COROT-9b is an exoplanet orbiting the star COROT-9, approximately 1500 light years away in the constellation

Serpens Serpens ( grc, , , the Serpent) is a constellation in the northern celestial hemisphere. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it remains one of the 88 modern constellations designated by the International ...

. COROT-9b's distance of nearest approach to its parent star of approximately 0.36 AU was the largest of all known transiting planets at the time of its discovery, with an orbital period of 95 days. The transit of this planet lasts 8 hours. The planet is at a distance from its star where there is a strong increase in

albedo Albedo (; ) is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that refl ...

as the temperature decreases, because of the condensation of reflective water clouds in the atmosphere. This suggests its atmosphere may be locked into one of two states: a cloudless state with temperatures between and , or covered in water clouds with a temperature in the range to .

Discovery

COROT-9b was discovered by combining observations from the

CoRoT CoRoT (French: ; English: Convection, Rotation and planetary Transits) was a space telescope mission which operated from 2006 to 2013. The mission's two objectives were to search for extrasolar planets with short orbital periods, particularly th ...

satellite, which looks for a small dip in starlight as a planet passes in front of its parent star, and radial velocity measurements from the European Southern Observatory's High Accuracy Radial velocity Planet Searcher (HARPS) instrument on the 3.6 m Telescope. Its presence was confirmed by observations from several telescopes from the ESO.New exoplanet like 'one of ours' (BBC, March 17, 2010)
/ref> This discovery was announced in 2010 on St. Patrick's Day, after 145 days of continuous observations in summer 2008. File:Artist’s impression of exoplanet Corot-9b.jpg, Artist's impression of the transiting exoplanet Corot-9b. Credit: ESO/L. Calçada. File:Animation of the transiting exoplanet Corot-9b.ogv, Animation of an artist's impression.

Mass and size

COROT-9b has a

mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different eleme ...

of 0.84 times that of Jupiter ( M_J) as determined from

HARPS The High Accuracy Radial Velocity Planet Searcher (HARPS) is a high-precision echelle planet-finding spectrograph installed in 2002 on the ESO's 3.6m telescope at La Silla Observatory in Chile. The first light was achieved in February 2003. ...

spectroscopy, and has a

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

of 1.05 times that of Jupiter ( R_J) as determined from

photometry Photometry can refer to: * Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision * Photometry (astronomy), the measurement of the flux or intensity of an astronomical object's electro ...

of the transit light curve. This implies that this planet has a

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

of 96% that of water, and surface gravity 1.93 times that of Earth. A search for

rings Ring may refer to: * Ring (jewellery), a round band, usually made of metal, worn as ornamental jewelry * To make a sound with a bell, and the sound made by a bell :(hence) to initiate a telephone connection Arts, entertainment and media Film and ...

and satellites around this planet with the Spitzer space telescope was negative.

Atmosphere and interior

Since COROT-9b is the first temperate giant exoplanet found by the transit method, astronomers will be able to study the atmosphere of a temperate giant planet for the first time, examining the composition of clouds, the composition of the atmosphere, temperature distributions, and even some details of the interior of the planet. The atmosphere of this planet is presumably dominated by

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

and

helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...

(like

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...

and Saturn), with up to 20 Earth masses of other elements including water, as well as rock at high temperatures and pressures. The authors of the COROT-9b discovery paper refer to the planet as a class II ("water cloud") or class III ("clear") atmosphere planet, as described by the Sudarsky extrasolar planet classification.

References

External links

*
"CoRoT-9b, a temperate exoplanet"
- DLR Portal, 2010.march.17 {{DEFAULTSORT:CoRoT-9b Exoplanets discovered in 2010 Transiting exoplanets Giant planets Serpens (constellation) 9b Articles containing video clips

Discovery

Mass and size

Atmosphere and interior

See also

References

External links