Armazones Chile to be the Site for the 42 meter European Extremely Large Telescope?

Artist impression of the Extremely Large Telescope. Credit: ESO

Question: Where are the night skies always dark, cloud-free 360 days a year, bone-dry, and orbiting 3.5 km above sea level?
Answer: Armazones Mountain, Atacama desert, Chile.
Question: Who wants to go live there?
Answer: The European Extremely-Large Telescope (E-ELT)!

“We are talking about the biggest telescope in the world, the biggest for a long time to come. That means we have to choose the best spot. Chile has a superb location. It’s the best in the world, there’s no doubt,” the European Southern Observatory’s astronomer, Massimo Tarenghi, told AFP. He is one of four astronomers – two Chileans, an Italian (Tarenghi) and a German – who were in the desert this week to evaluate its suitability compared to the main other contender: the Spanish isle of La Palma in the Canary Islands off western Africa.

The European Southern Observatory (ESO), an intergovernmental astronomical research agency that already has three facilities operating in the Atacama desert, including the Very Large Telescope array in the town of Paranal which is currently considered Europe’s foremost observatory.

Work on the E-ELT is to begin in December 2011 and cost 90 million euros (120 million dollars) … once a decision is made on the site, which will be as early as March this year.

When complete, the E-ELT will be “the world’s biggest eye on the sky,” according to the ESO, which hopes it will “address many of the most pressing unsolved questions in astronomy.”

The E-ELT is likely to be as revolutionary in the field of astronomy as Galileo’s telescope 400 years ago that determined that the Sun, and not the Earth, was the center of our universe, according to the European agency based in Munich, Germany. The German astronomer in Chile, Wolfgang Gieren, waxed happily about the possibilities of the future telescope. “In no more than 15 years we could have the first good-resolution spectra of planets outside our universe that are the same size of Earth and see if we can detect signs of life,” he said.

One of the Chilean astronomers, Mario Harmuy, said the Armazones provided an ideal location. “Several things come together here. The cold Humboldt Current, which passes by Chile’s coast, means that there is a high pressure center in the Pacific that deflects high clouds and prevents cover over this part of the continent,” he said. “To the east, the high Andes mountains prevent humidity from moving in from the Atlantic with clouds. The higher you are, the less humidity there is, and thus the light from the stars go through less of the atmosphere and is distorted less when it hits the telescope.” To boot, the Chilean location is free of the storms that hit the Canary Islands and the Sahara, he said.

Tarneghi added that the ESO’s existing Paranal observatory nearby also meant that much of the ground infrastructure was already in place.

Chile’s government was equally enthusiastic about hosting the E-ELT. Gabriel Rodriguez, in charge of the foreign ministry’s science and technology division, said Chile was ready to cede the 600 hectares (1,500 acres) needed for the project. The government is to submit its offer to the ESO next Monday, with a decision expected early March.

The Italian astronomer cautioned that despite Chile’s obvious advantages, the tender had to be weighed carefully for all its aspects. “Neither any of us nor the ESO know what the final decision will be. We need to receive the Chilean and Spanish proposals and evaluate factors of operation, work and production costs,” Tarenghi said.

The other Chilean astronomer, Maria Teresa Ruiz, remained fired up at the potential of the new instrument. The “surface area of this telescope is bigger than all the others in Chile combined, which will allow us to explore things in the universe that we can’t even imagine today,” she said.

Source: AFP

New Technique to Find Earth-like Exoplanets

The Artists impression of HD 189733b, graph and image of the telescope Credit: NASA

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Another technique has been added to the exo-planet hunters’ toolkit, and it doesn’t require huge ground-based telescopes or space-based observatories. A group of astronomers developed the new technique by using a relatively small Earth-based infrared telescope to identify an organic molecule in the atmosphere of a Jupiter-sized planet nearly 63 light-years away. This new ground-based technique will enable the study of atmospheres of planets outside our Solar System, accelerating our search for Earth-like planets with life-related molecules.

On Aug. 11, 2007, Mark Swain from JPL and his team turned the NASA Infrared Telescope Facility – a 3-meter telescope on the summit of Mauna Kea, Hawaii, — to the hot, Jupiter-size planet HD 189733b in the constellation Vulpecula. Every 2.2 days, the planet orbits a K-type main sequence star slightly cooler and smaller than our Sun. HD189733b had already yielded breakthrough advances in exoplanet science, including detections of water vapor, methane and carbon dioxide using space telescopes.

Using a novel calibration method to remove systematic observation errors caused by instability of Earth’s atmosphere, they obtained a measurement revealing details of the HD189733b’s atmospheric composition and conditions, an unprecedented achievement from an Earth-based observatory.

They detected carbon dioxide and methane in the exo-planet’s atmosphere of HD 189733b with the SpeX spectrograph, which splits light into its components to reveal the distinctive spectral signatures of different chemicals. Their key work was development of the novel calibration method to remove systematic observation errors caused by the variability of Earth’s atmosphere and instability due to the movement of the telescope system as it tracks its target.

his scheme explains how the spectrum of the planet is isolated. First the spectrum of both, the planet and ist central star is registered; then, when the planet is hidden beyond the star, one obtains the spectrum of the star alone. If one subtracts the second from the first, one obtains the spectrum of the planet alone.

It took the researchers more than two years to develop their method so that it could be applied to spectroscopic observations with the 3 meter telescope, enabling the identification of specific molecules such as methane and carbon dioxide.

“As a consequence of this work, we now have the exciting prospect that other suitably equipped yet relatively small ground-based telescopes should be capable of characterizing exoplanets,” said John Rayner, the NASA Infrared Telescope Facility support scientist who built the SpeX spectrograph. “On some days we can’t even see the Sun with the telescope, and the fact that on other days we can now obtain a spectrum of an exoplanet 63 light-years away is astonishing.”

During their observations, the team found unexpected bright infrared emission from methane that stands out on the day side of HD198733b. This could indicate some kind of activity in the planet’s atmosphere which could be related to the effect of ultraviolet radiation from the planet’s parent star hitting the planet’s upper atmosphere, but more detailed study is needed.

“An immediate goal for using this technique is to more fully characterize the atmosphere of this and other exoplanets, including detection of organic and possibly prebiotic molecules” like those that preceded the evolution of life on Earth, said Swain. “We’re ready to undertake that task.” Some early targets will be the super-Earths. Used in synergy with observations from NASA’s Hubble, Spitzer and the future James Webb Space Telescope, the new technique “will give us an absolutely brilliant way to characterize super-Earths,” Swain said.

Their work is reported today in the Feb. 3, 2010 edition of Nature.

For a great FAQ about using spectrum to study exoplanets, see this page by the Max Planck Institute for Astronomy.

Sources: Max Planck Institute for Astronomy, STFC

First Direct Spectrum of an Exoplanet Orbiting a Sun-like Star

Image of the HR 8799 system. Image credit: MPIA / W. Brandner

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Astronomers have obtained the first direct spectrum – a “chemical fingerprint” – of a planet orbiting a distant, Sun-like star, providing direct data about the composition of the planet’s atmosphere. An international team of researchers studied the planetary system around HR 8799 a bright, young star with 1.5 times the mass of our Sun, and focused on one of three planets orbiting the star. While the results were unusual and pose a challenge to current models of the exoplanet’s atmosphere, the accomplishment represents a milestone in the search for life elsewhere in the Universe.

The planetary system resembles a scaled-up version of our own Solar System and includes three giant planets, which had been detected in 2008 in another study. “Our target was the middle planet of the three,” said team member and PhD student Carolina Bergfors, from the Max Planck Institute for Astronomy, (MPIA), “which is roughly ten times more massive than Jupiter and has a temperature of about 800 degrees Celsius,”

The NaCo instrument, mounted at ESO's Very Large Telescope on Paranal in Chile. Credit: ESO


Caption: The NaCo instrument, mounted at ESO’s Very Large Telescope on Paranal in Chile. NaCo is a combination of adaptive optics (which counteracts some of the blurring effect of the Earth’s atmosphere) and the camera/spectrograph CONICA, which was developed at the Max Planck Institute for Astronomy and the Max Planck Institute for Extraterrestrial Physics. Image credit: ESO

The researchers recorded the spectrum using the NACO instrument ion the Very Large Telescope (VLT) in Chile.

As the host star is several thousand times brighter than the planet, and the two are very close, obtaining such a spectrum is an immense feat.

“It’s like trying to see what a candle is made of, by observing it next to a blinding 300 Watt lamp – from a distance of 2 kilometres [1.3 miles],” said Markus Janson of the University of Toronto, lead author of the paper.

Bergfors added, “It took more than five hours of exposure time, but we were able to tease out the planet’s spectrum from the host star’s much brighter light.”

However, the spectra of the exoplanet’s atmosphere shows a clear deviation between the observed spectral shape and what is predicted by the current standard models. “The features observed in the spectrum are not compatible with current theoretical models,” said MPIA’s Wolfgang Brandner, a co-author of the study.

The models assume chemical equilibrium between the different chemical elements present in the atmosphere, and a continuous temperature profile (hotter layers below colder layers). At longer wavelengths (above 4 micrometres), the planet is significantly fainter than expected, which points to molecular absorption spectrum in its atmosphere. The simplest explanation is that the atmosphere contains less methane and more carbon monoxide than previously assumed.

“We need to take into account a more detailed description of the atmospheric dust clouds, or accept that the atmosphere has a different chemical composition than previously assumed,” Brandner said.

In time, the astronomers hope that this technique will help them gain a better understanding of how planets form. Next, they hope to record the spectra of the two other giant planets orbiting HR 8799 – which would represent the first time that astronomers would be able to compare the spectra of three exoplanets that form part of one and the same system. As a much more distant goal, the technique will allow astronomers to examine exoplanets for habitability, or even signs of life.

Source: Max Planck Institute for Astronomy

Second Smallest Exoplanet Found

This artists' rendition shows a super-Earth, or low mass exoplanet, orbiting close to its parent star. Credit: Keck Observatory

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Planet hunters have detected an extrasolar planet that is only four times the mass of Earth, making it the second smallest exoplanet ever discovered. Astronomers using the 10-meter Keck I telescope at the Keck Observatory in Hawaii found the un-poetically named HD156668b, which has a mass of roughly 4.15 Earth masses. It orbits its parent star in just over four days and is located roughly 80 light years from Earth in the direction of the constellation Hercules. This adds to the growing list of so-called “Super-Earths” now being found.

“This is quite a remarkable discovery,” said astronomer Andrew Howard of the University of California at Berkeley. “It shows that we can push down and find smaller and smaller planets.”

The researchers used the radial velocity or wobble method, using Keck’s High Resolution Echelle Spectrograph, or HIRES instrument, to spread light collected from the telescope into its component wavelengths or colors. When the planet orbits around the back of the parent star, its gravity pulls slightly on the star causing the star’s spectrum to shift toward redder wavelengths. When the planet orbits in front of the star, it pulls the star in the other direction. The star’s spectrum shifts toward bluer wavelengths.

This graphic shows the data confirming the existence of extrasolar planet HD 156668b as discovered using Keck/HIRES. The planet has a mass of roughly 4.15 Earth masses and is the second smallest exoplanet discovered to date. It orbits its host star (HD 156668) every 4.6 days. Credit: Andrew Howard, UCB

The color shifts give astronomers the mass of the planet and the characteristics of its orbit, such as the time it takes to orbit the star. Nearly 400 planets around other stars were discovered using this technique. But, the majority of these planets are Jupiter-sized or larger.

“It’s been astronomers long-standing goal to find low mass planets, but they are really hard to detect,” Howard said. He added that the new discovery has implications for not only exoplanet research but also for solving the puzzle of how planets and planetary systems form and evolve.

Astronomers have pieces of the formation and evolutionary puzzle from the discovery of hundreds of high-mass planets. But, “there are important pieces, we don’t have yet. We need to understand how low mass planets, like super-Earths, form and migrate,” Howard said.

The goal of the Eta-Earth Survey for Low Mass Planets, which was the brainchild of fellow planet hunter Geoff Marcy, also from UCB, to find these super-Earths. So far the survey has discovered two near-Earth-mass planets with more are on the way, Howard said.

Other collaborators included , Debra Fischer of Yale University, John Johnson of the California of Institute of Technology and Jason Wright of Penn State University.

The discovery was announced at the 215th American Astronomical Society meeting in Washington D.C.

Source: Keck

Kepler Discovers Planets-like Objects Hotter Than Stars

Possible habitable zones around stars. Credit: Kepler mission

The Kepler mission announced the discovery of 5 new extrasolar planets today at the American Astronomical Society meeting in Washington, DC, each with some very unusual properties. But additionally, the space telescope has spotted some Jupiter-sized objects orbiting stars, and these objects are hotter than the host star. The science team has no idea what these objects could be, but they are part of 100 planetary candidates Kepler has observed that are still being analyzed.

The Kepler mission’s objective is to search for Earth-size planets in the habitable zones of other stars, and the planets announced today are comparable in size to Neptune, Jupiter and the other gas giants of our solar system but are substantially less dense. This first set of five new planets discovered by the Kepler mission was discovered in the first six weeks of the telescope’s operation. “The quick discovery indicates that Kepler is performing well,” said William Borucki, from NASA’s Ames Research Center.

One of these new planets is similar in many ways to Neptune, although its irradiation level is much higher. A second planet is one of the least dense planets ever discovered, and along with the other three, confirms the existence of planets with densities substantially lower than those predicted for gas giant planets. Borucki said Kepler 7b has the density of styrofoam, at .17 grams per cubic centimeter, basically a density of zero.
The smallest planet, Kepler 4b, is 4.31 earth radii, or about Neptune-sized. The other four about the size of Jupiter. All five planets have short orbital periods, and follow-up observations will be made with ground-based telescopes.

Since these planets are close to their host stars, they are very hot, hotter than about 1500 K. 1300 K is the temperature where molten lava flows.

Kepler launched in March 2009 and the mission is expected to last 3½ years. The team now has an additional 8 months of data are now available to analyze. Borucki said in 2010 Kepler will focus on the discovery of smaller planets, with an Earth-sized planet being the “holy grail” of exoplanet discoveries.
Other objects detected by Kepler include unusual variable stars, including binaries, oscillating stars, pulsating variables, and more, including other extrasolar planets, but declined to divulge more, saying his team has to be patient and do the confirmations on all the objects before.

Borucki also said data from Kepler will be released to the public on a regular basis starting in June 2010.

Source: AAS Press conference

First Super-Earths Discovered Around Sun-like Stars

Astronomers say it’s a “neck-and-neck race” as to whether the first potentially habitable planets will be detected from the ground or from space, and today an international team of planet hunters announced they have discovered as many as six low-mass planets around two nearby Sun-like stars, using two ground-based observatories. This haul of planets includes two “super-Earths” with masses 5 and 7.5 times the mass of Earth.

The researchers, led by Steven Vogt of the University of California, Santa Cruz, and Paul Butler of the Carnegie Institution of Washington, said the two “super-Earths” are the first ones found around Sun-like stars. These planets have orbits close to their stars and so they would be too hot to support life or liquid water.

“These detections indicate that low-mass planets are quite common around nearby stars. The discovery of potentially habitable nearby worlds may be just a few years away,” said Vogt, a professor of astronomy and astrophysics at UCSC.

The team found the new planet systems by combining data gathered at the W. M. Keck Observatory in Hawaii and the Anglo-Australian Telescope (AAT) in New South Wales, Australia.

A comparison of the orbits of the planets of 61 Vir with the inner planets in our Solar System. All three planets discovered to date in this system would lie inside the orbit of Venus.
A comparison of the orbits of the planets of 61 Vir with the inner planets in our Solar System. All three planets discovered to date in this system would lie inside the orbit of Venus.

Three of the new planets orbit the bright star 61 Virginis, which can be seen with the naked eye under dark skies in the Spring constellation Virgo. Astronomers and astrobiologists have long been fascinated with this particular star, which is only 28 light-years away. Among hundreds of our nearest stellar neighbors, 61 Vir stands out as being the most nearly similar to the Sun in terms of age, mass, and other essential properties. Vogt and his collaborators have found that 61 Vir hosts at least three planets, with masses ranging from about 5 to 25 times the mass of Earth.

Click here to see an animation showing a simulation of the hot atmosphere of the 5.3 Earth-mass planet 61 Vir b as it circles around its star in a 4.2 day orbit. The imaginary observer sits in space above the planet, and sees the hot side (which always faces the star) rotate into and out of view.

Recently, a separate team of astronomers used NASA’s Spitzer Space Telescope to discover that 61 Vir also contains a thick ring of dust at a distance roughly twice as far from 61 Vir as Pluto is from our Sun. The dust is apparently created by collisions of comet-like bodies in the cold outer reaches of the system.

“Spitzer’s detection of cold dust orbiting 61 Vir indicates that there’s a real kinship between the Sun and 61 Vir,” said Eugenio Rivera, a postdoctoral researcher at UCSC. Rivera computed an extensive set of numerical simulations to find that a habitable Earth-like world could easily exist in the as-yet unexplored region between the newly discovered planets and the outer dust disk.

This image from a simulation of atmospheric flow shows temperature patterns on one of the newly discovered planets (61Virb), which is hot enough that it glows with its own thermal emission. A movie of the simulation is posted at the bottom of this story, showing global atmospheric flow for one full orbit of the planet around its star. Credit: J. Langton, Principia College.
This image from a simulation of atmospheric flow shows temperature patterns on one of the newly discovered planets (61Virb), which is hot enough that it glows with its own thermal emission. A movie of the simulation is posted at the bottom of this story, showing global atmospheric flow for one full orbit of the planet around its star. Credit: J. Langton, Principia College.

The second new system found by the team features a 7.5-Earth-mass planet orbiting HD 1461, another near-perfect twin of the Sun located 76 light-years away. At least one and possibly two additional planets also orbit the star. Lying in the constellation Cetus, HD 1461 can be seen with the naked eye in the early evening under good dark-sky conditions.

The 7.5-Earth-mass planet, assigned the name HD 1461b, has a mass nearly midway between the masses of Earth and Uranus. The researchers said they cannot tell yet if HD 1461b is a scaled-up version of Earth, composed largely of rock and iron, or whether, like Uranus and Neptune, it is composed mostly of water.

According to Butler, the new detections required state-of-the-art instruments and detection techniques. “The inner planet of the 61 Vir system is among the two or three lowest-amplitude planetary signals that have been identified with confidence,” he said. “We’ve found there is a tremendous advantage to be gained from combining data from the AAT and Keck telescopes, two world-class observatories, and it’s clear that we’ll have an excellent shot at identifying potentially habitable planets around the very nearest stars within just a few years.”

The 61 Vir and HD 1461 detections add to a slew of recent discoveries that have upended conventional thinking regarding planet detection. In the past year, it has become evident that planets orbiting the Sun’s nearest neighbors are extremely common. According to Butler, current indications are that fully one-half of nearby stars have a detectable planet with mass equal to or less than Neptune’s.

The Lick-Carnegie Exoplanet Survey Team led by Vogt and Butler uses radial velocity measurements from ground-based telescopes to detect the “wobble” induced in a star by the gravitational tug of an orbiting planet. The radial-velocity observations were complemented with precise brightness measurements acquired with robotic telescopes in Arizona by Gregory Henry of Tennessee State University.

“We don’t see any brightness variability in either star,” said Henry. “This assures us that the wobbles really are due to planets and not changing patterns of dark spots on the stars.”

Due to improvements in equipment and observing techniques, these ground-based methods are now capable of finding Earth-mass objects around nearby stars, according to team member Gregory Laughlin, professor of astronomy and astrophysics at UCSC.

“It’s come down to a neck-and-neck race as to whether the first potentially habitable planets will be detected from the ground or from space,” Laughlin said. “A few years ago, I’d have put my money on space-based detection methods, but now it really appears to be a toss-up. What is truly exciting about the current ground-based radial velocity detection method is that it is capable of locating the very closest potentially habitable planets.”

Lead image caption: 61 Virginis is one of only a handful of truly Sun-like stars that can be seen with the naked eye. Astronomers have discovered three low-mass planets orbiting the star. Credit: NASA’s Sky View

Papers:
A Super-Earth and two Neptunes Orbiting the Nearby Sun-like star 61 Virginis
A Super-Earth Orbiting the Nearby Sun-like Star HD 1461
A long-period planet orbiting a nearby Sun-like star

Source: UC Santa Cruz

Exoplanet Not Really There?

This artist’s concept shows the smallest star known to host a planet. Image credit: NASA/JPL-Caltech

In May 2009, astronomers were jubilant: finally, an extra solar planet had been found by using the method of astrometry. That’s great, except, they may not have found a planet after all. Researchers from JPL reported they found a Jupiter-like planet around a star smaller than our sun. But follow-up observations of the star VB10 are coming up empty. “The planet is not there,” said Jacob Bean from the Georg-August University in Gottingen, Germany, who used a different and more successful approach to look for exoplanets, radial velocity.

Astrometry measures the side-to-side motion of a star on the sky to see whether any unseen bodies might be orbiting it. Using this method is difficult and requires very precise measurements over long periods of time. Using astrometry to look for exoplanets has been around for 50 years, but it hadn’t bagged a verified exoplanet – until, astronomers thought, earlier this year. A team of researchers announced an exoplanet, six times more massive than Jupiter, orbiting a star about one-thirteenth the mass of the Sun, using a telescope at the Palomar Observatory in southern California (S. Pravdo and S. Shaklan Astrophys. J. 700, 623–632; 2009).

“This method is optimal for finding solar-system configurations like ours that might harbor other Earths,” astronomer Steven Pravdo of JPL said in May. “We found a Jupiter-like planet at around the same relative place as our Jupiter, only around a much smaller star. It’s possible this star also has inner rocky planets. And since more than seven out of 10 stars are small like this one, this could mean planets are more common than we thought.”

But using different methods, other astronomers aren’t finding anything.

“We would definitely have seen a significant amount of variation in our data if [the planet] was there,” said Bean, quoted in the online Nature News. Bean has submitted a paper to the Astrophysical Journal.

Radial velocity, which has found most of the extrasolar planets so far, looks for shifts in the lines of a star’s absorption spectrum to track its motion towards and away from Earth, which would be caused by the influence of a planet.

Pravdo says that Bean and his colleagues “may be correct, but there is hyperbole in their rejection of our candidate planet.” Bean’s paper, for instance, only rules out the presence of any planet that is at least three times more massive than Jupiter, says Pravdo, adding that the work “limits certain orbits for possible planets but not all planets.”

Astronomers expect astrometry to work much better above the distorting effects of the atmosphere. Two space missions in the works — the European Space Agency’s GAIA, due to launch in 2012, and NASA’s proposed SIM-lite (Space Interferometry Mission) will use the technique to search for planets as small as Earth around Sun-like stars. Astrometry potentially can yield the mass of a planet, whereas radial velocity only puts a lower limit on it.

Bean admits that astronomers might one day find a planet around VB10 if they scrutinize the star long and hard enough.

Source: Nature News

Exobiology

Exobiology (same thing as astrobiology) is about life in space (on other planets, and moons; in other solar systems): where it is, what it is, how it started, and how it evolved (all studied scientifically, of course). Because the origin of life right here on Earth, and its early evolution, is essentially unknown, and because of the distinct possibility of similiarities with the origin (and early evolution) of life elsewhere in the universe, exobiology includes research into abiogenesis (and early, and extreme, life on Earth).

Exobiology is very much a multi-disciplinary field, drawing on biology, chemistry, geology (and planetary science), physics, and astronomy.

Because we have a sample of just one – life on Earth – it is difficult to make anything but the most general decisions on what lines of exobiology research are likely to be productive (keep in mind that null results can, of course, be quite productive). Conservatively, looking for planets like Earth in orbit around stars like the Sun (in age as well as mass, metallicity, etc), and looking for clues for fossil life in planetary environments like those found today on Earth (e.g. early Mars) seem better options than investigating possible silicon-based life (to take just one example).

As the number of exosolar (or extrasolar) planetary systems known continues to grow, quickly, discovering the prevalence of Earth-mass planets, in goldilocks orbital zones, seems like a good idea … so today we have the Kepler mission and COROT.

As the early Mars becomes better understood – and the widespread distribution of liquid water then – so today we have plans for the Mars Science Laboratory and ExoMars (the discovery of methane in the Martian atmosphere certainly spurs such developments).

Less conservatively, the discovery of life around black smokers and sites like Lost City (not to mention entire ecosystems within crustal rocks … several km beneath the surface) sparked interest in the possibility of life in Europa, on Titan, even Enceladus (life – albeit rather simple life – we now know does not need to depend, ultimately, on the Sun’s (or another star’s) radiant energy … think chemolithoautotrophs).

Did you know that NASA has an exobiology branch? Check it out! Duke University’s Chemistry Department has an interesting Introduction to Exobiology you might find interesting too.

Universe Today stories on exobiology? Yep, lots; here’s a random selection: Martian Explorers Should Be Looking for Fossils, Did Life Arrive Before the Solar System Even Formed?, Extremophile Hunt Begins in Antarctica, Implications for Exobiologists , and New Targets to Search for Life on Europa.

Any Astronomy Cast episodes on exobiology? Yep … but it’s called Astrobiology.

Sources: NASA, ESA

Cool – Literally – Extrasolar Planet Imaged

Yet another planet outside of our Solar System has been directly imaged, bumping the list up past ten. 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. The newest one, planet GJ 758 B is also the coolest directly imaged planet, measuring 600 degrees 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.

Unlike many of the other directly imaged planets, GJ 758 B resides in a system remarkably like our own Solar System – the star at the center is Sun-like, and the orbit of the planet is at least the same distance from its star as Neptune is from our own. Current observations put the distance at 29 astronomical units.

“The discovery of GJ 758 B, an extrasolar planet or brown dwarf orbiting a star that is similar to our own sun, gives us an insight into the diversity of substellar objects that may form around Solar-type stars,” said Dr. Joseph Carson, from the Max Planck Institute for Astronomy. “This in turn helps show how our own Solar system, and the environments that are conducive to life, are just one of many scenarios that may be the outcome of planet or brown dwarf formation around Sun-like stars.”

Another object, labeled “C?” in the image above, could potentially be another companion to the star. Further observations will be required to determine whether the object in fact orbits the star or is merely another star in the background of the image which is not part of the system.

The mass of the star still has yet to be exactly determined, thus the 10-40 Jupiter mass range. It is 600 degrees Kelvin, which corresponds to 326 Celsius and 620 Fahrenheit, about the hottest temperature that a conventional oven can reach. Though this may seem hot, it’s actually pretty cool for an extrasolar planet. Even though it is so far away from its Sun that, like Neptune, it receives very little warmth from the star it orbits, GJ 758 B is in a stage of formation where the contraction of the planet due to gravity is converted into heat.

A size comparison of the GJ 758 system and corresponding members of our own Solar System, with the Earth for reference. Image Credit: Credit: MPIA/C. Thalmann
A size comparison of the GJ 758 system and corresponding members of our own Solar System, with the Earth for reference. Image Credit: Credit: MPIA/C. Thalmann

Dr. Markus Janson from the University of Toronto, a co-author of the paper announcing the imaging, said, “This is also why the mass of the companion is not well known: The measured infrared brightness could come from a 700 million year old planet of 10 Jupiter masses just as well as from a 8700 million year old companion of 40 Jupiter masses.” The paper detailing the results will be published in Astrophysical Journal Letters, but is available here on Arxiv.

The planet was imaged using the Subaru Telescope’s new High Contrast Instrument for the Subaru next generation Adaptive Optics (HiCIAO) instrument, which utilizes the technology of adaptive optics to eliminate the interference of our atmosphere that blurs images in ground-based telescopes. The imaging of GJ 758 B is part of the commissioning run of the HiCIAO instrument, which plans to take a larger survey to detect extrasolar planets and circumstellar disks in the next five years.

Source: Max-Planck Institute for Astronomy