R Chamaeleontis

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R Chamaeleontis
RChaLightCurve.png
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)1.102 ± 0.062  mas [7]
Distance 3,000 ± 200  ly
(910 ± 50  pc)
Details
Mass 2.5 [8]   M
Radius 246 274 [7]   R
Luminosity 4,574+1,258
−1,000
[7]   L
Surface gravity (log g)−0.27 to −0.35 [7]   cgs
Temperature 3,012–3,042 [7]   K
Metallicity [Fe/H]0.00 [8]   dex
Other designations
R Cha, HD  71793, TYC  9394-1962-1, GSC  09394-01962
Database references
SIMBAD data

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 .

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 246  R although this varies as it pulsates. It radiates about 4,600  L despite its relatively low surface temperature around 3,000  K . [7] The effective temperature also varies as the star pulsates, corresponding to the change in the spectral class. [12]

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References

  1. "Download Data". aavso.org. AAVSO. Retrieved 8 March 2023.
  2. "ASAS-SN Variable Stars Database". ASAS-SN Variable Stars Database. ASAS-SN. Retrieved 8 March 2023.
  3. "R Cha". The International Variable Star Index. AAVSO. Retrieved 9 March 2023.
  4. 1 2 3 4 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.
  5. 1 2 3 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. 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.
  7. 1 2 3 4 5 6 Béguin, E.; Chiavassa, A.; Ahmad, A.; Freytag, B.; Uttenthaler, S. (2024-10-01). "Retrieving stellar parameters and dynamics of AGB stars with Gaia parallax measurements and CO5BOLD RHD simulations". Astronomy & Astrophysics. 690: A125. arXiv: 2409.03422 . doi: 10.1051/0004-6361/202450245 . ISSN   0004-6361.
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  12. Celis s., L. (1977). "Light and colour variations of the Mira stars". Astronomy and Astrophysics Supplement Series. 29: 15. Bibcode:1977A&AS...29...15C.