V Coronae Australis

V Coronae Australis (V CrA) is a R Coronae Borealis variable (RCB) star in the constellation Corona Australis. These are extremely hydrogen-deficient supergiants thought to have arisen as the result of the merger of two white dwarfs; fewer than 100 have been discovered as of 2012.[9] V Coronae Australis dimmed in brightness from 1994 to 1998.[10]

V Coronae Australis

A visual band light curve for V Coronae Australis, from AAVSO data[1]
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Corona Australis
Right ascension 18h 47m 32.30962s[2]
Declination −38° 09′ 32.3079″[2]
Apparent magnitude (V) 9.4 - 17.9[3]
Characteristics
Evolutionary stage R CrB[3]
Spectral type R0[4]
Astrometry
Proper motion (μ) RA: −1.104[2] mas/yr
Dec.: −7.531[2] mas/yr
Parallax (π)−0.3793 ± 0.1513 mas[2]
Distance5,500[5] pc
Details
Mass0.6[6] M☉
Luminosity6,550[5] L☉
Surface gravity (log g)0.5[7] cgs
Temperature6,250[6] K
Other designations
V CrA, CD−38°13089, HD 173539, HIP 92207[8]
Database references
SIMBADdata

The visual apparent magnitude of V CrA has been observed to vary between magnitudes 9.4 and 17.9. A maximum magnitude of 8.3 has been estimated from photographic plates.[11] It has around 60% the mass of the Sun and an effective (surface) temperature of around 6250 K.[6]

The spectral class of R0 is typical of a carbon star, but the RCB stars are considered to a separate class of hydrogen-deficient stars, not normal asymptotic giant branch giants.[12]

References
  1. "Download Data". aavso.org. AAVSO. Retrieved 1 October 2021.
  2. 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. "V CrB". International Variable Star Index. AAVSO. Retrieved 2022-12-22.
  4. Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Volume_3. Declinations −40° to −26°. Bibcode:1982mcts.book.....H.
  5. Montiel, Edward J.; Clayton, Geoffrey C.; Sugerman, B. E. K.; Evans, A.; Garcia-Hernández, D. A.; Kameswara Rao, N.; Matsuura, M.; Tisserand, P.; Tisserand, P. (2018). "The Double Dust Envelopes of R Coronae Borealis Stars". The Astronomical Journal. 156 (4): 148. arXiv:1808.00618. Bibcode:2018AJ....156..148M. doi:10.3847/1538-3881/aad772. S2CID 51919128.
  6. Stasińska, G.; Szczerba, R.; Schmidt, M.; Siódmiak, N. (2006). "Post-AGB stars as testbeds of nucleosynthesis in AGB stars". Astronomy and Astrophysics. 450 (2): 701. arXiv:astro-ph/0601504. Bibcode:2006A&A...450..701S. doi:10.1051/0004-6361:20053553. S2CID 12040452.
  7. Hema, B. P.; Pandey, Gajendra; Lambert, David L. (2012). "The Galactic R Coronae Borealis Stars: The C2 Swan Bands, the Carbon Problem, and the 12C/13C Ratio". The Astrophysical Journal. 747 (2): 102. arXiv:1201.1357. Bibcode:2012ApJ...747..102H. doi:10.1088/0004-637X/747/2/102. S2CID 118653032.
  8. SIMBAD, V Coronae Australis (accessed 13 July 2014)
  9. Tisserand; Clayton; Welch; Pilecki; Wyrzykowski; Kilkenny (2012). "The Ongoing Pursuit of R Coronae Borealis Stars: ASAS-3 Survey Strikes Again". Astronomy & Astrophysics. 551: 22. arXiv:1211.2475. Bibcode:2013A&A...551A..77T. doi:10.1051/0004-6361/201220713. S2CID 59060842. A77.
  10. Skuljan, L.; Cottrell, P. L. (2002). "Recent declines of RS Telescopii, UW Centauri, and V Coronae Australis". The Observatory. 122: 322–29. Bibcode:2002Obs...122..322S.
  11. Milone, L. A. (1975). "A Note on V CrA and W Men". Information Bulletin on Variable Stars. 989: 1. Bibcode:1975IBVS..989....1M.
  12. Pandey, Gajendra; Hema, B. P.; Reddy, Arumalla B. S. (2021). "Revised Surface Abundances of R Coronae Borealis Stars". The Astrophysical Journal. 921 (1): 52. arXiv:2108.02736. Bibcode:2021ApJ...921...52P. doi:10.3847/1538-4357/ac1ad1. S2CID 236924306.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.