CoRoT-9b is an

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first det ...

orbiting the

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

CoRoT-9, approximately 1500 light years away in the constellation

Serpens Serpens () 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 Astronomical Union. It ...

. 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 fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...

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 t ...

satellite, which looks for a small dip in starlight as a planet passes in front of its parent star, and

radial velocity The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points. It is formulated as the vector projection of the target-observer relative velocity ...

measurements from the

European Southern Observatory The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental organization, intergovernmental research organisation made up of 16 m ...

'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 Saint Patrick's Day, or the Feast of Saint Patrick (), is a religious and cultural holiday held on 17 March, the traditional death date of Saint Patrick (), the foremost patron saint of Ireland. Saint Patrick's Day was made an official Chri ...

, 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 The European Southern Observatory is an astronomical research organisation. ESO may also refer to: *Employee stock option (also: executive stock option) *'' Ether Saga Odyssey'', a fantasy massively multiplayer online role-playing game *''The Elde ...

/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 and extrinsic properties, intrinsic property of a physical body, body. It was traditionally believed to be related to the physical quantity, quantity of matter in a body, until the discovery of the atom and particle physi ...

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 grating, echelle planet-finding spectrograph installed in 2002 on the ESO 3.6 m Telescope, ESO's 3.6m telescope at La Silla Observatory in Chile. The First l ...

spectroscopy, and has a

radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...

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 electr ...

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

density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...

of 96% that of water, and surface gravity 1.93 times that of Earth. A search for rings and satellites around this planet with the

Spitzer space telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003, that was deactivated when operations ended on 30 January 2020. Spitzer was the third space telescope dedicate ...

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 a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

and

helium Helium (from ) is a chemical element; it has chemical symbol, symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert gas, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is ...

(like

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...

and

Saturn Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...

), 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 9b Articles containing video clips

Discovery

Mass and size

Atmosphere and interior

See also

References

External links