| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquila |
| Right ascension | 19h 10m 21.858s[1] |
| Declination | 09° 05′ 02.53″[1] |
| Characteristics | |
| Spectral type | O2-3.5If*[2] |
| Astrometry | |
| Distance | 36,200 ly (11,100[2] pc) |
| Details[2] | |
| Mass | 130 – 370 M☉ |
| Radius | 55.29[a] R☉ |
| Luminosity | 4,365,000 L☉ |
| Temperature | 35,500 K |
| Other designations | |
TIC 202340617, 2MASS J19102185+0905025 | |
| Database references | |
| SIMBAD | data |
Westerhout 49-2 (W49-2) is a very massive and luminous star in the H II region Westerhout 49. At a mass of 250 solar masses (although with significant uncertainty) and a luminosity of over 4 million L☉, it is one of the most massive and most luminous known stars.[2]
Properties
[edit]Westerhout 49-2 is located within the H II region Westerhout 49, about 11.1 kiloparsecs from the Sun. The star is heavily reddened, by nearly 5 magnitudes in the K band, the most of any star in the region. Westerhout 49-2 is classified as an evolved slash star, with a spectral type of O2-3.5If*. The star is one of the most luminous stars known, with a luminosity of 4,365,000 L☉, and has a temperature of about 35,500 K, corresponding to a radius of over 55 times that of the Sun.[2][a]
Uncertainties
[edit]There is significant uncertainty about Westerhout 49-2's properties. One estimate using mass-luminosity relations finds a mass between 90 and 240 M☉. Its mass is likely higher than the theoretical upper limit of 150 M☉, which means it could be a binary, if x-rays are detected. Westerhout 49-1, 49-2 and 49-12 are all bright x-ray sources, which means they could all be binary stars and their masses would be lower than the predicted mass if they were single stars.[2]
Notes
[edit]- ^ a b Applying the Stefan–Boltzmann law with a nominal solar effective temperature of 5,772 K:
References
[edit]- ^ a b Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
- ^ a b c d e f Wu, Shi-Wei; Bik, Arjan; Bestenlehner, Joachim M.; Henning, Thomas; Pasquali, Anna; Brandner, Wolfgang; Stolte, Andrea (2016-05-01). "The massive stellar population of W49: A spectroscopic survey". Astronomy and Astrophysics. 589: A16. arXiv:1602.05190. Bibcode:2016A&A...589A..16W. doi:10.1051/0004-6361/201527823. ISSN 0004-6361. S2CID 59425112.
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction