Eta Horologii

Eta Horologii
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Horologium
Right ascension 02h 37m 24.37297s[1]
Declination −52° 32′ 35.0855″[1]
Apparent magnitude (V) 5.31[2]
Characteristics
Spectral type A6 V + F0 V[3]
B−V color index +0.27[2]
Astrometry
Radial velocity (Rv)−3.0±7.4[4] km/s
Proper motion (μ) RA: +112.70[1] mas/yr
Dec.: +3.73[1] mas/yr
Parallax (π)21.95 ± 1.10 mas[1]
Distance149 ± 7 ly
(46 ± 2 pc)
Absolute magnitude (MV)2.13[5]
Orbit[6]
Period (P)3.01±0.18 yr
Semi-major axis (a)0.0231±0.0014″
Eccentricity (e)0.16±0.14
Details
η Hor A
Mass1.75[7] M☉
Luminosity12.6[8] L☉
Surface gravity (log g)4.21[9] cgs
Temperature7,552±257[9] K
Rotational velocity (v sin i)6.6±2.2[5] km/s
Age474[9] Myr
η Hor B
Mass1.65[7] M☉
Other designations
η Hor, CPD−53° 457, FK5 2182, HD 16555, HIP 12225, HR 778, SAO 232835[10]
Database references
SIMBADdata

Eta Horologii (η Horologii, η Hor) is a binary star system[3] in the southern constellation of Horologium. It is visible to the naked eye with a combined apparent visual magnitude of 5.31.[2] Based upon an annual parallax shift of 21.95 mas as seen from Earth,[1] it is located around 149 light years from the Sun.

The orbit for this pair is not yet well constrained. They appear to have an orbital period of three years and an eccentricity of roughly 0.16.[6] As of 2012, the pair have an angular separation of 78.7 mas, which corresponds to a projected separation of 3.6 AU.[3] The primary member, component A, is an A-type main sequence star with a stellar classification of A6 V. The secondary, component B, has an inferred class of F0 V, which would indicate it is an F-type main sequence star.[3]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference Johnson1966 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference Marion2014 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference AmmlerVonEiff2012 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Malkov2012 was invoked but never defined (see the help page).
  7. ^ a b Asensio-Torres, R.; Janson, M.; Bonavita, M.; Desidera, S.; Thalmann, C.; Kuzuhara, M.; Henning, Th.; Marzari, F.; Meyer, M. R.; Calissendorff, P.; Uyama, T. (2018). "SPOTS: The Search for Planets Orbiting Two Stars. III. Complete sample and statistical analysis". Astronomy & Astrophysics. 619: A43. arXiv:1807.08687. Bibcode:2018A&A...619A..43A. doi:10.1051/0004-6361/201833349. S2CID 118953455.
  8. ^ Cite error: The named reference Mcdonald2012 was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference David2015 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).