Astronomy:Humason 1-2

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Hu 1-2
Emission nebula
Planetary nebula
Observation data: J2000 epoch
Right ascension 21h 33m 08s[1]
Declination39° 38′ 01″[1]
Apparent diameter20-25"[2]
ConstellationCygnus
DesignationsPN G086.5-08.8, PK 86-08.1, VV 267[1]
See also: Lists of nebulae

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]

Characteristics

The distance of Hu 1-2 has never been confirmed, One study gave a lower limit of ~1.17 kpc, although the galactocentric distance might be ~9 kpc, estimated from ~3.5 kpc.[5] The nebula is 8.8° above the plane, corresponding to 150-300 pc. 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 peak further from the central star than the [O III] line.[7] The [N II] emission in the knots implies shock-excitation, whereas the [O III] emissions are more like irradiation. The kinematical structure of the faint bipolar lobes remains completely unknown, but the lobes may 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 of 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

The type I nature of the nebula indicates that the star descended from a massive intermediate-mass progenitor star.[12] Alternatively, the abundances of α elements may be a result of a formation of a massive PN progenitor from metal-poor materials.[13]

References

  1. ↑ 1.0 1.1 1.2 "PN Hu 1-2". https://simbad.cds.unistra.fr/mobile/object.html?object_name=PN%20Hu%201-2. 
  2. ↑ Hajian, Arsen R.; Terzian, Yervant (February 1996). "Planetary Nebulae Expansion Distances: III". Publications of the Astronomical Society of Japan 108: 258. doi:10.1086/133719. Bibcode: 1996PASP..108..258H. https://www.researchgate.net/publication/234502181. 
  3. ↑ Manchado, A.; Guerrero, M. A.; Stanghellini, L. (26–30 August 1997) (in English). 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. https://link.springer.com/book/10.1007/978-94-011-5244-0#page=61. 
  4. ↑ Hmason, M. L. (1921). "Two New Planetary Nebulae". Publications of the Astronomical Society of the Pacific 33 (193): 193. doi:10.1086/123071. Bibcode: 1921PASP...33..175H. https://iopscience.iop.org/article/10.1086/123071. 
  5. ↑ 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. doi:10.1111/j.1365-2966.2012.20423.x. Bibcode: 2012MNRAS.421.1661M. 
  6. ↑ 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. doi:10.1111/j.1365-2966.2012.20423.x. Bibcode: 2012MNRAS.421.1661M. 
  7. ↑ Riera, A.; Gurrero, M. A.; Miranda, L. F.; Blanco, M.. Planetary Nebulae: An Eye to the Future. International Astronomical Union. 
  8. ↑ Hyung, S.; Pottasch, S. R.; Feibelman, W. A. (October 2004). "Photoionization model analysis of the planetary nebula Hu1-2". Astronomy & Astrophysics 425: 143–149. doi:10.1051/0004-6361:20041005. Bibcode: 2004A&A...425..143H. https://ui.adsabs.harvard.edu/abs/2004A%26A...425..143H/abstract. 
  9. ↑ 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. doi:10.1093/mnras/284.2.465. Bibcode: 1997MNRAS.284..465H. 
  10. ↑ 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. doi:10.1093/mnras/271.2.257. Bibcode: 1994MNRAS.271..257K. 
  11. ↑ 11.0 11.1 Hyung, S.; Pottasch, S. R.; Feibelman, W. A. (October 2004). "Photoionization model analysis of the planetary nebula Hu1-2". Astronomy & Astrophysics 425: 143–149. doi:10.1051/0004-6361:20041005. Bibcode: 2004A&A...425..143H. https://ui.adsabs.harvard.edu/abs/2004A%26A...425..143H/abstract. 
  12. ↑ 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. doi:10.1088/0004-637X/690/2/1130. Bibcode: 2009ApJ...690.1130K. https://ui.adsabs.harvard.edu/abs/2009ApJ...690.1130K/abstract. 
  13. ↑ 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. doi:10.1088/0004-637X/711/2/619. Bibcode: 2010ApJ...711..619M. https://ui.adsabs.harvard.edu/abs/2010ApJ...711..619M/abstract. 



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