Gliese 687
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Draco |
| Right ascension | 17h 36m 25.8999s[1] |
| Declination | +68° 20′ 20.909″[1] |
| Apparent magnitude (V) | 9.15[2] |
| Characteristics | |
| Spectral type | M3.5 V[3] |
| U−B color index | 1.06 |
| B−V color index | 1.49 |
| Astrometry | |
| Radial velocity (Rv) | –23.2[4] km/s |
| Proper motion (μ) | RA: –320.47[1] mas/yr Dec.: –1269.55[1] mas/yr |
| Parallax (π) | 220.86 ± 0.92[1] mas |
| Distance | 14.77 ± 0.06 ly (4.53 ± 0.02 pc) |
| Absolute magnitude (MV) | 10.87 |
| Details | |
| Mass | 0.401 ± 0.040[5] M☉ |
| Radius | 0.492 ± 0.038[5] R☉ |
| Surface gravity (log g) | 4.66[5] cgs |
| Temperature | 3,095 ± 107[5] K |
| Metallicity [Fe/H] | +0.11 ± 0.20[5] dex |
| Rotational velocity (v sin i) | <2.8[6] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Gliese 687, or GJ 687 (Gliese–Jahreiß 687) is a red dwarf in the constellation Draco. This is one of the closest stars to the Sun and lies at an approximate distance of less than 15 light years. Even though it is close by, it has a magnitude of about 9, so it can only be seen through a moderately sized telescope. Gliese 687 has a high proper motion, advancing 1.304 arcseconds per year across the sky. It has a net relative velocity of about 39 km/s.[2] It is known to have a Neptune-mass planet.[7]
Properties
Gliese 687 has about 40% of the Sun's mass and nearly 50% of the Sun's radius. Compared to the Sun, it has a slightly higher proportion of elements with higher atomic numbers than helium.[5] It appears to have a rotation of 60 days and to be somewhat chromospherically active.
It displays no excess of infrared radiation that would indicate orbiting dust.[8]
Planetary System
It is known to have a planet, Gliese 687 b, with a mass of 18.394 Earth masses (which makes it comparable to Neptune), an orbital period of 38.14 days, and a low orbital eccentricity.[7]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 18.394 M⊕ | 0.16353 | 38.14 | 0.04 | — | — |
X-ray source
See also
References
- 1 2 3 4 5 Perryman, M. A. C.; et al. (July 1997). "The HIPPARCOS Catalogue". Astronomy & Astrophysics. 323: L49–L52. Bibcode:1997A&A...323L..49P.
- 1 2 3 "LHS 450 -- High proper-motion Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-11-12.
- ↑ Endl, Michael; Cochran, William D.; Kürster, Martin; Paulson, Diane B.; Wittenmyer, Robert A.; MacQueen, Phillip J.; Tull, Robert G. (September 2006). "Exploring the Frequency of Close-in Jovian Planets around M Dwarfs". The Astrophysical Journal. 649 (1): 436–443. arXiv:astro-ph/0606121. Bibcode:2006ApJ...649..436E. doi:10.1086/506465.
- ↑ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Alan Henry Batten and John Frederick Heard. Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: Academic Press. Bibcode:1967IAUS...30...57E.
- 1 2 3 4 5 6 Berger, D. H.; et al. (2006). "First Results from the CHARA Array. IV. The Interferometric Radii of Low-Mass Stars". The Astrophysical Journal. 644 (1): 475–483. arXiv:astro-ph/0602105. Bibcode:2006ApJ...644..475B. doi:10.1086/503318.
- ↑ Jenkins, J. S.; Ramsey, L. W.; Jones, H. R. A.; Pavlenko, Y.; Gallardo, J.; Barnes, J. R.; Pinfield, D. J. (October 2009). "Rotational Velocities for M Dwarfs". The Astrophysical Journal. 704 (2): 975–988. arXiv:0908.4092. Bibcode:2009ApJ...704..975J. doi:10.1088/0004-637X/704/2/975.
- 1 2 The Lick–Carnegie exoplanet survey: Gliese 687 b: A Neptune-mass planet orbiting a nearby red dwarf
- ↑ Gautier, Thomas N., III; et al. (September 2007). "Far-Infrared Properties of M Dwarfs". The Astrophysical Journal. 667 (1): 527–536. arXiv:0707.0464. Bibcode:2007ApJ...667..527G. doi:10.1086/520667.
- ↑ Schmitt JHMM; Fleming TA; Giampapa MS (September 1995). "The X-ray view of the low-mass stars in the solar neighborhood". Astrophys. J. 450 (9): 392–400. Bibcode:1995ApJ...450..392S. doi:10.1086/176149.