[CENTRAAL] Exo-Planeten Topic

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Planetenjager ontdekt 32 exoplaneten

AMSTERDAM - Met een speciaal instrument op de 3,6 meter telescoop in Chili zijn 32 nieuwe exoplaneten ontdekt. Een exoplaneet is een planeet buiten ons zonnestelsel die om een andere dan onze zon draait. Met de ontdekking van 32 nieuwe aardse hemellichamen is het aantal bekende exoplaneten in een klap toegenomen met 30 procent.

Dat heeft de Nederlandse Onderzoekschool voor Astronomie (NOVA) maandag bekendgemaakt naar aanleiding van een internationale conferentie over exoplaneten in de Portugese stad Porto.

De 32 planeten buiten ons zonnestelsel zijn ontdekt met de HARPS, een uiterst nauwkeurig instrument dat in de wetenschappelijke wereld bekend staat als de belangrijkste exoplanetenjager van onze aarde. HARPS (High Accuracy Radial Velocity Planet Searcher) heeft de afgelopen vijf jaar meer dan 75 van de in totaal vierhonderd nu bekende exoplaneten gespot.

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Op woensdag 21 oktober 2009 23:00 schreef ExperimentalFrentalMental het volgende:
20-10-2009

Organische moleculen ontdekt in atmosfeer exoplaneet

[ afbeelding ]

NASA-onderzoekers hebben nu ook bij een tweede hete gasplaneet moleculen gedetecteerd die belangrijk zijn voor het ontstaan van leven zoals wij dat kennen.
Het betreft de planeet HD 209458b, die om een ster op 150 lichtjaar van de aarde draait.

Met behulp van instrumenten van de ruimtetelescopen Hubble en Spitzer zijn in de atmosfeer van deze exoplaneet water, methaan en kooldioxide gevonden. Deze ontdekking duidt er op dat deze levensbelangrijke verbindingen alom aanwezig zijn in het heelal.

Dat wil overigens niet zeggen dat er leven is op HD 209458b. Hij draait op een afstand van slechts 7 miljoen kilometer om zijn ster en heeft daardoor een oppervlaktetemperatuur van maar liefst 1000 graden.

© Eddy Echternach (www.astronieuws.nl)

(allesoversterrekunde)

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Op maandag 26 oktober 2009 09:38 schreef KlappernootatWork het volgende:

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http://www.astro.rug.nl/~(...)ndex.html#Discovered planets

hier een handig lijstje

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Planeet met veel water ontdekt

PARIJS - Buiten ons zonnestelsel is een planeet met veel water ontdekt. De zogenoemde exoplaneet GJ 1214b is veel kleiner en koeler dan eerder aangetroffen exoplaneten en lijkt ook meer op de aarde dan alle andere.

Dat stellen wetenschappers van het Harvard-Smithsonian Centrum voor Astrofysica.

De ontdekking van de 'Superaarde' betekent een belangrijke stap voorwaarts bij de zoektocht naar werelden die op de aarde lijken, aldus een commentaar in het woensdag verschenen tijdschrift Nature.

Groter

De planeet is ongeveer 42 lichtjaren van de aarde verwijderd en heeft een radius die bijna 2,7 keer zo groot is als die van de aarde. Mogelijk is drie vierde bedekt met water en ijs.

Ook zijn er aanwijzingen dat GJ 1214b een atmosfeer heeft. Ondanks het voorkomen van water lijkt de Superaarde te warm voor leven zoals op aarde.

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Op donderdag 17 december 2009 09:03 schreef ExperimentalFrentalMental het volgende:

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zie 2 posts hoger

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First Super-Earths Discovered Orbiting Sun-Like Stars

ScienceDaily (Dec. 14, 2009) — An international team of planet hunters has discovered as many as six low-mass planets around two nearby Sun-like stars, including two "super-Earths" with masses 5 and 7.5 times the mass of Earth. The researchers, led by Steven Vogt of the University of California, Santa Cruz, and Paul Butler of the Carnegie Institution of Washington, said the two "super-Earths" are the first ones found around Sun-like stars.

"These detections indicate that low-mass planets are quite common around nearby stars. The discovery of potentially habitable nearby worlds may be just a few years away," said Vogt, a professor of astronomy and astrophysics at UCSC.

The team found the new planet systems by combining data gathered at the W. M. Keck Observatory in Hawaii and the Anglo-Australian Telescope (AAT) in New South Wales, Australia. Two papers describing the new planets have been accepted for publication in the Astrophysical Journal.

Three of the new planets orbit the bright star 61 Virginis, which can be seen with the naked eye under dark skies in the Spring constellation Virgo. Astronomers and astrobiologists have long been fascinated with this particular star, which is only 28 light-years away. Among hundreds of our nearest stellar neighbors, 61 Vir stands out as being the most nearly similar to the Sun in terms of age, mass, and other essential properties. Vogt and his collaborators have found that 61 Vir hosts at least three planets, with masses ranging from about 5 to 25 times the mass of Earth.

Recently, a separate team of astronomers used NASA's Spitzer Space Telescope to discover that 61 Vir also contains a thick ring of dust at a distance roughly twice as far from 61 Vir as Pluto is from our Sun. The dust is apparently created by collisions of comet-like bodies in the cold outer reaches of the system.

"Spitzer's detection of cold dust orbiting 61 Vir indicates that there's a real kinship between the Sun and 61 Vir," said Eugenio Rivera, a postdoctoral researcher at UCSC. Rivera computed an extensive set of numerical simulations to find that a habitable Earth-like world could easily exist in the as-yet unexplored region between the newly discovered planets and the outer dust disk.

According to Vogt, the planetary system around 61 Vir is an excellent candidate for study by the new Automated Planet Finder (APF) Telescope recently constructed at Lick Observatory on Mount Hamilton near San Jose. "Needless to say, we're very excited to continue monitoring this system using APF," said Vogt, who is the principal investigator for the APF and is building a spectrometer for the new telescope that is optimized for finding planets.

The second new system found by the team features a 7.5-Earth-mass planet orbiting HD 1461, another near-perfect twin of the Sun located 76 light-years away. At least one and possibly two additional planets also orbit the star. Lying in the constellation Cetus, HD 1461 can be seen with the naked eye in the early evening under good dark-sky conditions.

The 7.5-Earth-mass planet, assigned the name HD 1461b, has a mass nearly midway between the masses of Earth and Uranus. The researchers said they cannot tell yet if HD 1461b is a scaled-up version of Earth, composed largely of rock and iron, or whether, like Uranus and Neptune, it is composed mostly of water.

According to Butler, the new detections required state-of-the-art instruments and detection techniques. "The inner planet of the 61 Vir system is among the two or three lowest-amplitude planetary signals that have been identified with confidence," he said. "We've found there is a tremendous advantage to be gained from combining data from the AAT and Keck telescopes, two world-class observatories, and it's clear that we'll have an excellent shot at identifying potentially habitable planets around the very nearest stars within just a few years."

The 61 Vir and HD 1461 detections add to a slew of recent discoveries that have upended conventional thinking regarding planet detection. In the past year, it has become evident that planets orbiting the Sun's nearest neighbors are extremely common. According to Butler, current indications are that fully one-half of nearby stars have a detectable planet with mass equal to or less than Neptune's.

The Lick-Carnegie Exoplanet Survey Team led by Vogt and Butler uses radial velocity measurements from ground-based telescopes to detect the "wobble" induced in a star by the gravitational tug of an orbiting planet. The radial-velocity observations were complemented with precise brightness measurements acquired with robotic telescopes in Arizona by Gregory Henry of Tennessee State University.

"We don't see any brightness variability in either star," said Henry. "This assures us that the wobbles really are due to planets and not changing patterns of dark spots on the stars."

Due to improvements in equipment and observing techniques, these ground-based methods are now capable of finding Earth-mass objects around nearby stars, according to team member Gregory Laughlin, professor of astronomy and astrophysics at UCSC.

"It's come down to a neck-and-neck race as to whether the first potentially habitable planets will be detected from the ground or from space," Laughlin said. "A few years ago, I'd have put my money on space-based detection methods, but now it really appears to be a toss-up. What is truly exciting about the current ground-based radial velocity detection method is that it is capable of locating the very closest potentially habitable planets."

The Lick-Carnegie Exoplanet Survey Team has developed a publicly available tool, the Systemic Console, which enables members of the public to search for the signals of extrasolar planets by exploring real data sets in a straightforward and intuitive way. This tool is available online at www.oklo.org.

This research was supported by the National Science Foundation and NASA. In addition to Vogt, Butler, Rivera, Laughlin, and Henry, the coauthors of the 61 Vir paper include Rob Wittenmyer, C. G. Tinney, and Jeremy Bailey of the University of New South Wales; Simon O'Toole and Hugh Jones of the University of Hertfordshire; Stefano Meschiari of UCSC; Brad Carter of the University of Southern Queensland; and Konstantin Batygin of Caltech. The authors of the HD 1461 paper are Rivera, Butler, Vogt, Laughlin, Henry, and Meschiari