HV 11423
.jpg) HV 11423 is visible in the full-size image, just to the left (south is up) of cluster NGC 361 (below centre, between the two bright foreground stars). (Digitized Sky Survey 2) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Tucana |
| Right ascension | 01h 00m 55.2s[1] |
| Declination | 71° 37′ 53″[1] |
| Apparent magnitude (V) | 11.84 - 12.46[2] |
| Characteristics | |
| Evolutionary stage | Red supergiant |
| Spectral type | K0/1 - M4.5/5 I[3] |
| B−V color index | +1.88 - +1.95[2] |
| Variable type | LSPV[4] |
| Astrometry | |
| Radial velocity (Rv) | 108.268[5] km/s |
| Distance | ~200,000 ly |
| Absolute magnitude (MV) | −6.5 - −8.4[3] |
| Details[3] | |
| December 2004 | |
| Radius | 1,060 R☉ |
| Luminosity | 350,000 L☉ |
| Surface gravity (log g) | −0.2 cgs |
| Temperature | 4,300 K |
| December 2005 | |
| Radius | 1,220 R☉ |
| Luminosity | 200,000 L☉ |
| Surface gravity (log g) | −0.4 cgs |
| Temperature | 3,500 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
HV 11423 (PMMR 114/140 LI-SMC) is a star in the Small Magellanic Cloud galaxy that is part of the Local Group and it is one of largest stars.
Distance
It is about 200,000 light-years away towards the constellation of Tucana.
Visibility
HV 11423 is one of the brightest red supergiants neighboring galaxy. Its spectral type is variable, from K0-1I (December 2004), to M4I (December 2005), and back to K0-1I (September 2006). VLA file spectra show that in December 2001 the star was even colder (M4-5I). By contrast, in October 1978 and a year later, he appeared as a star of M0I type. The spectral type M4-5 is the later observed in a supergiant of the Small Magellanic Cloud; in fact, the temperature in that state is beyond the limit Hayashi, in a region of the Hertzsprung-Russell where the star would not be in hydrostatic equilibrium. When the star enters a forbidden region of the HR diagram, you should seek quickly recover the lost balance, which is consistent with the return type K only months after passing through the M4 type (December 2005).
Characteristics
HV 11423 is a large star, with an estimate radius over 1,000 times bigger than the sun. It is also a variable star with a variation band 2 magnitudes in V band but essentially constant K. The bolometric luminosity ~300,000 times more than Sun, it appears to have remained unchanged. It is thought that the star is currently undergoing a period of intense instability, in which its effective temperature changes from 4,300 to 3,500 K in a time scale of months; V-band variability may be due primarily to variations in temperature as well as changes in the local extinction due to the creation and dissipation of circumstellar dust. It is speculated that the star may be nearing the end of his life.[3]
References
- 1 2 Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; Beichman, C. A.; Carpenter, J. M.; Chester, T.; Cambresy, L.; Evans, T.; Fowler, J.; Gizis, J.; Howard, E.; Huchra, J.; Jarrett, T.; Kopan, E. L.; Kirkpatrick, J. D.; Light, R. M.; Marsh, K. A.; McCallon, H.; Schneider, S.; Stiening, R.; Sykes, M.; Weinberg, M.; Wheaton, W. A.; Wheelock, S.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". VizieR On-line Data Catalog: II/246. Originally published in: 2003yCat.2246....0C. 2246. Bibcode:2003yCat.2246....0C.
- 1 2 Levesque, E. M.; Massey, P.; Olsen, K. A. G.; Plez, B. (2009). "The Coolest Stars in the Clouds: Unusual Red Supergiants in the Magellanic Clouds". The Biggest. 412: 33. Bibcode:2009ASPC..412...33L.
- 1 2 3 4 Massey, Philip; Levesque, Emily M.; Olsen, K. A. G.; Plez, Bertrand; Skiff, B. A. (2007). "HV 11423: The Coolest Supergiant in the SMC". The Astrophysical Journal. 660: 301. arXiv:astro-ph/0701769
. Bibcode:2007ApJ...660..301M. doi:10.1086/513182. - ↑ Yang, Ming; Jiang, B. W. (2012). "The Period-Luminosity Relation of Red Supergiant Stars in the Small Magellanic Cloud". The Astrophysical Journal. 754: 35. arXiv:1205.1275. Bibcode:2012ApJ...754...35Y. doi:10.1088/0004-637X/754/1/35.
- ↑ Kordopatis, G.; Gilmore, G.; Steinmetz, M.; Boeche, C.; Seabroke, G. M.; Siebert, A.; Zwitter, T.; Binney, J.; De Laverny, P.; Recio-Blanco, A.; Williams, M. E. K.; Piffl, T.; Enke, H.; Roeser, S.; Bijaoui, A.; Wyse, R. F. G.; Freeman, K.; Munari, U.; Carrillo, I.; Anguiano, B.; Burton, D.; Campbell, R.; Cass, C. J. P.; Fiegert, K.; Hartley, M.; Parker, Q. A.; Reid, W.; Ritter, A.; Russell, K. S.; et al. (2013). "The Radial Velocity Experiment (RAVE): Fourth Data Release". The Astronomical Journal. 146 (5): 134. Bibcode:2013AJ....146..134K. doi:10.1088/0004-6256/146/5/134.