Rho Octantis

Not to be confused with R Octantis.

Rho Octantis, Latinized from ρ Octantis, is a star located in the southern circumpolar constellation Octans. With an apparent magnitude of 5.57,^[2] its faintly visible to the naked eye under ideal conditions. The star is located 215 light years away from the Solar System,^[1] but is drifting closer with a radial velocity of −11 km/s.^[5]

ρ Octantis

Location of ρ Octantis (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Octans
Right ascension	15h 43m 16.927s[1]
Declination	−84° 27′ 54.99″[1]
Apparent magnitude (V)	5.57±0.01[2]
Characteristics
Spectral type	A1/2 V[3]
U−B color index	+0.08[4]
B−V color index	+0.11[4]
Astrometry
Radial velocity (Rv)	−11±10[5] km/s
Proper motion (μ)	RA: +131.101[1] mas/yr Dec.: +96.007[1] mas/yr
Parallax (π)	15.1565 ± 0.0796 mas[1]
Distance	215 ± 1 ly (66.0 ± 0.3 pc)
Absolute magnitude (MV)	+1.47[6]
Details
Mass	1.99[7] M☉
Radius	2.19±0.07[8] R☉
Luminosity	21±1[8] L☉
Surface gravity (log g)	4.06±0.14[9] cgs
Temperature	8,881±302[9] K
Rotational velocity (v sin i)	128[10] km/s
Age	431[7] Myr
Other designations
ρ Octantis, 24 G. Octantis, CPD–84 510, HD 13733, HIP 76996, HR 5729, SAO 258731, WDS J15433-8428A
Database references
SIMBAD	data

Rho Octantis has a classification of A1/2 V, which states its a star with the traits of an A1 and A2 main-sequence star. It has nearly twice the mass of the Sun,^[7] and has a radius of 2.19 solar radii.^[8] The star radiates at a luminosity 21 times greater than the Sun from its photosphere^[8] at an effective temperature of 8,881 K,^[9] which gives it a white hue. Like many A-type stars, Rho Octantis rotates rapidly, with a projected rotational velocity of 128 km/s;^[10] it is 431 million years old.^[7] Rho Octantis has a common proper motion K0 companion 65.7” away.^[11]

References

1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
2. Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN 0004-6361.
3. Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. Declinations -90_ to -53_ƒ0. Bibcode:1975mcts.book.....H.
4. Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99–110. Bibcode:1966CoLPL...4...99J.
5. Kharchenko, N. V.; Scholz, R. -D.; Piskunov, A. E.; Röser, S.; Schilbach, E. (November 2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889. arXiv:0705.0878. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776. ISSN 0004-6337. S2CID 119323941.
6. Anderson, E.; Francis, Ch. (1 May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. ISSN 1063-7737. S2CID 119257644.
7. Bressan, Alessandro; Marigo, Paola; Girardi, Léo.; Salasnich, Bernardo; Dal Cero, Claudia; Rubele, Stefano; Nanni, Ambra (November 2012). "PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code". Monthly Notices of the Royal Astronomical Society. 427 (1): 127–145. arXiv:1208.4498. Bibcode:2012MNRAS.427..127B. doi:10.1111/j.1365-2966.2012.21948.x. ISSN 0035-8711. S2CID 118303254.
8. Stassun, Keivan G.; et al. (2019-10-01). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. hdl:1721.1/124721. ISSN 0004-6256. S2CID 166227927.
9. David, Trevor J.; Hillenbrand, Lynne A. (May 2015). "The Ages of Early-type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. ISSN 0004-637X. S2CID 33401607.
10. Głȩbocki, R.; Gnaciński, P. (March 2005). "Systematic errors in the determination of stellar rotational velocities". 13th Cambridge Workshop on Cool Stars. 560: 571. Bibcode:2005ESASP.560..571G.
11. Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001-12-01). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. ISSN 0004-6256.