Three new Earthlike exoplanets, orbiting M dwarf stars in the habitable zone, have been identified by astronomers using Kepler data.
New observations from the new ground-based submillimeter ALMA telescope in Chile have given astronomers a clearer picture of the ring/disk of debris orbiting the nearby star Formalhaut. Moreover, the data suggests that two planets that are shepherding that ring are smaller than previously thought, no larger than a few times the size of the Earth.
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Want to study the more than 2000 exoplanets so far discovered by Kepler? There’s now an app to do it!
Based on discoveries already made, astronomers now estimate there are probably more than a hundred habitable superEarths within 30 light years of the Sun.
The blistering hot exoplanet where it snows.
These results have led to a suggestion that [HD 189733b] could continually experience silicate snow. In the lower atmosphere of [the exoplanet], magnesium silicate sublimates, that is, it passes directly from a solid into a gas. But we know there are small silicate particulates in the upper atmosphere. Formation of these particulates requires that the temperature be lowered, and so must have been formed at a temperature inversion in the atmosphere. The generally windy conditions would help some of the tiny particulates grow into respectable snow crystals.
More Kepler results: From the abstract of a preprint paper published today on the Los Alamos astro-ph website:
The mean eccentricity of the Kepler candidates decreases with decreasing planet size indicating that smaller planets are preferentially found in low-eccentricity orbits.
In other words, the smaller a planet is, the more likely its orbit will be circular like the Earth’s. This result is encouraging news for the search for life on other worlds. Before Kepler, astronomers had found that the orbits of most exoplanets were far more eccentric than the orbits of the planets in our solar system, a condition that scientists thought was unfriendly for the development of life. These new results counter that conclusion. The orbits of the planets in our solar system might not be as unusual as first thought.
An analysis of the most recent Kepler data suggests that Earthlike planets in orbits like our own are extremely rare.
Mapping the surface of an extrasolar planet light years away. From the paper’s abstract [pdf]:
We use archived Spitzer [Space Telescope] data of [the star] HD189733 … encompassing six transits, eight secondary eclipses, and a phase curve in a two-step analysis. The first step derives the planet-star system parameters. The second step investigates the structure found in eclipse scanning, using the previous planet-star system parameter derivation as Gaussian priors.
We find a 5-sigma deviation from the expected occultation ingress/egress shape for a uniform brightness disk, and demonstrate that this is dominated by large-scale brightness structure and not an occultation timing offset due to a non-zero eccentricity. Our analysis yields a 2D brightness temperature distribution showing a large-scale asymmetric hot spot whose finer structure is limited by the data quality and planet orbit geometry. [emphasis mine]
Planets galore! The Kepler team today announced the discovery of eleven new solar systems holding twenty-six planets.
The planets orbit close to their host stars and range in size from 1.5 times the radius of Earth to larger than Jupiter. Fifteen of them are between Earth and Neptune in size, and further observations will be required to determine which are rocky like Earth and which have thick gaseous atmospheres like Neptune. The planets orbit their host star once every six to 143 days. All are closer to their host star than Venus is to our sun.
No Earths in the habitable zone quite yet, but we are circling in on our prey.
In a preprint paper published today on the Los Alamos astro-ph website, astronomers have concluded that the exoplanet orbiting the star Formalhaut might not exist. This planet, the first exoplanet ever thought to be directly imaged in visible light, was first described in a paper published in 2008, and was actually tracked in its orbit over several years, as shown in the image on the right.
The new research used the Spitzer Space Telescope to see if the planet’s heat could be detected in infrared wavelengths. Unfortunately, the scientists found nothing.
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Want to find your very own exoplanet? Volunteers wanted!
Kepler has found two more planets orbiting double star systems.
The data also suggests that there will be millions of planets in the galaxy orbiting double stars.
FYI, all this astronomy news is because the American Astronomical Society is having its conference this week in Texas, and today is releasing has what I consider the best news stories.
Billions and billions! Astronomers have concluded that the stars in the Milky Way must average at least one planet per star. More importantly, the data says the galaxy should have billions of habitable planets.
[According to astronomer Uffe Gråe Jørgensen], a statistical analysis … shows that out of the Milky Way’s 100 billion stars, there are about 10 billion stars with planets in the habitable zone. This means that there may be billions of habitable planets in the Milky Way.
Want to read the actual paper, “A Sun-like star with three sub-Neptune exoplanets and two Earth-size candidates,” describing the discovery announced yesterday of two Earth-sized planet? You can download it here.
The paper’s closing paragraph sums the discovery up nicely:
A striking feature of the Kepler-20 planetary system is the presence of Earth-size rocky planet candidates interspersed between volatile-rich sub-Neptunes at smaller and larger orbital semi-major axes, as also seen in Kepler candidate multi-planet systems. Assuming that both [Kepler-20e] and [Kepler-20f] are planets, the distribution of the Kepler-20 planets in orbital order is as follows: Kepler-20b (3.7 days, 1.9 Earth radii), [Kepler-20e] (6.1 days, 0.9 Earth radii), Kepler-20c (10.9 days, 3.1 Earth radii), [Kepler-20f] (19.6 days, 1.0 Earth radii), and Kepler-20d (77.6 days, 2.8 Earth radii). Given the radii and irradiation fluxes of the two Earth-size planet candidates, they would not retain gas envelopes. The first, second, and fourth planets have high densities indicative of solid planets, while the other two planets have low densities requiring significant volatile content. The volatile-rich third planet, Kepler-20c dominates the inner part of the Kepler-20 system, by holding much more mass than the other three inner planets put together. In the Solar System, the terrestrial planets, gas-giants, and ice giants are neatly segregated in regions with increasing distance from the sun. Planet formation theories were developed to retrodict these Solar System composition trends. In the Kepler-20 system, the locations of the low-density sub-Neptunes that are rich in water and/or gas, and the Earth-size planet candidates does not exhibit a clean ordering with orbital period, challenging the conventional planet formation paradigm. In situ assembly may form multi-planet systems with close-in hot-Neptunes and super-Earths, provided the initial protoplanetary disk contained massive amounts of solids (∼ 50–100 Earth masses) within 1AU of the star.
Big news: The first Earth-sized planets have been found by Kepler.
The two planets, dubbed Kepler-20e and 20f, are the smallest planets found to date. They have diameters of 6,900 miles and 8,200 miles – equivalent to 0.87 times Earth (slightly smaller than Venus) and 1.03 times Earth. These worlds are expected to have rocky compositions, so their masses should be less than 1.7 and 3 times Earth’s.
Both worlds circle Kepler-20: a G-type star slightly cooler than the Sun and located 950 light-years from Earth. (It would take the space shuttle 36 million years to travel to Kepler-20.) Kepler-20e orbits every 6.1 days at a distance of 4.7 million miles. Kepler-20f orbits every 19.6 days at a distance of 10.3 million miles. Due to their tight orbits, they are heated to temperatures of 1,400 degrees Fahrenheit and 800 degrees F.
Once again, this is only the beginning. The announcement of an Earth in the habitable zone is only a matter of months away.
The Habitable Exoplanets Catalog, now online.
At a press conference today the science team at Kepler announced a swath of new discoveries from the space telescope, all of which point to the impending discovery of multiple Earth-like planets capable of harboring life.
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Eighteen new exoplanets found by astronomers using the Keck ground-based telescope.
Astronomers snap a picture of an exoplanet six times the mass of Jupiter but as cool as the Earth.
The plethora of new exoplanet discoveries has astronomers longing for a telescope that can see them up close.
Astronomers need either a giant space telescope equipped with a device for blocking starlight, or an interferometer, consisting of several telescopes flying in formation. NASA did develop a proposal for such a space telescope, called Terrestrial Planet Finder, and the European Space Agency hoped to fly a similar mission called Darwin. But budgetary constraints have left both missions in limbo, unlikely to advance to the front of either agency’s queue until well into the next decade. At the conference, Traub raised the issue. “People are not thinking deeply about the distant future. People are wrapped up with what they’re doing right now,” he says. “Clearly, I’m concerned.”
Using two European-built ground-based telescopes in Chile, astronomers have announced today the discovery of 50 new exoplanets, 16 of which are considered super Earths, one of which is in the habitable zone of its star. You can read the preprint of their research paper here [pdf].
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A super-Earth has been identified orbiting its star on the edge of the habitable zone.
More on the new Kepler results: Lots of multiple planet systems.
New results from Kepler.
Astronomers, Kepler, and SETI@home team up to find exoplanets.
Astronomers are considering the merger two space missions to create a new optical/ultraviolet space telescope. The mission would be designed to do both deep cosmology and exoplanet observations.
The two communities would both like to see a 4–8-metre telescope in space that would cost in excess of $5 billion. “Our interests are basically aligned,” says [Jim Kasting, a planetary scientist at Pennsylvania State University]. Such a mission would compete for top billing in the next decadal survey of astronomy by the US National Academy of Sciences, due in 2020.
This story is big news, as it indicates two things. First, the 2010 Decadal Survey, released in August 2010, is almost certainly a bust. The budget problems at NASA as well as a general lack of enthusiasm among astronomers and the public for its recommendations mean that the big space missions it proposed will almost certainly not be built.
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