| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Taurus |
| Right ascension | 04 42 55.7750 |
| Declination | +18° 57′ 29.396″ |
| Apparent magnitude (V) | 9.95 |
| Characteristics | |
| Spectral type | M2V |
| B−V color index | 1.523±0.025 |
| Variable type | None |
| Astrometry | |
| Radial velocity (Rv) | 26.4105±0.0004 km/s |
| Proper motion (μ) | RA: +656.647 mas/yr Dec.: −1116.594 mas/yr |
| Parallax (π) | 105.4275 ± 0.0210 mas |
| Distance | 30.937 ± 0.006 ly (9.485 ± 0.002 pc) |
| Absolute magnitude (MV) | 10.10±0.06 |
| Details | |
| Mass | 0.485±0.012 M☉ |
| Radius | 0.474±0.015 R☉ |
| Luminosity | 0.03516±0.00032 L☉ |
| Temperature | 3,632+58 −56 K |
| Metallicity | −0.1±0.2 dex |
| Rotation | 40.00±0.11 days |
| Rotational velocity (v sin i) | ≤0.8 km/s |
| Age | 8.8+2.5 −2.8 Gyr |
| Other designations | |
| BD+18°683, HD 285968, HIP 21932, Ross 33, 2MASS J04425581+1857285 | |
| Database references | |
| SIMBAD | data |
Gliese 176 is a small star with an orbiting exoplanet in the constellation of Taurus. With an apparent visual magnitude of 9.95, it is too faint to be visible to the naked eye. It is located at a distance of 30.9 light years based on parallax measurements, and is drifting further away with a heliocentric radial velocity of 26.4 km/s.
This is an M-type main-sequence star, sometimes called a red dwarf, with a stellar classification of M2V. 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 its photosphere at an effective temperature of 3,632 K. It is estimated to be around nine billion years old, and is spinning slowly with a rotation period of 40 days. The star is orbited by a Super-Earth.
Planetary system
A planetary companion to Gliese 176 was announced in 2008. Radial velocity observations with the Hobby-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 the HARPS spectrograph could not confirm the 10.24-day variation. 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 with Keck-HIRES also failed to confirm the 10.24-day signal. 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 −0.70 M🜨 |
0.066±0.001 | 8.776+0.001 −0.002 |
0.148+0.249 −0.036 |
— | — |
See also
References
- ^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data 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. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ Koen, C.; Kilkenny, D.; van Wyk, F.; Marang, F. (2010). "UBV(RI)C JHK 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.
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- 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. S2CID 18759600. Archived from the original on 2019-12-07. Retrieved 2013-09-11.
- ^ Brown, 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.
- ^ Pineda, 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. S2CID 235435757. 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. S2CID 118332426.
- 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. S2CID 119340839.
