Astronomy Archives

April 20, 2009December 24, 2015 by Anne Minard

Stars Strip Atmospheres of Close-forming Planets

It may be a while yet before astronomers agree on a standard model for planet formation around stars. Until recently, after all, Earthlings lacked reliable techniques for glimpsing much beyond our own solar system.

Based on our own backyard, one prevailing theory is that rocky planets like Mercury, Earth and Mars form slowly, close to the sun, from collisions of smaller, solid bodies while gas giants form faster, and farther from the star — often within the first two million years of a star’s life — from smaller rocky cores that readily attract gases.

But new data are suggesting that some gas giants form close to their stars — so close that intense stellar winds rob them of those gases, stripping them back to their cores.

An international research team has found that giant exoplanets orbiting very close to their stars — closer than 2 percent of an Astronomical Unit (AU) — could lose a quarter of their mass during their lifetime. An AU is the distance between the Earth and the Sun.

Such planets may lose their atmospheres completely.

The team, led by Helmut Lammer of the Space Research Institute of the Austrian Academy of Sciences, believes that the recently discovered CoRoT-7b “Super Earth,” which has less than twice the mass of the Earth, could be the stripped core of a Neptune-sized planet.

The team used computer models to study the possible atmospheric mass loss over a stellar lifecycle for exoplanets at orbiting distances of less than 0.06 AU, where the planetary and stellar parameters are very well known from observations.

Mercury is our only neighbor orbiting the Sun in that range; Venus orbits at about .72 AUs.

The 49 planets considered in the study included hot gas giants, planets with masses similar or greater than that of Saturn and Jupiter, and hot ice giants, planets comparable to Uranus or Neptune. All the exoplanets in the sample were discovered using the transit method, where the size and mass of the planet is deduced by observing how much its parent star dims as it the planet passes in front of it.

“If the transit data are accurate, these results have great relevance for planetary formation theories,” said Lammer, who is presenting results at the European Week of Astronomy and Space Science, April 20-23 at the University of Hertfordshire in the UK.

“We found that the Jupiter-type gas giant WASP-12b may have lost around 20-25 percent of its mass over its lifetime, but that other exoplanets in our sample had negligible mass loss. Our model shows also that one major important effect is the balance between the pressure from the electrically charged layer of the planet’s atmosphere and the pressure from the stellar wind and coronal mass ejections (CMEs). At orbits closer than 0.02 AU, the CMEs — violent explosions from the star’s outer layers — overwhelm the exoplanet’s atmospheric pressure causing it to lose maybe several tens of percent of its initial mass during its lifetime.”

The team found that gas giants could evaporate down to their core size if they orbit closer than 0.015 AU. Lower-density ice giants could completely lose their hydrogen envelope at 0.045 AU. Gas giants orbiting at more than 0.02 AU lost about 5-7 percent of their mass. Other exoplanets lost less than 2 percent. Results suggest that CoRoT-7b could be an evaporated Neptune-like planet but not the core of a larger gas giant. Model simulations indicate that larger mass gas giants could not have been evaporated to the mass range determined for CoRoT-7b.

For more information:

The European Week of Astronomy and Space Science
The Royal Astronomical Society

April 20, 2009December 24, 2015 by Anne Minard

Most Complex Organics Ever Detected in Interstellar Space

Is your mouth watering? It should be. That molecule at left is called ethyl formate (C2H5OCHO), and it’s partly responsible for the flavors in brandy, butter, raspberries and rum.

As for this one, it’s a solvent called n-Propyl cyanide (C3H7CN); not so tasty.

They’re both highly complex organics, and they’ve both been detected in space, according to new research — adding mouth-watering evidence to the search for extra-terrestrial life.

The research team hails from Cornell University in Ithaca, New York and the University of Cologne and the Max Planck Institute for Radio Astronomy (MPIfR), both in Germany. Their discoveries represent two of the most complex molecules yet discovered in interstellar space.

To make the observations, the team used the Institut de RadioAstronomie Millimétrique (IRAM) 30m Telescope at Pico Veleta in southern Spain.

Their computational models of interstellar chemistry also indicate that yet larger organic molecules may be present — including the so-far elusive amino acids, believed to be essential for life. The simplest amino acid, glycine (NH2CH2COOH), has been looked for in the past, but has not been successfully detected. However, the size and complexity of this molecule is matched by the two new molecules discovered by the team.

The results are being presented this week at the European Week of Astronomy and Space Science at the University of Hertfordshire, in the UK.

The IRAM was focused on the star-forming region Sagittarius B2, close to the centre of our galaxy. The two new molecules were detected in a hot, dense cloud of gas known as the “Large Molecule Heimat,” which contains a luminous newly-formed star. Large, organic molecules of many different sorts have been detected in this cloud in the past, including alcohols, aldehydes, and acids. The new molecules ethyl formate n-propyl cyanide represent two different classes of molecule — esters and alkyl cyanides — and they are the most complex of their kind yet detected in interstellar space.

Atoms and molecules emit radiation at very specific frequencies, which appear as characteristic “lines” in the electromagnetic spectrum of an astronomical source. Recognizing the signature of a molecule in that spectrum is akin to identifying a human fingerprint.

“The difficulty in searching for complex molecules is that the best astronomical sources contain so many different molecules that their “fingerprints” overlap, and are difficult to disentangle,” says Arnaud Belloche, scientist at the Max Planck Institute and first author of the research paper.

“Larger molecules are even more difficult to identify because their “fingerprints” are barely visible: their radiation is distributed over many more lines that are much weaker,” added Holger Mueller, researcher at the University of Cologne. Out of 3,700 spectral lines detected with the IRAM telescope, the team identified 36 lines belonging to the two new molecules.

The researchers then used a computational model to understand the chemical processes that allow these and other molecules to form in space. Chemical reactions can take place as the result of collisions between gaseous particles; but there are also small grains of dust suspended in the interstellar gas, and these grains can be used as landing sites for atoms to meet and react, producing molecules. As a result, the grains build up thick layers of ice, composed mainly of
water, but also containing a number of basic organic molecules like methanol, the simplest alcohol.

“But,” says Robin Garrod, an astrochemist at Cornell University, “the really large molecules don’t seem to build up this way, atom by atom.” Rather, the computational models suggest that the more complex molecules form section by section, using pre-formed building blocks that are provided by molecules, such as methanol, that are already present on the dust grains. The computational models show that these sections, or “functional groups,” can add together efficiently, building up a molecular “chain” in a series of short steps. The two newly-discovered molecules seem to be produced in this way.

Adds Garrod, “There is no apparent limit to the size of molecules that can be formed by this process — so there’s good reason to expect even more complex organic molecules to be there, if we can detect them.”

The team believes this will happen in the near future, particularly with future instruments like the Atacama Large Millimeter Array (ALMA) in Chile.

Sources: Royal Astronomical Society. The original paper is in press in the journal Astronomy & Astrophysics.

European Week of Astronomy and Space Science
Max Planck Institute for Radio Astronomy
Cologne Database for Molecular Spectroscopy
Reference list of all 150 molecules presently known in space
Cornell University
Institut fuer Radioastronomie im Millimeterbereich (IRAM)
Atacama Large Millimeter Array (ALMA)

April 19, 2009April 26, 2016 by Anne Minard

UK, US Astronomers: That’s One Cool Star

An international team, led by astronomers at the University of Hertfordshire in the UK, has discovered one of the coolest sub-stellar bodies ever found outside our own solar system.

The new object — dubbed Wolf 940B — orbits the red dwarf star Wolf 940, 40 light years from Earth. It’s thought to have formed like a star, but has ended up looking more like Jupiter. It is roughly the same size, despite being between 20 and 30 times as heavy, and when the infrared spectral “fingerprints” of the two objects are compared, their resemblance is striking, say Wolf 940B’s discoverers.

wfcam-fisheye_md — The Wide Field Camera (long black tube) on the United Kingdom Infrared Telescope on Mauna Kea, Hawaii.

Wolf 940B was initially discovered as part of a major infrared sky survey – the UKIRT Infrared Deep Sky Survey (UKIDSS) which is being carried out using the United Kingdom Infrared Telescope (UKIRT) on Mauna Kea in Hawaii. The telescope’s wide field camera is the long black tube in the image at left.

The object was found as part of a wider effort to find the coolest and least luminous bodies in our local Galactic neighborhood, but it was then found to be a companion to the nearby red dwarf Wolf 940 through its common motion across the sky. The data used to confirm the discovery were obtained using telescopes in Chile, the Canary Islands and Hawaii.

Its temperature was then confirmed using data from the Gemini-North telescope on Mauna Kea. The findings are being reported at the European Week of Astronomy and Space Science (NAM 2009) at the University of Hertfordshire, and will soon be published in the Monthly Notices of the Royal Astronomical Society.

The new object orbits its star at about 440 times the distance at which the Earth orbits the sun. At such a wide distance, it takes about 18,000 years to complete a single orbit.

Too small to be stars, so-called “brown dwarfs” have masses lower than stars but larger than gas giant planets like Jupiter. Due to their low temperatures, these objects are very faint in visible light, and are detected by their glow at infrared wavelengths.

“Although it has a temperature of 300 degrees Celsius [572 degrees F], which is almost hot enough to melt lead, temperature is relative when you study this sort of thing, and this object is very cool by stellar standards,” said Ben Burningham, of the University of Hertfordshire. “In fact, this is the first time we’ve been able to study an object as cool as this in such detail. The fact that it is orbiting a star makes it extra special.”

Modeling the atmospheres of cool brown dwarfs is a complex task, but it is key to understanding planets that orbit other stars. Models of emitted light from such objects, which are dominated by absorption due to water and methane gas, are sensitive to assumptions about their age and chemical make-up.

In most cases, astronomers don’t initially know much about the age and composition of brown dwarfs — and this can make it hard to tell where the models are right, and where they are going wrong.

“What’s so exciting in this case, is that we can use what we know about the primary star to find out about the properties of the brown dwarf, and that makes it an extremely useful find,” Burningham said. “You can think of it as a Rosetta Stone for decrypting what the light from such cool objects is telling us.”

Wolf 940A, the red dwarf star that is Wolf 940B’s namesake, was first catalogued by the pioneering German astronomer Max Wolf 90 years ago.

“Red dwarfs are the most populous stars in the Galaxy, and systems like this may be more common than we know” said David Pinfield, also of the University of Hertfordshire. “As the generation of ongoing large scale surveys continues, we may discover a pack of Wolf-940B-like objects in our solar back yard.”

Source: Joint Astronomy Centre. For more information, visit:

The UK Infrared Telescope
NAM 2009
Gemini Observatory

April 19, 2009April 26, 2016 by Anne Minard

Orion’s Belt Sees More Action Than We Knew

Using infrared telescopes, European and American astronomers have peered through the opaque molecular cloud that obscures much of Orion’s stellar nursery from view.

They’ve discovered a rowdy scene there — a crowded stellar nursery, with young stars shooting supersonic hydrogen jets in all directions — and they’re reporting there is much more going on in Orion than previously thought.

The new survey is the most wide-ranging census ever produced of dynamical star formation in and around the well-known Great Nebula of Orion.

In the United Kingdom Infrared Telescope/Spitzer Space Telescope image above, parts of the Orion Molecular cloud are illuminated by nearby stars and glowing an eerie green. The jets punch through the cloud and can be seen as tiny pink-purple arcs, knots and filaments. The golden orange young stars that drive the jets can usually be seen nearby.

Below, a gas jet (seen in red) pops out of a busy region of star formation in Orion. All the red wisps, knots and filaments are in fact associated with jets from young stars, which in this figure are colored orange. The data were acquired with the Wide Field Camera at the United Kingdom Infrared Telescope. (Story continues beneath image.)

The Orion Molecular Cloud is more than 20 times the angular size of the full moon, spanning from far above the hunter’s head to far below his feet. Most of the action is hidden from view in visible light. Earthbound stargazers can see he brightest stars, like Betelgeuse and Rigel at the shoulder and knee of the constellation, and perhaps the Orion Nebula as a vaguely fuzzy patch around the sword. The nebula, which is really just a blister on the surface of the cloud, gives the only indication of the chaos within.

The team studied the region with the United Kingdom Infrared Telescope (UKIRT) on Mauna Kea, the Spitzer Space Telescope, which works at even longer “mid-infrared” wavelengths, and the IRAM Millimeter-wave (radio) Telescope in Spain.

The power of the census came from the combination of data from all three facilities, the researchers say. Inspired by the richness of his images from UKIRT, Chris Davis, of Hawaii’s Joint Astronomy Centre, contacted colleagues in Europe and on the United States mainland.

Tom Megeath, an astronomer from the University of Toledo, provided a catalogue of the positions of the very youngest stars – sources revealed only recently by the Spitzer Space Telescope.

Thomas Stanke, a researcher based at the European Southern Observatory in Garching, Germany, then provided extensive IRAM maps of the molecular gas and dust across the Orion cloud.

Dirk Froebrich, a lecturer at the University of Kent, later used archival images from the Calar Alto Observatory in Spain (data acquired by Stanke some 10 years ago) to measure the speeds and directions of a large number of jets by comparing them with their positions in the new images.

Armed with these data, Davis was able to match the jets up to the young stars that drive them, as well as to density peaks within the cloud – the natal cores from which each star is being created.

“Regions like this are usually referred to as stellar nurseries, but we have shown that this one is not being well run: it is chaotic and seriously overcrowded,” Davis said. “Using UKIRT’s wide field camera, we now know of more than 110 individual jets from this one region of the Milky Way. Each jet is traveling at tens or even hundreds of miles per second; the jets extend across many trillions of miles of interstellar space. Even so, we have been able to pinpoint the young stars that drive most of them.”

Andy Adamson, associate director at the UKIRT, added that the dataset “demonstrates the power of survey telescopes like UKIRT. With on-line access to data from other telescopes around the world, and the ease with which one can communicate with collaborators across the globe, massive projects like the Orion study are very much the future of astronomy.”

Several of the researchers are presenting their discoveries with colleagues at this year’s annual National Astronomy Meeting of the UK (NAM 2009).

Source: Joint Astronomy Centre. For more information, visit

The UK Infrared Telescope
The Spitzer Space Telescope
The IRAM Millimeter-wave Telescope
NAM 2009
Royal Astronomical Society

April 18, 2009December 24, 2015 by Tammy Plotner

Reporting From the NorthEast Astronomy Forum

So what’s more fun than a barrel of monkeys? Try acres of telescopes and hundreds of amateur astronomers. If you’re not familiar with NEAF then let me introduce you into some of the fun that’s been going on for almost two decades at Rockland College in Suffern, New York.

When NEAF first began, it was a small affair sponsored by the Rockland Astronomy Club and held in a cozy corner of the college campus. As each successive year passed, the event expanded and grew more popular – drawing ever larger crowds from further distances and encompassing every aspect of astronomy. Today, some 18 years later, the NorthEast Astronomy Fourm’s speaker, vendor and guest list reads like a virtual “who’s who”… Yet, unlike other social events, a gathering of astronomers is, well… a gathering of astronomers. If you’re not wearing your favorite battered space t-shirt and willing to talk about telescopes, imaging techniques, eyepieces, tripods, supernovae and the latest recipe for calamari in chocolate sauce then you just might be in the wrong place.

If you want to know what’s new on the market? Then take a walk around. There’s what seems like endless acres of the latest technology and the best representatives of each company willing to take the time to talk to you about their products. It doesn’t matter whether you’re looking or cooking – the point is getting what’s available to the public to be seen, tested, talked about, and drooled on. There are telescopes here that none of us will ever be able to afford – but that’s part of the beauty of NEAF. At least these magnificent instruments are here for us to see, and more than a fair share of equipment we can’t usually find readily available offered at prices that are darn hard to refuse. And if you’re feeling lucky? The vendors who come here are hugely generous and give away thousands upon thousands of dollars worth of merchandise to the guests in door prizes.

But, NEAF is a whole lot more than just a sales floor. Two days prior to the event is the NorthEast Astro-Imaging Conference, where some of the finest minds share their talents and their secrets with all who are willing to listen. During the weekend, guests can enjoy planetarium programs, amateur telescope making workshops, or engage in fine array of guest speakers. Why not step outside and enjoy the sunshine while you’re here, too? Because the courtyard is always filled with a huge array of solar telescopes where you’ll have the opportunity to see our nearest star through every aperture and wavelength you can imagine.

Is it all about astronomy? Yeah. It is. The astronomy family. And nothing makes the astronomy family more happy than to see a smiling face. It can be the smiling face of the fellow you’ve seen at every star party and astronomy event for the last 15 years and never did catch his name – or it might be the smiling face of a child who has a plastic bag filled with tiny treaures accumlated through the day. And sometimes the smiling face you see?

Is your own at the end of a day at NEAF.

April 17, 2009December 24, 2015 by Anne Minard

How to Keep Asteroids Away: Tie Them Up

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It may not look like much, but that drawing could save a life someday — or 7 billion.

David French, a doctoral candidate in aerospace engineering at North Carolina State University is proposing a new tool for the anti-asteroid arsenal.

French said his PhD advisor Andre Mazzoleni, an associate professor of mechanical and aerospace engineering at the university, were not beholden to grant funds and “we just decided to go off on a direction that’s interesting and exciting.”

Mazzoleni has worked with tethers in other applications, and the two have now come up with a way to effectively divert asteroids and other threatening objects from impacting Earth by attaching a long tether and ballast to the incoming object.

By attaching the ballast, French explains, “you change the object’s center of mass, effectively changing the object’s orbit and allowing it to pass by the Earth, rather than impacting it.”

NASA’s Near Earth Object Program has identified more than 1,000 “potentially hazardous asteroids” and they are finding more all the time. “While none of these objects is currently projected to hit Earth in the near future, slight changes in the orbits of these bodies, which could be caused by the gravitational pull of other objects, push from the solar wind, or some other effect could cause an intersection,” French explains.

He said it’s hard to imagine the scale of both the problem and the potential solutions — but he points out that some asteroid impacts on Earth have been catastrophic.

“About 65 million years ago, a very large asteroid is thought to have hit the Earth in the southern Gulf of Mexico, wiping out the dinosaurs, and, in 1907, a very small airburst of a comet over Siberia flattened a forest over an area equal in size to New York City,” he said. “The scale of our solution is similarly hard to imagine.”

The idea is to use a tether somewhere in length between 1,000 kilometers (621 miles; roughly the distance from Raleigh to Miami) to 100,000 kilometers (62,137 miles; you could wrap this around the Earth two and a half times).

Other ideas that have emerged sound no less extreme, French notes. Those include painting the asteroids in order to alter how light may influence their orbit, a plan that would guide a second asteroid into the threatening one, and nuclear weapons.

“They probably all have their merits and drawbacks,” he said. “Nuclear weapons are already accessible; we’ve already made them. I can look at my own idea and say it’s long duration and very trackable.”

A tether effort could last in the ballpark of 20 to 50 years, he said, depending on the size and shape of the asteroid and its orbit, and the size of ballast.

French acknowledges there are “technical barriers that have to be surpassed.”

“First, you would have to mitigate the rotation of the asteroid,” he said, adding that the crescent-shaped piece connecting the poles on a globe might make a good conceptual model for a tether anchor, because it would allow for the asteroid’s rotation.

Another problem is the composition,” he added. “Some asteroids are just rubble piles.”

French said his idea was never to have all the kinks worked out on his model before presenting it; he just hoped to add another option to the asteroid-preparedness table.

“We’re opening up the concept, and we invite the broader scientific community to help us solve the issues,” he said.

Source: An NC State press release, via Eurekalert, and an interview with David French.

April 16, 2009December 24, 2015 by Tammy Plotner

Weekend SkyWatcher’s Forecast – April 17-19, 2009

Greetings, fellow SkyWatchers! Are you ready for a much darker weekend? I’m off to NEAF, but while I’m gone, I hope you’ll take advantage of the weekend to enjoy a little galaxy hunting and a minor meteor shower? If not, how about a great variable star – or the “Eight Burst Planetary”! Finding Comet Yi-SWAN will be easy Sunday night, but be sure to set your alarm early for Sunday morning, because there’s something very worth getting up to see…

Friday, April 17, 2009 – On this date in 1976, the joint German and NASA probe Helios 2 came closer to the Sun than any other spacecraft so far. One of its most important contributions helped us to understand the nature of gamma ray bursts.

Let’s begin our evening with a burst of galaxies in Hydra about 5 degrees due west of the Xi pairing (RA 10 36 35 Dec –27 31 03). Centermost are two fairly easy to spot ellipticals, NGC 3309 and NGC 3311, accompanied by spiral NGC 3322. Far fainter are other group members, such as NGC 3316 and NGC 3314 to the east of the 7th magnitude star; and NGC 3305 north of the 5th magnitude star. Although such galaxy clusters as the NGC 3308 region are not for everyone, studying those very faint fuzzies is a rewarding experience for those with large aperture telescopes.

Now let’s kick back and watch the peak of the Sigma Leonid meteor shower. The radiant is traditionally located on the Leo–Virgo border but has migrated to Virgo in recent years. Thanks to Jupiter’s gravity, this shower may eventually become part of the Virginid Complex as well. The fall rate is very low at around 1–2 per hour.

While we’re watching, let’s talk about Giovanni Riccioli, who was born on this date in 1598. Italian astronomer Riccioli was the first to observe a double star in the year 1650. . .and it was one you’ve probably observed, too – Mizar! He also watched shadow transits on Jupiter and did many lunar studies, including mapping. If you’ve ever wondered who gave such fanciful names to the lunar maria, or tagged the major craters with names of famous scientists and philosophers, now you know that it was Riccioli!

Saturday, April 18, 2009 – Today let’s take a look at the 1838 birth of Paul-Emile Lecoq de Boisbaudran on this date, who improved the field of spectroscopic identification and spent many years scanning minerals for undiscovered spectral lines. His persistence finally netted him the discovery of three new elements!

Tonight let’s start out ‘‘elemental’’ as we use binoculars to identify R Corvi , located almost dead center in the Corvus ‘‘rectangle’’ and to the southwest of its companion field stars. Although variable stars are not every one’s cup of tea, R (RA 12 19 37 Dec –19 15 21) has changed greatly in a little less than a year—from magnitude 8 to as faint as magnitude 14! This Mira-type star should be nearing its maximum, so be sure to try it before it fades away…

Now let’s head out in search of an object that is one royal navigation pain for the Northern Hemisphere but makes up for it in beauty. Start with the southernmost star in Crater, Beta. If you have difficulty identifying it, it’s the brightest star east of the Corvus rectangle. Now hop a little more than a fist-width southeast to reddish Alpha Antilae. Less than a fist-width below, you will see a dim 6th magnitude star, which may require binoculars in the high north. Another binocular field further southwest and about 4 degrees northwest of Q Velorum is our object,NGC 3132 (RA 10 07 01 Dec –40 26 11). If you still have no luck, try waiting until Regulus has reached your meridian and head fully 52 degrees south. More commonly known as the ‘‘Southern Ring’’ or the ‘‘Eight Burst Planetary,’’ this gem is brighter than the northern ‘‘Ring’’ (M57) and definitely shows more details. Able to be captured in even small instruments, larger ones will reveal a series of overlapping shells, giving this unusual nebula its name.

Sunday, April 19, 2009 – Don’t sleep in this morning! It’s worth getting up early to see Jupiter and the Moon only about a fingerwidth apart in the morning sky. If you check out the pair in binoculars, you’ll notice faint little Neptune is also a part of this early morning trio!

On this date in 1971, the world’s first space station was launched, the Soviet research vessel Salyut 1. Six weeks later, Soyuz 11 and its crew of three docked with the station, but a mechanism failed, denying them entry. The crew conducted their experiments, but were sadly lost when their re-entry module separated from the return spacecraft and depressurized. Although the initial phase of Salyut 1 seemed doomed, the mission continued to enjoy success through the early 1980s and paved the way for Mir.

Now, tonight let’s try picking up a globular cluster in Hydra that is located about three finger-widths southeast of Beta Corvi and just a breath northeast of the double star A8612—namely, M68. This class X globular cluster was discovered in 1780 by Charles Messier, and first resolved into individual stars by William Herschel in 1786. At a distance of approximately 33,000 light-years, it contains at least 2,000 stars, including 250 giants and 42 variables. It will show as a faint, round glow in binoculars, and small telescopes will perceive individual members. Large telescopes will fully resolve this small globular to the core!

If you managed M68, and can find the famous Perseus “Double Cluster”, then surely you can tackle Comet C/2009 Yi-SWAN! Need a chart? Then here it is…

Until next week? Dreams really do come true when you keep on reaching for the stars!

This week’s awesome images (in order of appearance) are: NGC 3308 region (credit—Palomar Observatory, courtesy of Caltech), Map showing Riccioli features (historical image), R Corvi and NGC 3132 (credit—Palomar Observatory, courtesy of Caltech), Salyut 1 (credit—NASA) and M68 (credit—Palomar Observatory, courtesy of Caltech. We thank you so much!

April 16, 2009December 24, 2015 by Anne Minard

Researchers Describe ‘Most Spectacular and Most Disturbed’ Galaxy Cluster

Composite image of MACSJ0717. Credit: X-ray (NASA/CXC/IfA/C. Ma et al.); Optical (NASA/STScI/IfA/C. Ma et al.)

It’s hot. It’s crowded. And it’s one of the most raucuous space parties astronomers have ever seen.

A research team using a combination of three powerful telescopes is spilling the beans on the galaxy cluster MACSJ0717.5+3745 (MACSJ0717 for short), located about 5.4 billion light years from Earth. The wild system contains four separate galaxy clusters undergoing a triple merger — the first time such a phenomenon has been documented — and that’s just the beginning.

Galaxy clusters are the largest objects bound by gravity in the Universe. Using data from NASA’s Chandra X-ray Observatory, Hubble Space Telescope and the Keck Observatory on Mauna Kea, Hawaii, astronomers were able to determine the three-dimensional geometry and motion in MACSJ0717.

Its 13-million-light-year-long stream of galaxies, gas and dark matter — known as a filament — is pouring into a region already full of galaxies. Like a freeway of cars emptying into a full parking lot, this flow of galaxies has caused one collision after another.

“In addition to this enormous pileup, MACSJ0717 is also remarkable because of its temperature,” said lead author Cheng-Jiun Ma, of the University of Hawaii. “Since each of these collisions releases energy in the form of heat, MACS0717 has one of the highest temperatures ever seen in such a system.”

While the filament leading into MACJ0717 had been previously discovered, these results show for the first time that it was the source of this galactic pummeling. The evidence is two-fold. First, by comparing the position of the gas and clusters of galaxies, the researchers tracked the direction of clusters’ motions, which matched the orientation of the filament in most cases. Secondly, the largest hot region in MACSJ0717 is where the filament intersects the cluster, suggesting ongoing impacts.

“MACSJ0717 shows how giant galaxy clusters interact with their environment on scales of many millions of light years,” said team member Harald Ebeling, also from the University of Hawaii. “This is a wonderful system for studying how clusters grow as material falls into them along filaments.”

Computer simulations show that the most massive galaxy clusters should grow in regions where large-scale filaments of intergalactic gas, galaxies, and dark matter intersect, and material falls inward along the filaments.

“It’s exciting that the data we get from MACSJ0717 appear to beautifully match the scenario depicted in the simulations,” said Ma.

In the future, Ma and his team hope to use even deeper X-ray data to measure the temperature of gas over the full 13-million-light-year extent of the filament. Much remains to be learned about the properties of hot gas in filaments and whether infall along these structures can significantly heat the gas in clusters over large scales.

“This is the most spectacular and most disturbed cluster I have ever seen,” says Ma, “and we think that we can learn a whole lot more from it about how structure in our Universe grows and evolves.”

The paper describing these results appeared in the March 10 issue of Astrophysical Journal Letters.

Source: Harvard University’s Chandra site. More information can be found at NASA’s Chandra site, and the paper is available here.

April 16, 2009December 24, 2015 by Tammy Plotner

Bridge Between the Stars – NGC 602: Hubble Visualization by Jukka Metsavainio

NGC 602 Parallel Hubble Visualization by Jukka Metsavainio

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It’s been awhile hasn’t it? Time may have passed, but absence makes the heart grow fonder. For those of you who have missed our very special dimensional looks into the Cosmos, then it’s high time we let our minds and eyes relax and we take a 200 thousand light-year distant journey towards the edge of the Small Magellanic Cloud for a look at a bright, young open cluster of stars known as NGC 602…

Whenever we present a dimensional visualization it is done in two fashions. The first is called “Parallel Vision” and it is much like a magic eye puzzle. When you open the full size image and your eyes are the correct distance from the screen, the images will seem to merge and create a 3D effect. However, for some folks, this doesn’t work well – so Jukka has also created the “Cross Version”, where you simply cross your eyes and the images will merge, creating a central image which appears 3D. Upon further study, we’ve also come to realize that there is a certain percentage of people who also are unable to make this happen as well. You aren’t weird – just a percentage. Here’s why…

Typical for hunting animals (as opposed to ‘prey’ animals), we have our eyes set in the front of our heads. Our eyes are typically about 2½ inches apart, and so they see slightly different versions of the scene in front of them, from which the visual part of our brain constructs an internal three-dimensional model. Thus a human being can directly estimate the distance of something without moving a muscle – an important evolutionary advantage for a hunter. The trick is to then ‘fool’ the brain into processing the photographic images as if they really were distant scenes, not just color photos a few inches away. First, you will need a piece of white card, about 12 inches long. You hold the card vertically between your eyes and the pictures, so that it touches the centerline of the stereo pairs. Next? A pair of cheap reading glasses. If you usually have to wear reading glasses then you’ll need a higher power. Try different pairs in the store until you find one that will allow you see sharply no further away than a little over 12 inches. That’s it! Then sit back, relax and prepare to be blown away…

NGC 602 Cross Hubble Visualization by Jukka Metsavainio

Cruising along some 200 thousand light-years away from the Milky Way is the Small Magellanic Cloud – a satellite galaxy of ours. Sitting on its edge is cloud of gas and dust which comprise a nebula known as M90, and within it shines a sparkling cluster of new stars called NGC 602. But these new stars aren’t shy… They’re hot and massive. The radiation and shock waves which pour from them have pushed the nebula away, compressing it and triggering new star formation. While these pre-main sequence embryonic suns lay hidden to all but infrared wavelengths, the beauty of this area is the chemical properties it shares with our own galaxy.

According to the studies of L.R. Carlson (et al) NGC 602’s star formation at a low chemical abundance makes it a “good analog to the early universe in terms of examining the processes and patterns of star formation. This cluster in particular is ideally suited to this aim. Its location in the wing of the SMC means that, while its chemical properties should be similar to those of the rest of the galaxy, it is relatively isolated.” Isolated… But young, very young. Says Carlson, “This pre-Main Sequence population formed coevally with the central cluster about 5 million years ago. Spitzer Space Telescope (SST) images of the region in all four Infrared Array Camera (IRAC) bands reveal a second population of Young Stellar Objects (YSOs), which formed after the stars seen with HST/ACS imaging. Some of these very young objects are still embedded in nebular material. We infer that star formation started in this region less than five million years ago with the formation of the central cluster and gradually propagated towards the outskirts where we find evidence of on going star formation less than a million years old.”

Another interesting factor is NGC 602’s position in the wing of the Small Magellanic Cloud leading to the Magellanic Bridge – a stream of neutral hydrogen which connects the two Magellanic Clouds like a invisible cord. While it’s mostly comprised of low-metallicity gas there have been two early-type stars found inside it. The Magellanic Bridge is also a favored region for investigations of interstellar gas and star formation in very low metallicity region… Much like the home of our bright young cluster. Why is this so fascinating? Because studying star formation in regions like this gives astronomers a look at what may happen during galaxy formation – long before heavier elements are created from successive generations of stars undergoing nuclear fusion.

So, as you look deep into this bridge between the stars, gaze with wonder at the long “elephant trunks” of dust and turn your mind towards these beautiful, bright blue stars still forming from gravitationally collapsing gas clouds. It is a very unique event, occurring where it should not happen – but is. A true bridge between the stars…

And touchstone to the Cosmos.

Many thanks to Jukka Metsavainio for his magic with Hubble Space Telescope images and allowing us this incredible look inside another mystery of space.

April 15, 2009December 24, 2015 by Ian O'Neill

Constraining the Orbits of Planet X and Nemesis

Artists impression of the hypothetical star, Nemesis (Wikipedia)

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If Planet X was out there, where would it be? This question posed by an Italian researcher turns out to be a lot more involved than you’d think. As opposed to all the 2012 ~~idiocy~~ hype flying around on the internet, this research is actually based on a little thing called science. By analysing the orbital precession of all the inner-Solar System planets, the researcher has been able to constrain the minimum distance a hypothetical object, from the mass of Mars to the mass of the Sun, could be located in the Solar System. As most of the astronomical community already knows, the two purveyors of doom (Planet X and the Sun’s evil twin, Nemesis) exist only in the over-active imaginations of a few misinformed individuals, not in reality…

Planet X and Nemesis are hypothetical objects with more grounding in ancient prophecy and doomsday theories based on pseudo-science. This might be the case, but Planet X came from far more rational beginnings.

The name “Planet X” was actually coined by Percival Lowell at the start of the 20th century when he predicted there might be a massive planet beyond the orbit of Neptune. Then, in 1930, Clyde Tombaugh appeared to confirm Lowell’s theory; a planet had been discovered and it was promptly named Pluto. However, as time went on, it slowly became apparent that Pluto wasn’t massive enough to explain the original observations of the perturbations of Uranus’ orbit (the reason for Lowell’s Planet X prediction in the first place). By the 1970’s and 80’s modern observation techniques proved that the original perturbations in Uranus’ orbit were measurement error and not being caused by a massive planetary body. The hunt for Planet X pretty much ended with the discovery of Pluto in 1930, but it never lived up to its promise as a massive planetary body (despite what the woefully erroneous doomsday theories say otherwise).

Now an Italian researcher has published results from a study that examines the orbital dynamics of the inner-Solar System planets, and relates them to the gravitational influence of a massive planetary body orbiting the Sun from afar.

To cut a long story short, if a massive planetary body or a small binary sibling of the Sun were close to us, we would notice their gravitational influence in the orbital dynamics of the planets. There may be some indirect indications that a small planetary body might be shaping the Kuiper Cliff, and that a binary partner of the Sun might be disturbing the Oort Cloud every 25 million years or so (relating to the cyclical mass extinctions in Earth’s history, possibly caused by comet impacts), but hard astronomical proof has yet to be found.

Lorenzo Iorio from the National Institute of Nuclear Physics in Pisa (Italy) has taken orbital data from many years of precise observations and used his computations to predict the closest possible distance at which a massive planet could orbit if it was out there.

It turns out that all the planets the mass of Mars and above have been discovered within the Solar System. Iorio computes that the minimum possible distances at which a Mars-mass, Earth-mass, Jupiter-mass and Sun-mass object can orbit around the Sun are 62 AU, 430 AU, 886 AU and 8995 AU respectively. To put this into perspective, Pluto orbits the Sun at an average distance of 39 AU.

So if we used our imaginations a bit, we could say that a sufficiently sized Planet X could be patrolling a snail-paced orbit somewhere beyond Pluto. But there’s an additional problem for Planet X conspiracy theorists. If there was any object of sufficient size (and by “sufficient” I mean Pluto-mass, I’m being generous), according to a 2004 publication by David Jewitt, from the Institute for Astronomy, University of Hawaii, we would have observed such an object by now if it orbited within 320 AU from the Sun.

Suddenly, the suggestion that Planet X will be making an appearance in 2012 and the crazy idea that anything larger than a Pluto-sized object is currently 75 AU away seems silly. Sorry, between here and a few hundred AU away, it’s just us, the known planets and a load of asteroids (and perhaps the odd plutino) for company.

Source: arXiv, Astroengine.com