Sher 25

HST image of NGC 3603. Sher 25 is the bright star at the 1 o'clock position relative to the center of the cluster, between two patches of nebula and with a faint ring surrounding it.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Carina
Right ascension 11h 15m 7.645s[1]
Declination −61° 15′ 17.61″[1]
Apparent magnitude (V) 12.23[2]
Characteristics
Spectral type B1Iab[2]
U−B color index 0.13[3]
B−V color index 1.42[3]
Variable type cLBV[4]
Astrometry
Proper motion (μ) RA: −5.387[1] mas/yr
Dec.: +2.116[1] mas/yr
Parallax (π)0.1560 ± 0.0166 mas[1]
Distance25,000[2] ly
(7,600[2] pc)
Absolute magnitude (MV)−7.8[2]
Details
Mass40±5[5] M☉
Radius54[2] R☉
Luminosity (bolometric)608,000[2] L☉
Surface gravity (log g)2.6[5] cgs
Temperature22,000[2][5] K
Rotational velocity (v sin i)65[4] km/s
Age4[2] Myr
Other designations
Sher 25, NGC 3603-25, NGC 3603 MTT 13, NGC 3603 MDS 5
Database references
SIMBADdata

Sher 25 is a blue supergiant star in the constellation Carina, located approximately 25,000 light years from the Sun in the H II region NGC 3603 of the Milky Way.[6] It is a spectral type B1Iab star with an apparent magnitude of 12.2.[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.[5]

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).[8] The same star was numbered 13 by Melnick, Tapia, and Terlevich[3] (MTT 13) and 5 in a Hubble Space Telescope survey by Moffat, Drissen, and Shara[9] (NGC 3603 MDS 5).

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.[4]

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.[10]

References

  1. 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. 1 2 3 4 5 6 7 8 9 Melena, N. W.; Massey, P.; Morrell, N. I.; Zangari, A. M. (2008). "The Massive Star Content of Ngc 3603". The Astronomical Journal. 135 (3): 878. arXiv:0712.2621. Bibcode:2008AJ....135..878M. doi:10.1088/0004-6256/135/3/878. S2CID 16765414.
  3. 1 2 3 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.
  4. 1 2 3 Smartt, S. J.; Lennon, D. J.; Kudritzki, R. P.; Rosales, F.; Ryans, R. S. I.; Wright, N. (2002). "The evolutionary status of Sher 25 - implications for blue supergiants and the progenitor of SN 1987A". Astronomy and Astrophysics. 391 (3): 979. arXiv:astro-ph/0205242. Bibcode:2002A&A...391..979S. doi:10.1051/0004-6361:20020829. S2CID 14933392.
  5. 1 2 3 4 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. arXiv:0803.4262. Bibcode:2008MNRAS.388.1127H. doi:10.1111/j.1365-2966.2008.13347.x. S2CID 16802111.
  6. ↑ Sher, D. (1965). "Distances of Five Open Cluster Near Eta Carinae". Monthly Notices of the Royal Astronomical Society. 129 (3): 237–262. Bibcode:1965MNRAS.129..237S. doi:10.1093/mnras/129.3.237. ISSN 0035-8711.
  7. ↑ 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: L45. arXiv:astro-ph/9611046. Bibcode:1997ApJ...475L..45B. doi:10.1086/310460. S2CID 18830644.
  8. ↑ Sher, D. (1965). "Distances of five open cluster near Eta Carinae". Monthly Notices of the Royal Astronomical Society. 129 (3): 237. Bibcode:1965MNRAS.129..237S. doi:10.1093/mnras/129.3.237.
  9. ↑ 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. Bibcode:1994ApJ...436..183M. doi:10.1086/174891.
  10. ↑ 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. arXiv:1405.2101. Bibcode:2014MNRAS.442.1483T. doi:10.1093/mnras/stu925. ISSN 0035-8711.
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