Astronomy:NGC 6891
| Nebula | |
|---|---|
| Planetary nebula | |
| File:300px Hubble Space Telescope image of NGC 6891 | |
| Observation data: J2000.0 epoch | |
| Right ascension | 20h 15m 08.84s[1] |
| Declination | +12° 42′ 15.6″[1] |
| Distance | 12,400[2] ly |
| Apparent magnitude (V) | 12.51±0.23[3] |
| Constellation | Delphinus |
| Designations | PN G054.1-12.1, PK 54-12.1, IRAS 20127+1233[1] |
NGC 6891 is a bright, asymmetrical planetary nebula located in the northern constellation of Delphinus.[4][5][6] It was discovered on 22 September 1884, by Scottish astronomer Ralph Copeland, who observed it using visual spectroscopy with a 6.1-inch refractor at the Dun Echt Observatory in Aberdeen, Scotland.[7][1]
Characteristics
NGC 6891 displays a triple-shell structure, consisting of a bright inner nebula, an attached intermediate shell, and a detached outer halo.[8] High-resolution imaging reveals filaments, knots, and intricate details in the interior surrounding the central white dwarf star named HD 192563, along with at least two ellipsoidal shells oriented differently and a spherical outer halo expanding faster than the inner regions.[9] The bright optical regions have an apparent diameter of approximately 15 arcseconds.[7] The nebula shows evidence of multiple mass ejection episodes from its progenitor star.[8][4]
Observation
NGC 6891 has an apparent visual magnitude of around 10.5 to 12 and appears as a small, bluish disc in amateur telescopes of 6 inches (150 mm) aperture or larger, with the central star faintly visible under good conditions.[3] It lies near the celestial equator in Delphinus and is observable from both hemispheres.[6] The nebula has been imaged in detail by the Hubble Space Telescope, contributing to studies of planetary nebula structure, formation, evolution, and distance determination.[4]
Reference
- ↑ 1.0 1.1 1.2 1.3 "Simbad - Object view". https://simbad.cds.unistra.fr/mobile/object.html?object_name=NGC%206891.
- ↑ Stanghellini, Letizia; Shaw, Richard A.; Villaver, Eva (2008). "The Magellanic Cloud Calibration of the Galactic Planetary Nebula Distance Scale" (in en). The Astrophysical Journal 689 (1): 194–202. doi:10.1086/592395. ISSN 0004-637X.
- ↑ 3.0 3.1 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars" (in en). Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361.
- ↑ 4.0 4.1 4.2 "Hubble's View of Planetary Nebula Reveals Complex Structure - NASA Science" (in en-US). 2021-11-29. https://science.nasa.gov/missions/hubble/hubbles-view-of-planetary-nebula-reveals-complex-structure/.
- ↑ Lazaro, Enrico de (2021-11-30). "Hubble Spots Beautiful Planetary Nebula: NGC 6891 | Sci.News" (in en-US). https://www.sci.news/astronomy/hubble-planetary-nebula-ngc-6891-10320.html.
- ↑ 6.0 6.1 "NGC 6891 - Planetary Nebula in Delphinus | TheSkyLive" (in en). https://theskylive.com/sky/deepsky/ngc6891-object.
- ↑ 7.0 7.1 "Planetary Nebula NGC 6891 | Deep⋆Sky Corner" (in en). https://www.deepskycorner.ch/obj/ngc6891.en.php.
- ↑ 8.0 8.1 Guerrero, Martín A.; Miranda, Luis F.; Manchado, Arturo; Vázquez, Roberto (2000). "The triple-shell structure and collimated outflows of the planetary nebula NGC 6891" (in en). Monthly Notices of the Royal Astronomical Society 313 (1): 1–7. doi:10.1046/j.1365-8711.2000.03159.x. ISSN 0035-8711.
- ↑ Palen, Stacy; Balick, Bruce; Hajian, Arsen R.; Terzian, Yervant; Bond, Howard E.; Panagia, Nino (2002). "Hubble Space Telescope Expansion Parallaxes of the Planetary Nebulae NGC 6578, NGC 6884, NGC 6891, and IC 2448" (in en). The Astronomical Journal 123 (5): 2666–2675. doi:10.1086/339838. ISSN 0004-6256.
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