R Cancri

Not to be confused with Rho Cancri.

R Cancri is a Mira variable in the constellation Cancer. Located approximately 250 parsecs (830 ly) distant, it varies between magnitudes 6.07 and 12.3 over a period of approximately 357 days.^[3] At its brightest, it is very faintly visible to the naked eye.

R Cancri

The visual band light curve of R Cancri, from AAVSO data[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Cancer
Right ascension	08h 16m 33.82673s[2]
Declination	+11° 43′ 34.4691″[2]
Apparent magnitude (V)	6.07 - 12.3[3]
Characteristics
Spectral type	M6e-M9e[3]
U−B color index	0.49[4]
B−V color index	1.53[4]
Variable type	Mira[3]
Astrometry
Radial velocity (Rv)	35.42 ± 0.52[5] km/s
Proper motion (μ)	RA: 0.635±0.195[2] mas/yr Dec.: −10.785±0.106[2] mas/yr
Parallax (π)	3.9375±0.1792 mas[2]
Distance	854+36 −39 ly (262+11 −12 pc)[6]
Details
Mass	1.43[7] M☉
Radius	371±37[8] R☉
Luminosity	5,700[8][a] L☉
Surface gravity (log g)	−0.69[7] cgs
Temperature	2,604±300[8] K
Metallicity [Fe/H]	+0.22[7] dex
Other designations
BD+12°1803, HD 69243, HIP 40534, HR 3248, SAO 97694
Database references
SIMBAD	data

Friedrich Magnus Schwerd discovered R Cancri in 1829.^[9] It was one of the first variable stars to be discovered.^[10]

Notes

1. Calculated using the given radius and temperature by the Stefan-Boltzmann law.