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Search begins for Earth-sized planets around other stars

June 27, 2009 By admin Leave a Comment

Washington, June 26 (ANI): The Space Telescope Science Institute (STScI) in Baltimore, US, is partnering on a historic search for Earth-sized planets around other stars.

STScI is the data archive center for NASA’s Kepler mission, a spacecraft that is undertaking a survey for Earth-size planets in our region of the galaxy.

The spacecraft sent its first raw science data to STScI on June 19.

The Institute’s role is to convert the raw science data into files that can be analyzed by Kepler researchers and to store the files every three months in an archive.

“We are part of this mission because of our experience with Hubble data processing and archiving,” explained David Taylor, project manager for the development of Kepler’s Data Management Center at the Institute.

Launched on March 6 on a Delta II rocket from Cape Canaveral, Florida, the Kepler spacecraft will spend the next 3 1/2 years searching for habitable planets by staring nonstop at more than 100,000 Sun-like stars out of about 4.5 million catalogued stars in the spacecraft’s field-of-view, located in the summer constellations Cygnus and Lyra.

The spacecraft simultaneously measures the variations in brightness of the more than 100,000 stars every 30 minutes, searching for periodic dips in a star’s brightness that happen when an orbiting planet crosses in front of it and partially blocks the light.

These fluctuations are tiny compared with the brightness of the star.

For an Earth-size planet transiting a solar-type star, the change in brightness is less than 1/100 of 1 percent.

This event is similar to the dimming one might see if a flea were to crawl across a car’s headlight viewed from several miles away.

When the mission is completed in several years, the survey should tell astronomers how common Earth-size planets are around stars.

“The mission’s main purpose is to find planets that are the same distance from its solar-type star as Earth is from the Sun,” said Daryl Swade, who directed the systems engineering development of Kepler’s Data Management Center at the Institute.

“So that means that the planet would cross in front of its star every year. We would need three or four of these transits to confirm the detection, which will take about three or four years,” he added. (ANI)

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Tiny crystals in frozen comets created by outbursts from stars

May 14, 2009 By admin Leave a Comment

Washington, May 14 (ANI): Astronomers have used NASA’s Spitzer Space Telescope to determine that outbursts from stars create tiny silicate crystals in frozen comets.

Scientists have long wondered how tiny silicate crystals, which need sizzling high temperatures to form, have found their way into frozen comets, born in the deep freeze of the solar system’s outer edges.

The crystals would have begun as non-crystallized silicate particles, part of the mix of gas and dust from which the solar system developed.

Now, a team of astronomers believes they have found a new explanation for both where and how these crystals may have been created, by using NASA’s Spitzer Space Telescope to observe the growing pains of a young, Sun-like star.

The researchers from Germany, Hungary and the Netherlands found that silicate appears to have been transformed into crystalline form by an outburst from a star.

They detected the infrared signature of silicate crystals on the disk of dust and gas surrounding the star EX Lupi during one of its frequent flare-ups, or outbursts, seen by Spitzer in April 2008.

These crystals were not present in Spitzer’s previous observations of the star’s disk during one of its quiet periods.

“We believe that we have observed, for the first time, ongoing crystal formation,” said Attila Juhasz of the Max-Planck Institute for Astronomy in Heidelberg, Germany, one of the research paper’s authors.

“We think that the crystals were formed by thermal annealing of small particles on the surface layer of the star’s inner disk by heat from the outburst. This is a completely new scenario about how this material could be created,” Juhasz added.

Annealing is a process in which a material is heated to a certain temperature at which some of its bonds break and then re-form, changing the material’s physical properties.

The crystals appear to be forsterite, a material often found in comets and in protoplanetary disks.

The crystals also appear hot, evidence that they were created in a high-temperature process, but not by shock heating.

“At outburst, EX Lupi became about 100 times more luminous,” said Juhasz.

“Crystals formed in the surface layer of the disk but just at the distance from the star where the temperature was high enough to anneal the silicate – about 1,000 Kelvin – but still lower than 1,500 Kelvin. Above that, the dust grains will evaporate,” Juhasz added.

The radius of this crystal formation zone, the researchers note, is comparable to that of the terrestrial-planet region in the solar system. (ANI)

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Planets around cool suns have different mix of life-forming chemicals

April 8, 2009 By admin Leave a Comment

Washington, April 8 (ANI): A new study from NASA’s Spitzer Space Telescope hints that planets around stars cooler than our Sun might possess a different mix of potentially life-forming, or “prebiotic,” chemicals.

Astronomers used Spitzer to look for a prebiotic chemical, called hydrogen cyanide, in the planet-forming material swirling around different types of stars.

Hydrogen cyanide is a component of adenine, which is a basic element of DNA.

The researchers detected hydrogen cyanide molecules in disks circling yellow stars like our Sun – but found none around cooler and smaller stars, such as the reddish-colored “M-dwarfs” and “brown dwarfs” common throughout the universe.

“Prebiotic chemistry may unfold differently on planets around cool stars,” said Ilaria Pascucci, lead author of the new study from Johns Hopkins University, Baltimore, Maryland.

Young stars are born inside cocoons of dust and gas, which eventually flatten to disks.

Dust and gas in the disks provide the raw material from which planets form. Scientists think the molecules making up the primordial ooze of life on Earth might have formed in such a disk.

Prebiotic molecules, such as adenine, are thought to have rained down to our young planet via meteorites that crashed on the surface.

“It is plausible that life on Earth was kick-started by a rich supply of molecules delivered from space,” said Pascucci.

But, could the same life-generating steps take place around other stars?

Pascucci and her colleagues addressed this question by examining the planet-forming disks around 17 cool and 44 Sun-like stars using Spitzer’s infrared spectrograph, an instrument that breaks light apart, revealing signatures of chemicals.

The stars are all about one to three million years old, an age when planets are thought to be growing.

The astronomers specifically looked for ratios of hydrogen cyanide to a baseline molecule, acetylene.

They found that the cool stars, both the M-dwarf stars and brown dwarfs, showed no hydrogen cyanide at all, while 30 percent of the Sun-like stars did.

“Perhaps ultraviolet light, which is much stronger around the Sun-like stars, may drive a higher production of the hydrogen cyanide,” said Pascucci.

The team did detect their baseline molecule, acetylene, around the cool stars, demonstrating that the experiment worked.

This is the first time that any kind of molecule has been spotted in the disks around cool stars.

The findings have implications for planets that have recently been discovered around M-dwarf stars. (ANI)

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NASA’s Kepler mission to search for Earth-sized planets

March 5, 2009 By admin Leave a Comment

London, March 4 (ANI): NASA’s Kepler mission, which is all set to launch on March 6, will take a long look at the stars in the constellation Cygnus, searching for an Earth-sized planet elsewhere in the Galaxy.

According to a report in Nature News, the Kepler space telescope, which is the single instrument on board Kepler, will hunt for Earth-like ‘exoplanets’ – planets beyond the Solar System.

Project scientists expect to find hundreds of such worlds, including perhaps the first exact Earth analogue.

Kepler will detect exoplanets by watching them passing, or ‘transiting’, in front of their star, dimming the starlight temporarily.

It needs to do this at least three times to confirm a planet. If an exoplanet is in an Earth-like orbit, that will take three years.

Of the 342 exoplanets spotted to date, most have been found through the radial velocity method, which picks up slight wobbles in a star’s position caused by the gravitational tug of an orbiting planet.

This method is most likely to find large planets close to their stars, however.

Transits are better suited to finding something more like Earth in size and orbit. So far, 58 transiting planets have been found.

The COROT satellite, launched by the French space agency CNES in 2006, has found seven of those transiting planets, and is in many ways a forerunner to Kepler.

Kepler, however, will orbit the Sun rather than Earth, as COROT does, which means it can spend more time looking at the stars.

Kepler also has a bigger telescope: its mirror is 1.4 metres across, compared with COROT’s 30 centimetres.

Kepler will stare at 100,000 preselected Sun-like stars 180-920 parsecs away, sending data back to Earth every 30 days.

Scientists will scan those data for planets that might be habitable: not too close to their parent star, nor too far away that liquid water won’t exist.

“We all hope this mission will deliver what is promised,” said Giovanna Tinetti, a senior research fellow at University College London.

“If Kepler comes up with empty hands, that will be truly astonishing,” said Alan Boss, an exoplanet theorist from the Carnegie Institution in Washington DC.

According to William Borucki, the project’s principal investigator at NASA’s Ames Research Center in Moffett Field, California, even if Kepler doesn’t identify any Earth-like planets, that would mean our Solar System really is unique. (ANI)

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Search begins for Earth-sized planets around other stars

Tiny crystals in frozen comets created by outbursts from stars

Planets around cool suns have different mix of life-forming chemicals

NASA’s Kepler mission to search for Earth-sized planets

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