Eta Geminorum

"Propus" redirects here. For the AMD processor core, see Athlon II.
Eta Geminorum
Location of η Geminorum (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Gemini
A
Right ascension 06h 14m 52.657s[1]
Declination +22° 30′ 24.48″[1]
Apparent magnitude (V) 3.1 – 3.7[2]
B
Right ascension 06h 14m 52.569s[1]
Declination +22° 30′ 24.31″[1]
Apparent magnitude (V) 6.04[1]
Characteristics
Spectral type M2 IIIa[3] (Aa)
A[4] (Ab)
G0 III[5] (B)
Variable type SRa + EA[6]
Astrometry
Proper motion (μ) RA: −59.530±1.450[7] mas/yr
Dec.: −7.766±1.385[7] mas/yr
Parallax (π)8.48 ± 1.23 mas[8]
Distanceapprox. 380 ly
(approx. 120 pc)[8]
Absolute magnitude (MV)−1.87[9]
Orbit[10][4]
PrimaryAa
CompanionAb
Period (P)8.161 yr
Semi-major axis (a)0.077″
Eccentricity (e)0.5507
Periastron epoch (T)JD 2444489.1
Argument of periastron (ω)
(primary)		174.20°
Semi-amplitude (K1)
(primary)		9.438 km/s
Orbit[11]
PrimaryA
CompanionB
Period (P)473.7 yr
Semi-major axis (a)1.08″
Eccentricity (e)0.54
Details
Aa
Mass5.1[4] M☉
Radius275+49
−66[12] R☉
Luminosity10,276±4,445[12] L☉
Temperature3,502[12] K
Metallicity [Fe/H]+0.04[13] dex
Age0.81[5] Gyr
Ab
Mass2[4] M☉
Radius1.65[4] R☉
Luminosity16[4] L☉
Temperature9,000[4] K
Other designations
Propus,[14] Praepes, Tejat Prior, Pish Pai,[15] η Geminorum, 7 Geminorum, HD 42995, HR 2216, BD+22°1241, HIP 29655, SAO 78135, CCDM J06149+2230, ADS 4841
Database references
SIMBADdata

Eta Geminorum (η Geminorum, abbreviated Eta Gem, η Gem), formally named Propus /ˈproʊpəs/,[16][14] is a triple star system in the constellation of Gemini. It is a naked-eye variable star around 380 light years from the Sun.

  1. ^ a b c d e Cite error: The named reference tycho2 was invoked but never defined (see the help page).
  2. ^ "VSX : Detail for eta Gem", AAVSO, retrieved 2024-06-25
  3. ^ Cite error: The named reference perkins was invoked but never defined (see the help page).
  4. ^ a b c d e f g Cite error: The named reference Torres was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference hunsch was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference gcvs was invoked but never defined (see the help page).
  7. ^ a b Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  8. ^ a b Cite error: The named reference validation was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Ryon2009 was invoked but never defined (see the help page).
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  11. ^ Cite error: The named reference msc was invoked but never defined (see the help page).
  12. ^ a b c Cite error: The named reference baines2021 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference huang was invoked but never defined (see the help page).
  14. ^ a b Cite error: The named reference IAU-CSN was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference allen1963 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Kunitzsch was invoked but never defined (see the help page).