Astronomy:Gliese 687

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Short description: Star in the constellation Draco

Coordinates: Sky map 17h 36m 25.8999s, +68° 20′ 20.909″

Gliese 687
Gliese 687.jpg
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
Distance14.839 ± 0.001 ly
(4.5498 ± 0.0004 pc)
Absolute magnitude (MV)10.87
Details
Mass0.401 ± 0.040[6] M
Radius0.492 ± 0.038[6] R
Luminosity0.0213 ± 0.00023[7][8] L
Surface gravity (log g)4.66[6] cgs
Temperature3,095 ± 107[6] K
Metallicity [Fe/H]+0.11 ± 0.20[6] dex
Rotational velocity (v sin i)<2.8[9] km/s
Other designations
BD +68°946, GCTP 4029.00, GJ 687, HIP 86162, LHS 450, LTT 15232, SAO 17568.[2]
Database references
SIMBADdata
Gliese 687 is located in the constellation Draco.
Gliese 687 is located in the constellation Draco.
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]

The Gliese 687 planetary system[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

References

  1. 1.0 1.1 1.2 1.3 Perryman, M. A. C. (July 1997). "The HIPPARCOS Catalogue". Astronomy & Astrophysics 323: L49–L52. Bibcode1997A&A...323L..49P. 
  2. 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. 
  3. 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. Bibcode2006ApJ...649..436E. 
  4. Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". University of Toronto: Academic Press. Bibcode1967IAUS...30...57E. 
  5. 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. Bibcode2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  6. 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. Bibcode2006ApJ...644..475B. 
  7. 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. Bibcode2012ApJ...757..112B. 
  8. 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. Bibcode2014ApJ...789..114B. 
  9. 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. Bibcode2009ApJ...704..975J. 
  10. 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. Bibcode1890MNRAS..50..519L. 
  11. Gautier, Thomas N., III (September 2007). "Far-Infrared Properties of M Dwarfs". The Astrophysical Journal 667 (1): 527–536. doi:10.1086/520667. Bibcode2007ApJ...667..527G. 
  12. 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. 
  13. 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. Bibcode1995ApJ...450..392S. 

Notes

External links