B90 (star)
Red supergiant star in the constellation Dorado
From Wikipedia, the free encyclopedia
B90 (often referred to as [W60] B90) is a large and highly luminous[9][4] red supergiant star similar to Betelgeuse[4] in the Large Magellanic Cloud.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Dorado |
| Right ascension | 05h 24m 19.3095s[1] |
| Declination | −69° 38′ 49.374″[1] |
| Apparent magnitude (V) | 14.271±0.194[2] |
| Characteristics | |
| Evolutionary stage | Extreme red supergiant[3] |
| Spectral type | M3−4 I[4] |
| Apparent magnitude (U) | 19.519[5] |
| Apparent magnitude (B) | 16.688[5] |
| Apparent magnitude (R) | 11[5] |
| Apparent magnitude (G) | 12.135779±0.004246[6] |
| Apparent magnitude (I) | 10.804±0.105[5] |
| Apparent magnitude (J) | 8.360±0.018[5] |
| Apparent magnitude (H) | 7.375±0.038[5] |
| Apparent magnitude (K) | 6.809±0.023[5] |
| Variable type | SRc[4] |
| Astrometry | |
| Radial velocity (Rv) | 263.49±1.02[7] km/s |
| Proper motion (μ) | RA: 1.913±0.037[7] mas/yr Dec.: 0.411±0.034[7] mas/yr |
| Parallax (π) | 0.0457±0.027 mas[6] |
| Distance | 45,590[8] pc |
| Details | |
| Mass | 25 (initial)[4] M☉ |
| Radius | 1,210[4] R☉ |
| Luminosity | 209,000+4,870 −4,760[4] L☉ |
| Surface gravity (log g) | −0.2+0.20 −0.30[4] cgs |
| Temperature | 3,550±40[4] K |
| Metallicity | 0.0+0.2 −0.1[4] dex |
| Other designations | |
| WOH S264, LI-LMC 976, MSX LMC 461, RM 1-339, SP77 47-10[1] | |
| Database references | |
| SIMBAD | data |
Discovery
B90 was discovered in 1956 by Karl Gordon Henize in a catalogue of H-alpha emission stars and nebulae in the Large Magellanic Cloud. He designated it LHA 120-N 132E, indicating emission line nebula 132E on plate 120. The LHA is originally LHα, standing for H-alpha emission objects identified at the Lamont-Hussey Observatory.[10]
Properties
B90 is believed to be one of the largest and most luminous red supergiants in the Large Magellanic Cloud. Its luminosity was first measured to be of more than 280,000 solar luminosities (L☉) and a radius of around 1,390 solar radii (R☉),[9] although a more detailed study put it at 209,000 L☉ and 1,210 R☉.[4]
Mass-loss
The star has episodic mass-loss with a high rate of 4.4+5.1
−1.7×10−6 M☉ yr−1 and a nebula of ~1 pc (~3 ly) surrounding the star. This nebula could indicate that the star has a bow shock, which supplies evidence that the star does undergo episodic mass-loss, which makes it more likely that this is the case for almost all red supergiants.
The variability of the star and possible "great dimming" events are also consistent with episodic mass-loss, similar to those of Betelgeuse and RW Cephei. The rebrightening of B90, just like RW Cephei, took twice as long as that of Betelgeuse which could indicate a relation between the time taken and the radius of red supergiants, where B90 is 1,210 R☉.[4][a]
Velocity
B90 has a very high velocity of (19 – 27) ± 11 km s−1 towards its nebular bar, therefore proving that it is a "walkaway" star. This potentially makes the possibility that it has a bow shock more likely.[4]
See also
Notes
- Discrepancy in radius is caused by possible underestimation of the effective temperature measured using Titanium(II) oxide bands.
