Tag Archives: exoplanets

Exoplanet Atmospheres Provide Clues to Solar System Formation

One of the discovery images of the system obtained at the Keck II telescope using the adaptive optics system and NIRC2 Near-Infrared Imager. The rectangle indicates the field-of-view of the OSIRIS instrument for planet C. Credit: Image courtesy of NRC-HIA, C. Marois and Keck Observatory.

One of the discovery images of the system obtained at the Keck II telescope using the adaptive optics system and NIRC2 Near-Infrared Imager. The rectangle indicates the field-of-view of the OSIRIS instrument for planet C. Credit: Image courtesy of NRC-HIA, C. Marois and Keck Observatory.

The most detailed look yet at the atmosphere of a distant exoplanet has revealed a mixture of water vapor and carbon monoxide blanketing a world ten times the size of Jupiter about 130 light years away from Earth. But even with water present on this world, it is incredibly hostile to life. Like Jupiter, it has no solid surface, and it has a temperature of more than a thousand degree. Additionally, no tell-tale methane signals were detected in the atmosphere. But this solar system is still of great interest, as three other giant worlds orbit the same star and scientists said studying this system will not only help solve mysteries of how it was formed, but also how our own solar system formed as well.The observations were made at the Keck II telescope in Hawaii, using an infrared imaging spectrograph called OSIRIS, which was able to uncover the chemical fingerprints of specific molecules.

“This is the sharpest spectrum ever obtained of an extrasolar planet,” said Dr. Bruce Macintosh, from the Lawrence Livermore National Laboratory. “This shows the power of directly imaging a planetary system. It is the exquisite resolution afforded by these new observations that has allowed us to really begin to probe planet formation.”

“With this level of detail,” said co-author Travis Barman from the Lowell Observatory, “we can compare the amount of carbon to the amount of oxygen present in the atmosphere, and this chemical mix provides clues as to how the planetary system formed.”

Artist’s rendering of HR 8799c at an early stage in the evolution of the planetary system, showing the planet, a disk of gas and dust, rocky inner planets, and HR 8799. Credit: Dunlap Institute for Astronomy & Astrophysics

Artist’s rendering of HR 8799c at an early stage in the evolution of the planetary system, showing the planet, a disk of gas and dust, rocky inner planets, and HR 8799. Credit: Dunlap Institute for Astronomy & Astrophysics

The planets around the star, known as HR 8799, weigh in between five to 10 times the mass of Jupiter and are still glowing in infrared with the heat of their formation. The research team says their observations suggest the solar system was created in a similar way to our own, with gas giants forming far away from their parent star and smaller, rocky planets closer in. However, no Earth-like rocky planets have yet been detected in this system.

“The results suggest the HR 8799 system is like a scaled-up Solar System,” said Quinn Kanopacky, an astronomer from the University of Toronto in Canada. “Once the solid cores grew large enough, their gravity quickly attracted surrounding gas to become the massive planets we see today. Since that gas had lost some of its oxygen, the planet ends up with less oxygen and less water than if it had formed through a gravitational instability.”

There are two leading models of planetary formation: core accretion and gravitational instability. When stars form, a planet-forming disk surrounds them. With core accretion, planets form gradually as solid cores slowly grow big enough to start acquiring gas from the disk, while in the gravitational instability model, planets form almost instantly as the disk collapses on itself.

Properties such as the composition of a planet’s atmosphere are clues to how the planet formed, and in this case core accretion seems to win out. Although there was evidence of water vapor, that signature is weaker than would be expected if the planet shared the composition of its parent star. Instead, the planet has a high ratio of carbon to oxygen – a fingerprint of its formation in the gaseous disk tens of millions of years ago. As the gas cooled with time, grains of water ice formed, depleting the remaining gas of oxygen. Planetary formation then began when ice and solids collected into planetary cores.

“Once the solid cores grew large enough, their gravity quickly attracted surrounding gas to become the massive planets we see today,” said Konopacky. “Since that gas had lost some of its oxygen, the planet ends up with less oxygen and less water than if it had formed through a gravitational instability.”

“Spectral information of this quality not only provides clues about the formation of the HR8799 planets but also provides the guidance we need to improve our theoretical understanding of exoplanet atmospheres and their early evolution,” said Barman. “The timing of this work could not be better as it comes on the heels of new instruments that will image dozens more exoplanets, orbiting other stars, that we can study in similar detail.”

This system was also the study as part of remote reconnaissance imaging with Project 1640. The video below explains more:

 

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Closest Star System Found in a Century

WISE J104915.57-531906 is at the center of the larger image, which was taken by the NASA's Wide-field Infrared Survey Explorer (WISE). Image credit: NASA/JPL/Gemini Observatory/AURA/NSF

NASA’s Wide-field Infrared Survey Explorer (WISE) has discovered a pair of stars that has taken over the title for the third-closest star system to the sun. The duo is the closest star system discovered since 1916.

Both stars in the new binary system are “brown dwarfs,” which are stars that are too small in mass to ever become hot enough to ignite hydrogen fusion. As a result, they are very cool and dim, resembling a giant planet like Jupiter more than a bright star like the sun.

“The distance to this brown dwarf pair is 6.5 light-years — so close that Earth’s television transmissions from 2006 are now arriving there,” said Kevin Luhman, an associate professor of astronomy and astrophysics at Penn State University, University Park, Pa., and a researcher in Penn State’s Center for Exoplanets and Habitable Worlds.

 

“It will be an excellent hunting ground for planets because the system is very close to Earth, which makes it a lot easier to see any planets orbiting either of the brown dwarfs.”

The results will be published in the Astrophysical Journal Letters.

The star system is named “WISE J104915.57-531906″ because it was discovered in an infrared map of the entire sky obtained by WISE. It is only slightly farther away than the second-closest star, Barnard’s star, which was discovered 6 light-years from the sun in 1916. The closest star system consists of: Alpha Centauri, found to be a neighbor of the sun in 1839 at 4.4 light-years away, and the fainter Proxima Centauri, discovered in 1917 at 4.2 light-years.

Edward (Ned) Wright, the principal investigator for the WISE satellite at UCLA, said, “One major goal when proposing WISE was to find the closest stars to the sun. WISE J1049-5319 is by far the closest star found to date using the WISE data, and the close-up views of this binary system we can get with big telescopes like Gemini and the future James Webb Space Telescope will tell us a lot about the low-mass stars known as brown dwarfs.”

The Gemini South telescope in Chile was also used in this study for follow-up observations.

WISE completed its all-sky survey in 2011, after surveying the entire sky twice at infrared wavelengths. The maps have been released to the public, but an ongoing project called “AllWISE” will combine data from both sky scans. AllWISE will provide a systematic search across the sky for the nearby moving stars such as WISE J104915.57-531906, and also uncover fainter objects from the distant universe. Those data will be publicly available in late 2013.

Are we ready to meet ET?

Once only science fiction, astronomers are now finding hundreds of planetary systems beyond our own. Given recent discoveries through space exploration, it is entirely feasible that we may soon discover the existence of extra-terrestrial life (ET) forms on other planets.

The idea of extra-terrestrial life forms fascinates some and terrifies others. And even though our search for ET never quite panned out, we never stopped looking.

However, could this all be about to change following the discovery of hundreds of exoplanets (planets outside our Solar System), and thousands of candidate exoplanetary systems, some of which might be habitable for life.

 

Speaking about these momentous discoveries at the Cambridge Science Festival on March 16, NASA’s Dr Jennifer Wiseman will reveal how these exoplanets may provide evidence of biological activity, and discuss the profound invigoration of scientific and related religious and philosophical thought this might inspire if we find that life could thrive beyond Earth.

In a recent interview, Dr Wiseman said: “It’s a very exciting time for astronomy; we are finding a plethora of planets around other stars, including some that may be similar to Earth in size and temperature. The question that humans have had for centuries – whether or not there are planets similar to our own around other stars – seems more and more to be best answered as, ‘Yes!’”

It is expected that there is at least one planet, on average, orbiting around each star in our Milky Way galaxy, resulting in hundreds of billions of exoplanets, some fraction of which are the size of Earth at similar distances from their parent stars as Earth is to the Sun. These staggering numbers means there is a real possibility that we are on the verge of discovering our twin. If so, could this also mean the discovery of alien life forms similar to humans? And, what could this mean for humanity’s self-image if we were to discover that we are not unique or alone in the universe?

As Senior Project Scientist for NASA’s Hubble Space Telescope and Director of the Dialogue on Science, Ethics and Religion for the American Association for the Advancement of Science, Dr Wiseman is uniquely placed to provide both insights into the latest developments in the search for inhabitable exoplanets, as well as reflections on philosophical and religious implications of finding life on another planet.

From identifying seismic wave activity and colour patterns on these other worlds, to the use of enormous telescopes that could potentially hunt for evidence of alien life by their atmospheres, astronomers are continuing to find new ways to look for that tantalising hint of life.

In January this year, astronomers announced the discovery of an Earth-like exoplanet candidate orbiting a star similar to our Sun in the ‘habitable zone’ – the area around a star within which it is theoretically possible for water to exist on a planet’s surface (and therefore also the possibility of supporting life). And in February, Harvard researchers identified three planets as ‘objects of interest’ – meaning they could also be potentially habitable.

Harvard astronomer and lead author Courtney Dressing, who presented the findings at the Harvard-Smithsonian Center for Astrophysics, said: “We thought we would have to search vast distances to find an Earth-like planet. Now we realise another Earth is probably in our own backyard, waiting to be spotted.”

In addition, the World Economic Forum Global Risks report for 2013 states that, “Given the pace of space exploration, it is increasingly conceivable that we may discover the existence of alien life or other planets that could support human life. … In 10 years’ time, we may have evidence not only that Earth is not unique, but also that life exists elsewhere in the universe.”

The report continued, “The discovery of even simple life would fuel speculation about the existence of other intelligent beings and challenge many assumptions that underpin human philosophy and religion.”

Professor Meric Srokosz, Associate Director of The Faraday Institute for Science and Religion, Cambridge (the organisers of the event) said: “This is a unique opportunity to hear a genuine expert in her field, and to learn and think about one of the questions that continues to fascinate: is there life out there in the universe?”