Humason 1-2
| Emission nebula | |
|---|---|
| Planetary nebula | |
| Observation data: J2000 epoch | |
| Right ascension | 21h 33m 08s[1] |
| Declination | 39° 38′ 01″[1] |
| Apparent diameter | 20-25"[2] |
| Constellation | Cygnus |
| Designations | PN G086.5-08.8, PK 86-08.1, VV 267[1] |
Humason 1-2 (Hu 1-2) is a bipolar hourglass shaped planetary nebula.[3] Hu 1-2 was discovered by astronomer Milton L. Humason in October 11, 1920.[4]
The distance of Hu 1-2 has never been confirmed, One study gave a lower limit of ~1.17 kpc, but the galactocentric distance might be ~9 kpc, estimated from ~3.5 kpc.[5] A study identified two bipolar knots moving at velocities greater than 340 kms⁻¹.[6] These knots were found to contain N II and O III emission lines, the N II line seems to get larger when it is further from the central star than the O III line.[7] The N II emission in the knots implies shock-excitation, while the O III emissions are more like irradiation. The kinematical structure of the faint bipolar lobes remains completely unknown, but the lobes have an inclination of ≤10° and a polar expansion velocity of ~150 kms⁻¹, resulting in a lower-limit expansion age of ≤1100 yr. The high abundance of He/H and N/O ratios in the bright inner reigons of Hu 1-2 suggest it is a Type I PN, though analysis found abundances of α elements.[8] Hu 1-2 could be a halo PN, but this is unconfirmed.[9] The nebula is enriched in α elements, especially hydrogen and helium.[10][11]
The NW structure/knot shows O II/O III and He II/Hα ratios than those typically seen in the low-ionization structures and outflows of other PNe.[11]
The central star
[edit]Type I nature of the nebula indicates that the star descended from a massive intermediate-mass progenitor star,[12] or the abundances of α elements may be a result of a formation of a massive PN progenitor from metal-poor materials.[13]
References
[edit]- 1 2 3 "PN Hu 1-2". simbad.cds.unistra.fr.
- ↑ Hajian, Arsen R.; Terzian, Yervant (February 1996). "Planetary Nebulae Expansion Distances: III". Publications of the Astronomical Society of Japan. 108: 258. Bibcode:1996PASP..108..258H. doi:10.1086/133719.
- ↑ Manchado, A.; Guerrero, M. A.; Stanghellini, L. (26–30 August 1997). The IAC morphological catalog of northern Galactic planetary nebulae (1st ed.). Springer Dordrecht. pp. 1–50. doi:10.1007/978-94-011-5244-0. ISBN 978-94-011-5244-0.
- ↑ Hmason, M. L. (1921). "Two New Planetary Nebulae". Publications of the Astronomical Society of the Pacific. 33 (193): 193. Bibcode:1921PASP...33..175H. doi:10.1086/123071.
- ↑ Guerrero, M. A.; Miranda, L. F.; Riera, A.; Blanco, M. (2 April 2012). "The collimated outflows of the planetary nebula Hu 1-2: proper motion and radial velocity measurements". Monthly Notices of the Royal Astronomical Society. 421 (2): 1661–1665. arXiv:1112.5007. Bibcode:2012MNRAS.421.1661M. doi:10.1111/j.1365-2966.2012.20423.x.
- ↑ Miranda, L. F.; Gurrero, M. A.; Blanco, M. (April 2012). "The collimated outflows of the planetary nebula Hu 1-2: proper motion and radial velocity measurements". Monthly Notices of the Royal Astronomical Society. 421 (2): 1661–1665. arXiv:1112.5007. Bibcode:2012MNRAS.421.1661M. doi:10.1111/j.1365-2966.2012.20423.x.
- ↑ Riera, A.; Gurrero, M. A.; Miranda, L. F.; Blanco, M. Planetary Nebulae: An Eye to the Future. International Astronomical Union.
- ↑ Hyung, S.; Pottasch, S. R.; Feibelman, W. A. (October 2004). "Photoionization model analysis of the planetary nebula Hu1-2". Astronomy & Astrophysics. 425: 143–149. Bibcode:2004A&A...425..143H. doi:10.1051/0004-6361:20041005.
- ↑ Howard, J. W.; Henry, R. B. C.; MaCartney, S. (January 1997). "A detailed abundance analysis of nine halo planetary nebulae". Monthly Notices of the Royal Astronomical Society. 284 (2): 456–476. Bibcode:1997MNRAS.284..465H. doi:10.1093/mnras/284.2.465.
- ↑ Barlow, M. J.; Kingdburgh, R. L. (November 1994). "Elemental abundances for a sample of southern galactic planetary nebulae". Monthly Notices of the Royal Astronomical Society. 271 (2): 257–299. Bibcode:1994MNRAS.271..257K. doi:10.1093/mnras/271.2.257.
- 1 2 Hyung, S.; Pottasch, S. R.; Feibelman, W. A. (October 2004). "Photoionization model analysis of the planetary nebula Hu1-2". Astronomy & Astrophysics. 425: 143–149. Bibcode:2004A&A...425..143H. doi:10.1051/0004-6361:20041005.
- ↑ Karakas, A. I.; Van Raai, M. A.; Lugaro, M.; Sterling, N. C.; Dinerstein, H. L. (January 2009). "Nucleosynthesis Predictions for Intermediate-Mass Asymptotic Giant Branch Stars: Comparison to Observations of Type I Planetary Nebulae". The Astrophysical Journal. 690 (2): 1130–1140. arXiv:0809.1456. Bibcode:2009ApJ...690.1130K. doi:10.1088/0004-637X/690/2/1130.
- ↑ Henry, R. B. C.; Milingo, J. B.; Kwitter, K. B.; Souza, S. P. (March 2010). "Alpha Element Abundances in a Large Sample of Galactic Planetary Nebulae". The Astrophysical Journal. 711 (2): 619–630. arXiv:1002.3606. Bibcode:2010ApJ...711..619M. doi:10.1088/0004-637X/711/2/619.