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] |
| Temperature | 3,095 ± 107[5] K |
| Metallicity | ![\begin{smallmatrix}\left[\frac{Fe}{H}\right]\ =\ %2B0.11 \pm 0.20\end{smallmatrix}](/2012-wikipedia_en_all_nopic_01_2012/I/16c87800d33c3c7616779e994b35c422.png) [5] |
| 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 star 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 moderate sized telescope. The star has a high proper motion across the sky, advancing 1.304 arc seconds per year. It has a net relative velocity of about 39 km/s.[2]
Contents |
Properties
GJ 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] This star displays no excess of infrared radiation that would indicate orbiting dust.[7] Thus far no companion has been discovered orbiting this star.[8][9]
X-ray source
Gliese 687 is a solitary red dwarf that emits X-rays.[10]
See also
References
- ^ a b c d e Perryman, M. A. C. et al (July 1997). "The HIPPARCOS Catalogue". Astronomy & Astrophysics 323: L49–L52. Bibcode 1997A&A...323L..49P.
- ^ a b c "LHS 450 -- High proper-motion Star". SIMBAD. Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=LHS+450. 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.
- ^ a b c d e f 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. Bibcode 2009ApJ...704..975J. doi:10.1088/0004-637X/704/2/975.
- ^ Gautier, Thomas N., III; et al. (September 2007). "Far-Infrared Properties of M Dwarfs". The Astrophysical Journal 667 (1): 527–536. Bibcode 2007ApJ...667..527G. doi:10.1086/520667.
- ^ Hinz, Joannah L.; McCarthy, Donald W., Jr.; Simons, Doug A.; Henry, Todd J.; Kirkpatrick, J. Davy; McGuire, Patrick C. (April 2002). "A Near-Infrared, Wide-Field, Proper-Motion Search for Brown Dwarfs". The Astronomical Journal 123 (4): 2027–2032. arXiv:astro-ph/0201140. Bibcode 2002AJ....123.2027H. doi:10.1086/339555.
- ^ Endl, Michael; Cochran, William D.; Tull, Robert G.; MacQueen, Phillip J. (December 2003). "A Dedicated M Dwarf Planet Search Using The Hobby-Eberly Telescope". The Astronomical Journal 126 (6): 3099–3107. arXiv:astro-ph/0308477. Bibcode 2003AJ....126.3099E. doi:10.1086/379137.
- ^ Schmitt JHMM, Fleming TA, Giampapa MS (September 1995). "The X-ray view of the low-mass stars in the solar neighborhood". Ap J. 450 (9): 392–400. Bibcode 1995ApJ...450..392S. doi:10.1086/176149.
External links
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