Astronomy:Gliese 687
Coordinates: 
17h 36m 25.8999s, +68° 20′ 20.909″
 Gliese 687 is the small orange star located in the center of the above image. | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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) | 219.7898 ± 0.0210[5] mas |
| Distance | 14.839 ± 0.001 ly (4.5498 ± 0.0004 pc) |
| Absolute magnitude (MV) | 10.87 |
| Details | |
| Mass | 0.401 ± 0.040[6] M☉ |
| Radius | 0.492 ± 0.038[6] R☉ |
| Luminosity | 0.0213 ± 0.00023[7][8] L☉ |
| Surface gravity (log g) | 4.66[6] cgs |
| Temperature | 3,095 ± 107[6] K |
| Metallicity [Fe/H] | +0.11 ± 0.20[6] dex |
| Rotational velocity (v sin i) | <2.8[9] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
  Gliese 687 Location of Gliese 687 in the constellation Draco | |
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.[8] Old books and articles refer to it as Argelander Oeltzen 17415.[10]
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.[6] It seems to rotate every 60 days and exhibit some chromospheric activity.
It displays no excess of infrared radiation that would indicate orbiting dust.[11]
Planetary system
In 2014, it was discovered to have a planet, Gliese 687 b, with a minimum mass of 18.394 Earth masses (which makes it comparable to Neptune), an orbital period of 38.14 days, a low orbital eccentricity and inside the habitable zone.[8] Another Neptune mass planet candidate was discovered in 2020, in a further out and much colder orbit.[12]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥17.2 M⊕ | 0.163 | 38.142 | 0.17 | — | — |
| c | ≥16 M⊕ | 1.165 | 727.562 | 0.40 | — | — |
X-ray source
Gliese 687 is a solitary red dwarf that emits X-rays.[13]
See also
- List of nearest stars and brown dwarfs
- List of exoplanets discovered in 2014 - Gliese 687 b
- List of exoplanets discovered in 2020 - Gliese 687 c
References
- ↑ 1.0 1.1 1.2 1.3 Perryman, M. A. C. (July 1997). "The HIPPARCOS Catalogue". Astronomy & Astrophysics 323: L49–L52. Bibcode: 1997A&A...323L..49P.
- ↑ 2.0 2.1 2.2 "LHS 450 -- High proper-motion Star". SIMBAD. Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=LHS+450.
- ↑ 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. doi:10.1086/506465. Bibcode: 2006ApJ...649..436E.
- ↑ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". University of Toronto: Academic Press. Bibcode: 1967IAUS...30...57E.
- ↑ Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G. Gaia EDR3 record for this source at VizieR.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Berger, D. H. (2006). "First Results from the CHARA Array. IV. The Interferometric Radii of Low-Mass Stars". The Astrophysical Journal 644 (1): 475–483. doi:10.1086/503318. Bibcode: 2006ApJ...644..475B.
- ↑ Boyajian, Tabetha S. et al. (2012). "Stellar Diameters and Temperatures. Ii. Main-Sequence K- and M-Stars". The Astrophysical Journal 757 (2): 112. doi:10.1088/0004-637X/757/2/112. ISSN 0004-637X. Bibcode: 2012ApJ...757..112B.
- ↑ 8.0 8.1 8.2 Burt, Jennifer; Vogt, Steven S.; Butler, R. Paul; Hanson, Russell; Meschiari, Stefano; Rivera, Eugenio J.; Henry, Gregory W.; Laughlin, Gregory (2014). "The Lick–Carnegie exoplanet survey: Gliese 687 b: A Neptune-mass planet orbiting a nearby red dwarf". The Astrophysical Journal 789 (2): 114. doi:10.1088/0004-637X/789/2/114. Bibcode: 2014ApJ...789..114B.
- ↑ 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. doi:10.1088/0004-637X/704/2/975. Bibcode: 2009ApJ...704..975J.
- ↑ Lynn, W. T. (June 1890). "On the proper motions of three stars". Monthly Notices of the Royal Astronomical Society 50 (8): 519–520. doi:10.1093/mnras/50.8.519. Bibcode: 1890MNRAS..50..519L.
- ↑ Gautier, Thomas N., III (September 2007). "Far-Infrared Properties of M Dwarfs". The Astrophysical Journal 667 (1): 527–536. doi:10.1086/520667. Bibcode: 2007ApJ...667..527G.
- ↑ 12.0 12.1 Feng, Fabo; Shectman, Stephen A.; Clement, Matthew S.; Vogt, Steven S.; Tuomi, Mikko; Teske, Johanna K.; Burt, Jennifer; Crane, Jeffrey D. et al. (2020). Search for Nearby Earth Analogs. III. Detection of ten new planets, three planet candidates, and confirmation of three planets around eleven nearby M dwarfs. doi:10.3847/1538-4365/abb139.
- ↑ 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. doi:10.1086/176149. Bibcode: 1995ApJ...450..392S.
Notes
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