Astronomers find ‘super Earths’ circling a star

WASHINGTON (AP) — European astronomers have found a trio of “super-Earths” closely circling a star that astronomers once figured had nothing orbiting it, demonstrating that planets keep popping up in unexpected places.

Monday’s announcement is the first time three planets close to Earth’s size were found orbiting a single star, said Swiss astronomer Didier Queloz. He was part of the Swiss-French team using the European Southern Observatory’s La Silla Observatory in the desert in Chile.

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(Full Article: http://news.wired.com)

Astronomers find ‘super Earths’ circling a star

WASHINGTON (AP) — European astronomers have found a trio of “super-Earths” closely circling a star that astronomers once figured had nothing orbiting it, demonstrating that planets keep popping up in unexpected places.

Monday’s announcement is the first time three planets close to Earth’s size were found orbiting a single star, said Swiss astronomer Didier Queloz. He was part of the Swiss-French team using the European Southern Observatory’s La Silla Observatory in the desert in Chile.

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(Full Article: http://news.wired.com)

Scientists Narrow In On the Best Shot at ET Contact

“If those civilizations are out there – and we don’t know that they are – those that inhabit star systems that lie close to the plane of the Earth’s orbit around the sun will be the most motivated to send communications signals toward Earth, because those civilizations will surely have detected our annual transit across the face of the sun, telling them that Earth lies in a habitable zone, where liquid water is stable. Through spectroscopic analysis of our atmosphere, they will know that Earth likely bears life. Knowing where to look tremendously reduces the amount of radio telescope time we will need to conduct the search.”

~ Richard Conn Henry, Johns Hopkins University

At a meeting of the American Astronomical Society in St Louis, Missouri, US, on Wednesday, Richard Conn Henry of Johns Hopkins University and colleagues proposed that we limit our search for extra-terrestrial intelligence (SETI) to the ecliptic plane in which our solar system’s planets orbit. This ecliptic band comprises only about 3 percent of the sky, which could make it easier for scientists to effectively narrow their search for intelligent ET.

The logic behind it postulates that if there is another, perhaps more advanced alien civilization in our galaxy out there; they may be trying to contact us, as well. If this is the case, Henry says a search focused on the ecliptic “should lead rapidly to the detection of other civilizations”.

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(Full Article: http://www.dailygalaxy.com/my_weblog/2008/06/the-ecliptic-sc.html)

Gliese 581 Might have Planets in the Habitable Zone

The discovery of Gliese 581 was one of the most exciting moments in extrasolar planetary researcher. Astronomers found an Earth-massed planet orbiting within the habitable zone of a distant star. This would mean that liquid water could be on its surface – and maybe life. Now there’s even more evidence that Gliese 581 is living up to the speculation. Astronomers have published two independent studies this week, claiming that there are least 2 Earthlike planets orbiting the star within the habitability zone.

The first team, led by Franck Selsis, computed the properties of planetary atmospheres at various distances from the star. As we’ve seen with Venus, Earth and Mars in our own Solar System, your distance from the star matters a great deal. Get too close, and the water is vaporized and blown out into space. Get too far away and your carbon dioxide can’t trap in enough heat to keep the planet warm. You want to be just right.

Selsis and his team calculated that the inner boundary of this habitable zone around Gliese 581 should be somewhere between 0.7 and 0.9 astronomical units (an AU is the distance from the Earth to the Sun). And the outer zone should be between 1.7 and 2.4 AU. At least one planet orbiting Gliese 581 falls within this range.

The second team used a different technique to calculate habitability. They studied a narrower region where Earth-like photosynthesis is possible. For the super-Earths thought to be orbiting Gliese 581, they calculated the sources of atmospheric CO2 (volcanos and ridges) and then the potential sinks through weathering. If a planet’s too old, if might not be active any more, and wouldn’t release enough CO2 to keep the planet warm.

Once again, the age of the planets, and therefore the amount of carbon dioxide, is within this region of habitability.

Thanks to this new research, the planets orbiting Gliese 581 are primary targets for future planet hunting observatories, such as ESA’s Darwin and NASA’s Terrestrial Planet Finder. These observatories should be able to directly measure the atmospheres of these planets, and determine if they harbour life.

A third paper on the topic has recently been accepted for publication in the journal Astronomy and Astrophysics. In this, another team of researchers have studied the long term orbits of planets going around Gliese 581. Here you want stability, without highly eccentric orbits that might cause extreme warm and glacial eras. Once again, the planets around Gliese 581 are surprisingly stable.

Things are looking really hopeful. Now we just need someone to uncancel the Terrestrial Planet Finder.

(Source: http://www.universetoday.com)

3 New Exo-Planets

A British-led team of scientists have discovered three planets which are hotter and heavier than Jupiter, but with a little bit of help from internet auction site eBay.

The planets, named Wasp-3b, Wasp-4b and Wasp-5b, were found by a team led by astronomers from St Andrews University in Fife -partof SuperWASP, the UK’s leading extra-solar planet detection program comprising of a consortium of eight academic institutions.

The team used a powerful instrument fitted with 16 cameras to produce the new images but as they assembled the equipment they discovered that they were 13 lenses short and that the camera’s manufacturer had discontinued the product.

Luckily the scientists were able to track down the crucial £4000 lenses from a dealer in South Korea by looking on eBay.

SuperWASP consists of two robotic observatories that operate continuously all year around, allowing them to cover both hemispheres of the sky.

WASP-4 and WASP-5 are the first planets discovered by the WASP project’s cameras in South Africa, and were confirmed by a collaboration with Swiss and French astronomers. “These two are now the brightest transiting planets in the Southern hemisphere” said Dr Hellier. WASP-3 is the third planet that the team has found in the North, using the SuperWASP camera sited in the Canary Islands. Dr Don Pollacco, of Queen’s University Belfast, said “We are the only team to have found transiting planets in both the Northern and Southern hemispheres; for the first time we have both SuperWASP cameras running, giving complete coverage of the whole sky”.

Exoplanet expert Professor Andrew Cameron, of St. Andrews University, comments “All three planets are similar to Jupiter, but are orbiting their stars so closely that their `year’ lasts less than two days. These are among the shortest orbital periods yet discovered”. Being so close to their star the surface temperatures of the planets will be more than 2000 degrees Celsius, so it is unlikely that life as we know it could survive there.

The finding of Jupiter-mass planets around other stars supports the idea that there are also many Earth-sized planets waiting to be discovered as astronomers’ technology improves.

The team conducted huge “mosaic sweeps” of the sky at night, capturing images of millions of stars.
The data was then analysed at the Haute-Provence Observatory in France.

The three ‘wasps’ were located using specialist cameras in La Palma in the Canary Islands and Sutherland in South Africa.The first, SuperWASP-North is located on the island of La Palma amongst the Isaac Newton Group of telescopes (ING). The second, SuperWASP-South is located at the site of the South African Astronomical Observatory.

The observatories each consist of eight wide-angle cameras that simultaneously monitor the sky for planetary transit events. A transit occurs when a planet passes in front of its parent star temporarily blocking some of the light from it . The eight wide-angle cameras allows the SuperWASP teams to monitor millions of stars simultaneously enabling them to detect the rare transit events.

The SuperWASP consortium includes Cambridge University, the Instituto de Astrofisica de Canarias, the Isaac Newton Group of telescopes, Keele University, Leicester University, the Open University, Queen’s University Belfast and St. Andrew’s University.

(Source: http://www.dailygalaxy.com/my_weblog/2007/11/brits-discover-.html)

Exoplanet – The Search for Habitable Planets around Red Giant Stars

A planet orbiting a giant red star in the constellation Perseus (the Greek hero who slew Medusa) has been discovered by an astronomy team led by Penn State’s Alex Wolszczan, who in 1992 discovered the first planets ever found outside our solar system. The new planet circles the giant star every 360 days and is located about 300 light years from Earth.

“After astronomers have spent more than 10 years searching for planets around Sun-like stars and discovering over 250 planets elsewhere in our galactic neighborhood, we still do not know whether our solar system’s properties, including life-supporting conditions on our planet, are typical or exceptional among solar systems throughout the Galaxy,” Wolszczan says. “The picture for now, based on the searches for planets around stars like our Sun, is that our planetary system appears to be unusual in a number of ways.”

The discovery resulted from an ongoing effort that the research team -a collaboration between astronomers at Penn State, Nicholas Copernicus University in Poland, the McDonald Observatory, and the California Institute of Technology- began three years ago to find Jupiter-mass planets around red-giant stars that are typically farther from Earth than those included in most other planet searches.

“This planet is the first one discovered by Penn State astronomers with the Hobby-Eberly Telescope, and it is in one of the most distant of the ten published solar systems discovered around red-giant stars,” according to Lawrence Ramsey, a member of the discovery team and the head of the Department of Astronomy and Astrophysics at Penn State.

Astronomers now are branching out with different strategies for searching for planets, with the hope of more quickly detecting life elsewhere in the universe, of discovering all the possible kinds of solar systems, and of learning how they form around different kinds of stars. The Penn State team used one of these new strategies — searching for planets around giant stars, which have evolved to a later stage of life than our Sun’s.

“We have compiled a catalog of nearly a thousand giant stars that are candidates for hosting solar systems,” Wolszczan says. Because the method for discovering planets involves repeated measurements of their gravitational effect on the star they circle, and because planets around red giants can take years to make one orbit around the star, the research team is just now beginning to reap discoveries from years of systematic observations.

“It took us 3 years to gather enough data on over 300 stars to start identifying those that are good candidates for having planetary companions,” Wolszczan said. “This planet is just the first of a number of planet discoveries that this research program is likely to produce.”

One reason for studying red-giant stars is to understand how their habitable zones move farther out as the star’s radiating surface becomes bigger. Based on how long it took for life to develop on Earth, scientists speculate that there is more than enough time during a star’s giant phase for life to get a start somewhere in the evolving habitable zones. “In our solar system, places like Europa – a satellite of Jupiter that now is covered by a thick layer of water ice — might warm up enough to support life for more than a billion years or so, over the time when our Sun begins to evolve into a red giant, making life on Earth impossible,” Wolszczan said.

Another reason astronomers are trying to discover planets around different kinds of stars at different stages of stellar evolution is to find out how different kinds of planetary systems change when their stars become red giants and how they ultimately end their lives as burnt-out, shrunken white-dwarfs.

“We really are at the very beginning of this effort and it is going to take time to get a consistent picture of planetary formation and evolution,” Wolszczan says. “The more we learn, the greater the chance will be that sooner or later we will discover how ordinary or extraordinary is our home — the Earth’s solar system.”

Posted by Casey Kazan

Adapted from a Pennsylvania State University news release
“Planet Orbiting a Giant Red Star Discovered with Hobby-Eberly Telescope”

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Life from the Center of the Earth – The Shadow World of Our Hidden Biosphere

New Phoenix Mission Technology to Search for Mars Life

Cruising the Goldilocks Zone -The Search for “Super-Earths”

Adventures of a Planet Hunter

Non-Carbon Lifeforms -Why We May Overlook Extraterrestrial Life

The Milky Way Enigma -How Galactic Forces May Control Life on Earth

Astro-Engineering Artifacts as Evidence of Extraterrestrial Life

The Biological Universe -A New Copernican Revolution?

Jupiter’s Europa & the Search for Extraterrestrial Life

“42″: Hitchhiker’s Guide to the Galaxy Foreshadows Actual Weight of Universe!

Andromeda Galaxy & Its Mystery Core: Destined to Merge With the Milky Way?

Earth’s Twin Habitable?

Search for Extraterrestrial Genomes

(Source: http://www.dailygalaxy.com/my_weblog/2007/08/can-red-dwarfs-.html)

28 new planets, 7 new brown dwarfs reported by California, Carnegie team

The world’s largest and most prolific team of planet hunters announced the discovery of 28 new planets outside our solar system, increasing to 236 the total number of known exoplanets.

University of California, Berkeley, post-doctoral fellow Jason T. Wright and newly minted Ph.D. John Asher Johnson reported the new exoplanets at a noon media briefing at the semi-annual meeting of the American Astronomical Society (AAS) in Honolulu. The findings are a result of the combined work of the California and Carnegie Planet Search team and the Anglo-Australian Planet Search team.

The planets are among 37 new objects – all of them orbiting a star, but smaller than a star –discovered by the teams within the past year. Seven of the 37 are confirmed brown dwarfs, which are failed stars that are nevertheless much more massive than the largest, Jupiter-sized planets. Two others are borderline and could be either large, gas giant planets or small brown dwarfs.

Wright said the research teams have become much more sophisticated in their analyses and are able to detect smaller planets as well as planets farther from their parent stars. In both cases, he said, these planets produce much smaller wobbles in the parent star, making them harder to detect.

“We’ve added 12 percent to the total in the last year, and we’re very proud of that,” said Wright of the 28 new exoplanets. “This provides new planetary systems so that we can study their properties as an ensemble.”

The California and Carnegie Planet Search team is headed by Geoffrey Marcy, professor of astronomy at UC Berkeley; Paul Butler of the Carnegie Institution of Washington; Debra Fischer of San Francisco State University; and Steve Vogt, professor of astronomy at UC Santa Cruz. The Anglo-Australian Planet Search team is headed by Chris Tinney of the University of New South Wales and Hugh Jones of the University of Hertfordshire. They and colleagues Shannon Patel of UC Santa Cruz and Simon O’Toole of the Anglo-Australian Observatory have published their exoplanet results in papers over the past year, but the AAS meeting is the first time the teams have presented their findings together.

In addition to reporting 37 new substellar objects, Wright singled out an exoplanet discovered by their teams two years ago as “extraordinarily rich.” Circling the star Gliese 436 (GJ 436), a red M dwarf only 30 light years from Earth, was an ice-giant planet the teams calculated to be at least 22 Earth masses, slightly larger than the mass of Neptune (17 Earth masses). After the discovery in 2004 and publication of the exoplanet’s orbit earlier this year, a Belgian astronomer, Michael Gillon at Liege University, observed the planet crossing in front of the star – the first Neptune-sized planet observed to transit a star. Gillon and colleagues reported two weeks ago how this transiting planet allowed them to precisely pin down the mass, 22.4 Earth masses, and to calculate the planet’s radius and density, which turns out to be similar to Neptune’s.

“From the density of two grams per cubic centimeter – twice that of water – it must be 50 percent rock and about 50 percent water, with perhaps small amounts of hydrogen and helium,” Marcy said. “So this planet has the interior structure of a hybrid super-Earth/Neptune, with a rocky core surrounded by a significant amount of water compressed into solid form at high pressures and temperatures.”

Its short, 2.6-day orbit around Gliese 436 means the exoplanet is very close to the star – only 3 percent of the sun-Earth distance – making it a hot Neptune, Wright said. It also has an eccentric orbit, not a circular orbit like most giant planets found orbiting close to their parent stars. This orbit, in fact, suggests that the star may have another planetary companion in a more distant orbit.

“I’m sure people will immediately follow up and try to measure the atmospheric composition of this planet.” Wright predicted.

Also among the 28 new exoplanets are at least four new multiple-planet systems, plus three stars that probably contain a brown dwarf as well as a planet. Wright said that at least 30 percent of all stars known to have planets have more than one. Because smaller planets and outer planets of a star are harder to detect, he predicts that the percentage will continue to rise as detection methods improve.

“We’re just now getting to the point where, if we were observing our own solar system from afar, we would be seeing Jupiter,” he said, pointing out that the teams’ Doppler technique is now sensitive to stellar wobbles of a meter per second, much less than the 10-meter per second limit they started out with 15 years ago.

Wright keeps track of all known exoplanets for the California and Carnegie Planet Search team’s Web site, http://exoplanets.org, which hosts the only peer-reviewed catalog of exoplanets within 200 parsecs (652 light years) of Earth. This includes “everything that is close enough to study and possibly follow up with imaging,” he said.

Three of the newly reported planets are around large stars between 1.6 and 1.9 times the mass of our sun. Johnson has focused on exoplanets around massive stars, known as A and F stars, with masses between 1.5 and 2.5 solar masses. Planets around these massive stars are normally very hard to detect because they typically rotate fast and have pulsating atmospheres, effects that can hide or mimic the signal from an orbiting planet. He discovered, however, that cooler “retired” A stars – “subgiant” stars that have nearly completed hydrogen burning and have stabilized for a short period of time – are more stable, making planet-caused wobbles detectable.

So far, Johnson has tracked down six previously discovered exoplanets around retired A stars, and by combining this set with the three newly discovered exoplanets, has been able to draw preliminary conclusions. For one, planets around more massive stars seem to be farther from their host stars, Johnson said.

“Only one of the 9 planets is within 1 AU (astronomical unit, or 93 million miles), and none of them is within 0.8 AU, of their host stars, which is very different than the distribution around sun-like stars,” he said, noting that many sun-like stars harbor hot gas giants that whip around their host stars in two to 100 days. Even though such planets are easier to detect, no such planets have been detected orbiting retired A stars, whose typical planets have an orbital distance about equal to Earth’s orbit or greater, with an orbital period of a few years.

Based on the results of his search for planets around retired A stars, Johnson has discovered that massive stars are more likely to harbor Jupiter-sized planets than are lower-mass stars. The chance of having a Jupiter-like, giant planet orbiting within 2 AU is 8.7 percent for stars between 1.3 and 2 solar masses, versus 4 percent for sun-like stars with masses ranging from 0.7 solar masses to 1.3 solar masses, and 1.2 percent for M stars with less than 0.7 solar masses. As would be expected from the core accretion model of planet formation, large planets are more often observed around massive stars, probably because these stars start out with more material in their disks during the early formation period.

Johnson will continue to focus on the retired A stars, 450 of which have been added to the teams’ target list. As more planets are discovered around subgiants, it should become clearer whether larger orbits are “a result of different formation and migration mechanisms in the disks of A–type stars, or simply a consequence of the small number of massive subgiants currently surveyed,” he and colleagues wrote in a paper submitted in April to the Astrophysical Journal.

(Source: http://www.physorg.com/news99649587.html)