| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hydra |
| Right ascension | 10h 58m 35.08837s[1] |
| Declination | −31° 08′ 38.2008″[1] |
| Apparent magnitude (V) | 11.95[2] |
| Characteristics | |
| Evolutionary stage | Main sequence |
| Spectral type | M2.5V[2] |
| Astrometry | |
| Radial velocity (Rv) | 4.93±0.26[1] km/s |
| Proper motion (μ) | RA: -566.980mas/yr[1] Dec.: -91.397mas/yr[1] |
| Parallax (π) | 49.0331±0.0241 mas[1] |
| Distance | 66.52 ± 0.03 ly (20.39 ± 0.01 pc) |
| Details | |
| Mass | 0.45 (± 0.05)[2] M☉ |
| Radius | 0.43 (±0.03)[2] R☉ |
| Luminosity | 0.02[3] L☉ |
| Metallicity [Fe/H] | +0.04±0.06[4] dex |
| Age | > 3[3] Gyr |
| Other designations | |
| LP 905-36 LHS 2335 2MASS J10583513-3108382 | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
| ARICNS | data |
GJ 3634 (sometimesGliese 3634) is ared dwarf star in theHydra constellation. One planet has been discovered in its orbit,GJ 3634 b. GJ 3634 is under half the mass and size of the Sun, and is estimated to be at least a billion years younger, and lies near to Earth, with a distance of 66.5light-years (20.4parsecs).[1] It was targeted by astronomers during an over six-year survey of red dwarfs. The astronomers had recently changed their strategy to search for planets with extremely short orbits so they could narrow down candidates thattransited, or crossed in front of, their host stars as seen from the Earth. Thesuper-Earth GJ 3634 b was the first planet discovered using this new strategy.[3] The planet was confirmed usingDoppler spectroscopy, or the observation and extrapolation of data from a recordedDoppler effect in the star's light, but later observations found no transiting pattern.[3] The planet was published by its discoverers on February 8, 2011.
GJ 3634 is named for its location in theGliese Catalogue of Nearby Stars; a later expansion of the original catalogue was compiled jointly by Gliese andHartmut Jahreiß. The Third Catalogue, the most recent catalogue, was formed to tag all then-known stars within 25 parsecs of Earth (81.54light years).[5] GJ 3634 was first catalogued in 1987.[3] The discoverers of GJ 3634 b worked through theHigh Accuracy Radial Velocity Planet Searcher (HARPS) at theEuropean Southern Observatory'sLa Silla Observatory in Chile for over six years in search of planets that orbited low-mass red dwarfs. After the discoveries of eleven prior planets, the researchers changed their strategy to search for planets with extremely short orbits. They would first discover the system using theradial velocity method, in which an observedDoppler shift in the star's light would be measured and interpreted; and would then follow up with a search fortransits, in which the planet crosses in front of and dims its star as seen from Earth. Radial velocity measurements would help determine the most efficient and time-effective means of observing potential planetary transits.[3]
Radial velocity measurements revealed the existence of a planet with a mass of at least 7 Earths. This planet,GJ 3634 b, became the first planet to be discovered under the new strategy.[3] The team of astronomers then followed up with transit measurements using instruments on theSpitzer Space Telescope; they found that there was most likely no transit event present at the star, but they were able to discover its true mass.[3] GJ 3634 b was published to the journalAstronomy and Astrophysics on February 8, 2011.[3]
GJ 3634 is anM-typered dwarf, a cool, small and dim star that shines with reddish light. It lies in theHydra constellation. The star is 45% themass of the Sun, and is 43% the Sun'ssize. GJ 3634, described by its discoverers as an "intermediately active star," has aluminosity of 0.02, meaning that it releases about 2% of the energy that the Sun radiates. The star is relatively metal-poor; with ametallicity of [Fe/H] -0.10, GJ 3634 has 79% the amount of iron that has been measured in the Sun. With an estimated age of more than three billion years, the star is similar in age to that of the Sun.[3]
GJ 3634 has anapparent magnitude of 11.95. Thus, despite its relative proximity at 66.5light-years (20.4parsecs) away from the Earth, it cannot be seen with the unaided eye.[2] The star is of a similar distance from Earth as planet-bearing51 Pegasi, which lies at a distance of 50.6 light-years (15.5 parsecs).[6]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 8.4+4.0 −1.5 M🜨 | 0.0287 | 2.64561 | 0.08 | 59+18 −24° | — |
| (unconfirmed) | >32M🜨 | >0.6 | >200 | — | — | — |
GJ 3634 has one confirmed planet in orbit:GJ 3634 b. The planet was called asuper-Earth by its discoverers because of its mass, which was deduced to be 8.4 times that of Earth's[3] and 0.02 times that of Jupiter's.[2] GJ 3634 b has an extremely shortorbital period, orbiting GJ 3634 every 2.64561 days. The planet orbits near to its star, and is at anaverage distance of 0.0287AU away. It has anorbital eccentricity of 0.08, meaning that its orbit is very circular.[2]
The initial study into the system suggests that a second planet in the inner system is unlikely. The discoverers of GJ 3634 b, however, noted the possible signal of a secondary body of an unknown nature that most likely orbits GJ 3634 with a period longer than 200 days and a mass that is at least double that ofNeptune.[3]
