42 Capricorni

42 Capricorni

A visual band light curve of BY Capricorni, adapted from Henry et al. (1995)[1]
Observation data
Epoch J2000      Equinox
Constellation Capricornus
Right ascension 21h 41m 32.85882s[2]
Declination −14° 02′ 51.3964″[2]
Apparent magnitude (V) 5.18[3]
Characteristics
Spectral type G1 IV[4] (G1 IV + G2 V)[5]
U−B color index +0.20[3]
B−V color index +0.65[3]
Variable type RS CVn[5]
Astrometry
Radial velocity (Rv)−1.20±0.05[6] km/s
Proper motion (μ) RA: −123.05[2] mas/yr
Dec.: −308.50[2] mas/yr
Parallax (π)30.09 ± 0.32 mas[2]
Distance108 ± 1 ly
(33.2 ± 0.4 pc)
Absolute magnitude (MV)+2.73[7] (2.79 + 4.73)[5]
Orbit[8]
Period (P)13.174 d
Eccentricity (e)0.1763±0.0025
Periastron epoch (T)2447863.626 ± 0.027 JD
Argument of periastron (ω)
(secondary)		166.45±0.83°
Semi-amplitude (K1)
(primary)		25.57±0.06 km/s
Semi-amplitude (K2)
(secondary)		35.16±0.25 km/s
Details
42 Cap A
Mass1.09[9] M☉
Radius2.6[5] R☉
Surface gravity (log g)3.76[4] cgs
Temperature5,634[4] K
Metallicity [Fe/H]−0.10[4] dex
Rotational velocity (v sin i)5.2[5] km/s
Age6.7[9] Gyr
42 Cap B
Rotational velocity (v sin i)4.4[5] km/s
Other designations
BY Cap, 42 Cap, BD−14° 6102, FK5 1150, HD 206301, HIP 107095, HR 8283, SAO 164580[10]
Database references
SIMBADdata

42 Capricorni is a binary star[11] system in the zodiac constellation of Capricornus. It has a combined apparent visual magnitude of 5.18,[3] so it is faintly visible to the naked eye. Its annual parallax shift of 30.09 mas yields a distance estimate of about 108 light years; the system is moving closer to the Sun with a radial velocity of −1.2 km/s.[6] 42 Capricorni is 0.2 degree south of the ecliptic and so is subject to lunar occultations.[12]

This is a double-lined close spectroscopic binary with an orbital period of 13.174 days and an eccentricity of 0.18.[8] The binary nature of this system was discovered in 1918 by the English astronomer Joseph Lunt. It has a combined spectrum that matches a stellar classification of G1 IV,[4] with the individual components having estimated classes of G1 V and G2 V. This is an RS Canum Venaticorum variable, indicating the presence of an active chromosphere with star spots.[5] The system is a source of X-ray emission.[13]

  1. ^ Cite error: The named reference Henry was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference ducati2002 was invoked but never defined (see the help page).
  4. ^ a b c d e Cite error: The named reference Gray2006 was invoked but never defined (see the help page).
  5. ^ a b c d e f g Cite error: The named reference Fekel1997 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference karatas2004 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference AAA542_A116 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Pourbaix2009 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Chen2000 was invoked but never defined (see the help page).
  10. ^ "42 Cap". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-01-27.
  11. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Herr1969 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Haakonsen2009 was invoked but never defined (see the help page).