Gliese 876 d
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Exoplanet Gliese 876 d |
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| Artist's impression of the possible appearance of Gliese 876 d as a large rock planet (top left) or a small gas planet (bottom right) | |
| Constellation | Aquarius |
| Position equinox : J2000.0 |
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| Right ascension | 22h 53m 16.73352s |
| declination | −14 ° 15 ′ 49.3186 ″ |
| Orbit data | |
| Central star | Peter 876 |
| Major semi-axis | 0.021 ± 0.001 AU |
| eccentricity | 0.082 +0.043−0.025 |
| Period of circulation | 1.938 ± 0.001 d |
| Further data | |
| Minimum dimensions | 6.91 +0.22−0.27 M ♁ |
| distance | 4.660 ± 0.004 pc |
| history | |
| discovery | Rivera et al. |
| Date of discovery | 2005 |
| Catalog names | |
| GJ 876 d, IL Aqr d, HIP 113020 d | |
Gliese 876 d a is Exoplanet which the 15 light-years from the sun away red dwarf Gliese 876 in the constellation Aquarius orbits. It is the innermost known planet in the star's planetary system .
discovery
On the basis of very precise measurements of the radial velocity of Gliese 876 by the Keck Observatory , which stretched over eight years, a team of astronomers led by Eugenio Rivera provided evidence of a third planet in 2005 after the previous discoveries of Gliese 876 b and Gliese 876 c .
At the time of its discovery, Gliese 876 d was the lowest-mass known exoplanet after the three planets around the pulsar PSR B1257 + 12 discovered in 1992 and 1994 and the lowest-mass around a main sequence star . It was also the first exoplanet from a main sequence star to be classified as super-earth .
properties
Gliese 876 d orbits its central star at a distance of only 0.021 AU , and it takes a little less than two days for one orbit. Initial estimates of its mass were around 7.53 Earth masses , and were refined to around 6.83 Earth masses following the discovery of the fourth planet, Gliese 876 e in 2010. According to more recent studies from 2014, the minimum mass of Gliese 876 d is around 5.85 earth masses .; a work published in October 2017 states a minimum mass of about 6.91 earth masses.
Since the planet was discovered using only the radial velocity method, its actual radius and composition are unknown. The proximity of the planet to its central star suggests a bound rotation . Assuming a distribution of the heat on the planet similar to that of Venus in the solar system , there may be an effective temperature of 430 to 650 Kelvin (157 to 377 ° C ) on Gliese 876 d .
According to model calculations, the planet may have been created from material that migrated inward towards the star during the migration of the system's gas planets further out . A model proposed by Gliese 876 d in 2005 is based on a silicate core surrounded by a deep ocean and an atmosphere of hydrogen. Gliese 876 d could also be the core of a gas planet that migrated into orbit in extreme proximity to the star and lost its gas envelope (at least to a large extent).
Individual evidence
- ↑ SIMBAD: Gliese 876. Retrieved July 5, 2015 .
- ↑ a b c d NASA Exoplanet Archive: GJ 876 d. Retrieved January 18, 2018 .
- ↑ a b c d e Rivera, Eugenio J. et al .: A ~ 7.5 Earth-Mass Planet Orbiting the Nearby Star, GJ 876 . arxiv : astro-ph / 0510508 .
- ↑ a b Rivera, Eugenio J. et al .: The Lick-Carnegie Exoplanet Survey: A Uranus-mass Fourth Planet for GJ 876 in an Extrasolar Laplace Configuration . arxiv : 1006.4244 .
- ^ Kammer, J. et al .: A Spitzer Search for Transits of Radial Velocity Detected Super-Earths . arxiv : 1310.7952 .
- ↑ The CARMENES search for exoplanets around M dwarfs. First visual-channel radial-velocity measurements and orbital parameter updates of seven M-dwarf planetary systems. (PDF) October 4, 2017, p. 15 , accessed on January 18, 2018 . doi : 10.1051 / 0004-6361 / 201731442 , arxiv : 1710.01595
- ^ Fogg, MJ; Nelson, RP: Oligarchic and giant impact growth of terrestrial planets in the presence of gas giant planet migration . arxiv : astro-ph / 0507180 .
- ↑ Zhou, J.-L. et al .: Origin and Ubiquity of Short-Period Earth-like Planets: Evidence for the Sequential-Accretion Theory of Planet Formation . arxiv : astro-ph / 0508305 .