Astronomy:Sher 25
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Carina[1] |
| Right ascension | 11h 15m 7.645s[2] |
| Declination | −61° 15′ 17.61″[2] |
| Characteristics | |
| Evolutionary stage | Blue supergiant[3] |
| Spectral type | B1Iab[4] |
| U−B color index | 0.13[5] |
| B−V color index | 1.42[5] |
| Variable type | cLBV[6] |
| Astrometry | |
| Proper motion (μ) | RA: −5.387[2] mas/yr Dec.: +2.116[2] mas/yr |
| Parallax (π) | 0.1560 ± 0.0166[2] mas |
| Distance | 17,700±2,300 ly (5,440±700 pc) |
| Absolute magnitude (MV) | −7.05±0.34[7] |
| Details[7] | |
| Mass | 25.5±1.7 M☉ |
| Radius | 42±7 R☉ |
| Luminosity (bolometric) | 308,000+115,000 −83,000 L☉ |
| Surface gravity (log g) | 2.61±0.06 cgs |
| Temperature | 20,900±500 K |
| Rotational velocity (v sin i) | 60±5 km/s |
| Age | 7.24+0.70 −0.64 Myr |
| Other designations | |
Sher 25, NGC 3603-25, NGC 3603 MTT 13, NGC 3603 MDS 5 | |
| Database references | |
| SIMBAD | data |
Sher 25 is a blue supergiant star in the constellation Carina, located approximately 25,000 light years from the Sun.[8] It is a spectral type B1Iab star with an apparent magnitude of 12.2.[9] The star lies close to the H II region NGC 3603 of the Milky Way, but is a foreground star.[7] Its initial main sequence mass is calculated at 60 times the mass of the Sun, but a star of this type will have already lost a substantial fraction of that mass. It is unclear whether Sher 25 has been through a red supergiant phase or has just evolved from the main sequence, so the current mass is very uncertain.[3]
The name derives from the original cataloguing of stars in NGC 3603 by David Sher. This catalogue entry is more fully referred to as NGC 3603 Sher 25 to distinguish it from stars potentially numbered 25 by Sher in other clusters (eg. NGC 3766).[10] The same star was numbered 13 by Melnick, Tapia, and Terlevich[5] (MTT 13) and 5 in a Hubble Space Telescope survey by Moffat, Drissen, and Shara[11] (NGC 3603 MDS 5).
Sher 25 has long being thought to be a member of NGC 3603, but calculations based on spectroscopy give a closer distance: 5,440 pc (17,700 ly) versus 6,250 pc (20,400 ly) for NGC 3603. Furthermore, its hourglass-shaped nebula does not seem to be affected by the stellar winds of OB stars in the cluster, ruling out membership to NGC 3603.[7]
It is speculated that Sher 25 is near the point of exploding as a supernova, as it has recently thrown off matter in a pattern similar to that of supernova 1987A in the Large Magellanic Cloud, with a circumstellar ring and bipolar outflow filaments.[6]
Regular variations in the doppler shift of the star's spectral lines with a period of a few days may be due to orbital motion about a companion star, or to pulsations of the star's surface.[12]
References
- ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific 99 (617): 695. doi:10.1086/132034. Bibcode: 1987PASP...99..695R Constellation record for this object at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 3.0 3.1 Hendry, M. A.; Smartt, S. J.; Skillman, E. D.; Evans, C. J.; Trundle, C.; Lennon, D. J.; Crowther, P. A.; Hunter, I. (2008). "The blue supergiant Sher 25 and its intriguing hourglass nebula". Monthly Notices of the Royal Astronomical Society 388 (3): 1127. doi:10.1111/j.1365-2966.2008.13347.x. Bibcode: 2008MNRAS.388.1127H.
- ↑ Cite error: Invalid
<ref>tag; no text was provided for refs namedmelena - ↑ 5.0 5.1 5.2 Melnick, J.; Tapia, M.; Terlevich, R. (1989). "The galactic giant H II region NGC 3603". Astronomy and Astrophysics 213: 89. Bibcode: 1989A&A...213...89M.
- ↑ 6.0 6.1 Smartt, S. J.; Lennon, D. J.; Kudritzki, R. P.; Rosales, F.; Ryans, R. S. I.; Wright, N. (2002). "The evolutionary stat9us of Sher 25 - implications for blue supergiants and the progenitor of SN 1987A". Astronomy and Astrophysics 391 (3): 979. doi:10.1051/0004-6361:20020829. Bibcode: 2002A&A...391..979S.
- ↑ 7.0 7.1 7.2 7.3 Weßmayer, D.; Przybilla, N.; Ebenbichler, A.; Aschenbrenner, P.; Butler, K. (2023-09-01). "The blue supergiant Sher 25 revisited in the Gaia era". Astronomy and Astrophysics 677: A175. doi:10.1051/0004-6361/202347253. ISSN 0004-6361. Bibcode: 2023A&A...677A.175W. https://ui.adsabs.harvard.edu/abs/2023A&A...677A.175W/abstract.
- ↑ Sher, D. (1965). "Distances of Five Open Cluster Near Eta Carinae". Monthly Notices of the Royal Astronomical Society 129 (3): 237–262. doi:10.1093/mnras/129.3.237. ISSN 0035-8711. Bibcode: 1965MNRAS.129..237S.
- ↑ Brandner, Wolfgang; Grebel, Eva K.; Chu, You-Hua; Weis, Kerstin (January 1997). "Ring Nebula and Bipolar Outflows Associated with the B1.5 Supergiant Sher 25 in NGC 3603". Astrophysical Journal Letters 475 (1): L45. doi:10.1086/310460. Bibcode: 1997ApJ...475L..45B.
- ↑ Sher, D. (1965). "Distances of five open cluster near Eta Carinae". Monthly Notices of the Royal Astronomical Society 129 (3): 237. doi:10.1093/mnras/129.3.237. Bibcode: 1965MNRAS.129..237S.
- ↑ Moffat, A. F. J.; Drissen, L.; Shara, M. M. (1994). "NGC 3603 and its Wolf-Rayet stars: Galactic clone of R136 at the core of 30 Doradus, but without the massive surrounding cluster halo". The Astrophysical Journal 436: 183. doi:10.1086/174891. Bibcode: 1994ApJ...436..183M.
- ↑ Taylor, W. D.; Evans, C. J.; Simon-Diaz, S.; Sana, H.; Langer, N.; Smith, N.; Smartt, S. J. (2014). "Sher 25: pulsating but apparently alone". Monthly Notices of the Royal Astronomical Society 442 (2): 1483–1490. doi:10.1093/mnras/stu925. ISSN 0035-8711. Bibcode: 2014MNRAS.442.1483T.
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