IC 4997
 | This article, IC 4997, has recently been created via the Articles for creation process. Please check to see if the reviewer has accidentally left this template after accepting the draft and take appropriate action as necessary.
Reviewer tools: Inform author |
| This article, IC 4997, has recently been created via the Articles for creation process. Please check to see if the reviewer has accidentally left this template after accepting the draft and take appropriate action as necessary.
Reviewer tools: Inform author |
| Emission nebula | |
|---|---|
| Planetary nebula | |
 | |
| Observation data: J2000 epoch | |
| Right ascension | 20h 20m 08.76s[1] |
| Declination | +16° 43′ 53.7″[1] |
| Distance | 14,090 (4,320 pc)[2] ly |
| Apparent magnitude (V) | 11.15[1] |
| Apparent dimensions (V) | 2.7″ x 1.4″ [3] |
| Notable features | Bipolar outflow, Bipolar nebula |
| Designations | IC 4997 PNG 058.3-10.9 |
IC 4997 is a planetary nebula located in the constellation of Sagitta. It was discovered in 1896 by Edward Charles Pickering and Williamina Fleming in 1896,[4] and independently by Gustav Gruss in 1896.[5] This nebula is about 14,000 light-years from Earth.[2] It looks like an ordinary star in smaller telescopes, and only detailed study of its spectrum reveals its nebular characteristics.[6]
Physical Characteristics
IC 4997 is very young and very dense with a very high nebular temperature of around 20,000 K,[7] which is twice those measured in most nebulae. The mean expansion velocity of the nebula seems to be slow at 20 km/s at the outer layer,[6] while it also reaches a maximum expansion velocity of 60 km/s relative to its central star.[7] Its central star has a magnitude of around 14m[6] and a temperature of around 47,000--59 000 K.[8]
The most characteristic feature of IC 4997 is its variability.[9] In the 1960s, there was a sudden change in its spectrum. Variability could be related to the nebula expansion[10] or an episodic smoothly changing stellar wind.[11]
See also
References
- ^ a b c "IC 4997". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved July 4, 2022.
- ^ a b Bailer-Jones, C. A. L.; Rybizki, J.; Fouesneau, M.; Mantelet, G.; Andrae, R. (2018). "Estimating Distance from Parallaxes. IV. Distances to 1.33 Billion Stars in Gaia Data Release 2". The Astronomical Journal. 156 (2): 58. arXiv:1804.10121. Bibcode:2018AJ....156...58B. doi:10.3847/1538-3881/aacb21.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Miranda, Luis F.; Torrelles, Jose M.; Eiroa, Carlos (1996). "The Double-Shell Structure of the Variable Young Planetary Nebula IC 4997". The Astrophysical Journal Letters. 461: L111. Bibcode:1996ApJ...461L.111M. doi:10.1086/310017.
- ^ Pickering, E. C.; Fleming, W. P. (1896). "Harvard College Observatory, circular no. 9. Stars having peculiar spectra". The Astrophysical Journal. 4: 142–143. Bibcode:1896ApJ.....4..142P. doi:10.1086/140257.
- ^ "IC 4997 in Celestial Atlas". cseligman.com.
- ^ a b c "IC 4997, Jim Kaler's STARS". illinois.edu.
- ^ a b Danehkar, A.; Parthasarathy, M. (2022). "Physical conditions and chemical abundances of the variable planetary nebula IC 4997". Monthly Notices of the Royal Astronomical Society. 514 (1): 1217–1230. arXiv:2205.14250. Bibcode:2022MNRAS.514.1217D. doi:10.1093/mnras/stac1364.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Feibelman, W. A.; Hobbs, R. W.; McCracken, C. W.; Brown, L. W. (1979). "Reversal of the [O III] lambda 4363/Hgamma lambda 4340 ratio in the planetary nebula IC 4997". The Astrophysical Journal. 231: 111–114. Bibcode:1979ApJ...231..111F. doi:10.1086/157167.
- ^ Arkhipova, V. P.; Burlak, M. A.; Ikonnikova, N. P.; Komissarova, G. V.; Esipov, V. F.; Shenavrin, V. I. (2020). "Surprising Variability of the Planetary Nebula IC 4997 = QV Sge". Astronomy Letters. 46 (2): 100–119. arXiv:2002.10005. Bibcode:2020AstL...46..100A. doi:10.1134/S1063773720020012.
- ^ Kiser, J.; Daub, C. T. (1982). "Physical variations in the planetary nebula IC 4997". The Astrophysical Journal. 253: 679–681. Bibcode:1982ApJ...253..679K. doi:10.1086/159668.
- ^ Miranda, Luis F.; Torrelles, José M.; Lillo-Box, Jorge (2022). "An episodically variable stellar wind in the planetary nebula IC 4997". Astronomy & Astrophysics. 657: L9. arXiv:2112.13607. Bibcode:2022A&A...657L...9M. doi:10.1051/0004-6361/202142730.
 | This nebula-related article is a stub. You can help Wikipedia by expanding it. |