Gliese 687

Coordinates: Sky map 17h 36m 25.8999s, +68° 20′ 20.909″
Source: Wikipedia, the free encyclopedia.
Gliese 687

Gliese 687 is the small orange star located in the center of the above image.
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
Distance
14.839 ± 0.001 ly
(4.5498 ± 0.0004 pc)
Absolute magnitude (MV)10.87
Details
Rotational velocity (v sin i)
<2.8[9] km/s
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 (

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. ^
    Bibcode:1997A&A...323L..49P
    .
  2. ^
    Centre de Données astronomiques de Strasbourg
    . Retrieved 2009-11-12.
  3. S2CID 14461746
    .
  4. Bibcode:1967IAUS...30...57E
    .
  5. doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR
    .
  6. ^
    S2CID 14966363
    .
  7. ISSN 0004-637X
    .
  8. ^
    S2CID 17668957
    .
  9. S2CID 119203469
    .
  10. doi:10.1093/mnras/50.8.519
    .
  11. S2CID 15732144.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  12. ^
    S2CID 221150644. {{cite journal}}: Cite journal requires |journal= (help
    )
  13. doi:10.1086/176149
    .

Notes

External links
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