Epsilon Octantis
Epsilon Octantis, Latinized from ε Octantis, is a star in the southern circumpolar constellation of Octans. It is a faintly visible to the naked eye with an apparent visual magnitude of about 5. The annual parallax shift of 11.22 mas yields a distance estimate of around 291 light years. It is moving further from the Sun with a radial velocity of +11.7 km/s. This is an evolved, cool red giant star with a stellar classification of class M5III. It is a semiregular variable with a magnitude range of 4.58 to 5.30 and a (poorly defined) period around 55 days. The star has 1.34 times the mass of the Sun and has expanded to around 112 times the Sun's radius. It is radiating 1,819 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,560 K. Epsilon Octantis was found to be variable on a survey of the southern sky conducted by the Bamberg observatory, which was reported in 1966. In 1972, it was assigned the variable star designation BO Octantis, although this is now recognised as a mistake since stars with Bayer designations are not given a separate variable star designation.
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Octans |
| Right ascension | 22h 20m 01.67970s[1] |
| Declination | −80° 26′ 23.0947″[1] |
| Apparent magnitude (V) | 4.58 - 5.30[2] |
| Characteristics | |
| Spectral type | M5III[3] |
| U−B color index | +1.18[4] |
| B−V color index | +1.47[4] |
| Variable type | SRb[2] |
| Astrometry | |
| Radial velocity (Rv) | +11.70[5] km/s |
| Proper motion (μ) | RA: +56.81[1] mas/yr Dec.: −43.47[1] mas/yr |
| Parallax (π) | 11.22±0.23 mas[1] |
| Distance | 291 ± 6 ly (89 ± 2 pc) |
| Absolute magnitude (MV) | +0.34[6] |
| Details | |
| Mass | 1.34[7] M☉ |
| Radius | 112±15[8] R☉ |
| Luminosity | 1,819[8] L☉ |
| Surface gravity (log g) | 2.15[7] cgs |
| Temperature | 3,560±264[8] K |
| Other designations | |
| BO Oct, ε Oct, CD−81°831, FK5 839, GC 31166, HD 210967, HIP 110256, HR 8481, SAO 258928 | |
| Database references | |
| SIMBAD | data |
Epsilon Octantis, Latinized from ε Octantis, is a star in the southern circumpolar constellation of Octans. It is a faintly visible to the naked eye with an apparent visual magnitude of about 5. The annual parallax shift of 11.22[1] mas yields a distance estimate of around 291 light years. It is moving further from the Sun with a radial velocity of +11.7 km/s.[5]
This is an evolved, cool red giant star with a stellar classification of class M5III.[3] It is a semiregular variable with a magnitude range of 4.58 to 5.30 and a (poorly defined) period around 55 days.[2] The star has 1.34[7] times the mass of the Sun and has expanded to around 112[8] times the Sun's radius. It is radiating 1,819[8] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,560 K.[8]
Epsilon Octantis was found to be variable on a survey of the southern sky conducted by the Bamberg observatory, which was reported in 1966.[10] In 1972, it was assigned the variable star designation BO Octantis,[11] although this is now recognised as a mistake since stars with Bayer designations are not given a separate variable star designation.[2]
References
[edit]- ^ a b c d e f Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600. Vizier catalog entry
- ^ a b c d Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
- ^ a b Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
- ^ a b Mermilliod, J. C. (2006). "VizieR Online Data Catalog: Homogeneous Means in the UBV System (Mermilliod 1991)". VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie. 2168. Bibcode:2006yCat.2168....0M.Vizier catalog entry
- ^ a b Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
- ^ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644. Vizier catalog entry
- ^ a b c Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. Vizier catalog entry
- ^ a b c d e f Arroyo-Torres, B.; et al. (June 2014), "VLTI/AMBER observations of cold giant stars: atmospheric structures and fundamental parameters", Astronomy & Astrophysics, 566: 11, arXiv:1404.7384, Bibcode:2014A&A...566A..88A, doi:10.1051/0004-6361/201323264, S2CID 16778588, A88
- ^ "/ftp/cats/more/HIP/cdroms/cats". Centre de Données astronomiques de Strasbourg. Strasbourg astronomical Data Center. Retrieved 15 October 2022.
- ^ Strohmeier, W.; Fischer, H.; Ott, H. (1966). "Bright Southern BV-Stars". Information Bulletin on Variable Stars. 120: 1. Bibcode:1966IBVS..120....1S.
- ^ Kukarkin, B. V.; Kholopov, P. N.; Kukarkina, N. P.; Perova, N. B. (1 September 1972). "58th Name-List of Variable Stars". Information Bulletin on Variable Stars. 717: 1. Bibcode:1972IBVS..717....1K. ISSN 0374-0676.
