Sh 2-155
| Emission nebula | |
|---|---|
 Sh2–155 | |
| Observation data: J2000.0 epoch | |
| Right ascension | 22h 57m 17.14s |
| Declination | +62° 28′ 33.4" |
| Distance | 2400 ly |
| Apparent magnitude (V) | 7.7 |
| Apparent dimensions (V) | 50.0'x30.0' |
| Constellation | Cepheus |
| Physical characteristics | |
| Radius | 35 ly |
| Absolute magnitude (V) | 16 |
| Designations | Sh2-155, Caldwell 9 |
Sh2-155[1] (old designation S 155), also tentatively known as the Cave Nebula, is a faint and diffuse bright nebula within a larger nebula complex containing emission, reflection, and dark nebulosity. It is in the constellation Cepheus.
Sh2-155 was first noted as an galactic emission in 1959 in the extended edition of the Sharpless catalogue[2], being a part of the much larger Cep III Association.[2] Although telescopically very faint, some of Sh-155's structure may be seen visually through a moderately sized telescope under dark skies.[3][4] Radiation pressure exerted from a nearby O-type star may be triggering star formation in this nebula.[5]
Other name designations
The proposed name "Cave Nebula" was coined by Patrick Moore, presumably derived from photographic images showing a curved arc of emission nebulosity corresponding to a cave mouth.[6] The name "Cave Nebula" is used for another reflection nebula in Cepheus known as Ced 201,[7] or VdB 152,[8] positioned at R.A.: 22h 13m 27s Dec.: +70° 15′ 18″ (2000). Its common name is a recent invention, which has only come into vogue mostly through the creation of the Caldwell catalogue[9] as object Caldwell 9. SIMBAD does not recognise the name "Cave Nebula" for Sh2-155, but does in the case of Ced 201.[1][7]
References
- ^ a b "Sh2-155 – SIMBAD". simbad.u-strasbg.fr. Retrieved 11 March 2017.
- ^ a b Sharpless, S. (1959). "A Catalogue of H II Regions". Astrophysical Journal Supplement. 4: 257. Bibcode:1959ApJS....4..257S. doi:10.1086/190049. Retrieved 9 March 2017.
- ^ Patrick Moore (1990). The Amateur Astronomer (11th ed), W.W. Norton & Company, ISBN 0-393-02864-X
- ^ Trusock, T. (11 March 2017). "The Caldwell Objects – Deep Sky Companions" (PDF).
- ^ Chen; et al. (2010). "Radiation-driven implosion in the Cepheus B molecular cloud". Research in Astronomy and Astrophysics. 10: 777. arXiv:1004.5171. Bibcode:2010RAA....10..777C. doi:10.1088/1674-4527/10/8/007.
{{cite journal}}: Explicit use of et al. in:|last2=(help) - ^ Mobberley, M. (9 March 2017). "The Caldwell Objects and How to Observe Them".
- ^ a b "Ced 201 – SIMBAD". simbad.u-strasbg.fr. Retrieved 11 March 2017.
- ^ "APOD: 2012 October 31 - VdB 152: A Ghost in Cepheus". apod.nasa.gov. Retrieved 11 March 2017.
- ^ O'Meara, Stephen James (2002). The Caldwell Objects. Cambridge University Press. ISBN 978-0-521-82796-6.
External links
- Sh 2-155 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
- The Scale of the Universe (Astronomy Picture of the Day 2012 March 12)
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