R Chamaeleontis (abbreviated to R Cha), also known as HD 71793, is a Mira variable located in the southern circumpolar constellation Chamaeleon. It has an apparent magnitude that ranges from 7.5 to 14.1, which is below the limit for naked eye visibility. Gaia DR3 parallax measurements place it about 3,000 light years away and it is currently approaching with a heliocentric radial velocity of 22 km/s.
 Visual band light curves for R Chamaeleontis. The upper plot shows AAVSO data,[1] and the lower plot shows ASAS-SN data[2] folded with the star's period of 338 days.[3] | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Chamaeleon |
| Right ascension | 08h 21m 46.4589s[4] |
| Declination | −76° 21′ 18.302″[4] |
| Apparent magnitude (V) | 7.5 - 14.1[5] |
| Characteristics | |
| Spectral type | M4e-M8e[5] |
| Variable type | Mira[5] |
| Astrometry | |
| Radial velocity (Rv) | −21.893±6.065[6] km/s |
| Proper motion (μ) | RA: −16.420 mas/yr[4] Dec.: +14.578 mas/yr[4] |
| Parallax (π) | 1.0761 ± 0.0617 mas[4] |
| Distance | 3,000 ± 200 ly (930 ± 50 pc) |
| Details | |
| Mass | 2.5[7] M☉ |
| Radius | 588[4] R☉ |
| Luminosity | 3,908[8] L☉ |
| Surface gravity (log g) | −0.77[7] cgs |
| Temperature | 2,569[7] K |
| Metallicity [Fe/H] | 0.00[7] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
This star was first reported to be variable in 1906, the first to be discovered in the constellation of Chamaeleon.[9]
R Cha has a stellar classification that has been recorded between M4e near maximum and M8e near minimum.[10] It is an asymptotic giant branch star that has exhausted its core hydrogen and helium and is now fusing hydrogen and helium in separate shells outside its core.[11] It has expanded to about 588 R☉ although this varies as it pulsates.[4] It radiates about 4,000 L☉ despite its relatively low surface temperature around 2,500 K. The effective temperature also varies as the star pulsates, corresponding to the change in the spectral class.[12]
References
edit- ^ "Download Data". aavso.org. AAVSO. Retrieved 8 March 2023.
- ^ "ASAS-SN Variable Stars Database". ASAS-SN Variable Stars Database. ASAS-SN. Retrieved 8 March 2023.
- ^ "R Cha". The International Variable Star Index. AAVSO. Retrieved 9 March 2023.
- ^ a b c d e f 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.
- ^ a b c 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.
- ^ Kunder, Andrea; Kordopatis, Georges; Steinmetz, Matthias; Zwitter, Tomaž; McMillan, Paul J.; Casagrande, Luca; Enke, Harry; Wojno, Jennifer; Valentini, Marica; Chiappini, Cristina; Matijevič, Gal; Siviero, Alessandro; De Laverny, Patrick; Recio-Blanco, Alejandra; Bijaoui, Albert; Wyse, Rosemary F. G.; Binney, James; Grebel, E. K.; Helmi, Amina; Jofre, Paula; Antoja, Teresa; Gilmore, Gerard; Siebert, Arnaud; Famaey, Benoit; Bienaymé, Olivier; Gibson, Brad K.; Freeman, Kenneth C.; Navarro, Julio F.; Munari, Ulisse; et al. (2017). "The Radial Velocity Experiment (RAVE): Fifth Data Release". The Astronomical Journal. 153 (2): 75. arXiv:1609.03210. Bibcode:2017AJ....153...75K. doi:10.3847/1538-3881/153/2/75. S2CID 118835808.
- ^ a b c d Anders, F.; Khalatyan, A.; Queiroz, A. B. A.; Chiappini, C.; Ardevol, J.; Casamiquela, L.; Figueras, F.; Jimenez-Arranz, O.; Jordi, C.; Monguio, M.; Romero-Gomez, M.; Altamirano, D.; Antoja, T.; Assaad, R.; Cantat-Gaudin, T.; Castro-Ginard, A.; Enke, H.; Girardi, L.; Guiglion, G.; Khan, S.; Luri, X.; Miglio, A.; Minchev, I.; Ramos, P.; Santiago, B. X.; Steinmetz, M. (2022). "VizieR Online Data Catalog: StarHorse2, Gaia EDR3 photo-astrometric distances (Anders+, 2022)". Vizier Online Data Catalog. Bibcode:2022yCat.1354....0A.
- ^ 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.
- ^ Pickering, E. C.; Colson, H. R.; Fleming, W. P.; Wells, L. D. (1901). "Sixty-four new variable stars". The Astrophysical Journal. 13: 226. Bibcode:1901ApJ....13..226P. doi:10.1086/140808.
- ^ Skiff, B. A. (October 2014). "Catalogue of Stellar Spectral Classifications". Lowell Observatory. VizieR On-line Data Catalog: B/mk. Bibcode:2014yCat....1.2023S.
- ^ Lançon, A.; Mouhcine, M. (2002). "The modelling of intermediate-age stellar populations. II. Average spectra for upper AGB stars, and their use". Astronomy and Astrophysics. 393: 167. arXiv:astro-ph/0206252. Bibcode:2002A&A...393..167L. doi:10.1051/0004-6361:20020585. S2CID 15944377.
- ^ Celis s., L. (1977). "Light and colour variations of the Mira stars". Astronomy and Astrophysics Supplement Series. 29: 15. Bibcode:1977A&AS...29...15C.