Gliese 176
| Observation data EpochJ2000.0EquinoxJ2000.0 | |
|---|---|
| Constellation | Taurus |
| Right ascension | 04h42m55.7750s[1] |
| Declination | +18° 57′ 29.396″[1] |
| Apparent magnitude(V) | 9.95[2] |
| Characteristics | |
| Spectral type | M2V[3] |
| B−Vcolor index | 1.523±0.025[4] |
| Variable type | None[5] |
| Astrometry | |
| Radial velocity(Rv) | 26.4105±0.0004[3]km/s |
| Proper motion(μ) | RA:+656.647[1]mas/yr Dec.:−1116.594[1]mas/yr |
| Parallax(π) | 105.4275 ± 0.0210mas[1] |
| Distance | 30.937 ± 0.006ly (9.485 ± 0.002pc) |
| Absolute magnitude(MV) | 10.10±0.06[3] |
| Details | |
| Mass | 0.485±0.012[6]M☉ |
| Radius | 0.474±0.015[6]R☉ |
| Luminosity | 0.03516±0.00032[6]L☉ |
| Temperature | 3,632+58 −56[6]K |
| Metallicity[Fe/H] | −0.1±0.2[3]dex |
| Rotation | 40.00±0.11[3]days |
| Rotational velocity(vsini) | ≤0.8[3]km/s |
| Age | 8.8+2.5 −2.8[5]Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Gliese 176is a smallstarwith an orbitingexoplanetin theconstellationofTaurus.With anapparent visual magnitudeof 9.95,[2]it is too faint to be visible to the naked eye. It is located at a distance of 30.9light yearsbased onparallaxmeasurements,[1]and is drifting further away with a heliocentricradial velocityof 26.4 km/s.[3]
This is anM-type main-sequence star,sometimes called ared dwarf,with astellar classificationof M2V.[3]It has 49% of the Sun's mass and 47% of the radius of the Sun. The star is radiating just 3.5% of the luminosity of the Sun from itsphotosphereat aneffective temperatureof 3,632 K. It is estimated to be around nine billion years old,[5]and is spinning slowly with arotation periodof 40 days. The star is orbited by aSuper-Earth.
Planetary system
[edit]A planetary companion to Gliese 176 was announced in 2008.[7]Radial velocity observations with theHobby-Eberly Telescope(HET) showed a 10.24-day periodicity, which was interpreted as being caused by a planet. With a semi-amplitude of 11.6 m/s, its minimum mass equated to 24.5 Earth masses, or approximately 1.4 Neptune masses.
Observations with theHARPSspectrograph could not confirm the 10.24-day variation.[3]Instead, two other periodicities were detected at 8.78 and 40.0 days, with amplitudes below the HET observational errors. The 40-day variation coincides with the rotational period of the star and is therefore caused by activity, but the shorter-period variation is not explained by activity and is therefore caused by a planet. Its semi-amplitude of 4.1 m/s corresponds to a minimum mass of 8.4 Earth masses, making the planet a Super-Earth.
In an independent study, observations withKeck-HIRES also failed to confirm the 10.24-day signal.[8]An 8.77-day periodicity - corresponding to the planet announced by the HARPS team - was detected to intermediate significance, though it was not deemed significant enough to claim a planetary cause with their data alone.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥9.06+1.54 −0.70M🜨 |
0.066±0.001 | 8.776+0.001 −0.002 |
0.148+0.249 −0.036 |
— | — |
See also
[edit]References
[edit]- ^abcdefVallenari, A.; et al. (Gaia collaboration) (2023)."GaiaData Release 3. Summary of the content and survey properties ".Astronomy and Astrophysics.674:A1.arXiv:2208.00211.Bibcode:2023A&A...674A...1G.doi:10.1051/0004-6361/202243940.S2CID244398875. Gaia DR3 record for this sourceatVizieR.
- ^abKoen, C.; Kilkenny, D.; van Wyk, F.; Marang, F. (2010)."UBV(RI)CJHK observations of Hipparcos-selected nearby stars ".Monthly Notices of the Royal Astronomical Society.403(4): 1949–1968.Bibcode:2010MNRAS.403.1949K.doi:10.1111/j.1365-2966.2009.16182.x.
- ^abcdefghiForveille, Thierry; Bonfils, Xavier; Delfosse, Xavier; Gillon, Michaël; Udry, Stéphane; Bouchy, François; Lovis, Christophe; Mayor, Michel; Pepe, Francesco; Perrier, Christian; Queloz, Didier; Santos, Nuno C.; Bertaux, Jean-Loup (2009)."The HARPS search for southern extra-solar planets. XIV. Gl 176b, a super-Earth rather than a Neptune, and at a different period".Astronomy and Astrophysics.493(2): 645–650.arXiv:0809.0750.Bibcode:2009A&A...493..645F.doi:10.1051/0004-6361:200810557.S2CID115697713.Archivedfrom the original on 2021-02-27.Retrieved2018-03-16.
- ^van Leeuwen, F. (2007)."Validation of the new Hipparcos reduction".Astronomy and Astrophysics.474(2): 653–664.arXiv:0708.1752.Bibcode:2007A&A...474..653V.doi:10.1051/0004-6361:20078357.S2CID18759600.Archivedfrom the original on 2019-12-07.Retrieved2013-09-11.
- ^abcBrown, Alexander; et al. (May 2023)."Coronal X-Ray Emission from Nearby, Low-mass, Exoplanet Host Stars Observed by the MUSCLES and Mega-MUSCLES HST Treasury Survey Projects".The Astronomical Journal.165(5): 195.arXiv:2303.12929.Bibcode:2023AJ....165..195B.doi:10.3847/1538-3881/acc38a.195.
- ^abcdPineda, J. Sebastian; et al. (September 2021)."The M-dwarf Ultraviolet Spectroscopic Sample. I. Determining Stellar Parameters for Field Stars".The Astrophysical Journal.918(1): 23.arXiv:2106.07656.Bibcode:2021ApJ...918...40P.doi:10.3847/1538-4357/ac0aea.S2CID235435757.40.
- ^Endl, Michael; et al. (2008). "An m sin i = 24 M🜨Planetary Companion to the Nearby M Dwarf GJ 176 ".The Astrophysical Journal.673(2): 1165–1168.arXiv:0709.0944.Bibcode:2008ApJ...673.1165E.doi:10.1086/524703.S2CID118332426.
- ^Butler, R. Paul; et al. (2009)."Nondetection of the Neptune-Mass Planet Reported Around GJ 176".The Astrophysical Journal.691(2): 1738–1743.Bibcode:2009ApJ...691.1738B.doi:10.1088/0004-637X/691/2/1738.
- ^Trifonov, Trifon; Kürster, Martin; Zechmeister, Mathias; Tal-Or, Lev; Caballero, José A.; Quirrenbach, Andreas; Amado, Pedro J.; Ribas, Ignasi; Reiners, Ansgar; et al. (2018). "The CARMENES search for exoplanets around M dwarfs. First visual-channel radial-velocity measurements and orbital parameter updates of seven M-dwarf planetary systems".Astronomy and Astrophysics.609.A117.arXiv:1710.01595.Bibcode:2018A&A...609A.117T.doi:10.1051/0004-6361/201731442.S2CID119340839.
