Posted on by Jon Voisey

New Evidence For Fomalhaut Planets

Fomalhaut's exoplanet (NASA, ESA, P. Kalas (UC, Berkeley))

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The planetary system of the star Fomalhaut has been one of intense debate over the past few years. In 2008, it was announced that a large, Saturn mass planet shepherd a large dust ring and was spotted in visual images from Hubble. But in late 2011 infrared observations called the previous detections into question. Now joining the discussion is the recently completed Atacama Large Millimeter/sub-millimeter Array (ALMA). This radio observatory suggests that there may be more planets than previously detected.

ALMA sits in the high Atacama desert in northern Chile. This dry location is ideal for linking together the 66 radio dishes (although only 15 were used in the new observations) to give unprecedented resolution. With this new set of eyes, astronomers from the University of Florida and Bryant Space Science Center were able to study the fine details in the dust ring. These details were then compared to various models of how rings should function in different conditions.

The dust ring has several characteristics that any explanation would have to reproduce. The first was that the ring is slightly oval shaped. It must be exceptionally thin and have a sharp cutoff both on the interior and exterior edges. If the previously claimed planet, Fomalhaut b, were the only one present, it could not account for the outer edge of the disk being sharply truncated as well as the inner edge. Another possibility is that the ring is simply newly formed as the result of a collision between two planets and has not yet had time to dissipate giving it the sharp appearance. However, the authors note that planets at such a distance from the parent star shouldn’t have high enough relative velocities to crush them so finely.

Since neither of these explanations are sufficient, the team proposes that there are two planets that shepherd the ring: One interior and one exterior to it. Within our own solar system, we see similar effects in Uranus’ ε ring which is constrained by the moons Cordelia and Ophelia. Similarly, Saturn’s F ring is shepherded by Prometheus and Pandora. By varying the mass of hypothetical planets in the models, the authors could create a ring similar to that seen around Fomalhaut. However, the best fit was created by a pair of planets that were less than three times the mass of the Earth which would mean that the proposed mass for Fomalhaut b was significantly too high, further casting doubt on its existence. Additionally, the proposed orbit of Fomalhaut bwas 10 AU off from the orbit of the hypothetical interior shepherd planet.

Ultimately, these two planets are only hypothetical. Detecting them in a more direct fashion will prove challenging. The fact that their orbits wouldn’t be very close to line of sight as well as their distance from the star would make radial velocity detection impossible. Given the low proposed mass and the distance, they would reflect too little light to be able to be directly observed with current telescopes.

Posted on by Nancy Atkinson

Kepler Mission Extended to 2016

Artist concept of Kepler in space. Credit: NASA/JPL

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With NASA’s tight budget, there were concerns that some of the agency’s most successful astrophysics missions might not be able to continue. Anxieties were rampant about one mission in particular, the very fruitful exoplanet-hunting Kepler mission, as several years of observations are required in order for Kepler to confirm a repeated orbit as a planet transits its star. But today, after a long awaited Senior Review of nine astrophysics missions, surprisingly all have received funding to continue at least through 2014, with several mission extensions, including Kepler.

“Ad Astra… Kepler mission extended through FY16! We are grateful & ecstatic!” the @NASAKepler Twitter account posted today.

Additionally, missions such as Hubble, Fermi and Swift will receive continued funding. The only mission that took a hit was the Spitzer infrared telescope, which – as of now — will be closed out in 2015, which is sooner than requested.

The Senior Review of missions takes place every two years, with the goal assisting NASA to optimize the scientific productivity of its operating missions during their extended phase. In the Review, missions are ranked as which are most successful; previous Senior Reviews led to the removal of funding for the weakest 10-20% of extended missions, some of which had partial instrument failures or significantly reduced capabilities.

But this year’s review found all the astrophysics mission to be successful.

“These nine missions comprise an extremely strong ensemble to enter the Senior Review process and we find that all are making very significant scientific contributions,” the Review committee wrote in their report.

Here’s a rundown of the missions and how their funding was affected by the Senior Review:

• The Hubble Space Telescope will continue at the currently funded levels.

• Chandra will also continue at current levels, but its Guest Observer budget will actually be increased to account for decreases in Fiscal Year 2011.

• Fermi operations are extended through FY16, with a 10 percent per year reduction starting in FY14.

• Swift and Kepler mission operations are extended through FY16, including funding for data analysis.

• Planck will support one year extended operations of the Low Frequency Instrument (LFI).

• Spitzer’s operations are extended through FY14 with closeout in FY15.

• U.S. science support of Suzaku is extended to March 2015.

• Funding for U.S. support of XMM-Newton is extended through March 2015.

NASA says that all FY15-FY16 decisions are for planning purposes and they will be revisited in the 2014 Senior Review.

Read more in the full report (pdf).

Posted on by Nancy Atkinson

Astronomers Discover Ancient Planetary System

Artist’s impression of HIP 11952 and its two Jupiter-like planets. Image credit: Timotheos Samartzidis

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From a press release from the Max Planck Institute for Astronomy:

A group of European astronomers has discovered an ancient planetary system that is likely to be a survivor from one of the earliest cosmic eras, 13 billion years ago. The system consists of the star HIP 11952 and two planets, which have orbital periods of 290 and 7 days, respectively. Whereas planets usually form within clouds that include heavier chemical elements, the star HIP 11952 contains very little other than hydrogen and helium. The system promises to shed light on planet formation in the early universe – under conditions quite different from those of later planetary systems, such as our own.

It is widely accepted that planets are formed in disks of gas and dust that swirl around young stars. But look into the details, and many open questions remain – including the question of what it actually takes to make a planet. With a sample of, by now, more than 750 confirmed planets orbiting stars other than the Sun, astronomers have some idea of the diversity among planetary systems. But also, certain trends have emerged: Statistically, a star that contains more “metals” – in astronomical parlance, the term includes all chemical elements other than hydrogen and helium – is more likely to have planets.

This suggests a key question: Originally, the universe contained almost no chemical elements other than hydrogen and helium. Almost all heavier elements have been produced, over time inside stars, and then flung into space as massive stars end their lives in giant explosions (supernovae). So what about planet formation under conditions like those of the very early universe, say: 13 billion years ago? If metal-rich stars are more likely to form planets, are there, conversely, stars with a metal content so low that they cannot form planets at all? And if the answer is yes, then when, throughout cosmic history, should we expect the very first planets to form?

Now a group of astronomers, including researchers from the Max-Planck-Institute for Astronomy in Heidelberg, Germany, has discovered a planetary system that could help provide answers to those questions. As part of a survey targeting especially metal-poor stars, they identified two giant planets around a star known by its catalogue number as HIP 11952, a star in the constellation Cetus (“the whale” or “the sea monster”) at a distance of about 375 light-years from Earth. By themselves, these planets, HIP 11952b and HIP 11952c, are not unusual. What is unusual is the fact that they orbit such an extremely metal-poor and, in particular, such a very old star!

For classical models of planet formation, which favor metal-rich stars when it comes to forming planets, planets around such a star should be extremely rare. Veronica Roccatagliata (University Observatory Munich), the principal investigator of the planet survey around metal-poor stars that led to the discovery, explains: “In 2010 we found the first example of such a metal-poor system, HIP 13044. Back then, we thought it might be a unique case; now, it seems as if there might be more planets around metal-poor stars than expected.”

HIP 13044 became famous as the “exoplanet from another galaxy” – the star is very likely part of a so-called stellar stream, the remnant of another galaxy swallowed by our own billions of years ago.

Compared to other exoplanetary systems, HIP 11952 is not only one that is extremely metal-poor, but, at an estimated age of 12.8 billion years, also one of the oldest systems known so far. “This is an archaeological find in our own backyard,” adds Johny Setiawan of the Max Planck Institute for Astronomy, who led the study of HIP 11952: “These planets probably formed when our Galaxy itself was still a baby.”

“We would like to discover and study more planetary systems of this kind. That would allow us to refine our theories of planet formation. The discovery of the planets of HIP 11952 shows that planets have been forming throughout the life of our Universe”, adds Anna Pasquali from the Center for Astronomy at Heidelberg University (ZAH), a co-author of the paper.

Posted on by Nancy Atkinson

Billions of Habitable Worlds Likely in the Milky Way

Artist’s impression of sunset on the super-Earth world Gliese 667 Cc. Credit: ESO

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Could there be ‘tens of billions’ of habitable worlds in our own galaxy? That’s the results from a new study that searched for rocky planets in the habitable zones around red dwarf stars. An international team of astronomers using ESO’s HARPS spectrograph now estimates that there are tens of billions of such planets in the Milky Way galaxy, with probably about one hundred in the Sun’s immediate neighborhood, less than 30 light years away.

“Our new observations with HARPS mean that about 40% of all red dwarf stars have a super-Earth orbiting in the habitable zone where liquid water can exist on the surface of the planet,” said Xavier Bonfils, from IPAG, Observatoire des Sciences de l’Univers de Grenoble, France, and the leader of the team. “Because red dwarfs are so common — there are about 160 billion of them in the Milky Way — this leads us to the astonishing result that there are tens of billions of these planets in our galaxy alone.”

This is the first direct estimate of the number of smaller, rocky planets around red dwarf stars. Add this to another recent finding which suggested that every star in our night sky has at least one planet circling it — which didn’t include red dwarf stars – and our galaxy could be teeming with worlds.

This team used the HARPS spectrograph on the 3.6-metre telescope at ESO’s La Silla Observatory in Chile to search for exoplanets orbiting the most common kind of star in the Milky Way — red dwarf stars (also known as M dwarfs). These stars are faint and cool compared to the Sun, but very common and long-lived, and therefore account for 80% of all the stars in the Milky Way.

The Milky Way over the ESO 3.6-metre Telescope, a photo submitted via Your ESO Pictures Flickr Group. Credit: ESO/A. Santerne

The HARPS team surveyed a carefully chosen sample of 102 red dwarf stars in the southern skies over a six-year period. A total of nine super-Earths (planets with masses between one and ten times that of Earth) were found, including two inside the habitable zones of Gliese 581 and Gliese 667 C respectively.

By combining all the data, including observations of stars that did not have planets, and looking at the fraction of existing planets that could be discovered, the team has been able to work out how common different sorts of planets are around red dwarfs. They find that the frequency of occurrence of super-Earths in the habitable zone is 41% with a range from 28% to 95%.

Bonfils and his team also found that rocky planets were far more common than massive gas giants like Jupiter and Saturn. Less than 12% of red dwarfs are expected to have giant planets (with masses between 100 and 1000 times that of the Earth).

However, the rocky worlds orbiting red dwarfs wouldn’t necessarily be a good place to spend your first exo-vacation – or for harboring life.

“The habitable zone around a red dwarf, where the temperature is suitable for liquid water to exist on the surface, is much closer to the star than the Earth is to the Sun,” said Stéphane Udry from the Geneva Observatory and member of the team. “But red dwarfs are known to be subject to stellar eruptions or flares, which may bathe the planet in X-rays or ultraviolet radiation, and which may make life there less likely.”

New Exoplanet Discovered

A new exoplanet was discovered in this HARPS survey of red dwarfs: Gliese 667 Cc. This is the second planet in this triple star system and seems to be situated close to the center of the habitable zone. Although this planet is more than four times heavier than the Earth it is the closest twin to Earth found so far and almost certainly has the right conditions for the existence of liquid water on its surface. This is the second super-Earth planet inside the habitable zone of a red dwarf discovered during this HARPS survey, after Gliese 581d was announced in 2007 and confirmed in 2009.

“Now that we know that there are many super-Earths around nearby red dwarfs we need to identify more of them using both HARPS and future instruments,” said Xavier Delfosse, another member of the team. “Some of these planets are expected to pass in front of their parent star as they orbit — this will open up the exciting possibility of studying the planet’s atmosphere and searching for signs of life.”

Research papers: Bonfils et al. and Delfosse et al.

Source: ESO

Posted on by Ray Sanders

Can “Warp Speed” Planets Zoom Through Interstellar Space?

Artist’s conception of a runaway planet zooming through interstellar space. A glowing volcano on the planet’s surface hints at active plate tectonics that may keep the planet warm. Image Credit: David A. Aguilar (CfA)

[/caption]Nearly ten years ago, astronomers were stunned to discover a star that had been apparently flung from its own system and travelling at over a million kilometers per hour. Over the years, a question was brought up: If stars can be ejected at a high velocity, what about planets?

Avi Loeb (Harvard-Smithsonian Center for Astrophysics) states, “These warp-speed planets would be some of the fastest objects in our Galaxy. If you lived on one of them, you’d be in for a wild ride from the center of the galaxy to the Universe at large.”

Idan Ginsburg (Dartmouth College) adds, “Other than subatomic particles, I don’t know of anything leaving our galaxy as fast as these runaway planets.”

The mechanics responsible for the super-fast planets are similar to those responsible for “hypervelocity” stars. With stars, if a binary system drifts too closely to a supermassive black hole (such as the ones in the center of galaxies), the gravitational forces can separate the stars – sending one outward at incredible speeds, and the other in orbit around the black hole. Interestingly enough, “Warp Speed” planets can theoretically travel at a few percent of the speed of light – not quite as fast as Star Trek’s Enterprise, but you get the point.

The team, which includes Loeb and Ginsburg, created computer models to simulate the outcome if each star had planets orbiting it. The outcome of the model showed that the star shot into interstellar space would keep its planets, but the star “captured” into orbit around the black hole would have its planets stripped and sent outward at incredible speeds. Typical speeds for the planets range from 11-16 million kilometers per hour, but given the proper conditions could approach even higher velocities.

As of now, it’s impossible for astronomers to detect a wandering planet due to their small size, distance, and rarity. By detecting the dimming of light levels from a hypervelocity star as an orbiting planet crosses its face, astronomers could detect planets that orbit said star.

Ginsburg added, “With one-in-two odds of seeing a transit, if a hypervelocity star had a planet, it makes a lot of sense to watch for them.”

Loeb concluded with, “Travel agencies advertising journeys on hypervelocity planets might appeal to particularly adventurous individuals.”

If you’d like to learn more about hypervelocity planets, you can access a draft version of the upcoming paper at: http://arxiv.org/abs/1201.1446

Source(s): Harvard-Smithsonian Center for Astrophysics , Hypervelocity Planets and Transits Around Hypervelocity Stars

Posted on by Nancy Atkinson

The Latest Exoplanet News from Kepler

We love exoplanets! And the Kepler mission is giving us more to love. Our special guest on our latest live interview via a Google+ Hangout On Air was astronomer Darin Ragozzine with the Kepler mission, sharing insight how Kepler is blowing our previous concepts on exoplanets out of the water. Darin is an ITC Fellow at the Harvard Institute for Theory and Computation. He studies the theory and dynamics of transiting exoplanets around other stars and Kuiper belt objects in the outer solar system.

Posted on by Nancy Atkinson

Excellent Exoplanet Visualization: The Kepler Orrery II

About a year ago, Daniel Fabrycky from the Kepler spacecraft science team put together a terrific orrery-type visualization of all the multiple-planet systems discovered by the Kepler spacecraft as of February of 2011. With a new round of exoplanets just announced, here’s part two. This one is a visualization of the planetary systems discovered by Kepler that have more than one transiting object. There are 885 planet candidates in 361 systems, doubling the number of systems in the original Kepler Orrery. In the description of this video, Fabrycky says the orbits are to scale with respect to each other, and planets are to scale with respect to each other. The colors are in order of semi-major axis, and two-planet systems (242 in all) have a yellow outer planet; 3-planet (85) green, 4-planet (25) light blue, 5-planet (8) dark blue, 6-planet (1, Kepler-11) purple.

Watch and enjoy!

And as a reminder, we’ll be doing a live interview on Friday, March 2 to talk about the latest exoplanet discoveries by Kepler!

Posted on by Nancy Atkinson

More Details from Hubble Reveal Strange Exoplanet is a Steamy Waterworld

GJ1214b, shown in this artist’s view, is a super-Earth orbiting a red dwarf star 40 light-years from Earth. Credit: NASA, ESA, and D. Aguilar (Harvard-Smithsonian Center for Astrophysics)

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Would Kevin Costner’s character in the movie “Waterworld” be at home on this exoplanet? The planet GJ 1214b was discovered in 2009 and was one of the first planets where an atmosphere was detected. In 2010, scientists were able to measure the atmosphere, finding it likely was composed mainly of water. Now, with infrared spectra taken during transit observations by the Hubble Space Telescope, scientists say this world is even more unique, and that it represents a new class of planet: a waterworld underneath a thick, steamy atmosphere.

“GJ 1214b is like no planet we know of,” said Zachary Berta of the Harvard-Smithsonian Center for Astrophysics (CfA). “A huge fraction of its mass is made up of water.”

GJ 1214b is a super-Earth — smaller than Uranus but larger than Earth — and is about 2.7 times Earth’s diameter. That gives it a volume 20 times as great as Earth yet it has less than seven times as much mass, so it’s actually kind of a lightweight. This world is also hot: it orbits a red-dwarf star every 38 hours at a distance of 2 million kilometers, giving it an estimated temperature of 230 degrees Celsius.

Berta and a team of international astronomers used Hubble’s Wide Field Camera 3 (WFC3) to study GJ 1214b when it crossed in front of its host star. During such a transit, the star’s light is filtered through the planet’s atmosphere, giving clues to the mix of gases.

“We’re using Hubble to measure the infrared color of sunset on this world,” Berta said.

Hazes are more transparent to infrared light than to visible light, so the Hubble observations help to tell the difference between a steamy and a hazy atmosphere. They found the spectrum of GJ 1214b to be featureless over a wide range of wavelengths, or colors. The atmospheric model most consistent with the Hubble data is a dense atmosphere of water vapor.

Since the planet’s mass and size are known, astronomers can calculate the density, of only about 2 grams per cubic centimetre. Water has a density of 1 gram per cubic centimetre, while Earth’s average density is 5.5 grams per cubic centimetre. This suggests that GJ 1214b has much more water than Earth does, and much less rock.

As a result, the internal structure of GJ 1214b would be extraordinarily different from that of our world.

“The high temperatures and high pressures would form exotic materials like ‘hot ice’ or ‘superfluid water’, substances that are completely alien to our everyday experience,” Berta said.

Theorists expect that GJ 1214b formed further out from its star, where water ice was plentiful; later the planet migrated inward towards the star. In the process, it would have passed through the star’s habitable zone, where surface temperatures would be similar to Earth’s. How long it lingered there is unknown.

GJ 1214b is located in the constellation of Ophiuchus (The Serpent Bearer), and just 40 light-years from Earth. Scientists say it will be a prime candidate for study by the NASA/ESA/CSA James Webb Space Telescope, planned for launch later this decade.

This article was updated on Feb. 23

Read the team’s paper (pdf).

Source: ESA Hubble

Posted on by Paul Scott Anderson

New Study Shows How Trace Elements Affect Stars’ Habitable Zones

Comparison of the habitable zone around the Sun in our solar system and around the star Gliese 581. Credit: ESO

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Habitable zones are the regions around stars, including our own Sun, where conditions are the most favourable for the development of life on any rocky planets that happen to orbit within them. Generally, they are regions where temperatures allow for liquid water to exist on the surface of these planets and are ideal for “life as we know it.” Specific conditions, due to the kind of atmosphere, geological conditions, etc. must also be taken into consideration, on a case-by-case basis.

Now, by examining trace elements in the host stars, researchers have found clues as to how the habitable zones evolve, and how those elements also influence them. To determine what elements are in a star, scientists study the wavelengths of its light. These trace elements are heavier than the hydrogen and helium gases which the star is primarily composed of. Variations in the composition of these stars are now thought to affect the habitable zones around them.

The study was led by Patrick Young, a theoretical astrophysicist and astrobiologist at Arizona State University. Young and his team presented their findings on January 11, 2012 at the annual meeting of the American Astronomical Society in Austin, Texas. He and his colleagues have examined more than a hundred dwarf stars so far.

An abundance of these elements can affect how opaque a star’s plasma is. Calcium, sodium, magnesium, aluminum and silicon have been found to also have small but significant effects on a star’s evolution – higher levels tended to result in cooler, redder stars. As Young explains, “The persistence of stars as stable objects relies on the heating of plasma in the star by nuclear fusion to produce pressure that counteracts the inward force of gravity. A higher opacity traps the energy of fusion more efficiently and results in a larger radius, cooler star. More efficient use of energy also means that nuclear burning can proceed more slowly, resulting in a longer lifetime for the star.”

The lifetime of a star’s habitable zone can also be influenced by another element – oxygen. Young continues: “The habitable lifetime of an orbit the size of Earth’s around a one-solar-mass star is only 3.5 billion years for oxygen-depleted compositions but 8.5 billion years for oxygen-rich stars. For comparison, we expect the Earth to remain habitable for another billion years or so, for about 5.5 billion years total, before the Sun becomes too luminous. Complex life on Earth arose some 3.9 billion years after its formation, so if Earth is at all representative, low-oxygen stars are perhaps less than ideal targets.”

As well as the habitable zone, the composition of a star can determine the eventual composition of any planets that form. The carbon-oxygen and magnesium-silicon ratios of stars can affect whether a planet will have magnesium or silicon-loaded clay minerals such as magnesium silicate (MgSiO3), silicon dioxide (SiO2), magnesium orthosilicate (Mg2SiO4), and magnesium oxide (MgO). A star’s composition can also play a role in whether a rocky planet might have carbon-based rock instead of silicon-based rock like our planet. Even the interior of planets could be affected, as radiocative elements would determine whether a planet has a molten core or a solid one. Plate tectonics, thought to be important for the evolution of life on Earth, depend on a molten interior.

Young and his team are now looking at 600 stars, ones that are already being targeted in exoplanet searches. They plan to produce a list of the 100 best stars which could have potentially habitable planets.

Posted on by Nancy Atkinson

Potential ‘Goldilocks’ Planet Found

A planet 6 times the mass of Earth orbits around the star Gliese 667 C, which belongs to a triple system. Credit: ESO

A new-found planet is in a ‘just-right’ location around its star where liquid water could possibly exist on the planet’s surface. A team of international astronomers have discovered a potentially habitable super-Earth orbiting a nearby star in a habitable zone, where it isn’t too hot or too cold for liquid water to exist. The planet, GJ 667Cc, has an orbital period of about 28 days and with a mass about 4.5 times that of the Earth. The star that it orbits is quite interesting. It is an M-class dwarf star and is a member of a triple star system and appears to be quite different from our Sun, relatively lacking in metallic elements.

The team said this discovery demonstrates that habitable planets could form in a greater variety of environments than previously believed.

“This was expected to be a rather unlikely star to host planets,” said Steven Vogt from UC Santa Cruz, one of the scientists involved in the discovery. “Yet there they are, around a very nearby, metal-poor example of the most common type of star in our galaxy. The detection of this planet, this nearby and this soon, implies that our galaxy must be teeming with billions of potentially habitable rocky planets.”

“This planet is the new best candidate to support liquid water and, perhaps, life as we know it,” said Guillem Anglada-Escudé, from the University of Gottingen in Germany. He was with the Carnegie Institute for Science when the planet was first discovered.

The planet orbits quite close to its parent star at 0.12 astronomical units, which is much closer than Mercury to the Sun. However, the Planetary Habitability Laboratory says the star is much dimmer and provides enough energy for the planet to possibly maintain similar terrestrial temperatures. There’s a caveat, though, that astronomers aren’t sure what the planet’s composition is, because they have not been able to measure its size; therefore, it could be a either a rocky or a gas planet. I would need to have a radius between about 1.7 and 2.2 Earth radii to be a rocky world.

The team used public data from the European Southern Observatory combined with observations from the Keck Observatory in Hawaii and the new Carnegie Planet Finder Spectrograph at the Magellan II Telescope in Chile. To follow up and verify the findings, the team used the radial velocity method to measures the small wobbles in the star’s motion caused by the gravitational tug of a planet.

“With the advent of a new generation of instruments, researchers will be able to survey many M dwarf stars for similar planets and eventually look for spectroscopic signatures of life in one of these worlds,” said Anglada-Escudé.

The star, GJ 667C is 22 light years away. It has much lower abundance of elements heavier than helium, such as iron, carbon, and silicon, as does our Sun. The other two stars (GJ 667A and B) are a pair of orange K dwarfs, with a concentration of heavy elements only 25% that of our Sun’s. Such elements are the building blocks of terrestrial planets so it was thought to be unusual for metal-depleted star systems to have an abundance of low mass planets.

Diagram of the planets orbiting the star GJ 667C. Credit: UC Santa Cruz

GJ 667C had previously been observed to have another super-Earth (GJ 667Cb) with a period of 7.2 days, although this finding was never published. This orbit is too tight, and thus hot, to support life. The new study started with the aim of obtaining the orbital parameters of this super-Earth, and came to find an additional planet.

The new planet receives 90% of the light that Earth receives. However, because most of its incoming light is in the infrared, a higher percentage of this incoming energy should be absorbed by the planet. When both these effects are taken into account, the planet is expected to absorb about the same amount of energy from its star that the Earth absorbs from the Sun. This would allow surface temperatures similar to Earth and perhaps liquid water, but this extreme cannot be confirmed without further information on the planet’s atmosphere.

The team said there is a possibility of other planets in the system, potentially a gas-giant planet and an additional super-Earth with an orbital period of 75 days. However, further observations are needed to confirm these two possibilities.

This is the fourth potentially habitiable extrasolar planet. Three were found in 2011: Gliese 581d, which scientists say is likely a rocky world about 20 ight-years away; HD 85512 b, another planet orbiting in a habitable zone is about 36 light-years away from Earth; and Kepler 22b, about 600 light-years away. Vogt was involved in the discovery of another planet in 2010 (Gliese 581g) in which he said the “chances of life on this planet are 100%,” but other astronomers have cast doubt on whether that planet even exists.

Papers:
The HARPS search for southern extra-solar planets XXXI. The M-dwarf sample, and A planetary system around the nearby M dwarf GJ 667C with at least one super-Earth in its habitable zone (will add link when it becomes available)

Sources: UC Santa Cruz, Carnegie Institute for Science, Planetary Habitability Laboratory