Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Draco |
Right ascension | 17h 36m 25.89931s [1] |
Declination | +68° 20′ 20.9096″ [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) | −28.90±0.13 [1] km/s |
Proper motion (μ) |
RA: –320.675
mas/
yr
[1] Dec.: –1269.893 mas/ yr [1] |
Parallax (π) | 219.7898 ± 0.0210 mas [1] |
Distance | 14.839 ± 0.001
ly (4.5498 ± 0.0004 pc) |
Absolute magnitude (MV) | 10.87 |
Details | |
Mass | 0.40±0.02 [4] M☉ |
Radius | 0.4183±0.0070 [5] R☉ |
Luminosity | 0.02128±0.00023 [5] L☉ |
Surface gravity (log g) | 4.66 [6] cgs |
Temperature | 3,413±28 [5] K |
Metallicity [Fe/H] | +0.11 ± 0.20 [6] dex |
Rotation | 61.8±1.0 d [7] |
Rotational velocity (v sin i) | <2.8 [8] km/s |
Other designations | |
Database references | |
SIMBAD | data |
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 a distance of 14.84 light-years (4.55 parsecs). Even though it is close by, it has an apparent 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. [7] Old books and articles refer to it as Argelander Oeltzen 17415. [9]
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. [10]
Gliese 687 is a solitary red dwarf that emits X-rays. [11]
In 2014, Gliese 687 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. [7] Another Neptune-mass planet candidate was discovered in 2020, in a further out and much colder orbit. [4]
Companion (in order from star) |
Mass |
Semimajor axis ( AU) |
Orbital period ( days) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | ≥17.2±1.0 M🜨 | 0.163±0.003 | 38.142±0.007 | 0.17±0.05 | — | — |
c | ≥16.0±4.1 M🜨 | 1.165±0.023 | 727.562±12.198 | 0.40±0.22 | — | — |
{{
cite journal}}
: CS1 maint: multiple names: authors list (
link)
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Draco |
Right ascension | 17h 36m 25.89931s [1] |
Declination | +68° 20′ 20.9096″ [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) | −28.90±0.13 [1] km/s |
Proper motion (μ) |
RA: –320.675
mas/
yr
[1] Dec.: –1269.893 mas/ yr [1] |
Parallax (π) | 219.7898 ± 0.0210 mas [1] |
Distance | 14.839 ± 0.001
ly (4.5498 ± 0.0004 pc) |
Absolute magnitude (MV) | 10.87 |
Details | |
Mass | 0.40±0.02 [4] M☉ |
Radius | 0.4183±0.0070 [5] R☉ |
Luminosity | 0.02128±0.00023 [5] L☉ |
Surface gravity (log g) | 4.66 [6] cgs |
Temperature | 3,413±28 [5] K |
Metallicity [Fe/H] | +0.11 ± 0.20 [6] dex |
Rotation | 61.8±1.0 d [7] |
Rotational velocity (v sin i) | <2.8 [8] km/s |
Other designations | |
Database references | |
SIMBAD | data |
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 a distance of 14.84 light-years (4.55 parsecs). Even though it is close by, it has an apparent 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. [7] Old books and articles refer to it as Argelander Oeltzen 17415. [9]
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. [10]
Gliese 687 is a solitary red dwarf that emits X-rays. [11]
In 2014, Gliese 687 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. [7] Another Neptune-mass planet candidate was discovered in 2020, in a further out and much colder orbit. [4]
Companion (in order from star) |
Mass |
Semimajor axis ( AU) |
Orbital period ( days) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | ≥17.2±1.0 M🜨 | 0.163±0.003 | 38.142±0.007 | 0.17±0.05 | — | — |
c | ≥16.0±4.1 M🜨 | 1.165±0.023 | 727.562±12.198 | 0.40±0.22 | — | — |
{{
cite journal}}
: CS1 maint: multiple names: authors list (
link)