Jean 687

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Stern
Gliese 687
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Dragon
Right ascension 17 h 36 m 25.9 s
declination + 68 ° 20 ′ 20.9 ″
Apparent brightness 9.15 likes
Typing
Known exoplanets 1
B − V color index 1.50 
U − B color index 1.08 
R − I index 0.8 
Spectral class M3.5V
Astrometry
Radial velocity -28.58 ± 0.09 km / s
parallax 219.78 ± 0.03  mas
distance 14.83 ± 0.01  ly
4.55 ± 0.01  pc
Visual absolute brightness M vis 10.87 likes
Proper movement 
Rec. Share: -320.64 ± 0.07  mas / a
Dec. portion: -1269.53 ± 0.07  mas / a
Physical Properties
Dimensions 0.410 ± 0.008  M ☉
radius 0.407 ± 0.012  R ☉
Effective temperature 3,095 ± 107  K
Metallicity [Fe / H] +0.11 ± 0.20
Other names
and catalog entries
Bonn survey BD + 68 ° 946
Gliese catalog FY 687 [1]
Hipparcos catalog HIP 86162 [2]
SAO catalog SAO 17568 [3]
Tycho catalog TYC 4428-1943-1 [4]Template: Infobox star / maintenance / specification of the TYC catalog
2MASS catalog 2MASS J17362594 + 6820220 [5]
Other names GCTP 4029.00, LHS 450, LTT 15232

Gliese 687 (also GJ 687 ) is a red dwarf in the constellation Dragon . It is one of the stars closest to the Sun and is around 15 light years away. Despite its relative proximity, it has an apparent magnitude of only about 9 mag and can only be observed through a medium-sized telescope . Gliese 687 has a high self-motion and covers 1.304 arc seconds in the sky per year . The net relative speed is 39 km / s. An exoplanet is known to orbit the star and has roughly the mass of Neptune .

distance

Determining the distance for Gliese 687

source Parallax (mas) Distance (pc) Distance (Lj) Distance ( Pm )
Woolley et al. (1970) 214 ± 4 4.67 ± 0.09 15.24   +0.29−0.28 144   +2.7−2.6
Gliese & Jahreiß (1991) 212.7 ± 2.0 4.7 ± 0.04 15.33   +0.15−0.14 145.1 ± 1.4
van Altena et al. (1995) 219.1 ± 1.8 4.56 ± 0.04 14.89 ± 0.12 140.8   +1.2−1.1
Perryman et al. (1997) (Hipparcos) 220.85 ± 0.92 4.528 ± 0.019 14.77 ± 0.06 139.7 ± 0.6
Perryman et al. (1997) (Tycho) 210.60 ± 14.60 4.75   + 0.35−0.31 15.5   +1.2−1.0 146.5   +10.9−9.5
van Leeuwen (2007) 220.84 ± 0.94 4.528 ± 0.019 14.77 ± 0.06 139.7 ± 0.6
RECONS TOP100 (2012) 220.47 ± 0.83 4.536 ± 0.017 14.79 ± 0.06 140 ± 0.5
Gaia DR2 (2018) 219.78 ± 0.03 4.550 ± 0.001 14.83 ± 0.01 140.32 ± 0.02

Non-trigonometric distance determinations are marked in italics . The most precise determination is marked in bold .

properties

Gliese 687 is a single star and has around 40% of the solar mass and almost 50% of the solar radius . Compared to the sun, it has a higher proportion of elements with atomic numbers higher than helium . Its rotation is apparently 60 days and it is chromospheric active. It also emits X-rays . Gliese 687 shows no infrared excess , which would suggest circulating dust.

Planetary system

In 2014, a planet orbiting the star was discovered, named Gliese 687 b . It has a mass of 19 Earth masses and is comparable to the planet Neptune in the solar system . The planet orbits its central star once every 38.14 days with a slight orbital eccentricity .

Individual evidence

  1. ↑ a b c d e f g h BD + 68 946. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed on November 10, 2018 .
  2. ↑ Endl, Michael; Cochran, William D .; Kürster, Martin; Paulson, Diane B .; Wittenmyer, Robert A .; MacQueen, Phillip J .; Tull, Robert G .: Exploring The Frequency Of Close-In Jovian Planets Around M Dwarfs . arxiv : astro-ph / 0606121 .
  3. ↑ a b P. E. Kervella, F. Arenou, F. Mignard, F. Thévenin: Stellar and substellar companions of nearby stars from Gaia DR2. Binarity from proper motion anomaly . In: Astronomy & Astrophysics . 623, p. A72. arxiv : 1811.08902 . bibcode : 2019A & A ... 623A..72K . doi : 10.1051 / 0004-6361 / 201834371 .
  4. ↑ a b c Berger, DH et al .: First Results from the CHARA Array. IV. The Interferometric Radii of Low-Mass Stars . arxiv : astro-ph / 0602105 .
  5. ↑ a b c Burt, Jennifer; Vogt, Steven S .; Butler, R. Paul; Hanson, Russell; Meschiari, Stefano; Rivera, Eugenio J .; Henry, Gregory W .; Laughlin, Gregory: The Lick-Carnegie Exoplanet Survey: Gliese 687b: A Neptune-Mass Planet Orbiting a Nearby Red Dwarf . arxiv : 1405.2929 .
  6. ^ Woolley R .; Epps EA; Penston MJ; Pocock SB: Woolley 687. Retrieved April 26, 2015 .
  7. ↑ Gliese, W. and Jahreiß, H .: Gl 687. Accessed April 26, 2015 .
  8. ^ Van Altena WF, Lee JT, Hoffleit ED: GCTP 4029. Retrieved April 26, 2015 .
  9. ^ Perryman et al .: HIP 86162. Retrieved April 26, 2015 .
  10. ^ Perryman et al .: HIP 86162. Retrieved April 26, 2015 .
  11. ^ Van Leeuwen F .: HIP 86162. Accessed April 26, 2015 .
  12. ↑ RECONS: THE ONE HUNDRED NEAREST STAR SYSTEMS. Retrieved April 26, 2015 .
  13. ↑ Schmitt, Juergen HMM; Fleming, Thomas A .; Giampapa, Mark S .: The X-Ray View of the Low-Mass Stars in the Solar Neighborhood . bibcode : 1995ApJ ... 450..392S .
  14. ^ Gautier, Thomas N., III et al .: Far Infrared Properties of M Dwarfs . arxiv : 0707.0464 .