The rock chosen for the first contact science investigations for the Curiosity rover. Credit: NASA/JPL-Caltech
A strange rock encountered by the Mars Curiosity rover early in its mission has few similarities to other rocks found on the Red Planet, a new study says. In fact, the “Jake_M” rock is most similar to a rare kind of Earth rock called a mugearite, which is often found in ocean islands and continental rift zones.
“Such rocks are so uncommon on Earth that it would be highly unlikely that, if you landed a spacecraft on Earth in a random location, the first rock you encountered within a few hundred meters of your landing site would be an alkaline rock like Jake_M,” stated Edward Stolper, a geology professor at the California Institute of Technology.
Jake_M is named after Jacob “Jake” Matijevic, a Curiosity operations systems chief engineer who died two weeks after the rover landed last year. The rock was sampled about two weeks after Curiosity hit the surface, and was revealed to have sodium and potassium in it (which makes it chemically alkaline.)
The NASA team threw in every bit of data they could to model the Mars Curiosity landing. Credit: NASA
It’s probable that the rock came to be, the scientists said, after partially melting in the interior of Mars and then coming up to the surface. “As it cooled, crystals formed, and the chemical composition of the remaining liquid changed (just as, in the making of rock candy, a sugar-water solution becomes less sweet as it cools and sugar crystallizes from it),” CalTech stated.
Models examining the formation conditions suggest that Jake_M originated from an area some tens of miles or kilometers in the interior of Mars relative to the surface, and that the magma it formed in might have had a reasonably high proportion of dissolved water. This type of magma (called alkaline magma) is uncommon on Earth, but may be more common on Mars than previously believed.
You can read more details about the rock, as well as a series of four other papers published about science from MSL in the Sept. 27 edition of Science.
Artist's conception of GJ 1214 b passing across its host star, as viewed in blue light. Credit: NAOJ
Playing with the filters on a telescope can show us amazing things. In a recent case, Japanese astronomers looked at the star Gilese 1214 in blue light and watched its “super-Earth” planet (Gliese 1214 b, or GJ 1214 b) passing across the surface from the viewpoint of Earth. The result — a probable detection of water in the planet’s atmosphere.
Observations with the Subaru Telescope using a blue filter revealed the atmosphere does not preferentially scatter any light. If the Rayleigh scattering had been observed, this would have shown hydrogen in the atmosphere, researchers said. (On Earth, Rayleigh scattering of the atmosphere makes the sky blue.)
“When combined with the findings of previous observations in other colors, this new observational result implies that GJ 1214 b is likely to have a water-rich atmosphere,” stated the National Astronomical Observatory of Japan.
The planet is an ideal candidate for exoplanet observations because it is relatively close to Earth (40 light years away) and is about 2.7 times the size of our planet, allowing for possible comparisons between the worlds.
Three images showing the relationship between the atmosphere’s composition and the transmitted colors of light. Top: Hydrogen-dominated atmospheres see much of the blue light scattered, meaning that transits become more visible in blue light than red light. Middle: Atmospheres with less hydrogen scatter blue wavelengths more weakly. Bottom: Cloud-covered planets make it more difficult for light to make its way up through the atmosphere, even if the atmosphere is dominated by hydrogen. Credit: NAOJ
There’s still some debate over whether “super-Earths” are closer in nature to Earth or to Uranus or Neptune (each about four times Earth’s diameter), requiring scientists to scrutinize that class of exoplanets to learn more about their properties.
One area under investigation is where the super-Earths form. It is believed that planets arise out of a protoplanetary disk, or cloud of gas, ice and debris that surrounds a young star at the beginning of its life. Hydrogen is a big part of this disk, as well as water ice beyond the “snow line“, or the region in a planetary system where waning heat makes it possible for ice to form.
“Findings about where super-Earths have formed and how they have migrated to their current orbits point to the prediction that hydrogen or water vapor is a major atmospheric component of a super-Earth,” NAOJ stated. “If scientists can determine the major atmospheric component of a super-Earth, they can then infer the planet’s birthplace and formation history.”
The team acknowledges it’s still possible there is hydrogen in GJ 1214 b’s atmosphere, but add their findings do corroborate with past ones suggesting water.
Artist's conception of the snow line in TW Hydrae. Credit: Bill Saxton/Alexandra Angelich, NRAO/AUI/NSF
There’s an excellent chance of frost in this corner of the universe: astronomers have spotted a “snow line” in a baby solar system about 175 light-years away from Earth. The find is cool (literally and figuratively) in itself. More importantly, however, it could give us clues about how our own planet formed billions of years ago.
“[This] is extremely exciting because of what it tells us about the very early period in the history of our own solar system,” stated Chunhua Qi, a researcher with the Harvard-Smithsonian Center for Astrophysics who led the research.
“We can now see previously hidden details about the frozen outer reaches of another solar system, one that has much in common with our own when it was less than 10 million years old,” he added.
The real deal enhanced-color picture of TW Hydrae is below, courtesy of a newly completed telescope: the Atacama Large Millimeter/submillimeter Array in Chile. It is designed to look at grains and other debris around forming solar systems. This snow line is huge, stretching far beyond the equivalent orbit of Neptune in our own solar system. See the circle? That’s Neptune’s orbit. The green stuff is the snow line. Look just how far the green goes past the orbit.
The carbon monoxide line on TW Hydrae as seen by the Atacama Large Millimeter/submillimeter Array (ALMA) telescope. The circle represents the equivalent orbit of Neptune when comparing it to our own solar system. Credit: Karin Oberg, Harvard University/University of Virginia
Young stars are typically surrounded by a cloud of gas and debris that, astronomers believe, can in many cases form into planets given enough time. Snow lines form in young solar systems in areas where the heat of the star isn’t enough to melt the substance. Water is the first substance to freeze around dust grains, followed by carbon dioxide, methane and carbon monoxide.
It’s hard to spot them: “Snow lines form exclusively in the relatively narrow central plane of a protoplanetary disk. Above and below this region, stellar radiation keeps the gases warm, preventing them from forming ice,” the astronomers stated. In areas where dust and gas are more dense, the substances are insulated and can freeze — but it’s difficult to see the snow through the gas.
In this case, astronomers were able to spot the carbon monoxide snow because they looked for diazenylium, a molecule that is broken up in areas of carbon monoxide gas. Spotting it is a “proxy” for spots where the CO froze out, the astronomers said.
Here are some more of the many reasons this is exciting to astronomers:
Snow could help dust grains form faster into rocks and eventually, planets because it coats the grain surface into something more stickable;
Carbon monoxide is a requirement to create methanol, considered a building block of complex molecules and life;
The snow was actually spotted with only a small portion of ALMA’s 66 antennas while it was still under construction. Now that ALMA is complete, scientists are already eager to see what the telescope will turn up the next time it gazes at the system.
Canadian astronaut Jeremy Hansen after rescuing a rover out of the mud in the Arctic's Haughton Crater. Hansen was participating in a geology expedition in July 2013. Credit: Jeremy Hansen/Twitter
It takes gumption to go knee-deep in mud to save a stranded rover. Or to climb up precarious slopes in search of the perfect rock. Oh, and did we mention the location is best accessible by air, with no towns nearby?
Take these challenging conditions, which Canadian astronaut Jeremy Hansen faced in the Arctic this month, and then imagine doing this on the moon. Or an asteroid. Or Mars. Scary, isn’t it? But that’s what he’s thinking of and training for as he does geology work a few times a year.
“It’s important; it provides an opportunity in a somewhat uncomfortable, risky situation when we’re doing real science,” Hansen told Universe Today of his time in Haughton Crater in Canada’s north. In fact, it’s so important to Hansen that he’s gone on similar geology trips with this Western University group three times.
There would be vast differences between Earth exploration and heading to another location, however. Some examples:
While the Haughton Crater expedition is an analog for moon or Mars exploration, certain things will be different from the Earth experience. Here, Canadian astronaut Jeremy Hansen gathers water — a feat that would be way more difficult off-planet. Credit: Jeremy Hansen/Twitter
Water and supplies. The team Hansen joined had nine people and 29 checked bags for an expedition that lasted just over a week. They could also get water on site at a spot not too far from their camp, reducing the load of that heavy but important substance. NASA’s long-range planning, meanwhile, envisions scenarios such as a month on the moon, Hansen said. Supplies would be an interesting and heavy challenge in that situation. “The next time we’ll go back, what we’ll really be looking to do is travel much greater distances over a longer period of time,” he said. “We’ll be living in a rover for a month, covering 100 kilometers [62 miles] or more, looking for these important outcrops that tell us the story.”
Geology. The Earth is an erosive force on geology: wind, rain, glaciation, water, volcanic activity and more alters the landscape. “Sometimes the rocks look very similar” even when they are different, Hansen pointed out. Other places may have different erosion processes (think micrometeroids), making the rocks look strange to Earth-trained eyes.
Location. The landscape itself could be challenging for collecting samples. The moon, for example, has “stuff strewn everywhere and pounded into sand”, Hansen said, meaning that astronauts might have to travel much further to see something besides regolith or moon soil. Where Hansen was in the Arctic, by contrast, the group could get to more than a dozen different outcrops in a day of walking.
Gravity. The moon has a sixth of the Earth’s gravity. Mars is at about 38% Earth gravity. This means that the machines would need to be designed to work in that environment. For astronauts, it’s riskier to go up slopes or do heavy work in those conditions because their center of gravity is unfamiliar. As this Apollo 17 clip shows, astronauts sometimes fell over on the moon when doing something as simple as picking up as sample bag.
This stain in the rock showed evidence of hot water flowing for million of years after the impact that created the Arctic’s Haughton Crater, said Canadian astronaut Jeremy Hansen. “Could support life? Could crater on Mars? Research may answer,” he tweeted. Credit: Jeremy Hansen/Twitter
Hansen’s work in Haughton Crater did turn up some similarities to work at off-Earth locations, though. His crew had to work in a compressed time situation, learning how to find representative rocks from a 14-mile (23-kilometer) wide crater. That’s the same challenge you’d find during a moon or asteroid or Mars expedition.
“We explored not the entire crater — it’s a lot of ground to cover — but we explored some key areas,” Hansen said. “What’s important for someone like me, at my stage of geologist eyes, is to see the key aspects of the crater, those being what types of rocks that are formed and where do they end up in the crater.”
When a big rock slams into the Earth, it excavates material that is normally inaccessible to a surface visitor. Hansen was encouraged to seek the oldest or genesis rocks when on his expedition because, as in other locations, they provide clues about how the solar system was formed. The hard evidence firms up our theories on what happened.
“Explored rocks, learned origins of Earth. Want to do this on Mars someday like @MarsCuriosity but with a return ticket,” tweeted Canadian astronaut Jeremy Hansen, making a joking reference to the Mars One expedition. Credit: Jeremy Hansen/Twitter
It’s not only work in the field that is important, but work in the lab. In past years with Gordon Osinski‘s group at Western, Hansen has gone back to the university to talk with those looking at the rock samples. He asks if the samples were representative, easy to analyze. His goal is to do better with each expedition.
“It’s kind of like learning a fourth lagnguage,” said Hansen, who as a Canadian Space Agency astronaut is expected to speak English, French and Russian at a minimum.
“It’s one of those things — you can cram it all in, but you don’t retain a lot unless you use it repeatedly and continue to practice it. My elegant solution is I spend one, maybe two weeks total a year, working on this. It’s a good use of my time. I keep bringing it back, keep reviewing it and keep going a little further.”
Hansen has a busy summer ahead of him. He’s taking off soon for CF-18 training with the Royal Canadian Air Force, where he got his career start. (Funny enough, in his past career he used to survey the Arctic from the air during Canadian sovereignty operations.)
In September, Hansen is spending about a week underground in Sardinia, Italy as part of the European Space Agency’s ongoing CAVES expedition series. Besides geology, this also provides training in unfamiliar and dangerous environments.
Hansen has not been assigned to a flight yet, but continues to work in the International Space Station operations branch in Houston and to represent the Astronaut Office in operational meetings. Also in training is his colleague David Saint-Jacques. Both astronauts were selected in 2009.
The next Canadian spaceflight is expected to happen around 2018, but could be earlier depending on ongoing negotiations by the Canadian Space Agency.
Artist's concept of Jupiter-sized exoplanet that orbits relatively close to its star (aka. a "hot Jupiter"). Credit: NASA/JPL-Caltech)
Overheated and overinflated, hot Jupiters are some of the strangest extrasolar planets to be discovered by the Kepler mission… and they may be even more exotic than anyone ever thought. A new model proposed by Florida Gulf Coast University astronomer Dr. Derek Buzasi suggests that these worlds are intensely affected by electric currents that link them to their host stars. In Dr. Buzasi’s model, electric currents arising from interactions between the planet’s magnetic field and their star’s stellar wind flow through the interior of the planet, puffing it up and heating it like an electric toaster.
In effect, hot Jupiters are behaving like giant resistors within exoplanetary systems.
Many of the planets found by the Kepler mission are of a type known as “hot Jupiters.” While about the same size as Jupiter in our own solar system, these exoplanets are located much closer to their host stars than Mercury is to the Sun — meaning that their atmospheres are heated to several thousands of degrees.
One problem scientists have had in understanding hot Jupiters is that many are inflated to sizes larger than expected for planets so close to their stars. Explanations for the “puffiness” of these exoplanets have generally involved some kind of extra heating process — but no model successfully explains the observation that more magnetically active stars tend to have puffier hot Jupiters orbiting around them.
“This kind of electric heating doesn’t happen very effectively on planets in our solar system because their outer atmospheres are cold and don’t conduct electricity very well,” says Dr. Buzasi. “But heat up the atmosphere by moving the planet closer to its star and now very large currents can flow, which delivers extra heat to the deep interior of the planet — just where we need it.”
More magnetically active stars have more energetic winds, and would provide larger currents — and thus more heat — to their planets.
The currents start in the magnetosphere, the area where the stellar wind meets the planetary magnetic field, and enter the planet near its north and south poles. This so-called “global electric circuit” (GEC) exists on Earth as well, but the currents involved are only a few thousand amps at 100,000 volts or less.
On the hot Jupiters, though, currents can amount to billions of amps at voltages of millions of volts — a “significant current,” according to Dr. Buzasi.
A Spitzer-generated exoplanet weather map showing temperatures on hot Jupiter HAT-P-2b.
“It is believed that these hot Jupiter planets formed farther out and migrated inwards later, but we don’t yet fully understand the details of the migration mechanism,” Dr. Buzasi says. “The better we can model how these planets are built, the better we can understand how solar systems form. That in turn, would help astronomers understand why our solar system is different from most, and how it got that way.”
Other electrical heating processes have previously been suggested by other researchers as well, once hints of magnetic fields in exoplanets were discovered in 2003 and models of atmospheric wind drag — generating frictional heating — as a result of moving through these fields were made in 2010.
(And before anyone attempts to suggest this process supports the alternative “electric universe” (EU) theory… um, no.)
“No, nothing EU-like at all in my model,” Dr. Buzasi told Universe Today in an email. “I just look at how the field aligned currents that we see in the terrestrial magnetosphere/ionosphere act in a hot Jupiter environment, and it turns out that a significant fraction of the resulting circuit closes inside the planet (in the outer 10% of the radius, mostly) where it deposits a meaningful amount of heat.”
When the Moon was receiving its highest number of impacts, so was Earth. Credit: Dan Durda
Some questions about our own planet are best answered by looking someplace else entirely… in the case of impact craters and when, how and how often they were formed, that someplace can be found shining down on us nearly every night: our own companion in space, the Moon.
By studying lunar impact craters both young and old scientists can piece together the physical processes that took place during the violent moments of their creation, as well as determine how often Earth — a considerably bigger target — was experiencing similar events (and likely in much larger numbers as well.)
With no substantial atmosphere, no weather and no tectonic activity, the surface of the Moon is a veritable time capsule for events taking place in our region of the Solar System. While our constantly-evolving Earth tends to hide its past, the Moon gives up its secrets much more readily… which is why present and future lunar missions are so important to science.
Take the crater Linné, for example. A young, pristine lunar crater, the 2.2-km-wide Linné was formed less than 10 million years ago… much longer than humans have walked the Earth, yes, but very recently on lunar geologic terms.
It was once thought that the circular Linné (as well as other craters) is bowl-shaped, thus setting a precedent for the morphology of craters on the Moon and on Earth. But laser-mapping observations by NASA’s Lunar Reconnaissance Orbiter (at right) determined in early 2012 that that’s not the case; Linné is actually more of a truncated inverted cone, with a flattened interior floor surrounded by sloping walls that rise up over half a kilometer to its rim.
On our planet the erosive processes of wind, water, and earth soon distort the shapes of craters like Linné, wearing them down, filling them in and eventually hiding them from plain sight completely. But in the Moon’s airless environment where the only weathering comes from more impacts they retain their shape for much longer lengths of time, looking brand-new for many millions of years. By studying young craters in greater detail scientists are now able to better figure out just what happens when large objects strike the surface of worlds — events that can and do occur quite regularly in the Solar System, and which may have even allowed life to gain a foothold on Earth.
Most of the craters visible on the Moon today — Linné excluded, of course — are thought to have formed within a narrow period of time between 3.8 and 3.9 billion years ago. This period, called the Late Heavy Bombardment, saw a high rate of impact events throughout the inner Solar System, not only on the Moon but also on Mars, Mercury, presumably Venus and Earth as well. In fact, since at 4 times its diameter the Earth is a much larger target than the Moon, it stands to reason that Earth was impacted many more times than the Moon as well. Such large amounts of impacts introduced material from the outer Solar System to the early Earth as well as melted areas of the surface, releasing compounds like water that had been locked up in the crust… and even creating the sorts of environments where life could have begun to develop and thrive.
(It’s been suggested that there was even a longer period of heavy impact rates nicknamed the “late late heavy bombardment” that lingered up until about 2.5 billion years ago. Read more here.)
In the video below lunar geologist David Kring discusses the importance of impacts on the evolution of the Moon, Earth and eventually life as we know it today:
“Impact cratering in Earth’s past has affected not only the geologic but the biologic evolution of our planet, and we were able to deduce that in part by the lessons we learned by studying the Moon… and you just have to wonder what other things we can learn by going back to the Moon and studying that planetary body further.”
It’s these sorts of connections that make lunar exploration so valuable. Keys to our planet’s past are literally sitting on the surface of the Moon, a mere 385,000 km away, waiting for us to just scoop them up and bring them back. While the hunt for a biological history on Mars or resource-mining an asteroid are definitely important goals in their own right, only the Moon holds such direct references to Earth. It’s like an orbiting index to the ongoing story of our planet — all we have to do is make the connections.
Learn more about lunar research at the LPI site here, and see the latest news and images from LRO here.
From the initial expansion of the Big Bang to the birth of the Moon, from the timid scampering of the first mammals to the rise — and fall — of countless civilizations, this fascinating new video by melodysheep (aka John D. Boswell) takes us on a breathless 90-second tour through human history — starting from the literal beginnings of space and time itself. It’s as imaginative and powerful as the most gripping Hollywood trailer… and it’s even inspired by a true story: ours.
Over 4 billion miles (6.7 billion km) from the Sun, the Kuiper Belt is a vast zone of frozen worlds we still know very little about. Image: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)
Today marks the 20th anniversary of the discovery of the first Kuiper Belt Object, 1992QB1. KBOs are distant and mostly tiny worlds made up of ice and rock that orbit the Sun at incredible distances, yet are still very much members of our Solar System. Since 1992 over 1,300 KBOs have been found, and with NASA’s New Horizons spacecraft speeding along to its July 2015 rendezvous with Pluto and Charon (which one could argue are technically the first KBOs ever found) and then onwards into the Belt, we will soon know much more about these far-flung denizens of deep space.
But how has the discovery of the Kuiper Belt — first proposed by Gerard Kuiper in 1951 (and in a fashion even earlier by Kenneth Edgeworth) — impacted our current understanding of the Solar System? New Horizons Principal Investigator Alan Stern from the Southwest Research Institute recently discussed this on his mission blog, “The PI’s Perspective.”
First, Stern lists some of the surprisingly diverse physical aspects of KBOs that have been discovered so far:
Some are red and some are gray;
The surfaces of some are covered in water ice, but others (like Pluto) have exotic volatile ices like methane and nitrogen;
Many have moons, though none with more known moons than Pluto;
Some are highly reflective (like Pluto), others have much darker surfaces;
Some have much lower densities than Pluto, meaning they are primarily made of ice. Pluto’s density is so high that we know its interior is about 70% rock in its interior; a few known KBOs are more dense than Pluto, and even rockier!
But although these features are fascinating in themselves, just begging for further exploration, Stern notes that there are three very important lessons that the Kuiper Belt has taught us about the Solar System:
1. Our planetary system is much larger than we had ever thought.
“In fact, we were largely unaware of the Kuiper Belt — the largest structure in our solar system — until it was discovered 20 years ago,” Stern writes. “It’s akin to not having maps of the Earth that included the Pacific Ocean as recently as 1992!”
2. Planetary locations and orbits can change over time.
“This even creates whole flocks of migration of planets in some cases. We have firm evidence that many KBOs (including some large ones like Pluto), were born much closer to the Sun, in the region where the giant planets now orbit.”
3. Our solar system, and likely others as well, was very good at making small planets.
“Today we know of more than a dozen dwarf planets in the solar system, and those dwarfs already outnumber the number of gas giants and terrestrial planets combined. But it is estimated that the ultimate number of dwarf planets we will discover in the Kuiper Belt and beyond may well exceed 10,000. Who knew?”
And with a little jab at the whole Pluto-isn’t-a-planet topic, Stern asks: “And which class of planet is the misfit now?”
The discovery of the Kuiper Belt has shown us that our solar system — and very likely planetary systems across the galaxy, even the Universe — aren’t neat and tidy things that can be easily summed up with grade-school models or chalkboard diagrams. Instead they are incredibly diverse and dynamic, continually evolving and consisting of countless, varied worlds spanning enormous distances… yet still connected through the ever-present effects of gravity (not to mention the occasional-yet-unavoidable collision.)
“What an amazing set of paradigm shifts in our knowledge the Kuiper Belt has brought so far. Our quaint 1990s and earlier view of the solar system missed its largest structure!”
Artist's impression of a red giant star. Image credit: ESO
How’s this for a depressing look into Earth’s potential future: astronomers have witnessed the first evidence of a planet’s destruction by its aging star as it expands into a red giant.
“A similar fate may await the inner planets in our solar system, when the Sun becomes a red giant and expands all the way out to Earth’s orbit some five-billion years from now,” said Alex Wolszczan, from Penn State, University, who led a team which found evidence of a missing planet having been devoured by its parent star. Wolszczan also is the discoverer of the first planet ever found outside our solar system.
The planet-eating culprit, a red-giant star named BD+48 740 is older than the Sun and now has a radius about eleven times bigger than our Sun.
The evidence the astronomers found was a massive planet in a surprising highly elliptical orbit around the star – indicating a missing planet — plus the star’s wacky chemical composition.
“Our detailed spectroscopic analysis reveals that this red-giant star, BD+48 740, contains an abnormally high amount of lithium, a rare element created primarily during the Big Bang 14 billion years ago,” said team member Monika Adamow from the Nicolaus Copernicus University in Torun, Poland. “Lithium is easily destroyed in stars, which is why its abnormally high abundance in this older star is so unusual.
“Theorists have identified only a few, very specific circumstances, other than the Big Bang, under which lithium can be created in stars,” Wolszczan added. “In the case of BD+48 740, it is probable that the lithium production was triggered by a mass the size of a planet that spiraled into the star and heated it up while the star was digesting it.”
The other piece of evidence discovered by the astronomers is the highly elliptical orbit of the star’s newly discovered massive planet, which is at least 1.6 times as massive as Jupiter.
“We discovered that this planet revolves around the star in an orbit that is only slightly wider than that of Mars at its narrowest point, but is much more extended at its farthest point,” said Andrzej Niedzielski, also from Nicolaus Copernicus University. “Such orbits are uncommon in planetary systems around evolved stars and, in fact, the BD+48 740 planet’s orbit is the most elliptical one detected so far.”
The Hobby-Eberly Telescope
Because gravitational interactions between planets are responsible for such peculiar orbits, the astronomers suspect that the dive of the missing planet toward the star could have given the surviving massive planet a burst of energy, throwing it into an eccentric orbit like a boomerang.
“Catching a planet in the act of being devoured by a star is an almost improbable feat to accomplish because of the comparative swiftness of the process, but the occurrence of such a collision can be deduced from the way it affects the stellar chemistry,” said Eva Villaver of the Universidad Autonoma de Madrid in Spain Villaver. “The highly elongated orbit of the massive planet we discovered around this lithium-polluted red-giant star is exactly the kind of evidence that would point to the star’s recent destruction of its now-missing planet.”
The team used the Hobby-Eberly Telescope – searching for planets – when they detected evidence of the missing planet’s destruction.
The paper describing this discovery is posted in an early online edition of the Astrophysical Journal Letters (Adamow et al. 2012, ApJ, 754, L15), or another version is available on arXiv.
Lead image caption: Artist’s impression of a red giant star. Image credit: ESO
Astronomy has always taught us that planets form from vast clouds of dust and gas orbiting young stars. It’s a gradual process of accretion that takes hundreds of thousands, perhaps even millions, of years… or does it?
During a 1983 sky survey with the Infrared Astronomical Satellite (IRAS) astronomers identified a young Sun-like star with a large cloud of dust surrounding it. The star, named TYC 8241 2652 1, is 450 light years away and what they had found around it was thought to be the beginnings of a solar system – the protoplanetary disc from which planets form.
Fast forward to 2008. Astronomers observed at the same star with a different infrared telescope, the Gemini South Observatory in Chile. What was observed looked a lot like what was previously seen in ’83.
Then, in 2009, they looked again. Curiously, the brightness of the dust cloud was only a third of what it was the year before. And in WISE observations made the very next year, it had disappeared entirely.
“It’s like the classic magician’s trick: now you see it, now you don’t. Only in this case we’re talking about enough dust to fill an inner solar system, and it really is gone.”
– Carl Melis, lead author and postdoctoral fellow at UC San Diego
Abracadabra?
“It’s as if you took a conventional picture of the planet Saturn today and then came back two years later and found that its rings had disappeared,” said study co-author and circumstellar disk expert Ben Zuckerman of UCLA.
It’s always been thought that planets take some time to form, in the order of hundreds of thousands of years. Although that may seem like forever to humans, it’s quick in cosmic time scales. But if what they’ve seen here with TYC 8241 is in fact planetary formation, well… it may happen a lot faster than anyone thought.
On the other hand, the star could have somehow blown all the dust out of the system. More research will be needed to see if that was the case.
The really interesting thing here is that astronomers have traditionally looked for these kinds of dust clouds around stars to spot planetary formation in action. But if planets form quicker than we thought, and the dust clouds are only fleeting features, then there may be a lot more solar systems out there that we can’t directly observe.
“People often calculate the percentage of stars that have a large amount of dust to get a reasonable estimate of the percentage of stars with planetary systems, but if the dust avalanche model is correct, we cannot do that anymore,” said study co-author Inseok Song, assistant professor of physics and astronomy at the University of Georgia. “Many stars without any detectable dust may have mature planetary systems that are simply undetectable.”
