NGC 7354

NGC 7354 is a planetary nebula located in the northern circumpolar constellation of Cepheus, at a distance of approximately 5.5 kly from the Sun.[2] It was discovered by German-born astronomer William Herschel on November 3, 1787. John L. E. Dreyer described it as, "a planetary nebula, bright, small, round, pretty gradually a very little brighter middle".[4]

NGC 7354
Emission nebula
Planetary nebula
Hubble Space Telescope image of NGC 7354
Credit: HST/NASA/ESA/Judy Schmidt
Observation data: J2000 epoch
Right ascension22h 40m 19.87387s[1]
Declination+61° 17′ 08.7444″[1]
Distance5,538[2] ly   (1,698 pc)
Apparent dimensions (V)20.0″[2]
ConstellationCepheus
DesignationsPN G107.8+02.3, IRAS 22384+6101, NGC 7354[3]

This nebula is the result of an aging star casting off its outer atmosphere.[5] Overall the nebula is elliptical in form, with a complex interior structure having inner and outer shells, several bright equatorial knots, and two jet-like features near the nebula poles.[6] The rim of the inner shell is ellipsoidal with an aspect ratio of 1.6 and a major axis spanning 30″. The outer shell is more circular, and is approximately 33″ in diameter.[5] The faint outer shell is expanding with a higher velocity than the inner shell, and the knots are moving at the same velocity as the outer shell. The outer shell has an estimated age of 2,500 years, while the inner shell is 1,600 years old.[6]

The morphological features of the nebula may be explained by an interacting binary star system with one of the pair passing through the asymptotic giant branch phase. The jets may be generated by an accretion disk surrounding the resulting white dwarf star.[6]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Stanghellini, Letizia; et al. (2008). "The Magellanic Cloud Calibration of the Galactic Planetary Nebula Distance Scale". The Astrophysical Journal. 689 (1): 194–202. arXiv:0807.1129. Bibcode:2008ApJ...689..194S. doi:10.1086/592395.
  3. "NGC 7354". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-10-09.
  4. Seligman, Courtney. "NGC Objects: NGC 7350 - 7399". Retrieved 2020-10-09.
  5. Phillips, J. P.; et al. (November 2009). "Rings and haloes in the mid-infrared: the planetary nebulae NGC 7354 and NGC 3242". Monthly Notices of the Royal Astronomical Society. 399 (3): 1126–1144. arXiv:0909.1829. Bibcode:2009MNRAS.399.1126P. doi:10.1111/j.1365-2966.2009.15379.x.
  6. Contreras, M. E.; et al. (April 2010). "Observational Study of the Multistructured Planetary Nebula NGC 7354". The Astronomical Journal. 139 (4): 1426–1437. arXiv:1002.0881. Bibcode:2010AJ....139.1426C. doi:10.1088/0004-6256/139/4/1426.
  • Media related to NGC 7354 at Wikimedia Commons
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