Upsilon Octantis
Star in the constellation of Octans
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Upsilon Octantis (Upsilon Oct), Latinized from υ Octantis, is a solitary star[11] in the southern circumpolar constellation Octans. It is faintly visible to the naked eye with an apparent magnitude of 5.75[2] and is located 343 light years away from the Solar System.[1] However, it is receding with a heliocentric radial velocity of 19 km/s.[5]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Octans |
| Right ascension | 22h 31m 37.5152s[1] |
| Declination | −85° 58′ 02.110″[1] |
| Apparent magnitude (V) | 5.75±0.01[2] |
| Characteristics | |
| Spectral type | K0 III[3] |
| U−B color index | +0.88[4] |
| B−V color index | +1.02[4] |
| Astrometry | |
| Radial velocity (Rv) | 19±7.8[5] km/s |
| Proper motion (μ) | RA: −37.556 mas/yr[1] Dec.: +61.431 mas/yr[1] |
| Parallax (π) | 9.5042±0.0351 mas[1] |
| Distance | 343 ± 1 ly (105.2 ± 0.4 pc) |
| Absolute magnitude (MV) | +0.77[6] |
| Details[7] | |
| Mass | 2.12±0.07 M☉ |
| Radius | 10.3±0.2 R☉ |
| Luminosity | 56±1.1 L☉ |
| Surface gravity (log g) | 2.7±0.1 cgs |
| Temperature | 4,910±42 K |
| Metallicity [Fe/H] | 0.00±0.03 dex |
| Rotational velocity (v sin i) | 1.5±1.3[8] km/s |
| Other designations | |
| υ Oct, 71 G. Octantis[9], CPD−86°406, FK5 1670, GC 31327, HD 211539, HIP 111196, HR 8505, SAO 258932[10] | |
| Database references | |
| SIMBAD | data |
Upsilon Oct has a stellar classification of K0 III,[3] indicating that it is a red giant. At present it has 2.12 times the mass of the Sun but has expanded to 10.3 times its girth.[7] It shines with a luminosity of 56 L☉ from its enlarged photosphere at an effective temperature of 4,910 K,[7] giving a yellowish orange hue when viewed at night. Upsilon Oct has a solar metallicity, with an iron abundance equivalent to the Sun's.[7] It spins leisurely with a poorly-constrained projected rotational velocity of 1.5 km/s.[8]