Pistol Star

The Pistol Star is an extremely luminous blue hypergiant star, one of the most luminous and massive known in the Milky Way. It is one of many massive young stars in the Quintuplet cluster in the Galactic Center region. The star owes its name to the shape of the Pistol Nebula, which it illuminates. It is located approximately 25,000 light years from Earth in the direction of Sagittarius. The star has a large mass comparable to the V4998 Sagittarii and a luminosity more than a million times the Sun (L☉). It would be visible to the naked eye as a fourth magnitude star if it were not for the interstellar dust that completely hides it from view in visible light.

Pistol Star

False-color image of the Pistol Star and Pistol Nebula
Credit: HST NICMOS
Observation data
Epoch J2000      Equinox J2000
Constellation Sagittarius
Right ascension 17h 46m 15.3s[1]
Declination −28° 50′ 04″[1]
Apparent magnitude (V) >28[2]
Characteristics
Spectral type LBV[2]
Apparent magnitude (J) 11.828[3]
Apparent magnitude (H) 8.920[1]
Apparent magnitude (K) 7.291[1]
Variable type cLBV[4]
Astrometry
Radial velocity (Rv)+130[2] km/s
Distance7,700[5] pc
Details
Mass27.5[6] M☉
Radius420[7][lower-alpha 1] R☉
Luminosity3,300,000[7][8] L☉
Temperature11,800[6]–12,000[7] K
Metallicity [Fe/H]0.1[9] dex
Age~4[10] Myr
Other designations
V4647 Sgr, qF 134, 2MASS J17461524-2850035
Database references
SIMBADdata

Properties
Quintuplet cluster region, centered on the Pistol Star and its surrounding nebula

The Pistol Star was discovered using the Hubble Space Telescope in the early 1990s by Don Figer, an astronomer at UCLA.

The star is thought to have ejected almost 10 solar masses of material in giant outbursts perhaps 4,000 to 6,000 years ago (as observed from Earth). Its stellar wind is over 10 billion times stronger than the Sun's. Its exact age and future are not known, but it is expected to end in a brilliant supernova or hypernova in 1 to 3 million years. The mass is equally uncertain, thought to have been over 100 times the Sun when initially formed but now considerably less due to extreme mass loss. Modelling the star itself to match its spectrum gives a mass of 27.5 M☉,[6] while matching its current properties to an evolutionary model gives a much higher mass (86–92 M☉).[11] Earlier studies once claimed the Pistol Star as the most massive star known at around 250 M☉.[5]

Later studies have reduced its estimated luminosity making it a candidate luminous blue variable about 1,600,000 L☉ (one-third as luminous as the binary star system Eta Carinae), hence a radius of 306 R☉ based on an effective temperature around 12,000 K,[6] or as high as 3,300,000 L☉, hence a correspondingly radius of 435 R☉.[7][lower-alpha 1][12] Even so, it radiates about as much energy in 20 seconds as the Sun does in a year.

A close point source has been discovered hidden in the surrounding nebulosity, but there has been no confirmation of this being a star or whether it is physically associated.[13]

The Pistol Star is the brightest star in this image of the Quintuplet cluster, just below centre.

See also

Notes
  1. Applying the Stefan-Boltzmann Law with a nominal solar effective temperature of 5,772 K:

References
  1. 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: 0. Bibcode:2003yCat.2246....0C.
  2. Figer, Donald F.; Morris, Mark; Geballe, T. R.; Rich, R. Michael; Serabyn, Eugene; McLean, Ian S.; Puetter, R. C.; Yahil, Amos (1999). "High-Resolution Infrared Imaging and Spectroscopy of the Pistol Nebula: Evidence for Ejection". The Astrophysical Journal. 525 (2): 759. arXiv:astro-ph/9906479. Bibcode:1999ApJ...525..759F. doi:10.1086/307927. S2CID 19404691.
  3. 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.
  4. Nazé, Y.; Rauw, G.; Hutsemékers, D. (2012). "The first X-ray survey of Galactic luminous blue variables". Astronomy & Astrophysics. 538: A47. arXiv:1111.6375. Bibcode:2012A&A...538A..47N. doi:10.1051/0004-6361/201118040. S2CID 43688343.
  5. Martayan, Christophe; Blomme, Ronny; Jean-Baptiste Le Bouquin; Merand, Antoine; Montagnier, Guillaume; Selman, Fernando; Girard, Julien; Fox, Andrew; Baade, Dietrich; Fremat, Yves; Lobel, Alex; Martins, Fabrice; Patru, Fabien; Rivinius, Thomas; Sana, Hugues; Stefl, Stan; Zorec, Jean; Semaan, Thierry (2010). "X-shooter, NACO, and AMBER observations of the LBV Pistol Star \footnote{Based on ESO runs 85.D-0182A, 085.D-0625AC}". arXiv:1010.3344 [astro-ph.SR].
  6. Najarro, F.; Figer, D. F.; Hillier, D. J.; Geballe, T. R.; Kudritzki, R. P. (2009). "Metallicity in the Galactic Center: The Quintuplet Cluster". The Astrophysical Journal. 691 (2): 1816–1827. arXiv:0809.3185. Bibcode:2009ApJ...691.1816N. doi:10.1088/0004-637X/691/2/1816. S2CID 15473563.
  7. Lau, R. M.; Herter, T. L.; Morris, M. R.; Adams, J. D. (2014). "Nature Versus Nurture: Luminous Blue Variable Nebulae in and Near Massive Stellar Clusters at the Galactic Center". The Astrophysical Journal. 785 (2): 120. arXiv:1403.5298. Bibcode:2014ApJ...785..120L. doi:10.1088/0004-637X/785/2/120. S2CID 118447462.
  8. Mauerhan, J. C.; Morris, M. R.; Cotera, A.; Dong, H.; Wang, Q. D.; Stolovy, S. R.; Lang, C.; Glass, I. S. (2010). "Discovery of a Luminous Blue Variable with an Ejection Nebula Near the Quintuplet Cluster". The Astrophysical Journal. 713 (1): L33–L36. arXiv:1002.3379. Bibcode:2010ApJ...713L..33M. doi:10.1088/2041-8205/713/1/L33. S2CID 42696538.
  9. Bono, G.; Matsunaga, N.; Inno, L.; Lagioia, E. P.; Genovali, K. (2013). "Stellar Populations in the Galactic Center". Cosmic Rays in Star-Forming Environments. Astrophysics and Space Science Proceedings. 34: 115–132. arXiv:1304.6211. Bibcode:2013ASSP...34..115B. doi:10.1007/978-3-642-35410-6_9. ISBN 978-3-642-35409-0. S2CID 118491792.
  10. Liermann, A.; Hamann, W.-R.; Oskinova, L. M. (2012). "The Quintuplet cluster. III. Hertzsprung-Russell diagram and cluster age". Astronomy & Astrophysics. 540: A14. arXiv:1203.2435. Bibcode:2012A&A...540A..14L. doi:10.1051/0004-6361/201117534. S2CID 118741449.
  11. Yungelson, L. R.; Van Den Heuvel, E. P. J.; Vink, Jorick S.; Portegies Zwart, S. F.; De Koter, A. (2008). "On the evolution and fate of super-massive stars". Astronomy and Astrophysics. 477 (1): 223–237. arXiv:0710.1181. Bibcode:2008A&A...477..223Y. doi:10.1051/0004-6361:20078345. S2CID 18269577.
  12. Humphreys, R.; Stanek, K. (2005). "The Fate of the Most Massive Stars". The Fate of the Most Massive Stars. 332. Bibcode:2005ASPC..332.....H.
  13. Martayan, Christophe; Blomme, Ronny; Le Bouquin, Jean-Baptiste; Merand, Anthony; Montagnier, Guillaume; Selman, Fernando; Girard, Julien; Fox, Andrew; Baade, Dietrich; Frémat, Yves; Lobel, Alex; Martins, Fabrice; Patru, Fabien; Rivinius, Thomas; Sana, Hugues; Štefl, Stanislas; Zorec, Juan; Semaan, Thierry (2011). "High-angular resolution observations of the Pistol star". Active OB Stars: Structure. 272: 616–617. arXiv:1010.3342. Bibcode:2011IAUS..272..616M. doi:10.1017/S1743921311011574. S2CID 117073391.


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