 BO Carinae is the brightest red star, towards upper left, in this image of the Carina Nebula. Credit: ESO | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Carina |
| Right ascension | 10h 46m 00.53s |
| Declination | 59° 29′ 19.5″ |
| Apparent magnitude (V) | 7.18 - 8.50 [1] |
| Characteristics | |
| Spectral type | M4 Ib [1] |
| Variable type | Lc [1] |
| Astrometry | |
| Proper motion (μ) | RA: −7.334±0.027 [2] mas/yr Dec.: −1.420±0.028 [2] mas/yr |
| Parallax (π) | 0.6020±0.0259 mas [2] |
| Distance | 5,400 ± 200 ly (1,660 ± 70 pc) |
| Absolute magnitude (MV) | −5.53 [3] |
| Details | |
| Radius | 790 [3] R☉ |
| Luminosity | 78,000 [3] L☉ |
| Temperature | 3,525 [3] K |
| Other designations | |
| BO Car, IDS 10419−5858, IRAS 10438−5913, 2MASS J10455065−5929193, AAVSO 1042−58, SAO 238447, CD−58 3547, HD 93420 | |
| Database references | |
| SIMBAD | data |
BO Carinae, also known as HD 93420, is an irregular variable star in the constellation Carina.
BO Car has a maximum apparent magnitude of +7.18. Its distance and membership is uncertain, but its possible membership to the star cluster Trumpler 15 allows a distance estimate of approximately 2,500 parsecs (8,150 light-years ). [4] [5] The Gaia Data Release 2 parallax of 0.73±0.08 mas suggests a closer distance, but the value is considered unreliable due to excess astrometric noise. [6]
BO Car is a red supergiant of spectral type M4Ib with an effective temperature of 3,525 K , a radius of 790 solar radii . Its bolometric luminosity is 78,000 L☉. [3] Mass-loss is on the order of 0.3×10−9 solar masses per year. [5]
In 1919, William Matthew Worssell of the Union Observatory announced that the star, then known as CPD-58 2683, is a variable star. [8] It was given its variable star designation, BO Carinae, in 1921. [9] Billed as an irregular variable like TZ Cassiopeiae or V528 Carinae; its apparent brightness fluctuates between magnitude +7.18 and +8.50 without clear periodicity. [1] [10] Some observers have found BO Car not to be variable, [11] but more extensive studies find small amplitude variations with a possible period of 145 days. [12]
Multiple star catalogues list an 11th-magnitude star as a companion to BO Car. The separation was 14.2″ in 2015, and slowly increasing. [13] The companion is a distant blue giant. [14]
