From WIkipedia:
Sh2-308, also designated as Sharpless 308, RCW 11, or LBN 1052,[1] and commonly known as the Dolphin-Head Nebula, is an H II region located near the center of the constellation Canis Major, composed of ionised hydrogen.[2] It is about 8 degrees south of Sirius, the brightest star in the night sky. The nebula is bubble-like and surrounds a Wolf–Rayet star named EZ Canis Majoris. This star is in the brief, pre-supernova phase of its stellar evolution. The nebula is about 4,530 light-years (1,389 parsecs) away from Earth,[3] but some sources indicate that both the star and the nebula are up to 5,870 ly (1,800 pc) away.[4][5] Yet others indicate the nebula is as close as 1,875 ly (575 pc) from Earth.[6]
References
1. "Sh 2-308". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-04-30.
2.^ab "Inflating Sh2-308".
www.spacetelescope.org. Retrieved 2017-05-22.
3.^ van Leeuwen, F. (2007-11-01). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. ISSN 0004-6361. S2CID 18759600.
4.^ "APOD: 2009 April 23 - Sharpless 308". apod.nasa.gov. Retrieved 2017-05-02.
5.^ Morris, P W; Crowther, P A; Houck, J R (2004-06-01). "Spitzer-IRS Sectroscopy of the Prototype Wolf–Rayet star EZ CMa (HD 50896)". arXiv:astro-ph/0406074.
6.^ Burningham, Ben; Naylor, Tim; Jeffries, R. D.; Devey, C. R. (2003-12-01). "On the nature of Collinder 121: insights from the low-mass pre-main sequence". Monthly Notices of the Royal Astronomical Society. 346 (4): 1143–1150. arXiv:astro-ph/0308488. Bibcode:2003MNRAS.346.1143B. doi:10.1111/j.1365-2966.2003.07160.x. ISSN 0035-8711. S2CID 16366019.
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