Epoch J2000 Equinox J2000
|Right ascension||17h 46m 15.3s|
|Declination||−28° 50′ 04″|
|Apparent magnitude (V)||invisible (4)|
V4647 Sgr, [FMM95] 3 
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.
The Pistol Star was discovered by the Hubble Space Telescope in the early 1990s. 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.
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. Even so, it radiates about as much energy in 20 seconds as does the Sun 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.
Objects in this class have 80 to 150 times the mass of the Sun 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.
- Eta Carinae
- LBV 1806-20
- List of largest stars
- List of most luminous stars
- Quintuplet cluster
- Wolf–Rayet star
- 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.
- SIMBAD: Pistol Star
- Najarro, F. (2005). "The Fate of the Most Massive Stars". "ASP Conference 332". pp. 58–68.
- 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.
|Wikimedia Commons has media related to Pistol Star.|
- NASA Discovery press release, Oct 7, 1997
- Pistol Star Fact Sheet
- Further details on the Pistol Star from hubblesite.org
- "The Pistol Star", Donald F. Figer et al.
- Tim Thompson about the Pistol Star