GJ 625 b

The planet GJ 625 b, orbits around an M dwarf star called GJ 625 located about 21.2 light-years from Earth. It is thought to be at least 2.8 times the mass of Earth and orbits its host star in about 14.6 days. The findings,  led by the Canary Islands Institute of Astrophysics, will be published in the Journal of Astronomy and Astrophysics.

GJ 625 b is located on the inner edge of the habitable zone, where temperatures are just right for liquid water to exist. It orbits at a distance of about 0.08 AU (astronomical units, 1 AU is the distance from Earth to the Sun).

“GJ 625 b is a small super-Earth in the habitable zone of a nearby M-dwarf,” lead author Alejandro Suarez Mascareño, from the Canary Islands Institute of Astrophysics, told IFLScience. “Even after the last round of discoveries of small exoplanets around M-dwarfs, the number of rocky planets known around this kind of star is relatively small.”

Journal Articles:

1.) HADES RV Programme with HARPS-N at TNG V. A super-Earth on the inner edge of the habitable zone of the nearby M-dwarf GJ 625

2.) Equilibrium Temperatures and Albedos of Habitable Earth-Like Planets in a Coupled Atmosphere-Ocean GCM

WEB Articles:

1.) Super-Earth Discovered Around Nearby Red Dwarf Star

2.) A new Super-Earth discovered near the habitable zone of a cool star.

CoRoT 10 b

(Imaginary Image of Corot 10b　Ryusuke Kuroki, Fuka Takagi, and Yosuke A. Yamashiki)

COROT-10b is an enormous exoplanet discovered in 2007 (reported in 2010) by the CoRoT satellite (this satellite preceded the Kepler Space Telescope in searching for planets using the transit method) after 142 days of observation. The planet has a radius of about 0.97 that of Jupiter and orbits its host star, COROT-10, in about 13.4 days. COROT-10 is a K1-type star with a surface temperature of 5075 K. It is slightly smaller in mass and radius (0.89 times the mass and 0.79 times the radius) than the Sun.

The orbital eccentricity of this planet is very large at 0.53 ± 0.04, and its orbit is elliptical, not a perfect circle. It of great interest to understand how such a large planet with such a large orbital eccentricity could exist within our knowledge of the planetary formation process.

(Yuta Notsu)

Journal Articles:

1.) Transiting exoplanets from the CoRoT space mission X. CoRoT-10b: a giant planet in a 13.24 day eccentric orbit

WEB Articles:

1.) CoRoT-10 b

2.) Planet CoRoT-10 b

CoRoT 3 b

COROT-exo-3b fits into the category of a failed star known as a brown dwarf, but the team that made the discovery has not ruled out the possibility that it is a planet. Brown dwarfs are failed stars. They burn lithium but are not massive enough to generate the thermonuclear fusion of hydrogen and helium that powers real stars. Planets do none of that.

The object has a mass 20 times greater than that of Jupiter but is roughly the same size. It falls outside the range of planets and stars discovered to date, with the largest planets having 12-Jupiter-mass and the smallest stars 70-Jupiter-mass.

If astronomers confirm the object as a planet, it would weigh in as the most massive and densest planet found so far. A full study will be detailed in the journal Astronomy and Astrophysics.

“COROT-exo-3b might turn out to be a rare object found by sheer luck”, said Francois Bouchy, an astronomer at the Institut d’Astrophysique in Paris. “But it might just be a member of a new-found family of very massive planets that encircle stars more massive than our sun. We’re now beginning to think that the more massive the star, the more massive the planet.”

The host star CoRoT 3 has an apparent magnitude of 13.3, with an absolute magnitude of 4.14. It is 1.41 times more massive and 1.44 times bigger compared with our sun. The surface temperature is 6558 K with its spectral type of F3V. In this planetary system, the extrasolar planet CoRoT 3 b orbits around the star CoRoT 3 with its orbital distance of 0.0570.

Paper:

https://www.aanda.org/10.1051/0004-6361:200810625

Journal Articles:

1.) The Rossiter-McLaughlin effect of CoRoT-3b and HD 189733b

2.) Transiting exoplanets from the CoRoT space mission, VI. CoRoT-Exo-3b: the first secure inhabitant of the brown-dwarf desert

3.) CoRoT’s first seven planets: An overview

WEB Articles:

1.) Huge Planet Defies Explanation

2.) 系外惑星の分類に疑問投げかける天体を発見

Floating Planets

(Image credit: Rina Maeda, SGH Moriyama high school)

GJ667Cc

(Image of a tidally locked planet like GJ667Cc Credit: Natsuki Shirako, SGH Moriyama High School)

(Imaginary Image of GJ667Cc Credit: Miu Shimizu  (SGH Moriyama High School) )

The planet, dubbed GJ 667Cc, orbits a red dwarf star 22 light-years from Earth, in the constellation Scorpio. A binary pair of orange dwarf stars are part of the same system.

The new planet has a mass 4.5 times that of Earth and orbits its host star every 28 days.

The red dwarf is relatively dim, so the planet receives slightly less light from its star than Earth does from the sun. But most of the star’s light is infrared, so the planet should absorb more of its incoming energy than Earth does from sunlight.

That means if the planet has a rocky surface—which is predicted for planets less than ten times Earth’s mass—and an atmosphere, it could support liquid water and maybe life said co-discoverer Guillem Anglada-Escudé, who conducted the work while at the Carnegie Institution for Science in Washington, D.C.

“If it has an atmosphere, it’s probably reddish all the time, because the star is really red,” Anglada-Escudé said. “It would be like being evening all the time.”

The host star GJ 667 C has an apparent magnitude of 10.2, with an absolute magnitude of 11.04. It is 0.33 times more massive and 0.34 times bigger compared with our sun. The surface temperature is 3600 K with it’ spectral type of M1.5v. In this planetary system, the extrasolar planet GJ 667 Cc orbits around the star GJ 667 C with its orbital distance of 0.125.

（梨元昴・山敷庸亮）

Reference

http://www.eso.org/public/archives/releases/sciencepapers/eso1328/eso1328a.pdf

GJ667Cc’s Habitable Zone (Kopparapu et al. 2013)

Location of GJ667C on the Stellar Map

For more information about GJ667Cc, please visit the ExoKyoto Database:
http://www.exoplanetkyoto.org/exohtml/GJ_667_C_cJP.html

CoRoT-7b

(Imaginary Image of CoRoT-7b by Rina Maeda from Moriyama SGH)　A tidally locked planet with a surface temperature of over 2000 degrees on the day-side, and ice on the night-side.

(Imaginary Image of CoRoT-7b　Credit: Ryusuke Kuroki, Yosuke Yamashiki )

CoRoT-7b is an exoplanet discovered by the COROT space telescope mission, using the transit method in February 2009. The planet is located in the center of the constellation Monoceros, 489 light years away from our solar system. It has a very small radius at 1.52 times that of the Earth, which was the smallest exoplanet when it was discovered. It has an extremely short orbit of only 0.85 days (about 20 hours) and orbits very close to its host star at a distance of 2.57 million km (0.02 AU, less than 1/20th of the distance between the Sun and Mercury).
Due to its density, CoRoT-7b is classified as a Super Earth, but it has also been considered as a Super Io.
Io, one of Jupiter’s moons, is volcanically active, with an interior temperature that rises due to tidal heating, which is caused by Jupiter’s gravity. CoRoT-7b is thought to be the same, experiencing tidal heating due to the influence of its hoststar CoRoT-7 along with another orbiting planet CoRoT-7c.
CoRoT-7b is tidally locked, due to its short orbital length radius, and because one surface is always facing the host star, that side of the planet can reach over 2000 degrees Celsius, while the opposite side can reach -200 degrees Celsius. ExoKyoto estimates the temperature on the day-side to be about 2110 K (assuming an albedo of 0.1) or 1982 K (assuming an albedo of 0.3).
CoRoT-7b is thought to be a rocky planet like Earth, but it is unlikely to support life due to its severe temperatures. Land on the star side would be covered with molten lava, and there is a possibility of active volcanic activity on the other side.

（執筆　佐藤啓明　修正担当　山敷庸亮）
Victoria Jaggard （2010）「最も地球に似た系外惑星はスーパーイオ」（Reference 2018-1-19）

“AstroArts” 　(2009)　「最小の系外惑星を発見」（参照2018-1-19）

“AstroArts”　(2009)「最小系外惑星は、地球に似た岩石惑星か」（参照2018-1-19）

CoRoT-7’s Habitable Zone

CoRoT-7’s Location on the Stellar Map

For more information on CoRoT-7b, please see the following:
http://www.exoplanetkyoto.org/exohtml/CoRoT-7_bJP.html