HD 20644 is a suspected binary star[6] system in the constellation Aries. It has an orange hue and is visible to the naked eye with an apparent visual magnitude of 4.47.[2] The system is located at a distance of approximately 540 light years from the Sun based on parallax,[1] but is drifting closer with a radial velocity of −3 km/s.[2]
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Aries |
Right ascension | 03h 20m 20.36111s[1] |
Declination | +29° 02′ 54.4451″[1] |
Apparent magnitude (V) | 4.47[2] |
Characteristics | |
Spectral type | K3IIIa Ba0.5[3] |
B−V color index | 1.555±0.020[2] |
Astrometry | |
Radial velocity (Rv) | −3.09±0.28[2] km/s |
Proper motion (μ) | RA: −7.71[1] mas/yr Dec.: −16.91[1] mas/yr |
Parallax (π) | 6.01 ± 0.25 mas[1] |
Distance | 540 ± 20 ly (166 ± 7 pc) |
Absolute magnitude (MV) | −1.63[2] |
Details | |
Mass | 3.07±0.39[4] M☉ |
Radius | 75.32+3.30 −7.57[5] R☉ |
Luminosity | 1,292±89[5] L☉ |
Surface gravity (log g) | 2.00[4] cgs |
Temperature | 3,987+217 −85[5] K |
Metallicity [Fe/H] | −0.27±0.04[2] dex |
Rotational velocity (v sin i) | 1.4[6] km/s |
Age | 350±140[4] Myr |
Other designations | |
Database references | |
SIMBAD | data |
The visible component is an aging giant star with a stellar classification of K3IIIa Ba0.5,[3] where the suffix notation indicates this is a mild barium star. The atmosphere of this star is enriched with s-process elements that are posited to have been transferred from what is now a white dwarf companion when it evolved along the asymptotic giant branch (AGB).[8] Alternatively, this star may itself be on the AGB.[9]
HD 20644 is about 350[4] million years old with three[4] times the mass of the Sun and is spinning with a projected rotational velocity of 1.4 km/s.[6] With the supply of hydrogen at its core exhausted, it has expanded to 75[5] times the Sun's radius. It is radiating 1,292[5] times the luminosity of the Sun from its photosphere at an effective temperature of 3,987 K.[5]