HD 2638

HD 2638
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]
Distance179.5 ± 0.5 ly
(55.0 ± 0.2 pc)
Absolute magnitude (MV)5.96[2]
Orbit[5]
PrimaryHD 2638 A
CompanionHD 2638 BC
Period (P)130 yr
Semi-major axis (a)25.5±1.9 AU
Details[6]
A
Mass0.89±0.02 M☉
Radius0.8±0.01 R☉
Luminosity0.407±0.004 L☉
Surface gravity (log g)4.58±0.02 cgs
Temperature5,160±24 K
Metallicity [Fe/H]0.12±0.05[7] dex
Age1.9±2.6 Gyr
BC
Mass0.425±0.067[4] M☉
Radius0.46±0.02[4] R☉
Luminosity0.030±0.005[4] L☉
Surface gravity (log g)4.80±0.02[4] cgs
Temperature3571±48[4] K
Other designations
BD–06°82, Gaia DR2 2526925389919277056, HD 2638, HIP 2350, WDS J00293-0555BC, NLTT 1594, 2MASS J00295988-0545502[8]
Database references
SIMBADdata
Exoplanet Archivedata

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]

  1. ^ a b c d e f g Cite error: The named reference Gaia DR2 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Houk1999 was invoked but never defined (see the help page).
  4. ^ a b c d e f g h i Cite error: The named reference Wittrock2016 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Roberts2015 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Bonfanti2015 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference aanda was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference Riddle2015 was invoked but never defined (see the help page).