HD 37974
File:Supersized Disk.tif Artist concept of the stars, Sun and planets not drawn to scale | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Dorado |
| Right ascension | Template:RA[1] |
| Declination | Template:DEC[1] |
| Apparent magnitude (V) | 10.95[2] |
| Characteristics | |
| Spectral type | B0.5Ia+[3] |
| U−B Template:Engvar | −0.88[2] |
| B−V Template:Engvar | +0.15[2] |
| Variable type | LBV?[4][5] |
| Astrometry | |
| Radial velocity (Rv) | 258[6] km/s |
| Proper motion (μ) | RA: -1.8[1] mas/yr Dec.: -15.1[1] mas/yr |
| Parallax (π) | 0.22±0.42 mas[7] |
| Absolute magnitude (MV) | −8.4[4] |
| Details[3] | |
| Mass | 70 Template:Solar mass |
| Radius | Template:Solar radius calculatorTemplate:Efn Template:Solar radius |
| Luminosity | 1,400,000 Template:Solar luminosity |
| Temperature | 22,500 K |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Other designations | |
| RMC 126, R 126, HD 37974, GSC 09167-00518, AL 361, GV 408, MSX LMC 890, CPD-69°420, MWC 123, LHA 120-S 127, LI-LMC 1413, LMC V3566; 2MASS J05362586-6922558[5] | |
| Database references | |
| SIMBAD | data |
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HD 37974 (or R 126) a variable B[e] hypergiant in the Large Magellanic Cloud. It is surrounded by an unexpected dust disk.
Properties
R126, formally RMC (Radcliffe observatory Magellanic Cloud) 126, is a massive luminous star with several unusual properties. It exhibits the B[e] phenomenon where forbidden emission lines appear in the spectrum due to extended circumstellar material. Its spectrum also shows normal (permitted) emission lines formed in denser material closer to the star, indicative of a power stellar wind.[8] The spectra include silicate and polycyclic aromatic hydrocarbon (PAH) features that suggest a dusty disc.[3]
The star itself is a hot supergiant thought to be seventy times more massive than the Sun and over a million times more luminous. It has evolved away from the main sequence (being an O-class star, when it was in MSScript error: No such module "Unsubst".) and is so luminous and large that it is losing material through its stellar wind over a billion times faster than the Sun. It would lose more material than the Sun contains in about 25,000 years.[9]
It is expected to evolve into Wolf–Rayet star in several hundred thousand years.Script error: No such module "Unsubst".
Dusty disc
The dust cloud around R126 is surprising because stars as massive as these were thought to be inhospitable to planet formation due to powerful stellar winds making it difficult for dust particles to condense. The nearby hypergiant HD 268835 shows similar features and is also likely to have a dusty disc, so R126 is not unique.[3]
The disc extends outwards for 60 times the size of Pluto's orbit around the Sun, and probably contains as much material as the entire Kuiper belt. It is unclear whether such a disc represents the first or last stages of the planet-forming process.[10]
Variability
The brightness of R126 varies in an unpredictable way by around 0.6 magnitude over timescales of tens to hundreds of days. The faster variations are characteristic of α Cygni variables, irregular pulsating supergiants. The slower variations are accompanied by changes in the colour of the star, with it being redder when it is visually brighter, typical of the S Doradus phases of luminous blue variables.[4]
See also
References
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- ↑ NASA's Spitzer Uncovers Hints of Mega Solar Systems Template:Webarchive, Nasa.gov, accessed 11 Feb 2006
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