R Chamaeleontis
Visual band light curves for R Chamaeleontis. The upper plot shows AAVSO data, and the lower plot shows ASAS-SN data folded with the star's period of 338 days. | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Chamaeleon |
| Right ascension | 08h 21m 46.4589s |
| Declination | −76° 21′ 18.302″ |
| Apparent magnitude (V) | 7.5 - 14.1 |
| Characteristics | |
| Spectral type | M4e-M8e |
| Variable type | Mira |
| Astrometry | |
| Radial velocity (Rv) | −21.893±6.065 km/s |
| Proper motion (μ) | RA: −16.420 mas/yr Dec.: +14.578 mas/yr |
| Parallax (π) | 1.102±0.062 mas |
| Distance | 3,000 ± 200 ly (910 ± 50 pc) |
| Details | |
| Mass | 2.5 M☉ |
| Radius | 246 – 274 R☉ |
| Luminosity | 4,574+1,258 −1,000 L☉ |
| Surface gravity (log g) | −0.27 to −0.35 cgs |
| Temperature | 3,012–3,042 K |
| Metallicity [Fe/H] | 0.00 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, it was the first variable star to be discovered in the constellation of Chamaeleon.
R Cha has a stellar classification that has been recorded between M4e near maximum and M8e near minimum. 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. 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. The effective temperature also varies as the star pulsates, corresponding to the change in the spectral class.