Gliese 625
Red dwarf in constellation of Draco
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GJ 625 (AC 54 1646-56) is a small red dwarf star with an exoplanetary companion in the northern constellation of Draco. The system is located at a distance of 21.1 light-years (6.4 parsecs) from the Sun based on parallax,[2] but is drifting closer with a radial velocity of −13 km/s.[8] It is too faint to be visible to the naked eye, having an apparent visual magnitude of 10.13[3] and an absolute magnitude of 11.06.[3]
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Draco[1] |
| Right ascension | 16h 25m 24.62304s[2] |
| Declination | +54° 18′ 14.7655″[2] |
| Apparent magnitude (V) | 10.13[3] |
| Characteristics | |
| Spectral type | M1.5V[4] |
| B−V color index | 1.591±0.027[3] |
| Astrometry | |
| Radial velocity (Rv) | −13.37±0.14[2] km/s |
| Proper motion (μ) | RA: 432.230(19) mas/yr[2] Dec.: −171.652(22) mas/yr[2] |
| Parallax (π) | 154.3503±0.0161 mas[2] |
| Distance | 21.131 ± 0.002 ly (6.4788 ± 0.0007 pc) |
| Absolute magnitude (MV) | 11.06[3] |
| Details | |
| Mass | 0.240±0.013[5] M☉ |
| Radius | 0.255±0.034[5] R☉ |
| Luminosity | 0.01482±0.00022[6] L☉ |
| Surface gravity (log g) | 4.94±0.06[7] cgs |
| Temperature | 3,557±9[8] K |
| Metallicity [Fe/H] | −0.401±0.005[8] dex |
| Rotation | 77.8±5.5 d[7] |
| Rotational velocity (v sin i) | 2.2±0.7[8] km/s |
| Other designations | |
| GJ 625, HIP 80459, AC +54 1646, G 202-48, G 226-7, G 225-62, LSPM J1625+5418, NLTT 42804, PLX 3740.03, TYC 3878-1193-1, 2MASS J16252459+5418148[9] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
This is an M-type main-sequence star with a stellar classification of M1.5V.[4] It is spinning slowly with a rotation period of roughly 78 days, and has a low magnetic activity level.[7] The star has about a quarter of the mass and size of the Sun,[5] and the metal content is 40% the abundances in the Sun's atmosphere. It is radiating just 1.5% of the luminosity of the Sun from its photosphere at an effective temperature of 3,557 K.[8]
Planetary system
On May 18, 2017, a planet was detected orbiting GJ 625 by the HARPS-N telescope. The planet, GJ 625 b, orbits near the inner edge of the optimistic circumstellar habitable zone of its star, and the discoverers speculate it may support liquid water, depending on atmospheric conditions.[7] Based on the habitable zone model of Kopparapu et al. 2013, the planet is not considered to be in the habitable zone as it would likely experience a runaway greenhouse effect, similar to Venus.[10][11][12][13]
Since the star is considered quiescent (having a low X-ray emission and flare rate), the radio emission from the system may be auroral in nature and coming from a short-period planet. Further observations will be needed to confirm this.[14]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b | ≥2.82±0.51 M🜨 | 0.078361+0.000044 −0.000046 |
14.628+0.012 −0.013 |
0.13+0.12 −0.09 |
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