Tammy was a professional astronomy author, President Emeritus of Warren Rupp Observatory and retired Astronomical League Executive Secretary. She’s received a vast number of astronomy achievement and observing awards, including the Great Lakes Astronomy Achievement Award, RG Wright Service Award and the first woman astronomer to achieve Comet Hunter's Gold Status.
(Tammy passed away in early 2015... she will be missed)
Pluto's newest found moon, P4, orbits between Nix and Hydra, both of which orbit beyond Charon. Could there be still more moons of Pluto? Perhaps, and the New Horizons team plans to look harder to ensure that we don't run into something that could damage or destroy New Horizons. Credit: NASA
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With nearly two-thirds of its journey complete, the New Horizons spacecraft is still alive and well. It recently experienced a “hibernation wakeup” which started on November 5th and will last until November 15th… and it will sleep again until a month-long call in January. However, the real “wakeup call” may be when it reaches the complicated Pluto system. Watch out for that rock!
As more and more moons are discovered around Pluto, the higher the probability becomes of one of them – or debris surrounding them – could impact the delicate probe. With P4 discovered just a few short months ago, scientists are beginning to wonder just how many more are there which are too small and faint to be seen.
Says New Horizons Principal Investigator Alan Stern: “Even more worrisome than the possibility of many small moons themselves is the concern that these moons will generate debris rings, or even 3-D debris clouds around Pluto that could pose an impact hazard to New Horizons as it flies through the system at high speed. After all, at our 14-kilometer-per-second flyby speed, even particles less than a milligram can penetrate our micrometeoroid blankets and do a lot of damage to electronics, fuel lines and sensors.”
To enable research into what might be a prospective problem, the New Horizons team brought together about 20 of the world’s experts in ring systems, orbital dynamics and state-of-the-art astronomical observing techniques to search for small satellites and rings at distant Pluto. During a two day workshop, the group hashed and rehashed every possible scenario – including all the hazards that a small moon and debris-strewn system might cause.
The presenters and attendees of the New Horizons Pluto Encounter Hazards Workshop on November 4, 2011. Credit: NASA
“We found a plausible chance that New Horizons might face real danger of a killer impact; and that to mitigate that hazard, we need to undertake two broad classes of work.” said Stern. “First, we need to look harder at the Pluto system for still undiscovered satellites and rings. The best tools for this are going to be the Hubble Space Telescope, some very large ground-based telescopes, telescopes that can make stellar occultation observations of the space between Pluto and Charon where New Horizons is currently targeted, and thermal observations of the system by the ALMA radio telescope array just now being commissioned.”
The next step is planning – planning on a possible safer route through the Pluto system in the event that observations confirm navigational hazards. Studies presented at the Encounter Hazards Workshop show a good “safe haven bailout trajectory” (or SHBOT) could be designed to target a closest-approach aim point about 10,000 kilometers farther than the nominal mission trajectory. In this case, it would be a matter of aiming more towards Charon’s orbit, where the moon itself has cleared a path. However, even 180 degrees away on closest approach may not be enough. There’s always a chance of a debris field – one that doesn’t follow a plane, but has created a torus. In this event, material could be sailing along at speeds of up to 1-2 kilometers per second. Enough to annihilate delicate instruments.
“The question of whether the Pluto system could be hazardous to New Horizons remains open –but one we’ll be studying hard over the next year, with everything from computer models to big ground-based telescopes to the Hubble.” concludes Stern. “I’ll report on results as we obtain them, but it is not lost on us that there is a certain irony that the very object of our long-held scientific interest and affection may, after so many years of work to reach her, turn out to be less hospitable than other planets have been. We’ll see.”
This image highlights the special cargo onboard NASA's Voyager spacecraft: the Golden Record. Each of the two Voyager spacecraft launched in 1977 carry a 12-inch gold-plated phonograph record with images and sounds from Earth. An artist's rendering of the Voyager spacecraft is shown at bottom right, with a yellow circle denoting the location of the Golden Record. The cover of the Golden Record, shown on upper right, carries directions explaining how to play the record, a diagram showing the location of our sun and the two lowest states of the hydrogen atom as a fundamental clock reference. The larger image to the left is a magnified picture of the record inside. Credit: NASA
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Greeting cards in space… We’ve certainly sent our share of them, haven’t we? So if humankind is foresighted enough to leave messages of our whereabouts – and our personalities – in space, then why haven’t other alien civilizations done the same? That’s a question a pair of postdoctoral researchers at Penn State are asking. By using mathematical equations, they’re showing us we simply haven’t looked in enough places… and would we recognize an alien artifact even if it were staring us in the face?
“The vastness of space, combined with our limited searches to date, implies that any remote unpiloted exploratory probes of extraterrestrial origin would likely remain unnoticed,” report Jacob Haqq-Misra, Rock Ethics Institute, and Ravi Kumar Kopparapu, Earth and Environmental Systems Institute, in a paper accepted by Acta Astronautica and posted online on ArXiv.
So far, we simply haven’t found any evidence of alien artifacts in our solar system – or anywhere else for that matter. According to the Penn State article, the Fermi paradox, originally formulated by Enrico Fermi, asks, if intelligent life is common, why have no technological civilizations been observed. Well, shucks… Maybe they’re shy – and maybe they’ve self-annihilated. There are hundreds of reasons “why” we haven’t found anything, but the most pertinent answer is we simply aren’t looking for the right thing in the right place at the right time. For example, have a look at just a few of the things we humans have sent into vastness of space to act as our ambassadors…
Duke Family Portrait: Apollo 16 Journal - Courtesy of Markus Mehring - Credit: NASA AS16-117-18841Pioneer 10 and 11's famed Plaque features a design engraved into a gold-anodized aluminum plate, 152 by 229 millimeters (6 by 9 inches), attached to the spacecrafts' antenna support struts to help shield it from erosion by interstellar dust. Image Credit: NASAThree LEGO figurines representing the Roman god Jupiter, his wife Juno and Galileo Galilei are shown here aboard the Juno spacecraft. Image credit: NASA/JPL-Caltech/KSC NASA's Jupiter-bound Juno spacecraft will carry the 1.5-inch likeness of Galileo Galilei, the Roman god Jupiter and his wife Juno to Jupiter when the spacecraft launches this Friday, Aug. 5. The inclusion of the three mini-statues, or figurines, is part of a joint outreach and educational program developed as part of the partnership between NASA and the LEGO Group to inspire children to explore science, technology, engineering and mathematics. Credit: NASA
And this is only just the tip of the human iceberg. How many of us have sent our name on missions to Mars, Pluto and more? There are footprints, plaques, flags, golf balls and an endless parade of human artifacts scattered far and wide. We might think they’re in plain sight, but would an alien culture see that? Would we comprehend what an alien culture might consider to be a greeting or sign or their presence? As far as we know, there could be unpiloted probes from alien civilizations out there right now, checking us out… But unless it were something the size of a proverbial school bus dropping itself on a house in Essex, our own arrogance would probably keep us from noticing it. And then again… it just might be hidden.
“Extraterrestrial artifacts may exist in the Solar System without our knowledge simply because we have not yet searched sufficiently,” said Haqq-Misra and Kopparapu. “Few if any of the attempts would be capable of detecting a 1 to 10 meter (3 to 33 foot) probe.”
Haqq-Misra and Kopparapu use a probabilistic method to determine the feasibility of aliens leaving us clues to their existence. Their work points to the Solar System as a fixed volume and then calculates the percentages of that volume that would need to be thoroughly searched to detect an alien probe or artifact. These searches would have to involve technology able to detect small, foreign objects and then apply it to a smaller portion of the volume to look for results. It’s a study which hasn’t been undertaken so far. We simply cannot say we’ve looked everywhere…
“The surface of the Earth is one of the few places in the Solar System that has been almost completely examined at a spatial resolution of less than 3 feet,” said Haqq-Misra and Kopparapu.
Sure. There are still a lot of nooks and crannies on Earth that haven’t been thoroughly explored – and our oceans are a good example. However, when it comes to searching elsewhere, it’s been a hit-or-miss proposition. While mapping the surface of the Moon, the Lunar Reconnaissance Orbiter is looking at the surface at a resolution of about 20 inches. It may take a few years, but perhaps something isn’t buried under the regolith. As for Mars, chances are slight – but new things seem to be discovered on Mars each day, don’t they? How about the LaGrange points, or the asteroid belt? Things could be hiding there, too.
“Searches to date of the Solar System are sufficiently incomplete that we cannot rule out the possibility that non terrestrial artifacts are present and may even be observing us,” said Haqq-Misra and Kopparapu. They add that “the completeness of our search for non terrestrial objects will inevitably increase as we continue to explore the Moon, Mars and other nearby regions of space.”
After all, what did we expect? E.T. to interrupt a prime time television program to announce their presence? A take-over of the Internet? Maybe each time a meteor makes it to Earth it’s a little calling card that life-possible organisms exists outside our own little sphere…
The circled cluster of stars is the dwarf galaxy Andromeda 29, which University of Michigan astronomers have discovered. The bright star within the circle is a foreground star within our own Milky Way galaxy. This image was obtained with the Gemini Multi-Object Spectrograph at the Gemini North telescope in Hawaii. Credit: Gemini Observstory/AURA/Eric Bell
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Yep. It’s that time of year again. Time to enjoy the Andromeda Galaxy at almost every observing opportunity. But now, rather than just look at the nearest spiral to the Milky Way and sneaking a peak at satellites M32 and M110, we can think about something more when we peer M31’s way. There are two newly discovered dwarf galaxies that appear to be companions of Andromeda!
Eric Bell, an associate professor in astronomy, and Colin Slater, an astronomy Ph.D. student, found Andromeda 28 and Andromeda 29 by utilizing the Sloan Digital Sky Survey and a recently developed star counting technique. To back up their observations, the team employed data from the Gemini North Telescope in Hawaii. Located at 1.1 million and 600,000 light-years respectively, Andromeda XXVIII and Andromeda XXIX have the distinction of being the two furthest satellite galaxies ever detected away from the host – M31. Can they be spotted with amateur equipment? Not hardly. This pair comes in about 100,000 fainter than Andromeda itself and can barely be discerned with some of the world’s largest telescopes. They’re so faint, they haven’t even been classified yet.
“With presently available imaging we are unable to determine whether there is ongoing or recent star formation, which prevents us from classifying it as a dwarf spheroidal or a dwarf irregular.” explains Bell.
The dwarf galaxy Andromeda 29, which University of Michigan astronomers have discovered, is clustered toward the middle of this image, obtained with the Gemini North telescope in Hawaii. Credit: Gemini Observstory/AURA/Eric Bell
In their work – published in a recent edition of the edition of the Astrophysical Journal Letters – the team of Bell and Slater explains how they were searching for dwarf galaxies around Andromeda to help them understand how physical matter relates to theoretical dark matter. While we can’t see it, hear it, touch it or smell it, we know it’s there because of its gravitational influence. And when it comes to gravity, many astronomers are convinced that dark matter plays a role in organizing galaxy structure.
“These faint, dwarf, relatively nearby galaxies are a real battleground in trying to understand how dark matter acts at small scales,” Bell said. “The stakes are high.”
Right now, current consensus has all galaxies embedded in surrounding dark matter… and each “bed” of dark matter should have a galaxy. Considering the volume of the Universe, these predictions are pretty much spot on – if we take only large galaxies into account.
“But it seems to break down when we get to smaller galaxies,” Slater said. “The models predict far more dark matter halos than we observe galaxies. We don’t know if it’s because we’re not seeing all of the galaxies or because our predictions are wrong.”
“The exciting answer,” Bell said, “would be that there just aren’t that many dark matter halos.” Bell said. “This is part of the grand effort to test that paradigm.”
Right or wrong… pondering dark matter and dwarf galaxies while observing Andromeda will add a whole new dimension to your observations!
For Further Reading: Andromeda XXVIII: A Dwarf Galaxy more than 350 kpc from Andromeda and Andromeda XXIX: A New Dwarf Spheroidal Galaxy 200 kpc from Andromeda.
Time for me to play with some new equipment? You betcha’. And this time it’s a Bushnell proprietary design – a large, tabletop dobsonian model manufactured specifically for Optics Planet. It’s called the ARES… named for NASA’s Ares rocket… but I think it’s a regular little “lighthouse”!
First let’s start off with some facts and figures. The Bushnell ARES 5″ Truss Tube Dobsonian Telescope 785000 isn’t little. It is a 130mm clear aperture (5″) Newtonian reflector. It has a focal length of 650mm which makes it a sweet f/5. It has a 0.92 arc sec resolving capability and knocks off a very respectable limiting stellar magnitude of 12.7. So how does a lightweight, tabletop dobsonian telescope manage to pull off an f/5 rating when it’s such a compact package? It does what all good telescopes should do… It telescopes! First check out this video…
When I first unpacked the Bushnell ARES, I was pretty upset. It felt like it was going to fall apart in my hands and I was truly worried it had gone through some bad experiences in shipping. But the fault was not in the stars, dear Brutus… It was in my own lack of ability to see exactly how it was put together. My first impression was to tighten down the side bearing to make everything stable – totally overlooking the fact that the telescope’s balance is a long, side-mounted dovetail. Once I realized what I was doing wrong, all systems were then “Go” and it was time to do this little telescope’s magic act and utilize the incorporated truss tubes and slide it up into observing position. My, my… Look at that clean and perfect little ellipsoidal secondary!
Next step… Attach included red dot finderscope. It goes on its own little metal pedestal and attaches via a dovetail. After that, a quick, cursory collimation check (and a thoughtfully provided center-marked mirror) and make sure everything is snug. When we’re set here, it’s time to take off the dust cover, which I am very happy to say has a slight offset to it which means it opens somewhat like a medicine bottle. This isn’t a dustcap that’s just going to pop off at one good bump. It is heavy duty and was very thoughtfully designed to truly protect the optics tube. Before I put in an eyepiece, however, I’d like to report that there’s nothing cheap about this little dobsonian telescope. Body parts, focuser holder, etc. are metal – not plastic. Friction bearings on the altitude and the azimuth are very positive, and once you’ve balanced the Bushnell ARES, you’ll find its weight to be very positive, secure and even major moves can be made without the assembly bumbling around. The “dobsonian” cabinet is a composite wood with overlay – and it’s actually more of an alt-az arrangement rather than the double side bearings we normally associate with a dob design. However, it is also well-crafted and sturdy.
OK! So, now we’re down to what else is in the box and putting in an eyepiece for real. The Bushnell ARES 5″ Dobsonian comes equipped with a standard 1.25″ rack and pinion focuser. Here again we’ve got good, standard quality. No “cheapie” parts… Just a solid focuser with a nice firm touch that’s not slopping around with the supplied 25mm Plossl. (Just out of curiousity, I did drop a barlow and a 32mm in it to see what kind of lifting capabilities it had, and I’m happy to report the focuser did just fine.) The focuser also has quite sufficient back focus, so there shouldn’t be any problem with almost any eyepiece you would choose to use. Time for a quick alignment of the red dot finder – which is accomplished with X and Y axis knobs… ones which I will invariably turn instead of turning the finder off and on. However! That’s besides the point. The red dot reflex sight is also good quality, all knobs and adjustments are firm and it has a rolling switch which allows you to adjust the brightness level. (Just don’t do like I have done in the past, and turn it down and forget! The only problem with a red laser dot finder is if your batteries go and you don’t have a spare? That’s it for the night… dig?)
Where were we? Yes! Yes. The focuser and eyepieces. Here is one thing I will caution you on. The sliding truss tube design of the Bushnell ARES means the truss tubes are slightly lubricated. Just take care not to touch the trusses and then smear an eyepiece or get near that exposed secondary. I realize for an experienced telescope user that you’re going to know that you have something oily on your fingers if you should touch it… and that you’re not going to endanger your optics… but perhaps an inexperienced user or a child just might not have the same savvy. The little Bushnell Dob comes supplied with a 25mm and 10mm Plossl that are also of good quality which don’t want to “unscrew” themselves around the seams and have fold-up rubber eyeguards. Very satisfactory workhorse eyepieces.
My first adventures were under dark skies with an average limiting magnitude of 5.5 with seeing a nice, steady 8. I had to see the Andromeda Galaxy… and boy, did I. While the ARES isn’t capable of picking out NGC objects in M31, it delivered all the way across the eyepiece and it’s quite possible to see M32 and M110 with slight to moderate aversion. M33 was very sweet in rich field – there were even hints to the pinwheel spiral structure! M15 was beginning to show signs of resolution even at low power… and the Double Cluster would just knock your socks off. If you want some more fun, then check out M57 and M27 before they’re gone. Just spectacular…
What do I see in deep, wide star fields? There’s a bit of coma at the edges – but I defy you to show me any reflector telescope that doesn’t display some coma. It is simply design inherent and I personally don’t think this telescope displays enough to be distracting and that is that.
The next “star test” is planetary and double stars under LM5/8. Even at the modest magnification the 25mm provides, Jupiter jumps right to life – exhibiting some rusty coloration, limb darkening and the dimensional effect of the Galiean moons. While I am not a fan of high magnification, I did use the 10mm and was pleased again that when this telescope is well-balanced that you can set the friction tension to an absolute minimum and track an object smoothly without disrupting the whole set up. After having viewed Jupiter, it was time to tackle a few favorite double stars, like Kappa Piscium, Gamma Piscium, Gamma Andromeda, Eta Cassiopeia, Alberio and Polaris. They were all fine, clean splits and the Bushnell 5″ ARES dob provides very nice coloration.
The last of my “tests” were a few nights that I got up close and personal with the Moon. (ok, ok… i’m guilty of looking at other things, too.) I’m equally pleased to report that during very steady pockets of seeing that the resolution was very, very nice. While the Bushnell 5″ dobsonian telescope didn’t perform like a 150mm Intes Mak on the Moon, it had absolutely nothing to be ashamed of. Crater edges were crisp and well defined. Limb edges and terminator features were sharp. All in all, it performed very well – even with high magnification!
So what’s the long and short of the story? If I had to complain about something, I would say it’s the “unsteady” feeling the scope has when the locking mechanism for the sliding dovetail balance is loose. It feels like it’s going to fall off – even though it didn’t and the feeling was only an illusion. The second complaint would just be that you need to be careful around the lubrication on the truss rods. Points in favor? Wow… The Bushnell ARES collapses into a very small, light-weight and very secure portable package. At approximately $150, it might be inexpensive – but it is not cheap. All the parts have been thoughtfully made to work together… and work together for years and years of service. The supplied accessories are of good quality and about the only thing I would suggest is a 1.25″ Moon filter and a collimator (if you don’t already have one). If placed on a tabletop, the assembly is a little hard to aim in some positions because the table gets in the way of the fixed finderscope angle – but it does an awesome job if placed on a stool, wooden cable spool, or even a couple of concrete blocks. Once you’ve found your “comfort zone”, the telescope performs admirably and has enough light-gathering ability to go far beyond the objects that I star-tested. (I know, because I did… and it does.) All, in all the Bushnell ARES is a real “little lighthouse”…
Or is that a lighthouse “keeper”?
Many thanks go to Optics Planet for being so kind as to trust me with the Bushnell ARES 5″ Truss Tube Dobsonian Telescope 785000 until Ohio skies cooperated long enough to allow me to use it with the time and attention it deserves. This would make an outstanding Christmas present for an older child looking for a quality telescope and an equally fine addition as a worthy “Grab and Go” telescope for the seasoned SkyWatcher.
A team of scientists has used the NASA/ESA Hubble Space Telescope to observe a quasar accretion disc — a brightly glowing disc of matter that is slowly being sucked into its galaxy’s central black hole. Their study makes use of a novel technique that uses gravitational lensing to give an immense boost to the power of the telescope. The incredible precision of the method has allowed astronomers to directly measure the disc’s size and plot the temperature across different parts of the disc. Image credit: NASA, ESA, J.A. Munoz (University of Valencia)
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Thanks to the magic of the NASA/ESA Hubble Space Telescope, a team of international astronomers have made an incredible observation – a quasar accretion disc surrounding a black hole. By employing a technique known as gravitation lensing, the researchers have been able to get an accurate size measurement and spectral data. While you might not think this exciting at first, know that this type of observation is akin to spotting individual grains of sand on the Moon!
Of course, we know we can’t see a black hole – but we’ve learned a lot about them with time. One of their properties is a bright, visible phenomenon called a quasar. These glowing discs of matter are engaged in orbit around the black hole, much like a coil on an electric stove. As energy is applied, the “coil” heats up and unleashes bright radiation.
“A quasar accretion disc has a typical size of a few light-days, or around 100 billion kilometres across, but they lie billions of light-years away. This means their apparent size when viewed from Earth is so small that we will probably never have a telescope powerful enough to see their structure directly,” explains Jose Munoz, the lead scientist in this study.
Because of the diminutive size of the quasar, most of our understanding of how they work has been based on theory… but great minds have found a way to directly observe their effects. By employing the gravity of stars in an intervening galaxy like a scanning microscope, astronomers have been able to observe the quasar’s light as the stars move. While most of these types of features would be too small to see, the gravitation lensing effect ramps up the strength of the quasar’s light and allows study of the spectra as it cruises across the accretion disc.
This diagram shows how Hubble is able to observe a quasar, a glowing disc of matter around a distant black hole, even though the black hole would ordinarily be too far away to see clearly. Credit: NASA and ESA
By observing a group of gravitationally lensed quasars, the team was able to paint a vivid color portrait of the activity. They were able to pick out small changes between single images and spectral shifts over a period of time. What causes these kaleidoscopic variances? For the most part, it’s the different properties in the gases and dust of the lensing galaxies. Because they travel at different angles to the quasar’s light, scientists were even able to distinguish extinction laws at work.
But there was something special about one of the quasars. Says the Hubble Team, “There were clear signs that stars in the intervening galaxy were passing through the path of the light from the quasar. Just as the gravitational effect due to the whole intervening galaxy can bend and amplify the quasar’s light, so can that of the stars within the intervening galaxy subtly bend and amplify the light from different parts of the accretion disc as they pass through the path of the quasar’s light.”
By documenting these color changes, the team could build a profile of the accretion disc. Unlike our Earthly electric stove coil which glows red as it heats up, the accretion disc of a black hole turns blue as it gets closer to the event horizon. By measuring the blue hue, the team was able to measure the disc diameter and the various tints gave them an indicator of distances from its center. In this case, they found that the disc is between four and eleven light-days across (approximately 100 to 300 billion kilometres). Of course, these are only rough estimates, but considering just how far away we’re looking at such a small object gives these types of observations great potential for future studies… and even improvements on accuracy.
“This result is very relevant because it implies we are now able to obtain observational data on the structure of these systems, rather than relying on theory alone,” says Munoz. “Quasars’ physical properties are not yet well understood. This new ability to obtain observational measurements is therefore opening a new window to help understand the nature of these objects.”
Today, November 4, 2011, the General Assembly of the International Union of Pure and Applied Physics (IUPAP) is meeting at the Institute of Physics in London, to approve the names of three new elements… one of which will honor the great Copernicus. Their names are: Element 110, darmstadtium (Ds), Element111, roentgenium (Rg) and Element 112. copernicium (Cn).
Are these new elements? Probably not. All the new ones were discovered long ago, but groups like IUPAC elect names to be used in scientific endeavors. Not only does this include the element, but new molecules which belong to it. As a general rule, these “new elements” are given names by their discoverer – which also leads to international debate. The elements can be named after a mythological concept, a mineral, a place or a country, a property or a very known scientist… even an astronomer!
As for element 112, this extremely radioactive synthetic element can only be created in a laboratory. Copernicium was created on February 9, 1996 by the Gesellschaft für Schwerionenforschung, but its original name – ununbium – didn’t get changed until almost two years ago when a German team of scientists provided enough information to prove its existence. When it was time to give it a moniker, the rules were that it had to end in “ium” and it couldn’t be named for a living person. On February 19, 2010, the 537th anniversary of Copernicus’ birth, IUPAC officially accepted the proposed name and symbol.
This “name calling” process comes from the Joint Working Party on the Discovery of Elements, which is a joint body of IUPAP and the International Union of Pure and Applied Chemistry (IUPAC). From there it is given to the General Assembly for approval. Dr. Robert Kirby-Harris, Chief Executive at IOP and Secretary-General of IUPAP, said, “The naming of these elements has been agreed in consultation with physicists around the world and we’re delighted to see them now being introduced to the Periodic Table.”
The General Assembly consists of 60 members from different countries. These delegates are elected from national academies and physical societies around the world. The five day meeting, which started session on Monday, October 31 will end today. The meeting included presentations from leading UK physicists, and the inauguration of IUPAP’s first female President, Professor Cecilia Jarlskog from the Division of Mathematical Physics at Lund University in Sweden.
The time evolution of case I. Color coded is the density at t = 0 kyr, t = 4.16 kyr and t = 8.33 kyr. The length scale is given in units of the radius of the initial cold core (R0 = 0.21 pc). Credit: M. Gritschneder (et al)
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Away in space some 4.57 billion years ago, in a galaxy yet to be called the Milky Way, a hydrogen molecular cloud collapsed. From it was born a G-type main sequence star and around it swirled a solar nebula which eventually gelled into a solar system. But just what caused the collapse of the molecular cloud? Astronomers have theorized it may have been triggered by a nearby supernova event… And now new computer modeling confirms that our Solar System was born from the ashes a dead star.
While this may seem like a cold case file, there are still some very active clues – one of which is the study of isoptopes contained within the structure of meteorites. As we are well aware, many meteorites could very well be bits of our primordial solar nebula, left virtually untouched since they formed. This means their isotopic signature could spell out the conditions that existed within the molecular cloud at the time of its collapse. One strong factor in this composition is the amount of aluminium-26 – an element with a radioactive half-life of 700,000 years. In effect, this means it only takes a relatively minor period of time for the ratio between Al-26 and Al-24 to change.
“The time-scale for the formation events of our Solar System can be derived from the decay products of radioactive elements found in meteorites. Short lived radionuclides (SLRs) such as 26Al , 41Ca, 53Mn and 60Fe can be employed as high-precision and high-resolution chronometers due to their short half-lives.” says M. Gritschneder (et al). “These SLRs are found in a wide variety of Solar System materials, including calcium-aluminium-rich inclusions (CAIs) in primitive chondrites.”
However, it would seem that a class of carbonaceous chondrite meteorites known CV-chondrites, have a bit more than their fair share of Al-26 in their structure. Is it the smoking gun of an event which may have enriched the cloud that formed it? Isotope measurements are also indicative of time – and here we have two examples of meteorites which formed within 20,000 years of each other – yet are significantly different. What could have caused the abundance of Al-26 and caused fast formation?
“The general picture we adopt here is that a certain amount of Al-26 is injected in the nascent solar nebula and then gets incorporated into the earliest formed CAIs as soon as the temperature drops below the condensation temperature of CAI minerals. Therefore, the CAIs found in chondrites represent the first known solid objects that crystalized within our Solar System and can be used as an anchor point to determine the formation time-scale of our Solar System.” explains Gritschneder. “The extremely small time-span together with the highly homogeneous mixing of isotopes poses a severe challenge for theoretical models on the formation of our Solar System. Various theoretical scenarios for the formation of the Solar System have been discussed. Shortly after the discovery of SLRs, it was proposed that they were injected by a nearby massive star. This can happen either via a supernova explosion or by the strong winds of a Wolf-Rayet star.”
While these two theories are great, only one problem remains… Distinguishing the difference between the two events. So Matthias Gritschneder of Peking University in Beijing and his colleagues set to work designing a computer simulation. Biased towards the supernova event, the model demonstrates what happens when a shockwave encounters a molecular cloud. The results are an appropriate proportion of Al-26 – and a resultant solar system formation.
“After discussing various scenarios including X-winds, AGB stars and Wolf-Rayet stars, we come to the conclusion that triggering the collapse of a cold cloud core by a nearby supernova is the most promising scenario. We then narrow down the vast parameter space by considering the pre-explosion survivability of such a clump as well as the cross-section necessary for sufficient enrichment.” says Gritschneder. “We employ numerical simulations to address the mixing of the radioactively enriched SN gas with the pre-existing gas and the forced collapse within 20 kyr. We show that a cold clump at a distance of 5 pc can be sufficiently enriched in Al-26 and triggered into collapse fast enough – within 18 kyr after encountering the supernova shock – for a range of different metallicities and progenitor masses, even if the enriched material is assumed to be distributed homogeneously in the entire supernova bubble. In summary, we show that the triggered collapse and formation of the Solar System as well as the required enrichment with radioactive 26Al are possible in this scenario.”
While there are still other isotope ratios yet to be explained and further modeling done, it’s a step toward the future understanding of how solar systems form.
Artist’s impression of a gamma-ray burst shining through two young galaxies in the early Universe. Credit: ESO
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“Shot through the heart and you’re to blame…” There’s nothing more powerful than a gamma-ray burst. These abrupt, mega-bright events are captured by orbiting telescopes where the information is immediately relayed to the ground for observation in visible light and infra-red. Some events are so powerful that they linger for hours or even days. But just how quick can we spot them? A burst cataloged as GRB 090323 was picked up by the NASA Fermi Gamma-ray Space Telescope, then confirmed by the X-ray detector on NASA’s Swift satellite and with the GROND system at the MPG/ESO 2.2-metre telescope in Chile. Within a day it was being studied by ESO’s Very Large Telescope. It was so intense it penetrated its host galaxy and another… heading out on a 12 billion light year journey just to get here.
“When we studied the light from this gamma-ray burst we didn’t know what we might find. It was a surprise that the cool gas in these two galaxies in the early Universe proved to have such an unexpected chemical make-up,” explains Sandra Savaglio (Max-Planck Institute for Extraterrestrial Physics, Garching, Germany), lead author of the paper describing the new results. “These galaxies have more heavy elements than have ever been seen in a galaxy so early in the evolution of the Universe. We didn’t expect the Universe to be so mature, so chemically evolved, so early on.”
As the brilliant beacon passed through the galaxies, the gases performed as a filter, absorbing some wavelengths of light. But the real kicker here is we wouldn’t have even known these galaxies existed if it weren’t for the gamma-ray burst! Because the light was affected, astronomers were able to detect the “composition of the cool gas in these very distant galaxies, and in particular how rich they were in heavy elements.” It had been surmised that early galaxies would have less heavy elements since their stellar populations weren’t old enough to have produced them… But the findings pointed otherwise. These new galaxies were rich in heavy elements and going against what we thought we knew about galactic evolution.
So exactly what does that mean? It would appear these new, young galaxies are forming stars at an incredible rate. To enrich their gases so quickly, it’s possible they are in a merger process. While this isn’t a new concept, it just may support the theory that gamma-ray bursts can be associated with “vigorous massive star formation”. Furthermore, it’s surmised that rapid stellar growth may have simply stopped in the primordial Universe. What’s left that we can observe some 12 billion years later are mere shadows of what once was… like cool dwarf stars and black holes. These two newly discovered galaxies are like finding a hidden stain on the outskirts of the distant Cosmos.
“We were very lucky to observe GRB 090323 when it was still sufficiently bright, so that it was possible to obtain spectacularly detailed observations with the VLT. Gamma-ray bursts only stay bright for a very short time and getting good quality data is very hard. We hope to observe these galaxies again in the future when we have much more sensitive instruments, they would make perfect targets for the E-ELT,” concludes Savaglio.
Diego Urbina looking out from the hatch inside Mars500 facility. Credits: ESA
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With less than 48 hours left to go – and after 520 days – the Mars500 crew will officially “open the hatch” on their isolation on November 4. Scientists are eagerly awaiting the last of the experiments, but the inside team is awaiting freedom. They’ve been there since June of last year!
It’s been 17 long months filled with countless hours of experiments. During this simulated Mars mission, these gents have had their brains monitored, bodies scanned, donated samples and kept house. On top of that, they’ve done it so well that scientists can’t wait to get their hands on the results. The most important question of all has already been answered.
And the answer is “Yes.”
Romain Charles taking an air sample for the European MICHA experiment in Mars500. Credits: ESA“And the scientists have already highlighted the importance of their investigations for terrestrial medical issues.” says Patrik Sundblad, the human life sciences specialist at ESA. “Yes, the crew can survive the inevitable isolation that is for a mission to Mars and back. Psychologically, we can do it.”
Can you imagine what would almost seem like purgatory? Even the most dedicated of us get days off, and knowing you truly aren’t in space would be a difficult hurdle to overcome. “They have had their ups and downs, but these were to be expected. In fact, we anticipated many more problems, but the crew has been doing surprisingly well.” continues Sunblad. “August was the mental low point: it was the most monotonous phase of the mission, their friends and families were on vacation and didn’t send so many messages, and there was also little variation in food.”
However, things didn’t stay bleak for long. Morale returned as the end came into sight after an artificial delay and communications with friends and family began again on September 15th. “The high fidelity of the simulation has been an important factor in the success of the experiment,” notes Patrik. “Simulating a real mission to Mars as closely as is possible on Earth has been very important for the crew. Knowing this mission is really helping to make a real mission to Mars possible has made the challenging long-duration experiment somehow easier for the crew.”
Wang Yue with EEG measurement device. Credits: ESAEven as grueling as these simulations might seem to be, it’s still not as stressful as a genuine mission to Mars would be. The reality check is the astronauts would know they couldn’t just be “rescued” in case of an emergency. Add to that weightlessness, radiation and the genuine separation of miles. While you might be able to hibernate in Antarctica to explore some facets of the human psyche, it’s not going to account for everything that goes on in our bodies and minds.“We are using to some extent the same psychological questionnaires with Mars500 as with over-wintering crews at the Concordia base and bedrest studies,” says Patrik. “Comparing them is extremely interesting.”
Crew portrait from May 2011. Credits: ESAYep. The mission is ending – but it’s about a lot more than just six men who chose to isolate themselves for science. It’s about international cooperation and the whole infrastructure surrounding the mission. “The crew has worked individually and as team very well, and the cooperation in the outside world has been outstanding,” observes Patrik. “Russia, China and Europe have maintained the integrity of the unique experiment. This is a very important lesson for any future mission to Mars: it is not only about the spacecraft and its crew, but also about close cooperation on Earth between all the teams and the international space agencies.”
Way to go, Mars500 crew! The first round is on the house…
How long has it been since you’ve taken a good look at Mercury? For the backyard astronomer, all we’ll ever see is the speedy little planet as a bright crescent a few times a year. But, for the MESSENGER spacecraft, Mercury isn’t quite as boring as you might think! Some strange new features have been spotted and a planetary geologist speculates they could be attributed to hydrogen venting from the planet’s interior.
While it’s only been a week since MESSENGER sent back some curious photos of Mercury’s surface, the revelation has created quite a stir in the planetary science community. These observations have included evidence of shallow depressions which have formed into non-uniform crater structures which appear to be recent. In addition, they have a high albedo – indicative of some sort of reflective material. But, what?
According to Marvin Herndon, an independent scientist based in San Diego, Mercury formed under great pressure and high temperature – enough to leave iron in a molten state. If so, it should be responsible for absorbing large amounts of hydrogen. As it cools and transforms to a solid state, the hydrogen is then released, forming a type of “geyser” on the planet’s surface.
“These hydrogen geysers could certainly have caused the rimless depressions that MESSENGER sees.” says Herndon, a self-proclaimed maverick in the world of planetary geology.
As the hydrogen is released from below the planet’s surface, it would also react with other elements it would encounter – possibly iron sulphide, commonly found on Mercury’s surface. This would cause a reduction to metallic iron. From there it would form a light “dust” which could account for the bright, new features seen by MESSENGER.
