Pismis 20
Pismis 20 is a compact open cluster in Circinus. It is located at the heart of the Circinus OB1 association in the Norma arm of the Milky Way Galaxy.[2] Pismis 20 is about 3,270 pc away and only about 5 million years old. HD 134959, a blue supergiant variable star also called CX Circinus, is the brightest star in Pismis 20.[3]
| Star name | MV number | Effective temperature | Absolute magnitude | Bolometric magnitude | Mass (M☉) | Spectral type | Ref. |
|---|---|---|---|---|---|---|---|
| WR 67 | 11 | 56000 | -4.03 | -8 | 9 | WN6-w | [4] |
| CX Circinus (HD 134959) | 1 | 20900 | -7.9 | -9.8 | 50 | B2.5Ia | [5] |
| 6 | 42600 | -4.2 | -8.2 | 34 | B | [5] | |
| 2 | 34400 | -5.4 | -8.8 | 34 | O8.5I | [5] | |
| 3 | 28800 | -5.5 | -8.4 | 26 | B0I | [5] | |
| 7 | 30200 | -5 | -8 | 23 | B0III | [5] | |
| 4 | 29500 | -5 | -7.9 | 23 | B0.2III | [5] | |
| 5 | 30200 | -4.5 | -7.5 | 20 | B0III | [5] | |
| Pismis 20 | |
|---|---|
 | |
| Observation data (J2000 epoch) | |
| Right ascension | 15h 15m 23.0s[1] |
| Declination | −59° 04′ 00″[1] |
| Distance | 3,270 pc |
| Physical characteristics | |
| Estimated age | 5×106 years |
| Other designations | VDBH 170, MWSC 2281, C 1511-588, OCl 932 |
| Associations | |
| Constellation | Circinus |
References
- "Pismis 20". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 30 December 2020.
- Turner, David G. (1996). "PISMIS 20 - A Case Study of a Young Cluster". Astronomical Journal. 111: 828. Bibcode:1996AJ....111..828T. doi:10.1086/117829.
- Orsatti, A. M.; Vega, E. I.; Marraco, H. G. (2003). "Pismis 20: One or two clusters?". Astronomy and Astrophysics. 408: 135–140. Bibcode:2003A&A...408..135O. doi:10.1051/0004-6361:20030919 – via 2003A&A...408..135O.
- Sota, A.; Maíz Apellániz, J.; Morrell, N. I.; Barbá, R. H.; Walborn, N. R.; Gamen, R. C.; Arias, J. I.; Alfaro, E. J.; Oskinova, L. M. (2019). "The Galactic WN stars revisited. Impact of Gaia distances on fundamental stellar parameters". Astronomy & Astrophysics. A57: 625. arXiv:1904.04687. Bibcode:2019A&A...625A..57H. doi:10.1051/0004-6361/201834850. S2CID 104292503.
- Massey, P.; Degioia-Eastwood, K.; Waterhouse, E. (2001). "The Progenitor Masses of Wolf-Rayet Stars and Luminous Blue Variables Determined from Cluster Turnoffs. II. Results from 12 Galactic Clusters and OB Associations". The Astronomical Journal. 121 (2): 1050–1070. arXiv:astro-ph/0010654. Bibcode:2001AJ....121.1050M. doi:10.1086/318769. S2CID 53345173.
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