Difference between revisions of "Barnard's loop"
(Created page with "{{Night Sky | image = | designation =Sharpless 276 | rightascension =05<sup>h</sup> 27<sup>m</sup> 30<sup>s</sup><ref name=simbad>[http://simbad.u-strasbg.fr/si...") |
m (→Properties and Structure: sp.) |
||
| (2 intermediate revisions by 2 users not shown) | |||
| Line 1: | Line 1: | ||
{{Night Sky | {{Night Sky | ||
| − | | image = | + | | image =Barnard Loop - Hunter Wilson.jpg |
| designation =Sharpless 276 | | designation =Sharpless 276 | ||
| rightascension =05<sup>h</sup> 27<sup>m</sup> 30<sup>s</sup><ref name=simbad>[http://simbad.u-strasbg.fr/simbad/sim-id?Ident=sh2-276&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id Barnard's Loop] from the [http://simbad.u-strasbg.fr/simbad SIMBAD Astronomical Database]</ref> | | rightascension =05<sup>h</sup> 27<sup>m</sup> 30<sup>s</sup><ref name=simbad>[http://simbad.u-strasbg.fr/simbad/sim-id?Ident=sh2-276&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id Barnard's Loop] from the [http://simbad.u-strasbg.fr/simbad SIMBAD Astronomical Database]</ref> | ||
| Line 17: | Line 17: | ||
==Properties and Structure== | ==Properties and Structure== | ||
| − | At 1,600 [[light year]]s away, the nebula's apparent size of over 20° corresponds to a physical size of at least 582 light years.<ref>By direct calculation using values given here.</ref> The segment that is | + | At 1,600 [[light year]]s away, the nebula's apparent size of over 20° corresponds to a physical size of at least 582 light years.<ref>By direct calculation using values given here.</ref> The segment that is visible is believed to be part of a larger shell of material, with only the easternmost segment being visible in optical light.<ref name=arxiv>O'Dell, C., Ferland, G., Porter, R. and van Hoof, P. (2011). Physical Conditions in Barnard’S Loop, Components of the Orion-Eridanus Bubble, and Implications for the Warm Ionized Medium Component of the Interstellar Medium. ''The Astrophysical Journal'', 733(1), p.9. [https://arxiv.org/abs/1103.2789 arXiv:1103.2789]</ref> The nebula is expanding at around 15-23 km/s.<ref name=arxiv/> The nebula contains several O and B [[Stellar Classifications|type]] [[star]]s. |
Even this nebula may be the inner surface of an even larger nebula that is at least 30 degrees in diameter.<ref>[http://www.daviddarling.info/encyclopedia/B/Barnards_Loop.html Barnard's Loop] from daviddarling.info</ref> As only the inner suface is [[ionization|ionized]], only this is visible. The enveloping nebula would be truly vast and comprise of very hot, low [[density]] [[gas]].<ref name=seds/> Observations of the nebula in [[ultraviolet|ultraviolet light]] have suggested the existence of this larger nebula. | Even this nebula may be the inner surface of an even larger nebula that is at least 30 degrees in diameter.<ref>[http://www.daviddarling.info/encyclopedia/B/Barnards_Loop.html Barnard's Loop] from daviddarling.info</ref> As only the inner suface is [[ionization|ionized]], only this is visible. The enveloping nebula would be truly vast and comprise of very hot, low [[density]] [[gas]].<ref name=seds/> Observations of the nebula in [[ultraviolet|ultraviolet light]] have suggested the existence of this larger nebula. | ||
Latest revision as of 23:13, May 17, 2019
Barnard's loop (Sharpless 276, part of the Orion-Eridanus Bubble) is a diffuse nebula in the constellation of Orion, the hunter.[2] The nebula was discovered by E. E. Barnard in 1895 utilising long exposure photographic methods.[3] However it may have been observed by William Herschel, one of the great nebula discoverers, in February 1786.[2] Unsurprisingly it is therefore far too faint to be observed with the naked eye. The nebula can be seen as a ring of bright gas surrounding Orion's belt. The Orion nebula along with the famous horsehead nebula are situated within Barnard's loop.
| Barnard's loop | |
|---|---|
| |
| Observational Data | |
| Designation | Sharpless 276 |
| Right ascension | 05h 27m 30s[1] |
| Declination | -03° 58′ 00″[1] |
| Constellation | Orion |
| Type of object | Diffuse nebula |
| Dimensions | >20°[2] |
| Astrometry | |
| Distance from Earth | 1,600 ly[2] |
Properties and Structure
At 1,600 light years away, the nebula's apparent size of over 20° corresponds to a physical size of at least 582 light years.[4] The segment that is visible is believed to be part of a larger shell of material, with only the easternmost segment being visible in optical light.[5] The nebula is expanding at around 15-23 km/s.[5] The nebula contains several O and B type stars.
Even this nebula may be the inner surface of an even larger nebula that is at least 30 degrees in diameter.[6] As only the inner suface is ionized, only this is visible. The enveloping nebula would be truly vast and comprise of very hot, low density gas.[2] Observations of the nebula in ultraviolet light have suggested the existence of this larger nebula.
References
- ↑ 1.0 1.1 Barnard's Loop from the SIMBAD Astronomical Database
- ↑ 2.0 2.1 2.2 2.3 2.4 Barnard's loop from messier.seds.org
- ↑ Barnard's Loop Around Orion from apod.nasa.gov
- ↑ By direct calculation using values given here.
- ↑ 5.0 5.1 O'Dell, C., Ferland, G., Porter, R. and van Hoof, P. (2011). Physical Conditions in Barnard’S Loop, Components of the Orion-Eridanus Bubble, and Implications for the Warm Ionized Medium Component of the Interstellar Medium. The Astrophysical Journal, 733(1), p.9. arXiv:1103.2789
- ↑ Barnard's Loop from daviddarling.info