Astronomy:Humason 2-1
| Emission nebula | |
|---|---|
| Planetary nebula | |
| File:Humason 2-1.png Image of Hu 2-1 seen in narrowband filters F658N & F656N | |
| Observation data: J2000 epoch | |
| Right ascension | 18h 49m 47.6s[1] |
| Declination | 20° 50′ 39″[1] |
| Apparent diameter | ~3"[2] |
| Constellation | Hercules |
| Designations | PN G051.4+09.6, PK 051+09 1[1] |
Humason 2-1 (Hu 2-1) is a bipolar planetary nebula. It has an elongated shape. This nebula has a radius of ~4.5 pc. The nebula was named after astronomer Milton Lassel Humason. It was discovered on June 23, 1992 at the Mount Wilson Observatory in California.[3]
Characteristics
Humason 2-1 has an angular radius of ~0.4[4] which corresponds to a liner radius of ~4.5 10-3 pc, assuming a distance of 2.35 kpc.[5]The expansion velocity of Hu 2-1 is approximately 10-15 km s-1.[6] Relatively speaking, the nebula has a electron density of ~10⁴ cm-3.[7] And a rather high 5-GHz temperature of 5GHz of ~3455 K.The structure of Hu 2-1, as revealed by VLA radio continuum observations,[8] displays an elongated shape with a major axis oriented at position angle (PA) of ~320°. And ~230°, and a small ring close to the central star has a major axis of ~0.7" long and a PA of 135°
The central star
The central star of Hu 2-1 has a temperature of ~25-40 10³ K and also has a luminosity of ~11.5 10³ L.[9] Placing it at the beginning of the PNe evolutionary tracks on the H-R diagram. The axisymmetric structure of Hu 2-1 may be caused by the interaction of a binary companion with the primary stars envelope during the common envelope (CE) evolution.[10] The moderate density between the equatorial and polar reigons may indicate that the progenitor star evolved to a late AGB stage before entering the CE phase.[11]
References
- ↑ 1.0 1.1 1.2 "PN G051.4+09.6". https://simbad.cds.unistra.fr/mobile/object.html?object_name=%09PN%20G051.4%2B09.6.
- ↑ "Humason 2-1, a 3" planetary nebula in Hercules". https://www.cloudynights.com/forums/topic/629959-humason-2-1-a-3-planetary-nebula-in-hercules/.
- ↑ Humason, M.L. (23 June 1992). "A New Planetary Nebula" (in English). The Astronomical Society of the Pacific (IOP Publishing) 34 (201): 296a–296. doi:10.1086/123227. ISSN 1538-3873. https://iopscience.iop.org/article/10.1086/123227/meta.
- ↑ Kowk, S. (January 1985). "High-resolution radio observations of compact planetary nebulae". The Astronomical Journal 90: 49. doi:10.1086/113707. https://www.researchgate.net/publication/234055404.
- ↑ Martin, W. (January 1994). "Extinction-distances to planetary nebulae.". Astronomy & Astrophysics 281: 526–535. Bibcode: 1994A&A...281..526M. https://ui.adsabs.harvard.edu/abs/1994A%26A...281..526M/abstract.
- ↑ Tamura, S.; Katsunori, M.; Shibata, M. (November 1990). "Expansion Analyses on Low-Excitation Nebulae with Stellar Images". Publications of the Astronomical Society of Japan 102: 1301. doi:10.1086/132764. Bibcode: 1990PASP..102.1301T. https://ui.adsabs.harvard.edu/abs/1990PASP..102.1301T/abstract.
- ↑ Stanghellini, L.; Kaler, J. B. (July 1989). "Electron densities in planetary nebulae". The Astrophysical Journal 343: 811. doi:10.1086/167751. https://www.researchgate.net/publication/234281526.
- ↑ Aaquist, O. B.; Kowk, S. (1990). "August 1990". Astronomy & Astrophysics 84: 229. Bibcode: 1990A&AS...84..229A. https://ui.adsabs.harvard.edu/abs/1990A%26AS...84..229A/abstract.
- ↑ Kaler, J. B.; Jacoby, G. H. (April 1991). "Central star temperatures of low-excitation planetary nebulae". The Astrophysical Journal 372: 215. doi:10.1086/169967. https://www.researchgate.net/publication/234251908.
- ↑ Livio, M.; Soker (May 1989). "Interacting winds and the shaping of planetary nebulae". The Astrophysical Journal 339: 268. doi:10.1086/167294. https://www.researchgate.net/publication/23622984.
- ↑ Livio, M.; Bond, H. E. (June 1990). "Morphologies of Planetary Nebulae Ejected by Close-Binary Nuclei". The Astrophysical Journal 355: 568. doi:10.1086/168789. Bibcode: 1990ApJ...355..568B. https://ui.adsabs.harvard.edu/abs/1990ApJ...355..568B/abstract.
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