Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Cetus |
Right ascension | 00h 29m 59.8721s[1] |
Declination | –05° 45′ 50.3987″[1] |
Apparent magnitude (V) | 9.44[2] |
Characteristics | |
Spectral type | K1V[3] (G8V + M1V)[4] |
B−V color index | +0.886±0.003[2] |
Astrometry | |
Radial velocity (Rv) | +9.576±0.0010[1] km/s |
Proper motion (μ) | RA: −107.019±0.094[1] mas/yr Dec.: −223.039±0.062[1] mas/yr |
Parallax (π) | 18.1656 ± 0.0510 mas[1] |
Distance | 179.5 ± 0.5 ly (55.0 ± 0.2 pc) |
Absolute magnitude (MV) | 5.96[2] |
Orbit[5] | |
Primary | HD 2638 A |
Companion | HD 2638 BC |
Period (P) | 130 yr |
Semi-major axis (a) | 25.5±1.9 AU |
Details[6] | |
A | |
Mass | 0.89±0.02 M☉ |
Radius | 0.8±0.01 R☉ |
Luminosity | 0.407±0.004 L☉ |
Surface gravity (log g) | 4.58±0.02 cgs |
Temperature | 5,160±24 K |
Metallicity [Fe/H] | 0.12±0.05[7] dex |
Age | 1.9±2.6 Gyr |
BC | |
Mass | 0.425±0.067[4] M☉ |
Radius | 0.46±0.02[4] R☉ |
Luminosity | 0.030±0.005[4] L☉ |
Surface gravity (log g) | 4.80±0.02[4] cgs |
Temperature | 3571±48[4] K |
Other designations | |
Database references | |
SIMBAD | data |
Exoplanet Archive | data |
HD 2638 is a ternary star system[9] system in the equatorial constellation of Cetus. The pair have an angular separation of 0.53″ along a position angle of 166.7°, as of 2015.[9] This is system too faint to be visible to the naked eye, having a combined apparent visual magnitude of 9.44;[2] a small telescope is required. The distance to this system is 179.5 light years based on parallax, and it is drifting further away with a radial velocity of +9.6 km/s.[1] The magnitude 7.76 star HD 2567 forms a common proper motion companion to this pair[9] at projected separation 839″.[5]
The HD 2638 members A and BC have a projected separation of about 25.5±1.9 AU and thus an orbital period of around 130 years.[4] They have a combined stellar classification of K1V.[3] The primary component is a G-type main-sequence star with a class of G8V.[4] It is smaller and less massive than the Sun, and has a lower luminosity.[6] The secondary is a binary consisting of who red dwarf stars on close orbit with combined mass less than half the mass of the primary, and a composite spectral class of M1V.[4]
Gaia DR2
was invoked but never defined (see the help page).Anderson2012
was invoked but never defined (see the help page).Houk1999
was invoked but never defined (see the help page).Wittrock2016
was invoked but never defined (see the help page).Roberts2015
was invoked but never defined (see the help page).Bonfanti2015
was invoked but never defined (see the help page).aanda
was invoked but never defined (see the help page).SIMBAD
was invoked but never defined (see the help page).Riddle2015
was invoked but never defined (see the help page).