an almost stellar appearance, but get tight on that focus and up the magnification to reveal its nature. This is anything but a star. As Martin A. Guerrero (et al) indicated in a 1999 study:
“Narrow-band and echelle spectroscopy observations show a great wealth of structures. The bright central nebula is surrounded by an attached shell and a detached outer halo. Both the inner and intermediate shells can be described as ellipsoids with similar major to minor axial ratios, but different spatial orientations. The kinematical ages of the intermediate shell and halo are 4800 and 28000 years, respectively. The inter-shell time lapse is in good agreement with the evolutionary inter-pulse time lapse. A highly collimated outflow is observed to protrude from the tips of the major axis of the inner nebula and impact on the outer edge of the intermediate shell. Kinematics and excitation of this outflow provide conclusive evidence that it is deflected during the interaction with the outer edge of the intermediate shell.”
If you’d like a real, big, telescope galaxy challenge, try galaxy group NGC 6927, NGC 6928 and NGC 6930. The brightest is NGC 6928 at magnitude 13.5, (RA 20h 32m 51.0s Dec: +09°55’49”). None of them will be easy… But what challenge is?
Ever since the project was first conceived, scientists have been eagerly awaiting the day that the James Webb Space Telescope (JWST) will take to space. As the planned successor to Hubble, the JWST will use its powerful infrared imaging capabilities to study some of the most distant objects in the Universe (such as the formation of the first galaxies) and study extra-solar planets around nearby stars.
However, there has been a lot of speculation and talk about which targets will be the JWST’s first. Thankfully, following the recommendation of the Time Allocation Committee and a thorough technical review, the Space Telescope Science Institute (STScI) recently announced that it has selected thirteen science “early release” programs, which the JWST will spend its first five months in service studying.
As part of the JWST Director’s Discretionary Early Release Science Program (DD-ERS), these thirteen targets were chosen by a rigorous peer-review process. This consisted of 253 investigators from 18 counties and 106 scientific institutions choosing from over 100 proposals. Each program has been allocated 500 hours of observing time, once the 6-month commissioning period has ended.
As Ken Sembach, the director of the Space Telescope Science Institute (STScI), said in an ESA press statement:
“We were impressed by the high quality of the proposals received. These programmes will not only generate great science, but will also be a unique resource for demonstrating the investigative capabilities of this extraordinary observatory to the worldwide scientific community… We want the research community to be as scientifically productive as possible, as early as possible, which is why I am so pleased to be able to dedicate nearly 500 hours of director’s discretionary time to these early release science observations.”
Each program will rely on the JWST’s suite of four scientific instruments, which have been contributed by NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA). These include the the Near-Infrared Spectrograph (NIRSpec) and the Mid-Infrared Instrument (MIRI) developed by the ESA, as well as the Near-Infrared Camera (NIRCam) developed by NASA and the STScI, and the Near-Infrared Imager and Slitless Spectrograph (NIRISS) developed by the CSA.
The thirteen programs selected include “Through the looking GLASS“, which will rely on the astronomical community’s experience using Hubble to conduct slitless spectroscopy and previous surveys to gather data on galaxy formation and the intergalactic medium, from the earliest epochs of the Universe to the present day. The Principal Investigator (PI) for this program is Tommaso Treu of the University of California Los Angeles.
Another is the Cosmic Evolution Early Release Science (CEERS) program, which will conduct overlapping observations to create a coordinated extragalactic survey. This survey is intended to let astronomers see the first visible light of the Universe (ca. 240,000 to 300,000 years after the Big Bang), as well as information from the Reionization Epoch (ca. 150 million to 1 billion years after the Big Bang) and the period when the first galaxies formed. The PI for this program is Steven Finkelstein of the University of Texas at Austin.
Then there’s the Transiting Exoplanet Community Early Release Science Program, which will build on the work of the Hubble, Spitzer, and Kepler space telescopes by conducting exoplanet surveys. Like its predecessors, this will consist of monitoring stars for periodic dips in brightness that are caused by planets passing between them and the observer (aka. Transit Photometry).
However, compared to earlier missions, the JWST will be able to study transiting planets in unprecedented detail, which is anticipated to reveal volumes about their respective atmospheric compositions, structures and dynamics. This program, for which the PI is Imke de Pater from the University of California Berkeley, is therefore expected to revolutionize our understanding of planets, planet formation, and the origins of life.
Also focused on the study of exoplanets is the High Contrast Imaging of Exoplanets and Extraplanetary Systems program, which will focus on directly imaged planets and circumstellar debris disks. Once again, the goal is to use the JWST’s enhanced capabilities to provide detailed analyses on the atmospheric structure and compositions of exoplanets, as well as the cloud particle properties of debris disks.
But of course, not all the programs are dedicated to the study of things beyond our Solar System, as is demonstrated by the program that will focus on Jupiter and the Jovian System. Adding to the research performed by the Galileo and Juno missions, the JWST will use its suite of instruments to characterize and produce maps of Jupiter’s cloud layers, winds, composition, auroral activity, and temperature structure.
This program will also focus on some of Jupiter’s largest moons (aka. the “Galilean Moons”) and the planet’s ring structure. Data obtained by the JWST will be used to produce maps of Io’s atmosphere and volcanic surface, Ganymede’s tenuous atmosphere, provide constrains on these moons thermal and atmospheric structure, and search for plumes on their surfaces. As Alvaro Giménez, the ESA Director of Science, proclaimed:
“It is exciting to see the engagement of the astronomical community in designing and proposing what will be the first scientific programs for the James Webb Space Telescope. Webb will revolutionize our understanding of the Universe and the results that will come out from these early observations will mark the beginning of a thrilling new adventure in astronomy.”
During its mission, which will last for a minimum of five years (barring extensions), the JWST will also address many other key topics in modern astronomy, probing the Universe beyond the limits of what Hubble has been capable of seeing. It will also build on observations made by Hubble, examining galaxies whose light has been stretched into infrared wavelengths by the expansion of space.
Beyond looking farther back in time to chart cosmic evolution, Webb will also examine the Supermassive Black Holes (SMBH) that lie at the centers of most massive galaxies – for the purpose of obtaining accurate mass estimates. Last, but not least, Webbwill focus on the birth of new stars and their planets, initially focusing on Jupiter-sized worlds and then shifting focus to study smaller super-Earths.
John C. Mather, the Senior Project Scientist for the JWST and a Senior Astrophysicist at NASA’s Goddard Space Flight Center, also expressed enthusiasm for the selected programs. “I’m thrilled to see the list of astronomers’ most fascinating targets for the Webb telescope, and extremely eager to see the results,” he said. “We fully expect to be surprised by what we find.”
For years, astronomers and researchers have been eagerly awaiting the day when the JWST begins gathering and releasing its first observations. With so many possibilities and so much waiting to be discovered, the telescope’s deployment (which is scheduled for 2019) is an event that can’t come soon enough!