The photo of a nearby star and its orbiting companion — whose temperature is like a hot summer day in Arizona — will be presented by Penn State Associate Professor of Astronomy and Astrophysics Kevin Luhman during the Signposts of Planets conference at NASA’s Goddard Space Flight Center on Oct. 20, 2011.

A paper describing the discovery will be published in the Astrophysical Journal.

“This planet-like companion is the coldest object ever directly photographed outside our solar system,” said Luhman, who led the discovery team. “Its mass is about the same as many of the known extra-solar planets — about six to nine times the mass of Jupiter — but in other ways it is more like a star. Essentially, what we have found is a very small star with an atmospheric temperature about cool as the Earth’s.”

Luhman classifies this object as a “brown dwarf,” an object that formed just like a star out of a massive cloud of dust and gas. But the mass that a brown dwarf accumulates is not enough to ignite thermonuclear reactions in its core, resulting in a failed star that is very cool. In the case of the new brown dwarf, the scientists have gauged the temperature of its surface to be between 80 and 160 degrees Fahrenheit — possibly as cool as a human.

(via Planet-sized object as cool as Earth revealed in record-breaking photo)

Darkest Planet Found: Coal-Black, It Reflects Almost No Light

It may be hard to imagine a planet blacker than coal, but that’s what astronomers say they’ve discovered in our home galaxy with NASA’s Kepler space telescope.

Orbiting only about three million miles out from its star, the Jupiter-size gas giant planet, dubbed TrES-2b, is heated to 1,800 degrees Fahrenheit (980 degrees Celsius). Yet the apparently inky world appears to reflect almost none of the starlight that shines on it, according to a new study.

“Being less reflective than coal or even the blackest acrylic paint—this makes it by far the darkest planet ever discovered,” lead study author David Kipping said.

“If we could see it up close it would look like a near-black ball of gas, with a slight glowing red tinge to it—a true exotic amongst exoplanets,” added Kipping, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

(via National Geographic)

Free-Floating Planets May be More Common Than Stars

Astronomers, including a NASA-funded team member, have discovered a new class of Jupiter-sized planets floating alone in the dark of space, away from the light of a star. The team believes these lone worlds were probably ejected from developing planetary systems. 

The discovery is based on a joint Japan-New Zealand survey that scanned the center of the Milky Way galaxy during 2006 and 2007, revealing evidence for up to 10 free-floating planets roughly the mass of Jupiter. The isolated orbs, also known as orphan planets, are difficult to spot, and had gone undetected until now. The newfound planets are located at an average approximate distance of 10,000 to 20,000 light-years from Earth. 

“Although free-floating planets have been predicted, they finally have been detected, holding major implications for planetary formation and evolution models,” said Mario Perez, exoplanet program scientist at NASA Headquarters in Washington. 

The discovery indicates there are many more free-floating Jupiter-mass planets that can’t be seen. The team estimates there are about twice as many of them as stars. In addition, these worlds are thought to be at least as common as planets that orbit stars. This would add up to hundreds of billions of lone planets in our Milky Way galaxy alone. 

“Our survey is like a population census,” said David Bennett, a NASA and National Science Foundation-funded co-author of the study from the University of Notre Dame in South Bend, Ind. “We sampled a portion of the galaxy, and based on these data, can estimate overall numbers in the galaxy.” 

The study, led by Takahiro Sumi from Osaka University in Japan, appears in the May 19 issue of the journal Nature.

(via NASA Jet Propulsion Laboratory)

Excellent.

unknownskywalker:

Orrery of Kepler’s Exoplanets

Here’s a terrific visualization of all the multiple-planet systems discovered by the Kepler spacecraft as of February 2, 2011. The planets’ orbits go through the entire 3.5 year mission. The different colors represent different sized planets — “hot” colors are the big planets, cooler colors are the smaller ones, relative to the other planets in the system. [Universe Today]

NASA’s Kepler finds its first five planets - an odd assortment - CSMonitor.com

NASA’s planet-hunting telescope Kepler has bagged its first quarry: five new planets Neptune’s size and larger, including one with the density of Styrofoam, making it one of the lightest planets yet found.

In addition to the new planets, Kepler results suggest that the light output from two-thirds of some 43,000 sun-like stars in its field of view is virtually as stable as the sun’s output.

That seemingly obscure observation suggests that the majority of stars potentially are as hospitable to life as Earth’s sun, assuming there was an Earth-like planet orbiting at the right distance from the star.

“If most stars are quiescent, that increases the havens for life in the universe,” says astronomer Caty Pilachowski of Indiana University. The reason: Periodic strong outbursts of radiation from a star could sterilize a planet’s surface, even if the planet orbited the star in the so-called habitable zone.

That zone represents distances where any water on a planet’s surface would receive just enough heat to remain liquid and stable on the planet’s surface.

Quiescent stars mean “we’re more likely to have habitats where life can evolve and increases our chances of finding that life down the road,” she says.

NASA’s Kepler mission confirmed the discovery of its first rocky planet, named Kepler-10b. Measuring 1.4 times the size of Earth, it is the smallest planet ever discovered outside our solar system. The discovery of this so-called exoplanet is based on more than eight months of data collected by the spacecraft from May 2009 to early January 2010. This video is narrated by Kepler Deputy Science Team Lead Natalie Batalha.

unknownskywalker:

First planet of extragalactic origin discovered

A planet with a minimum mass 1.25 times that of Jupiter has been discovered orbiting a star of extragalactic origin. It is part of the so-called Helmi stream — a group of stars that originally belonged to a dwarf galaxy that was devoured by our galaxy, the Milky Way, in an act of galactic merger about 6-9 billion years ago.

The star is known as HIP 13044, and it lies about 2000 light-years from Earth in the southern constellation of Fornax. Using the MPG/ESO 2.2-metre telescope at La Silla Observatory in Chile, the astronomers detected the planet, called HIP 13044 b, by looking for the tiny telltale wobbles of the star caused by the gravitational tug of an orbiting companion.

HIP 13044 b is very near to its host star, at about 0.055 times the Sun-Earth distance and completes an orbit in only 16.2 days. The planet’s orbit might initially have been much larger, but that it moved inwards during the red giant phase. HIP 13044 b is also one of the few exoplanets known to have survived the red giant phase of stellar evolution. The star has now contracted again and is burning helium in its core.

The star is rotating relatively quickly for an horizontal branch star, likely because it swallowed its inner planets during the red giant phase, which would make it spin more quickly. Although HIP 13044 b has escaped the fate of these inner planets so far, the star will expand again in the next stage of its evolution. HIP 13044 b may therefore be about to be engulfed by the star.

This could also foretell the demise of our outer planets — such as Jupiter — when the Sun approaches the end of its life.

Image: Artist’s impression of HIP 13044 b and its parent star. This visible light wide-field image shows the star HIP 13044 at the exact center, but the planet is much too faint to be seen in this image.

• Official source: ESO [video]

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unknownskywalker:

Sun’s Dust Ring Could Help Find Exo-Earths

Earth-like exoplanets could announce their presence through trailing clumps of dust — and new observations of the Earth’s own dust cloud could provide a way to find them.

Over the course of five years, the Spitzer Space Telescope drifted through a diffuse but extensive ring of dust particles that orbit the sun in lockstep with the Earth, showing astronomers for the first time what the dusty signature of an exo-Earth might look like. Astronomers can measure the structure of that cloud along the Earth’s orbit, using this moving space probe that travels through the cloud. That can be used as a key to understand the dust around other stars.

The observations showed that a ring of dust from comet tails and broken asteroids follows the Earth in its orbit, with particles about 0.02 mm in diameter or larger. An extra-thick cloud of these particles about 7 million miles wide trails behind the Earth at about 80 times the distance from the Earth to the moon. Spitzer sent images from directly inside this cloud from its launch in 2003 until its coolant ran out in 2009.

The sky is brighter in infrared wavelengths when looking backward along the Earth’s orbit than when looking forward, because dust glows in the infrared, the lightened sky was a clear sign that more dust follows the planet than leads it. This is because individual dust particles could get temporarily trapped in a special gravitational relationship called a resonant orbit with Earth.

Most of the dust in the plane of the solar system, called the zodiacal cloud, will eventually spiral into the sun. But particles tens of micrometers across, can feel a little gravitational push as they float by the Earth. That push counteracts the sun’s pull just enough to hold the dust particles in a loose halo around the sun.

The observations can feed models of what dust rings associated with extrasolar planets might look like. Of the few extrasolar planets to have their pictures taken by direct imaging, at least two hinted at their presence by warping the disk of dust and gas around their star. Earth-like planets that are too small or dim to find through usual methods may have a subtle but detectable influence on their dust disks.

Image: The S-shaped blue band in this infrared image from the COBE satellite is the zodiacal cloud of dust in the solar system. Image Creadit: NASA.

Source: Wired

Image: An artist’s illustration of the Upsilon Andromedae A system, where three Jupiter-type planets orbit the yellow-white star Upsilon Andromedae A. Astronomers have recently discovered that not all planets orbit this star in the same plane, as the major planets in our solar system orbit the Sun. The orbits of two of the planets are inclined by 30 degrees with respect to each other. Such a strange orientation has never before been seen in any other planetary system. This surprising finding will impact theories of how planetary systems form and evolve, say researchers. It suggests that some violent events can happen to disrupt planets’ orbits after a planetary system forms. The discovery was made by joint observations with the Hubble Space Telescope, the Hobby-Eberly Telescope, and other ground-based telescopes. Credit: NASA, ESA and A. Feild (STScI) / B. McArthur (University of Texas at Austin).

Disturbing the Habitable Zone

It’s AAS week in Miami, and the American Astronomical Society usually gives us plenty to talk about. Inclined orbits, for one thing. In our Solar System, the process of planetary formation seems relatively intuitive. The eight major planets orbit largely in the same plane, reinforcing the idea that the cloud of gas that collapsed to form the Sun contained leftover material that formed into a planet-yielding disk. We can point to outer system objects like Pluto (and certainly Sedna) as exceptions, but they’re much further out and subject to gravitational influences that this model can account for.

But as Barbara McArthur (University of Texas at Austin) and team told an AAS session yesterday, the star Upsilon Andromedae A has yielded a different result. We already knew that three Jupiter-class planets orbited the star, some 44 light years away and a bit younger and more massive than our Sun. But McArthur’s team now has determined the mass of two of the three known planets, and has produced the startling finding that the orbits of planets c and d are inclined by 30 degrees with respect to each other.

This is a fascinating find, and represents the first time that the mutual inclination of two planets orbiting another star has ever been measured. And McArthur points to the work’s significance:

“Most probably Upsilon Andromedae had the same formation process as our own solar system, although there could have been differences in the late formation that seeded this divergent evolution. The premise of planetary evolution so far has been that planetary systems form in the disk and remain relatively co-planar, like our own system, but now we have measured a significant angle between these planets that indicates this isn’t always the case.”

(via Centauri Dreams)

Scientists used Hubble data to create an image of the planet being swallowed

The Hubble Space Telescope has captured evidence of a Sun-like star “eating” a nearby planet.

Water World Around Gliese 581? at Centauri Dreams

Gliese 581, the star that teased us a few years back with reports of a ’super-Earth’ planet in the habitable zone, is back in the news. Michel Mayor’s Geneva team has located a fourth planet in the system, Gliese 581 e, which weighs in at a mere 1.9 Earth masses, making it the least massive exoplanet ever detected. Orbiting its primary in 3.15 days, the newly found world is too close to the star to be in the habitable zone, but the other shoe that drops here is that Gl 581 d may itself be.