R Chamaeleontis

R Chamaeleontis

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]
Distance3,000 ± 200 ly
(930 ± 50 pc)
Details
Mass2.5[7] M☉
Radius588[4] R☉
Luminosity3,908[8] L☉
Surface gravity (log g)−0.77[7] cgs
Temperature2,569[7] K
Metallicity [Fe/H]0.00[7] dex
Other designations
R Cha, HD 71793, TYC 9394-1962-1, GSC 09394-01962
Database references
SIMBADdata

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 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]

  1. ^ Cite error: The named reference aavso was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference ASAS-SN was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference IVSI was invoked but never defined (see the help page).
  4. ^ a b c d e f Cite error: The named reference dr3 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference gcvs was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference kunder2017 was invoked but never defined (see the help page).
  7. ^ a b c d Cite error: The named reference starhorse2 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference dr2 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference pickering1906 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference skiff2014 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference lancon2002 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference celis1977 was invoked but never defined (see the help page).