Eta Geminorum
Star in the constellation Gemini / From Wikipedia, the free encyclopedia
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"Propus" redirects here. For the AMD processor core, see Athlon II.
Eta Geminorum (η Geminorum, abbreviated Eta Gem, η Gem), formally named Propus /ˈproʊpəs/,[15][13] is a triple star system in the constellation of Gemini. It is a naked-eye variable star around 380 light years from the Sun.
Quick Facts Observation data Epoch J2000.0 Equinox J2000.0, Apparent magnitude (V) ...
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) | 3.15 - 3.90[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[2] |
Astrometry | |
Proper motion (μ) | RA: −59.530±1.450[6] mas/yr Dec.: −7.766±1.385[6] mas/yr |
Parallax (π) | 8.48 ± 1.23 mas[7] |
Distance | approx. 380 ly (approx. 120 pc)[7] |
Absolute magnitude (MV) | −1.87[8] |
Orbit[9][10][4] | |
Primary | Aa |
Companion | Ab |
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 | |
Primary | A |
Companion | B |
Period (P) | 473.7 yr |
Semi-major axis (a) | 1.08″ |
Eccentricity (e) | 0.54 |
Details | |
Aa | |
Mass | 5.1[4] M☉ |
Radius | 275+49 −66[11] R☉ |
Luminosity | 10,276[11] L☉ |
Temperature | 3,502[11] K |
Metallicity [Fe/H] | +0.04[12] dex |
Age | 0.81[5] Gyr |
Ab | |
Mass | 2[4] M☉ |
Radius | 1.65[4] R☉ |
Luminosity | 16[4] L☉ |
Temperature | 9,000[4] K |
Other designations | |
Database references | |
SIMBAD | data |
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