R Octantis

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R Octantis
ROctLightCurve.png
The visual band light curve of R Octantis, from AAVSO data [1]
Observation data
Epoch J2000.0        Equinox J2000.0 (ICRS)
Constellation Octans
Right ascension 05h 26m 06.19562s [2]
Declination −86° 23′ 17.7741″ [2]
Apparent magnitude  (V)6.4 –13.2 [3]
Characteristics
Spectral type M5.5e [4] (M5.3e –M8.4e [3] )
Variable type Mira [5]
Astrometry
Radial velocity (Rv)46±5 [6]  km/s
Proper motion (μ)RA: 0.540  mas/yr [2]
Dec.: 31.079  mas/yr [2]
Parallax (π)1.7152 ± 0.0862  mas [2]
Distance 1,900 ± 100  ly
(580 ± 30  pc)
Details
Mass 6.6 [7]   M☉
Radius 466 [7]   R☉
Luminosity 9,304 [8]   L☉
Temperature 2,571 [8]   K
Other designations
R Octantis, CD−86°52, CPD−86°72, HD  40857, HIP  25412 [9]
Database references
SIMBAD data

R Octantis, also known as HD 40857, is a solitary, red hued variable star located in the southern circumpolar constellation Octans. It has an apparent magnitude that varies in-between 6.4 and 13.2 within 405 days. [3] At is maximum, it is barely visible to the naked eye. The object is located relatively far at a distance of about 1,900 light years based on parallax measurements from Gaia DR3, [2] but is receding with a heliocentric radial velocity of 46  km/s . [6]

R Octantis has been known to have a peculiar spectra since 1892. [10] It was revealed to have emission lines in its spectrum in a 1954 paper [11] and was found to be a long period variable a year later. [12] In 1966, R Octantis was officially classified as a Mira variable. [4] Later observations reveal it to have an overabundance of oxygen on its outer layers. [13]

The object has an average stellar classification of M5.5e, indicating that it is a M-type star with emission lines in its spectrum. [4] However, this can range from M5.3 to M8.4e. [3] It is currently on the asymptotic giant branch, generating energy by fusing hydrogen and helium shells around an inert carbon core. As a result, it has expanded to 466 times the radius of the Sun. [7] R Octantis radiates over 9,000 times the luminosity of the Sun from its photosphere at an effective temperature of 2,571  K , [8] which is cooler than most Mira variables.

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References

  1. ↑ "Download Data". aavso.org. AAVSO. Retrieved 1 October 2021.
  2. 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  3. 1 2 3 4 Otero, Sebastian (26 April 2011). "R Octantis". AAVSO Website. American Association of Variable Star Observers . Retrieved 21 April 2016.
  4. 1 2 3 Keenan, Philip C. (June 1966). "A Catalogue of Spectra of Mira Variables of Types ME and Se". The Astrophysical Journal Supplement Series. 13: 333. Bibcode:1966ApJS...13..333K. doi: 10.1086/190139 . eISSN   1538-4365. ISSN   0067-0049.
  5. ↑ Samus’, N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (January 2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. eISSN   1562-6881. ISSN   1063-7729. S2CID   125853869.
  6. 1 2 Gontcharov, G. A. (November 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. eISSN   1562-6873. ISSN   1063-7737. S2CID   119231169.
  7. 1 2 3 Kervella, Pierre; Arenou, Frédéric; Thévenin, Frédéric (2022). "Stellar and substellar companions from Gaia EDR3". Astronomy & Astrophysics. 657: A7. arXiv: 2109.10912 . Bibcode:2022A&A...657A...7K. doi: 10.1051/0004-6361/202142146 . eISSN   1432-0746. ISSN   0004-6361.
  8. 1 2 3 McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (2012). "Fundamental Parameters and Infrared Excesses of Hipparcos Stars". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–57. arXiv: 1208.2037 . Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x. S2CID   118665352.
  9. ↑ "V* R Oct". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 21 April 2016.
  10. ↑ Fleming, M. (November 1892). "Stars having peculiar spectra". Astronomy and Astro-Physics. 11: 765–767. Bibcode:1892AstAp..11..765F.
  11. ↑ Bidelman, William P. (November 1954). "Catalogue and Bibliography of Emission-Line Stars of Types Later than B.". The Astrophysical Journal Supplement Series. 1: 175. Bibcode:1954ApJS....1..175B. doi:10.1086/190007. eISSN   1538-4365. ISSN   0067-0049.
  12. ↑ Campbell, Leon (1955). Studies of Long Period Variables. American Association of Variable Star Observers. Bibcode:1955slpv.book.....C.
  13. ↑ Jura, M.; Yamamoto, A.; Kleinmann, S. G. (August 1993). "Long-period oxygen-rich optical Miras in the solar neighborhood". The Astrophysical Journal. 413: 298. Bibcode:1993ApJ...413..298J. doi:10.1086/172997. eISSN   1538-4357. ISSN   0004-637X.
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