Pistol Star

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Pistol Star
Pistol star and nebula.jpg
False-color image of the Pistol Star and Pistol Nebula
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]
Spectral type LBV[2]
Apparent magnitude (J) 11.828[1]
Apparent magnitude (H) 8.920[1]
Apparent magnitude (K) 7.291[1]
Variable type cLBV[3]
Radial velocity (Rv) +130[2] km/s
Distance 8,000[4] pc
Mass 27.5[4] M
Radius 306[4] R
Luminosity 1,600,000[4] L
Temperature 11,800[4] K
Metallicity [Fe/H] 0.1[5] dex
Age ~4×106[6] years
Other designations
V4647 Sgr, qF 134, 2MASS J17461524-2850035
Database references

The Pistol Star is a blue hypergiant and is one of the most luminous known stars in the Milky Way Galaxy. 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. 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.


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

The Pistol Star was discovered by the Hubble Space Telescope in the early 1990s by Don Figer, Astronomer while 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,[4] while matching its current properties to an evolutionary model gives a much higher mass (86-92 M).[7]

Early reports suggested that it might be the most luminous star known, being almost 100 million times as luminous as the Sun. Later studies, however, have reduced its estimated luminosity, making it a candidate luminous blue variable about one-third as luminous as the binary star system Eta Carinae.[8] 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.[9]

Luminous stars[edit]

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

Objects in this class have 80 to 150 times the mass of the Sun when on the main sequence, and lifetimes of only a few million years. Unlike ordinary stars, they are strongly affected by the outward pressure of the light that they emit, which blows off massive winds from their outer atmospheres. Besides the Pistol Star, several other objects have been cited as the "most luminous star" in recent years. Almost all of them have been demoted by later, improved studies.[citation needed]

See also[edit]


  1. ^ a b c d e 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. ^ a b c 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): 759–771. doi:10.1086/307927. ISSN 0004-637X. 
  3. ^ Nazé, Y.; Rauw, G.; Hutsemékers, D. (2012). "The first X-ray survey of Galactic luminous blue variables". Astronomy & Astrophysics 538: A47. doi:10.1051/0004-6361/201118040. ISSN 0004-6361. 
  4. ^ a b c d e f 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. arXiv:0809.3185. Bibcode:2009ApJ...691.1816N. doi:10.1088/0004-637X/691/2/1816. 
  5. ^ Bono, G.; Matsunaga, N.; Inno, L.; Lagioia, E. P.; Genovali, K. (2013). "Cosmic Rays in Star-Forming Environments". Cosmic Rays in Star-Forming Environments. Astrophysics and Space Science Proceedings 34: 115. Bibcode:2013ASSP...34..115B. doi:10.1007/978-3-642-35410-6_9. ISBN 978-3-642-35409-0.  |chapter= ignored (help)
  6. ^ 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. 
  7. ^ Yungelson, L. R.; Van Den Heuvel, E. P. J.; Vink, J. S.; Portegies Zwart, S. F.; De Koter, A. (2008). "On the evolution and fate of super-massive stars". Astronomy and Astrophysics 477: 223. doi:10.1051/0004-6361:20078345. 
  8. ^ Humphreys, R.; Stanek, K. (2005). "The Fate of the Most Massive Stars". The Fate of the Most Massive Stars 332. Bibcode:2005ASPC..332.....H. 
  9. ^ Martayan, C.; Blomme, R.; Le Bouquin, J. B.; Merand, A.; Montagnier, G.; Selman, F.; Girard, J.; Fox, A.; Baade, D.; Frémat, Y.; Lobel, A.; Martins, F.; Patru, F.; Rivinius, T.; Sana, H.; Štefl, S.; Zorec, J.; Semaan, T. (2011). "High-angular resolution observations of the Pistol star". Proceedings of the International Astronomical Union 6: 616. doi:10.1017/S1743921311011574. 

External links[edit]