Posted on by Nancy Atkinson

ISS Will do Maneuver Friday to Avoid Collision with Satellite Debris

A view of the International Space Station as seen by the last departing space shuttle crew, STS-135. Credit: NASA

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It’s the gift that keeps on giving, unfortunately. Debris from the 2009 collision between an inactive Russian Cosmos 2251 satellite and a commercial Iridium satellite in low Earth orbit is coming dangerously close to the International Space Station. U.S. Space Command has suggested the space station perform a debris avoidance maneuver on Friday, January 13, 2012 to move out of harms’ way and dodge a possible collision with the piece of space junk, said to be about 10 centimeters in diameter.

UPDATE: The ISS has successfully been boosted about 300 meters (1,000 feet) by firing the thrusters on the Zarya module for 54 seconds.

This will be the 13th time since 1998 that the station has moved because of debris.

The thrusters on the Zvezda service module are planned to burn at 1610 UTC (11:10 a.m. EST) on Friday. Without the maneuver, the object would have made two close approaches to the station on consecutive orbits on Friday, passing within the “pizza box” -shaped region around the station, measuring 0.75 kilometers above and below the station and 25 kilometers on each side (2,460 feet above and below and 15.6 by 15.6 miles). NASA said ISS flight controllers are preparing for the maneuver and the crew onboard has been informed.

This debris avoidance maneuver does have one benefit, as the station needed a reboost anyway, and so it will eliminate the need for a reboost of the station next week. The reboost had been planned to put the station at the proper altitude for the launch and docking later this month of the ISS Progress 46 cargo ship.

There are more than 20,000 pieces of debris larger than a softball orbiting the Earth. They travel at speeds up to 17,500 mph, fast enough for a relatively small piece of orbital debris to damage a satellite or a spacecraft. There are 500,000 pieces of debris the size of a marble or larger. There are many millions of pieces of debris that are so small they can’t be tracked.

NASA says that even tiny paint flecks can damage a spacecraft when traveling at these velocities. In fact a number of space shuttle windows have been replaced because of damage caused by material that was analyzed and shown to be paint flecks.

“The greatest risk to space missions comes from non-trackable debris,” said Nicholas Johnson, NASA chief scientist for orbital debris.

Debris avoidance maneuvers are conducted when the probability of collision from a conjunction reaches specific limits set for the Space Station flight rules. If the probability of collision is greater than 1 in 100,000, a maneuver will be conducted if it will not result in significant impact to mission objectives. If it is greater than 1 in 10,000, a maneuver will be conducted unless it will result in additional risk to the crew.

These collision avoidance maneuvers for the ISS require about 30 hours to plan and execute, mainly due to the need to use the station’s Russian thrusters, or the propulsion systems on one of the docked Russian or European spacecraft.

Source: NASA

Posted on by Tammy Plotner

We Are Stardust… We Are Cold Then

This new image shows the Large Magellanic Cloud galaxy in infrared light as seen by the Herschel Space Observatory, a European Space Agency-led mission with important NASA contributions, and NASA's Spitzer Space Telescope. Image credit: ESA/NASA/JPL-Caltech/STScI

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When we think of stars, we might think of their building blocks as white hot… But that’s not particularly the case.The very “stuff” that creates a sun is cold dust and in this combined image produced by the Herschel Space Observatory, a European Space Agency-led mission with important NASA contributions; and NASA’s Spitzer Space Telescope, we’re taking an even more incredible look into the environment which forms stars. This new image peers into the dusty arena of both the Large and Small Magellanic Clouds – just two of our galactic neighbors.

Through the infra-red eyes of the Herschel-Spitzer observation, the Large Magellanic Cloud would almost appear to look like a gigantic fireball. Here light-years long bands of dust permeate the galaxy with blazing fields of star formation seen in the center, center-left and top right (the brightest center-left region is called 30 Doradus, or the Tarantula Nebula. The Small Magellanic Cloud is much more disturbed looking. Here we see a huge filament of dust to the left – known as the galaxy’s “wing” – and, to the right, a deep bar of star formation.

This new image shows the Small Magellanic Cloud galaxy in infrared light from the Herschel Space Observatory a European Space Agency-led mission with important NASA contributions, and NASA's Spitzer Space Telescope. Image credit: ESA/NASA/JPL-Caltech/STScI

What makes these images very unique is that they are indicators of temperature within the Magellanic Clouds. The cool, red areas are where star formation has ceased or is at its earliest stages. Warm areas are indicative of new stars blooming to life and heating the dust around them. “Coolest areas and objects appear in red, corresponding to infrared light taken up by Herschel’s Spectral and Photometric Imaging Receiver at 250 microns, or millionths of a meter. Herschel’s Photodetector Array Camera and Spectrometer fills out the mid-temperature bands, shown in green, at 100 and 160 microns.” says the research team. “The warmest spots appear in blue, courtesy of 24- and 70-micron data from Spitzer.”

Both the LMC and SMC are the two largest satellite galaxies of the Milky Way and are cataloged as dwarf galaxies. While they are large in their own right, this pair contains fewer essential star-forming elements such as hydrogen and helium – slowing the rate of star growth. Although star formation is generally considered to have reached its apex some 10 billion years ago, some galaxies were left with less basic materials than others.

“Studying these galaxies offers us the best opportunity to study star formation outside of the Milky Way,” said Margaret Meixner, an astronomer at the Space Telescope Science Institute, Baltimore, Md., and principal investigator for the mapping project. “Star formation affects the evolution of galaxies, so we hope understanding the story of these stars will answer questions about galactic life cycles.”

Original Story Source: NASA/Herschel News.

Posted on by Nancy Atkinson

Fun New App: MoonWalking

Screenshot from the Moonwalking app.

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Ever wish you could have been a fly on the wall of the Eagle lunar module (figuratively speaking, of course) and watched Neil Armstrong and Buzz Aldrin take their first steps on the Moon in 1969? A fun new app called MoonWalking allows you to bring Tranquility Base down to Earth to watch history unfold in front of you. Using your iPhone or iPad as an interactive magic window into history, you can watch all the action, and even take pictures of the events with your iPhone. MoonWalking is an augmented-reality app that recreates Tranquility Base in your backyard or neighborhood park.

You can learn more about MoonWalking here, and you can download it from iTunes for only $.99. But Universe Today has codes to give away to the first two people who leave a comment to get the app for free. Remember, this is for iPhones and iPads only.

Posted on by Amy Shira Teitel

Astronomers Find Saturn’s Possible Cosmic Doppelgänger

Credit: Michael Osadciw/University of Rochester

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By analyzing the silhouette of an exoplanet passing in front of its parent star some 420 light years from Earth, a team of astrophysicists has discovered an exoplanet that just might turn out to be Saturn’s cosmic doppelgänger. 

Assistant Professor of Physics and Astronomy at Rochester University Eric Mamajek and graduate student Mark Pecaut studied data from the international SuperWASP (Wide Angle Search for Planets) and All Sky Automated Survey (ASAS) project.

An artist's impression of a brown dwarf surrounded by a cloud of proto-planet dust. Image credit: JPL

They were looking at the star’s light pattern; periodic dimming is a telltale sign that a planet is passing in front of it. A spherical planet will dim a star’s light regularly. As seen from Earth, the star’s light will dim as the planet starts to cross it, getting darker until it reaches a point of maximum dimness – the point when the planet is directly between the Earth and the star. Then, the light will get brighter at the same pace as it previously dimmed.

But in December 2010, they noticed something odd. As they analyzed data gathered over a 54 day period in early 2007, the star 1SWASP J140747.93-394542.6 dimmed irregularly. The object passing in front of it couldn’t be a spherical planet, so what was it?

The object had an elliptical silhouette, it was blocking the star’s light in an intermittent and irregular pattern, and was obscuring a significant portion of the star’s light. At one point in the pass, 95 percent of the star’s light was obscured, most likely by dust.

“When I first saw the light curve, I knew we had found a very weird and unique object,” said Mamajek. “After we ruled out the eclipse being due to a spherical star or a circumstellar disk passing in front of the star, I realized that the only plausible explanation was some sort of dust ring system orbiting a smaller companion—basically a ‘Saturn on steroids.'” Rings were the likeliest culprit of the oscillating dimness in the star’s light.

“This marks the first time astronomers have detected an extrasolar ring system transiting a Sun-like star, and the first system of discrete, thin, dust rings detected around a very low-mass object outside of our solar system,” said Mamajek. But there are still some major questions about what exactly has been discovered.

A size comparison between the Sun, a low mass star, a brown dwarf, Jupiter, and the Earth. Image credit: NASA

It could be a very low-mass star, brown dwarf, or gas giant planet. But it’s still too early to know either way. To arrive at some answer, they will need to determine the object’s mass.

A planet that size will exert a gravitational pull on its star in the same way that Jupiter tugs on the Sun. The amount of wobbling this gravitational interaction creates can reveal the mass of the object and give astronomers a clue about what it might be. If it has a mass between 13 and 75 times that of Jupiter, it will likely be a brown dwarf. If it’s any smaller, astronomers will know that it’s likely a planet more similar to Saturn.

Two of Saturn's shepherd moons keep the planet's F ring in check. Image Credit: NASA/JPL

The object itself isn’t the only interesting part of the find; Mamajek is particularly interested in the gaps between the apparent rings that are optically similar to those around Saturn. Gaps are usually indicative of objects within the rings with enough gravitational influence to shape them, like Saturn’s shepherd moons.

But even if the rings turn out to be a cloud of dust, the discovery will be no less exciting. If the object turns out to be a brown dwarf with a cloud of dust, Mamajek thinks it’s likely his team has observed the late stages of planet formation. Or, if the object is a large planet, they may be observing the formation of moons around the giant planet.

Either way it’s an awesome discovery. As cool as finding Saturn’s twin would be, watching moons form around another planet would be equally fascinating. The team’s findings will be published in an upcoming issue of the Astronomical Journal.

Source: University of Rochester.

Posted on by Paul Scott Anderson

Tatooine the Sequel: Kepler Finds Two More Exoplanets Orbiting Binary Stars

Artist's conception of the Kepler-35 system. Lynette Cook / extrasolar.spaceart.org

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For exoplanet fans, this week has been an exciting one, with some amazing new discoveries being announced at the American Astronomical Society meeting in Austin, Texas – our galaxy is brimming with planets, probably billions, and the smallest known planets have been found (again), with one about the size of Mars. But that’s not all; it was also announced that Kepler has found not one but two more planets orbiting binary stars!

The two star systems are Kepler-34 and Kepler-35; they consist of double stars which orbit each other and are about 4,900 and 5,400 light-years from Earth. The two new planets, Kepler-34b and Kepler-35b, each orbit one of these pairs of stars and are both about the size of Saturn. Since they orbit fairly close to their stars, they are not in the habitable zones; Kepler 34-b completes an orbit in 289 days and Kepler-35b in 131 days. It’s more the fact that they orbit double stars that makes them so interesting.

This is now the third planet found in a binary star system. The first, Kepler-16b, was nicknamed Tatooine as it was reminiscent of the world orbiting two suns in the Star Wars films. Until recently, it was unknown if any such star systems had planetary companions. It was considered possible, although unlikely, and remained only a theory. But now, the view is that there may indeed be a lot of them out there, just as planets are now apparently common around single stars. That’s good news for planet-hunters, as most stars in our galaxy are binaries.

According to William Welsh of San Diego State University who participated in the study, “This work further establishes that such ‘two sun’ planets are not rare exceptions, but may in fact be common, with many millions existing in our galaxy. This discovery broadens the hunting ground for systems that could support life.”

Eric B. Ford, associate professor of astronomy at the University of Florida, stated: “We have long believed these kinds of planets to be possible, but they have been very difficult to detect for various technical reasons. With the discoveries of Kepler-16b, 34b and 35b, the Kepler mission has shown that the galaxy abounds with millions of planets orbiting two stars.”

The hope now is that Kepler will continue until 2016 to be able to further refine its findings so far. That will require a mission extension, but scientists involved are optimistic they will get it.

According to Ford, “Astronomers are practically begging NASA to extend the Kepler mission until 2016, so it can characterize the masses and orbits of Earth-size planets in the habitable zone. Kepler is revolutionizing so many fields, not just planetary science. It would be a shame not to maximize the scientific return of this great observatory. Hopefully common sense will prevail and the mission will continue.”

Yes, indeed.

The study was published January 11, 2012 in the journal Nature (payment or subscription required for access to full article).

See also PhysOrg.com for a good overview of the new findings.

Posted on by Nancy Atkinson

Hubble Provides Evidence for ‘Double Degenerate Progenitor’ Supernova

Supernova remnant SNR 0509-67.5. Supernovae provided the heavier elements in the Sun. Image credit: NASA/ESA/CXC
Supernova remnant SNR 0509-67.5. Supernovae provided the heavier elements in the Sun. Image credit: NASA/ESA/CXC

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What happened 400 years ago to create this stunningly beautiful supernova remnant – and were there two culprits or just one? This Hubble Space Telescope view of a Type Ia-created remnant has helped astronomers solve a longstanding mystery on the type of stars that cause some supernovae, known as a progenitor.

“Up until this point we haven’t really known where this type of supernova came from, despite studying them for decades,” said Ashley Pagnotta of Louisiana State University, speaking at a press briefing at the American Astronomical Society meeting on Wednesday. “But we now can say we have the first definitive identification of a Type 1a progenitor, and we know this one must have had a double degenerate progenitor – it is the only option.”

This supernova remnant that has a telephone number-like name of SNR 0509-67.5, lies 170,000 light-years away in the Large Magellanic Cloud galaxy.

Astronomers have long suspected that two stars were responsible for the explosion – as is the case with most type 1a supernovae — but weren’t sure what triggered the explosion. One explanation could be that it was caused by mass transfer from a companion star where a nearby star spills material onto a white dwarf companion, setting off a chain reaction that causes one of the most powerful explosions in the universe. This is known as the ‘single-degenerate’ path – which seems to be the most plausible, common and most preferred explanation for many Type 1a supernovae.

The other option is the collision of two white dwarfs, which is known as ‘double-degenerate, which seems to be the less common and not as widely accepted explanation for supernovae. To many astrophysicists, the merger scenario seemed to be less likely because too few double-white-dwarf systems appear to exist; indeed, there appear to be just handful that have been discovered so far.

The problem with SNR 0509-67.5 was that astronomers could not find any remnant of the companion star. That’s why the double degenerate scenario was considered, as in that case, there won’t be anything left as both white dwarfs are consumed in the explosion. In the case of a single progenitor, the non-white dwarf star will still be near the explosion site and will still look very much as it did before the explosion.

Therefore, a possible way to distinguish between the various progenitor models has been to look deep in the center of an old supernova remnant to search for the ex-companion star.

“We know Hubble has the sensitivity necessary to detect the faintest white dwarf remnants that could have caused such explosions,” said lead investigator Bradley Schaefer from LSU. “The logic here is the same as the famous quote from Sherlock Holmes: ‘when you have eliminated the impossible, whatever remains, however improbable, must be the truth.'”

In 2010, Schaefer and Pagnotta were preparing a proposal to look for any faint ex-companion stars in the center of four supernova remnants in the Large Magellanic Cloud when they saw an Astronomy Picture of the Day photo showing an image the Hubble Space Telescope had already had taken of one of their target remnants, SNR 0509-67.5.

(Note: the January 12, 2012 APOD image is of SNR 0509-67.5!)

Because the remnant appears as a nice symmetric shell or bubble, the geometric center can be determined accurately. In analyzing in more detail the central region, they found it to be completely empty of stars down to the limit of the faintest objects Hubble can detect in the photos. The young age also means that any surviving stars have not moved far from the site of the explosion. They were able to cross off the list all the possible single degenerate scenarios, and were left with the double degenerate model in which two white dwarfs collide.

“Since we can exclude all the possible single degenerates, we know it must be a double degenerate,” Pagnotta said. “The cause of SNR 0509-67.5 can be explained best by two tightly orbiting white dwarf stars spiraling closer and closer until they collided and exploded.”

Pagnotta also noted that this supernova is actually not a normal Type 1a supernova, but a subclass called 1991t, which is an extra bright supernova.

A paper in 2010 by Marat Gilfanov of the Max Planck Institute for Astrophysics indicated that perhaps many Type 1a supernova were caused by two white dwarf stars colliding, which was a surprise to many astronomers. Additionally, a review of the recent supernova SN 2011fe, which exploded in August of 2011, explores the possibility of the double degenerate progenitor. An open question remains whether these white dwarf mergers are the primary catalyst for Type Ia supernovae in spiral galaxies. Further studies are required to know if supernovae in spiral galaxies are caused by mergers or a mixture of the two processes.

Schaefer and Pagnotta plan to look at other supernova remnants in the Large Magellenic Cloud to further test their observations.

Pagnotta confirmed that anyone with an internet connection could have made this discovery, as all the Hubble images used were available publicly, and the use of the Hubble data was sparked by APOD.

Sources: Science Paper by Bradley E. Schaefer and Ashley Pagnotta (PDF document), HubbleSite, AAS press briefing

Posted on by Tammy Plotner

Dodging Black Hole Bullets

This 327-MHz radio view of the center of our galaxy highlights the position of the black hole system H1743-322, as well as other features. (Credit: J. Miller-Jones, ICRAR-Curtin Univ.; C. Brogan, NRAO)

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In mid-2009 a binary star system cataloged as H H1743–322 shot off something very unusual. Poised about 28,000 light years distant in the direction of the constellation of Scorpius, this rather ordinary system made up of a normal star and unknown mass black hole was busy exchanging mass. The pair orbits in mere days with a stream of material flowing continuously between them. This gas causes a flat accretion disk measuring millions of miles across to form and it is centered on the black hole. As the matter twirls toward the center, it becomes compressed and heats to tens of millions of degrees, spitting out X-rays… and bullets.

Utilizing data from NASA’s Rossi X-ray Timing Explorer (RXTE) satellite and the National Science Foundation’s (NSF) Very Long Baseline Array (VLBA) radio telescope, an international team of astronomers were able to confirm the moment a black hole located within our galaxy fired a super speedy clump of gas into surrounding space. Blasting forth at about one-quarter the speed of light, these “bullets” of ionized gas are hypothesized to have originated from an area just outside the black hole’s event horizon.

“Like a referee at a sports game, we essentially rewound the footage on the bullets’ progress, pinpointing when they were launched,” said Gregory Sivakoff of the University of Alberta in Canada. He presented the findings today at the American Astronomical Society meeting in Austin, Texas. “With the unique capabilities of RXTE and the VLBA, we can associate their ejection with changes that likely signaled the start of the process.”

As we have learned, some of the matter headed toward the center of a black hole can be ejected from the accretion disk as opposing twin jets. For the most part, these jets are a constant stream of particles, but can sometimes form into strong “outflows” which get spit out – rapid fire – as gaseous blobs. In early June 2009, H1743–322 did just that… and astronomers were on hand observing with RXTE, the VLBA, the Very Large Array near Socorro, N.M., and the Australia Telescope Compact Array (ATCA) near Narrabri in New South Wales. During this time they were able to confirm the happenings through X-ray and radio data. From May 28 to June 2, things were nominal “though RXTE data show that cyclic X-ray variations, known as quasi-periodic oscillations or QPOs, gradually increased in frequency over the same period” and by June 4th, ATCA verified that activity had pretty much sloughed off. By June 5th, even the QPOs were gone.

Then it happened…

On the same day that everything went totally quiet, H1743–322 fired off a bullet! Radio emissions jumped and a highly accurate and detailed VLBA image disclosed a energetic missile of gas blasting forth along a jet trajectory. The very next day a second bullet took out in the opposite direction. But this wasn’t the curious part of the event… It was the timing. Up to this point, researchers speculated that a radio outburst accompanied the firing of the gas bullet, but VLBA information showed they were launched around 48 hours in advance of the major radio flare. This information will be published in the Monthly Notices of the Royal Astronomical Society.

Radio imaging by the Very Long Baseline Array (top row), combined with simultaneous X-ray observations by NASA's RXTE (middle), captured the transient ejection of massive gas "bullets" by the black hole binary H1743-322 during its 2009 outburst. By tracking the motion of these bullets with the VLBA, astronomers were able to link the ejection event to the disappearance of X-ray signals seen in RXTE data. These signals, called quasi-periodic oscillations (QPOs), vanished two days earlier than the onset of the radio flare that astronomers previously had assumed signaled the ejection. (Credit: NRAO and NASA's Goddard Space Flight Center)

“This research provides new clues about the conditions needed to initiate a jet and can guide our thinking about how it happens,” said Chris Done, an astrophysicist at the University of Durham, England, who was not involved in the study.

These are just mini-ammo compared to what happens in the center of an active galaxy. They don’t just fire bullets – they blast off cannons. A massive black hole weighing in a millions to billions of times the mass of the Sun can shoot off its load across millions of light years!

“Black hole jets in binary star systems act as fast-forwarded versions of their galactic-scale cousins, giving us insights into how they work and how their enormous energy output can influence the growth of galaxies and clusters of galaxies,” said lead researcher James Miller-Jones at the International Center for Radio Astronomy Research at Curtin University in Perth, Australia.

Original Story Source: NASA News Feature.

Posted on by Ray Sanders

Wandering Stars Shed Light on Milky Way’s Past

Measurements of the metal content of stars in the disk of our galaxy. The bottom panel shows the decrease in metal content as the distance from the galactic center increases for stars near the plane of the Milky Way disk. In contrast, the metal content for stars far above the plane, shown in the upper panel, is nearly constant at all distances from the center of the Galaxy. Image Credit: Judy Cheng and Connie Rockosi (UCSC) and the 2MASS Survey.

[/caption]Like a worldly backpacker, many stars in the Milky Way Galaxy have made interesting journeys, and have interesting stories to tell about their past. For over a decade, the Sloan Digital Sky Survey (SDSS) has been mapping stars in our Galaxy.

This week at the American Astronomical Society meeting in Austin, Texas, astronomers from University of California – Santa Cruz presented new evidence that claims to answer many questions about stars located in the disk of our galaxy. The team’s results are based on data from the Sloan Extension for Galactic Understanding and Exploration 2 (SEGUE-2).

The SEGUE-2 data is comprised of the motions and chemical compositions of over 118,000 stars, most of which are in the disk of our galaxy, but a few stars in the survey take the “scenic” route in their orbit.

“Some disk stars have orbits that take them far above and below the plane of the Milky Way,” said Connie Rockosi (University of California – Santa Cruz), “We want to understand what kinds of stars those are, where they came from, and how they got there.”

Aside from the orbital paths of these “wandering” stars being different from most other Milky Way stars, their chemical composition also makes them unique. A team led by Judy Cheng (University of California – Santa Cruz) studied the metallicity of stars at different locations in the galaxy. By studying the metallicity, Cheng and her team were able to examine how the disk of the Milky Way disk grew over time. Cheng’s study also showed that stars closer to the center of the galaxy have higher metallicity than those farther from the galactic center. “That tells us that the outer disk of our Galaxy has formed fewer generations of stars than the inner disk, meaning that the Milky Way disk grew from the inside out,” added Cheng.

When Cheng studied the “wandering” stars, she found their metallicity doesn’t follow the same trend – no matter where she looked in the target area of the Galaxy, stars had low metal content. “The fact that the metal content of those stars is the same everywhere is a new piece of evidence that can help us figure out how they got to be so far away from the plane,” Rockosi mentioned.

What the team has yet to determine is if the stars formed with their “wandering” orbits, or if something in the past caused them to migrate to their unique paths. “If these stars were born with these orbits, they were born at the same rate all over the galaxy,” Cheng said. “If they were born with regular orbits, then whatever happened to them must have been very efficient at mixing them up and erasing any patterns in the metal content, such as the inside-out trend we see in the plane.”

Some possible reasons for this mixing include past mergers of our Galaxy and others, or possibly spiral arms sweeping through the disk. Cheng’s observations will help determine what causes stars to wander far from their birthplace. Other galaxies have shown stars in their disks as well, so solving the puzzle presented by these stars will help researchers better understand how spiral galaxies like the Milky Way form.

If you’d like to read Cheng and Rockosi’s paper “Metallicity Gradients In The Milky Way Disk As Observed By The SEGUE Survey”, you can download a copy at: http://www.ucolick.org/~jyc/gradient/cheng_apj_fullres.pdf

Source: UC Santa Cruz press release

Posted on by Amy Shira Teitel

Scientists Find Trio of Tiny Exoplanets

Image credit: NASA/JPL-Caltech

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NASA’s Kepler mission has detected no shortage of planets; more than a thousand candidates were discovered in 2011, a handful of which were Earth-like in size. As data from the mission keeps pouring in, astronomers are continuing to confirm and classify these possible exoplanets. Today, a team of astronomers from the California Institute of Technology added three more to the growing list. They have confirmed the three smallest exoplanets yet discovered.

Kepler searches for planets by looking at stars. The light from the star flickers or dips when a planet passes in front of it. At least three passes are required to confirm that the signal is from a planet, and further ground-based observations are necessary before a discovery can be confirmed.

An artist's impression of Kepler's field of view, the area in which it is constantly searching for new planets. Image Credit: Jon Lomberg/NASA

The Cal Tech team’s discovery was made with old data from Kepler. They found that the three planets are rocky like Earth and orbit a single star called KOI-961. They are also smaller than our planet; their radii are 0.78, 0.73 and 0.57 times that of Earth. As a comparison, the smallest of the three is roughly the size of Mars.

That these planets are so small is big news; they were thought to be much bigger when they were first found. Finding a planet as small as Mars is particularly amazing, said Doug Hudgins, Kepler program scientist at NASA Headquarters in Washington. It “hints that there may be a bounty of rocky planets all around us.”

The whole system is also small. The planets orbit so close to their star that their year lasts only two days. “This is the tiniest solar system found so far,” said John Johnson, the principal investigator of the research from NASA’s Exoplanet Science Institute at Cal Tech in Pasadena.

A view of Kepler's search area as seen from Earth. Image credit: Carter Roberts / Eastbay Astronomical Society

Their star, KOI-961, is a red dwarf with a diameter one-sixth that of our Sun and it is only 70 percent larger than Jupiter. This makes the system’s scale much closer to that of Jupiter and its moons than that of the Sun and the planets in our Solar System. As Johnson explains, this speaks to “the diversity of planetary systems in our galaxy.”

The type of star is also significant. Red dwarfs are the most common stars in the Milky Way galaxy, and the discovery of three rocky planets around one suggests that the galaxy could be teeming with similar rocky planets.

The team’s find, however, isn’t going to provide us with intergalactic vacation homes anytime soon. The planets are all too close to their star to be in the habitable zone, an orbit where water can exist as a liquid on the surface. Nevertheless, the tiny planets are a significant find. “These types of systems could be ubiquitous in the universe,” said Phil Muirhead, lead author of the new study from Caltech. “This is a really exciting time for planet hunters.”

Source: NASA’s Kepler Mission Find Three Smallest Exoplanets.