Phi Geminorum, Latinized from φ Geminorum, is a binary star[6] in the constellation Gemini, to the southeast of Pollux. It is visible to the naked eye with an apparent visual magnitude of 4.95.[2] Based upon an annual parallax shift of 14.66 mas,[1] this system is located around 220 light years from the Sun.
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Gemini |
Right ascension | 07h 53m 29.81390s[1] |
Declination | +26° 45′ 56.8252″[1] |
Apparent magnitude (V) | 4.95[2] |
Characteristics | |
Spectral type | A3 V[3] |
U−B color index | +0.08[2] |
B−V color index | +0.10[2] |
Astrometry | |
Radial velocity (Rv) | +8.0[4] km/s |
Proper motion (μ) | RA: −34.69[1] mas/yr Dec.: -30.10[1] mas/yr |
Parallax (π) | 14.66 ± 0.73 mas[1] |
Distance | 220 ± 10 ly (68 ± 3 pc) |
Absolute magnitude (MV) | +0.81[5] |
Orbit | |
Period (P) | 581.751 d[6] |
Eccentricity (e) | 0.0[6] |
Details | |
Mass | 1.9[7] M☉ |
Luminosity | 36.5[8] L☉ |
Surface gravity (log g) | 4.0[7] cgs |
Temperature | 8,551±291[7] K |
Rotational velocity (v sin i) | 165[9] km/s |
Age | 637[7] Myr |
Other designations | |
Database references | |
SIMBAD | data |
The two components of this system have a circular orbit with a period of 582 days.[6] The primary component is an A-type main sequence star with a stellar classification of A3 V.[3] It is around 600 million years old and spinning relatively rapidly with a projected rotational velocity of 165[9] km/s. This rate of spin is giving the star an oblate shape with an equatorial bulge that is 6% larger than the polar radius.[3] The star has nearly double the mass of the Sun and radiates 36.5[8] times the solar luminosity from its outer atmosphere at an effective temperature of 8,551[7] K.
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