20
Dec 10

Kepler Mission experiences problems

Source: NASA/Kepler


Artist's impression about the Kepler mission. Image credit: NASA.

During a regularly scheduled contact with the Kepler spacecraft on Dec. 13, 2010, the project team discovered Kepler had experienced an anomaly. Kepler was found in coarse point attitude, as opposed to finepoint. Coarse point means the Kepler is using its star trackers for pointing at the Kepler Field-of-View (FOV) instead of the fine guidance sensors that are hard-mounted to the Kepler focal plane array. To properly track Kepler’s target stars with fine accuracy, Kepler must be in finepoint attitude.

Project engineers began analysis of the situation to determine the cause of the anomaly. They determined that Kepler failed to transition properly from coarse point to finepoint attitude after a pre-planned momentum wheel de-saturation. Momentum wheel de-saturations occur on a regular basis for the spacecraft, approximately every three-and-one-half days. The de-saturation uses thrusters to dump momentum buildup on Kepler’s reaction wheels, which spin continuously to counter the solar wind, which pushes on the spacecraft body as Kepler points at its FOV.

The project team was able to recover the spacecraft to finepoint relatively quickly. Only 13 hours of science data collection were interrupted by this anomaly. The team will continue to evaluate telemetry from the event to confirm the root cause, and develop any further mitigations. The Kepler mission budgets for interruptions in the mission, including scheduled maintenance on the spacecraft and anomalies such as this. The mission remains well within the budget outages allowed.

Meanwhile, the project science team is preparing for Kepler-related sessions at the upcoming American Astronomical Society meeting in Seattle in early January. The Science Team also is preparing for the planned Feb. 1, 2011 release of Quarter 2 data and release of sequestered target data from Quarter 0 and Quarter 1.

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14
Dec 10

First four exoplanet system imaged directly

Source: KECK Observatory


An animation demonstrating plausible orbits of the HR 8799 planets through
one complete period (~465 years) of HR 8799b, the outermost planet.
Animation credit: LLNL & Q. M. Konopacky

Astronomers announced the discovery of a fourth giant planet joining three others orbiting a nearby star with information that challenges our current understanding of planet formation. The dusty young star named HR8799, located 129 light years away, was first recognized in 2008 when these same astronomers presented the first-ever images of a planetary system orbiting a star other than our sun.

Now, a research team from Lawrence Livermore National Laboratory (LLNL), National Research Council of Canada (NRC), the University of California Los Angeles, (UCLA) and Lowell Observatory has discovered a fourth planet that is about 7 times the mass of Jupiter – similar to the other three. Using high-contrast, near infrared adaptive optics on the Keck II telescope in Hawaii, the astronomers imaged the fourth planet (dubbed HR8799e) in 2009 and confirmed its existence and orbit in 2010. The research appears in the Dec. 8 edition of the journal, Nature.

“The images of this new inner planet in the system is the culmination of 10 years worth of innovations, making steady progress to optimize every observation and analysis step to allow the detection of planets located ever closer to their stars,” said Christian Marois, a former LLNL postdoc now at NRC, and first author of the new paper.

If this newly discovered planet was located in orbit around our sun, it would lie between Saturn and Uranus. This giant version of our solar system is young at about 30 million years old compared to our system, which is about 4.6 billion years old.

Scientific images of HR 8799.

Though the system is very much like our own, in other ways, it is much more extreme than our own – the combined mass of the four giant planets may be 20 times higher, and the asteroid and comet belts are dense and turbulent. In fact, the massive planets’ pull on each other gravitationally, and the system may be on the verge of falling apart.

This team of scientists simulated millions of years of evolution of the system, and showed that to have survived this long, the three inner planets may have to orbit like clockwork, with the new planet going around the star exactly four times while the second planet finishes two orbits in the time it takes the outer planet to complete one. This behavior was first seen in the moons of Jupiter but has never before been seen on this scale.

Studying the planet’s orbits also will help estimate their masses. “Our simulations show that if the objects were not planets, but supermassive ‘brown dwarfs’, the system would have fallen apart already,” said Quinn Konopacky, a postdoctoral researcher at LLNL’s Institute of Geophysics and Planetary Physics and a key author of the paper. “The implication is that we have truly found a unique new system of planets.” (Brown dwarfs are “failed stars”, too low in mass to sustain stable hydrogen fusion but larger than planets.) “We don’t yet know if the system will last for billions of years, or fall apart in a few million more. As astronomers carefully follow the HR 8799 planets during the coming decades, the question of just how stable their orbits are could become much clearer.”

The origin of these four giant planets remains a puzzle. It neither follows the “core accretion” model, in which planets form gradually close to stars where the dust and gas are thick or the “disk fragmentation” model in which a turbulent planet-forming disk rapidly cools and collapses out at its edges. Bruce Macintosh, a senior scientist at LLNL and the principal investigator for the Keck Observatory program, said: “There’s no simple model that can make all four planets at their current location. It’s a challenge for our theoretical colleagues.”

Previous observations had shown evidence for a dusty asteroid belt orbiting closer to the star – the new planet’s gravity helps account for the location of those asteroids, confining their orbits just like Jupiter does in our solar system. “Besides having four giant planets, both systems contain also two so-called “debris belts” composed of small rocky and/or icy objects along with lots of tiny dust particles, similar to the asteroid and Kuiper comet belts of our solar system”, noted co-author Ben Zuckerman, a professor of physics and astronomy at UCLA.

“Images like these bring the exoplanet field into the era of characterization. Astronomers can now directly examine the atmospheric properties of four giant planets orbiting another star that are all the same young age and that formed from the same building materials.” said Travis Barman, a Lowell Observatory exoplanet theorist and co-author of the current paper.

“I think there’s a very high probability that there are more planets in the system that we can’t detect yet,” Macintosh said. “One of the things that distinguishes this system from most of the extrasolar planets that are already known is that HR8799 has its giant planets in the outer parts - like our solar system does - and so has ‘room’ for smaller terrestrial planets – far beyond our current ability to see – in the inner parts.”

“It’s amazing how far we’ve come in a few years,” Macintosh said. “In 2007, when we first saw the system, we could barely see two planets out past the equivalent of Pluto’s orbit. Now we’re imaging a fourth planet almost where Saturn is on our solar system. It’s another step to the ultimate goal – still more than a decade away – of a picture showing another planet like Earth.”

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1
Dec 10

First Super-Earth Atmosphere Analysed

Source: ESO Science Release eso1047


Artist’s impression about the super-Earth exoplanet orbiting the nearby star GJ 1214.
Image credit: ESO/L.Calçada

The atmosphere around a super-Earth exoplanet has been analysed for the first time by an international team of astronomers using ESO’s Very Large Telescope. The planet, which is known as GJ 1214b, was studied as it passed in front of its parent star and some of the starlight passed through the planet’s atmosphere. We now know that the atmosphere is either mostly water in the form of steam or is dominated by thick clouds or hazes. The results will appear in the 2 December 2010 issue of the journal Nature.(read more)

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20
Nov 10

Planet from another galaxy discovered

Source: ESO Science Release eso1045


Artist’s impression of HIP 13044 b, an exoplanet orbiting a star that entered our galaxy.
Image credit: ESO/L. Calçada

An exoplanet orbiting a star that entered our Milky Way from another galaxy has been detected by a European team of astronomers using the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile. The Jupiter-like planet is particularly unusual, as it is orbiting a star nearing the end of its life and could be about to be engulfed by it, giving tantalising clues about the fate of our own planetary system in the distant future.(read more)

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21
May 10

Hubble finds star eating a planet

Source: HubbleSite


Artist's concept of the exoplanet WASP-12b.
Credit: NASA, ESA, and G. Bacon (STScI)

"The Star That Ate My Planet" may sound like a B-grade science fiction movie title, but this is really happening 600 light-years away. Like a moth in a candle flame, a doomed Jupiter-sized planet has moved so close to its sunlike parent star that it is spilling its atmosphere onto the star. This happens because the planet gets so hot that its atmosphere puffs up to the point where the star's gravity pulls it in. The planet will likely be completely devoured in 10 million years. Observations by Hubble's new Cosmic Origins Spectrograph measured a variety of elements in the planet's bloated atmosphere as the planet passed in front of its star. The planet, called WASP-12b, is the hottest known world ever discovered, with an atmosphere seething at 2,800 degrees Fahrenheit. (read more)

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19
May 10

Astronomers Find Nine New Planets and Upset the Theory of Planetary Formation

Source: Universtity of California, Santa Barbara


Gallery of exoplanets with retrograde orbits. Exoplanets, discovered by WASP together with ESO telescopes, that unexpectedly have been found to have retrograde orbits, are shown in this artist's conception. In all cases the star is shown to scale, with its rotation axis pointing up and with realistic colors. Credit: ESO/L. Calçada

The discovery of nine new planets challenges the reigning theory of the formation of planets, according to new observations by astronomers. Two of the astronomers involved in the discoveries are based at the UC Santa Barbara-affiliated Las Cumbres Observatory Global Telescope Network (LCOGT), based in Goleta, Calif., near UCSB.

Unlike the planets in our solar system, two of the newly discovered planets are orbiting in the opposite direction to the rotation of their host star. This, along with a recent study of other exoplanets, upsets the primary theory of how planets are formed. There is a preponderance of these planets with their orbital spin going opposite to that of their parent star. They are called exoplanets because they are located outside of our solar system. (read more)

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16
Apr 10

Wet Rocky Planets A Dime A Dozen In The Milky Way

Source: Space Daily

An international team of astronomers have discovered compelling evidence that rocky planets are commonplace in our Galaxy. Leicester University scientist and lead researcher Dr. Jay Farihi surveyed white dwarfs, the compact remnants of stars that were once like our Sun, and found that many show signs of contamination by heavier elements and possibly even water, improving the prospects for extraterrestrial life. (read more)

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20
Mar 10

Newly Discovered Planet Could Hold Water

Source: Space Daily

The Corot satellite strikes again with another fascinating planet discovery. This time, the newly discovered gas giant planet may have an interior that closely resembles those of Jupiter and Saturn in our own Solar System.

Very few planets are temperate enough to allow the presence of liquid water, but the newly discovered Corot-9b is one of them. It was found on 16 May 2008 and orbits its star every 95.274 days, a little longer than Mercury takes to go round the Sun. (read more)

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18
Mar 10

First Temperate Exoplanet Sized Up

Source: ESO Science Release eso1011

Combining observations from the CoRoT satellite and the ESO HARPS instrument, astronomers have discovered the first “normal” exoplanet that can be studied in great detail. Designated Corot-9b, the planet regularly passes in front of a star similar to the Sun located 1500 light-years away from Earth towards the constellation of Serpens (the Snake).(read more)

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26
Feb 10

Exoplanet disrupted by its star

Source: The Kavli Foundation


Illustration of WASP-12b in orbit about its host star (Credit: ESA/C Carreau)

The class of exotic Jupiter-mass planets that orbit very close to their parent stars were not explicitly expected before their discovery. Now an international group of astrophysicists has determined that a massive planet outside our Solar System is being distorted and destroyed by its host star – a finding that helps explain the unexpectedly large size of the planet, WASP-12b.

It’s a discovery that not only explains what’s happening to WASP-12b; it also means scientists have a one-of-a-kind opportunity to observe how a planet enters this final stage of its life.

The findings were published in the February 25 issue of Nature. (read more)

Links:
arXiv
Nature

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14
Jan 10

The quest for Extragalactic Exoplanets begins...

Source: arXiv:1001.2105v1

While the most distant exoplanets detected until today are OGLE-05-390L b, MOA-2007-BLG-400-L b at around 6,500 & 6,000 parsecs, which  roughly means ~21,190 & ~19,500 light-years away respectively, an international team of astronomers proposes  a new observational method that they believe will allow  the detection of exoplanets in the Andromeda galaxy (M31) that is at a distance of 2.9 million light-years from us.


A simulation of the expected microlensing event. Credit: Ingrosso et al. (2009)

The authors think that that exoplanets in the M31 galaxy may be detected with the pixel-lensing method by using telescopes making high cadence observations of an ongoing microlensing event.Although the mean mass for detectable exoplanets is about 2 MJ, even small mass exoplanets (inferior to 20 Earth masses) can cause significant deviations, which are observable with large telescopes. (read more)

Link:

Ingrosso,G., De Paolis,F., Novati,S.C., Jetzer,Ph.,  Nucita,A.A., Zakharov,A. F. (2009). Detection of Exoplanets in M31 with Pixel-Lensing: The Event Pa-99-N2 Case, in proceedings of the "Twelfth Marcel Grosmann Meeting", Paris.

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13
Jan 10

VLT Captures First Direct Spectrum of an Exoplanet

Source: ESO Science Release 02/10

ESO has just released the magnificent information that the VLT has been capable, for the first time in human, to provide data that allows the study of an exoplanet's atmosphere.

By studying a triple planetary system that resembles a scaled-up version of our own Sun’s family of planets, astronomers have been able to obtain the first direct spectrum — the “chemical fingerprint” — of a planet orbiting a distant star, thus bringing new insights into the planet's formation and composition. The result represents a milestone in the search for life elsewhere in the Universe. (read more)

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7
Jan 10

Second smallest exoplanet found to date discovered at Keck

Source:W.M. Keck Observatory News and Outreach

Artist's impression of an extrasolar planet.
Credit: ESO/L. Calçada.

Planet hunters using Keck Observatory have detected an extrasolar planet that is only four times the mass of Earth. The planet is the second smallest exoplanet ever discovered and adds to astronomers’ growing cadre of low mass planets called super-Earths. (read more)

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6
Jan 10

Astronomers say Alien dust is nothing to sneeze at

Credit: Gemini


Artist's impression of the events around HD 131488.
Credit: Lynette Cook for Gemini Observatory/AURA

Using the Gemini South telescope in Chile, astronomers at UCLA have found dusty evidence for the formation of young, rocky planets around a star some 500 light years distant. But these potential extrasolar worlds are alien in an even more intriguing way… In the aftermath of collisions between planetary embryos around this star the researchers discovered that the dusty debris bears no resemblance to the planetary building blocks of our own Solar System. (read more)

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6
Jan 10

Massive Stars: Good Targets for Planet Hunts, Bad Targets for SETI

Credit: Harvard Smithsonian Center for Astrophysics

Artist's conception shows a Jupiter-sized planet forming from a disk of dust and gas
surrounding a young, massive star. The planet's gravity has cleared a gap in the disk.
Credit: David A. Aguilar, CfA

Most searches for planets around other stars, also known as exoplanets, focus on Sun-like stars. Those searches have proven successful, turning up more than 400 alien worlds.

The prospects for hypothetical alien life are, by opposite, disappointing. The habitable zone, or region where liquid water could exist on a rocky surface, is at a greater distance from the star for A and B stars than for sun-like stars due to their greater luminosity. However, that luminosity comes at the price of a short lifetime. A and B stars live for only about 10 - 500 million years before running out of fuel. (read more)

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6
Jan 10

Earth-Like Planet Probably A Wasteland

Source: Space Daily

Artist's impression of an extrasolar planet.

When scientists confirmed in October that they had detected the first rocky planet outside our solar system, it advanced the longtime quest to find an Earth-like planet hospitable to life.

Now scientists led by a University of Washington astronomer say that if CoRoT-7 b's orbit is not almost perfectly circular, then the planet might also be undergoing fierce volcanic eruptions. It could be even more volcanically active than Jupiter's moon Io, which has more than 400 volcanoes and is the most geologically active object in our solar system. (read more)

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4
Jan 10

Astronomers Find World with Thick, Inhospitable Atmosphere and an Icy Heart

Source: ESO


Artists impression of the extrassolar planet. Credit: ESO/L.Calçada

Astronomers have discovered the second super-Earth exoplanet [1] for which they have determined the mass and radius, giving vital clues about its structure. It is also the first super-Earth where an atmosphere has been found. The exoplanet, orbiting a small star only 40 light-years away from us, opens up dramatic new perspectives in the quest for habitable worlds. The planet, GJ1214b, has a mass about six times that of Earth and its interior is likely to be mostly made of water ice. Its surface appears to be fairly hot and the planet is surrounded by a thick atmosphere, which makes it inhospitable for life as we know it on Earth.(read more)

Related links:
Portal to the Universe

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4
Dec 09

First image of cool extrasolar planet candidate around Sun-like star

Source: Max-Planck Institute

Extrasolar planet list keeps on growing. Another planet outside of our Solar System has been directly imaged using the Subaru telescope. Given that the first visible light image of an extrasolar planet was taken a little more than a year ago, the list is growing pretty fast since now we are over ten.

GJ758B-Subaru-2009

Discovery image of GJ 758 B, taken in August
2009 with Subaru HiCIAO in the near infrared.

Credit: MPIA/NAOJ

The newest one, planet GJ 758 B is also the coolest directly imaged planet, with a temperature of 600 Kelvin, and it orbits a star that is much like our own Sun. GJ 758 B has a mass of between 10-40 times that of Jupiter, making it either a really big planet or a small brown dwarf.

Other links:
Astrophysical Journal Letters (arXiv.org)
Universe Today

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