R85

For other uses, see R85 (disambiguation).

R85 (or RMC 85, after the Radcliffe Observatory Magellanic Clouds catalog^[5]) is a candidate luminous blue variable^[9] located in the LH-41 OB association^[10] in the Large Magellanic Cloud.

A visual band light curve for R85, plotted from ASAS-SN data^[11]

R85

The nebula N119; R85 is the brightest of the small triangle of stars in the lower right "arm". Credit: ESO
Observation data Epoch J2000      Equinox J2000
Constellation	Dorado
Right ascension	05h 17m 56.076s[1]
Declination	−69° 16′ 03.77″[1]
Apparent magnitude (V)	10.84[2] (10.65 - 10.80[3])
Characteristics
Evolutionary stage	LBV[4]
Spectral type	B5 Iae[3]
Apparent magnitude (U)	10.28[2]
Apparent magnitude (B)	10.93[2]
Apparent magnitude (V)	10.84[2]
Apparent magnitude (R)	10.53[2]
Apparent magnitude (I)	10.44[2]
Apparent magnitude (J)	10.103[1]
Apparent magnitude (H)	9.980[1]
Apparent magnitude (K)	9.822[1]
U−B color index	−0.65[2]
B−V color index	+0.09[2]
Variable type	LBV[4]
Astrometry
Radial velocity (Rv)	292[5] km/s
Proper motion (μ)	RA: −1.0[6] mas/yr Dec.: −2.3[6] mas/yr
Distance	160,000 ly (50,000[7] pc)
Absolute magnitude (MV)	−8.2 – −8.5[3]
Details
1960 (minimum)
Radius	135[8] R☉
Luminosity	350,000[3] L☉
Temperature	13,500[3] K
1983 - 1990 (maximum)
Luminosity	315,000[3] L☉
Temperature	10,000[3] K
Other designations
HD 269321, CPD−69°352, 2MASS J05175607-6916037, GSC 09162-00359, Sk−69°92
Database references
SIMBAD	data

R85 has been shown to vary erratically in brightness with an amplitude of about 0.3 magnitudes. It shows variations on several timescales, sometimes with a distinct 400 day period. It has also shown temperature changes associated with brightness changes over several years, a characteristic of luminous blue variables.^[12]

Based on R85's current properties and evolutionary models, it probably started out with an initial mass of 28 M_☉.^[10] It is theorized to be making a bubble known as DEM L132a with its stellar wind in the nebula LHA-120 N119, along with S Doradus.^[13] It has an infrared excess consistent with a stellar wind contribution.^[4]