NGC 6884

NGC 6884 is a planetary nebula^[4] located in the constellation Cygnus, less than a degree to the southwest of the star Ο¹ Cygni.^[5] It lies at a distance of approximately 12.5 kly from the Sun.^[2] The nebula was discovered on May 8, 1883, by American astronomer Edward C. Pickering.^[6]

NGC 6884

Emission nebula
Planetary nebula
Hubble Space Telescope (HST) image of NGC 6884
Observation data: J2000 epoch
Right ascension	20h 10m 23.64012s[1]
Declination	+46° 27′ 39.5478″[1]
Distance	12.5 kly (3.830 kpc)[2] ly
Apparent dimensions (V)	0.127′[2]
Constellation	Cygnus
Physical characteristics
Radius	0.23 ly
Designations	PNG 082.1+07.0[3], NGC 6766[4]
See also: Lists of nebulae

This nebula consists of the cast-off outer atmosphere of an aging star. It is young and compact with a kinematic age of 720 years.^[7] The nebula is point-symmetric with arcs forming an S-shaped inner core;^[8] the shape is likely explained by bipolar outflows with a velocity of 55 km/s.^[7] The core is surrounded by a filamentary ring structure that is inclined at an angle of around 40–45° to the line of sight from the Earth. The core has an overall shape of a prolate ellipsoid with axis ratios of 1.6:1 and is inclined by 40°.^[8] The expansion velocity of the nebula ranges over 19–25 km/s. The central star has a temperature of ~100,000 K^[7] and a class of WN b?.^[3]

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. (December 10, 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. S2CID 119257242.
3. Weidmann, W. A.; Gamen, R. (February 2011). "Central stars of planetary nebulae: New spectral classifications and catalogue". Astronomy and Astrophysics. 526: 16. arXiv:1010.5376. Bibcode:2011A&A...526A...6W. doi:10.1051/0004-6361/200913984. S2CID 118704591. A6.
4. "NGC 6884". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-10-06.
5. Sinnott, Roger W.; Perryman, Michael A. C. (1997). Millennium Star Atlas. Vol. 3. Sky Publishing Corporation and the European Space Agency. p. 1108. ISBN 0-933346-84-0.
6. Seligman, Courtney. "NGC Objects: NGC 6850 - 6899". Retrieved 2020-10-03.
7. Miranda, Luis F.; et al. (March 1999). "Multiwavelength Imaging and Long-Slit Spectroscopy of the Planetary Nebula NGC 6884: The Discovery of a Fast Precessing, Bipolar Collimated Outflow". The Astronomical Journal. 117 (3): 1421–1432. Bibcode:1999AJ....117.1421M. doi:10.1086/300774.
8. Palen, Stacy; et al. (May 2002). "Hubble Space Telescope Expansion Parallaxes of the Planetary Nebulae NGC 6578, NGC 6884, NGC 6891, and IC 2448". The Astronomical Journal. 123 (5): 2666–2675. arXiv:astro-ph/0202003. Bibcode:2002AJ....123.2666P. doi:10.1086/339838. S2CID 119426665.

External links

• Media related to NGC 6884 at Wikimedia Commons