Sh 2-308
Central star
Sh 2-308 surrounds the Wolf–Rayet star EZ Canis Majoris, also designated EZ CMa or WR 6. Its apparent magnitude varies from 6.71 to 6.95. Its spectral type indicates that the star is very hot and luminous. The spectrum shows that it is devoid of hydrogen at the surface. EZ Canis Majoris is expected eventually to explode in a supernova, therefore subsuming the nebula.
Formation
The nebula was formed about 70,000 years ago by the star EZ Canis Majoris throwing off its outer hydrogen layers, revealing inner layers of heavier elements. Fast stellar winds, blowing at 1,700 km/s (3.8 million mph) from this star, create the bubble-shaped nebula as they sweep up slower moving material from an earlier phase of the star's evolution. The hydrogen composing the nebula is ionised by intense ultraviolet radiation. The nebula is approximately 60 light-years across at its widest point.
Observation
The most favorable period for observing the nebula in the night sky is between the months of December and April. Its southern declination makes it easier to observe from the Southern Hemisphere, though it is easily visible from most of the Northern Hemisphere as well. It appears as a faint cloud in photographs taken with high-power amateur instruments, with the help of special filters.
Gallery
-
A portion of Sh 2-308 to the west of EZ Canis Majoris
-
A small portion of Sh 2-308 imaged by the Hubble Space Telescope (up is north-west)
-
Dolphin Head Nebula – SH 2-308. Processed by Jim DeLillo via TelescopeLive One-Click Imaging
References
- ^ "Sh 2-308". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-04-30.
- ^ "Inflating Sh2-308". www.spacetelescope.org. Retrieved 2017-05-22.
- ^ 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.
- ^ "APOD: 2009 April 23 - Sharpless 308". apod.nasa.gov. Retrieved 2017-05-02.
- ^ 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.
- ^ 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.
- ^ Hamann, W.-R.; Gräfener, G.; Liermann, A. (2006). "The Galactic WN stars". Astronomy and Astrophysics. 457 (3): 1015. arXiv:astro-ph/0608078. Bibcode:2006A&A...457.1015H. doi:10.1051/0004-6361:20065052. S2CID 18714731.
- ^ "Hubble Image of the Week - EZ Canis Majoris, Sh2-308". SciTech Daily. 2017-04-17. Retrieved 2017-05-26.
- ^ Toalá, J. A.; Guerrero, M. A.; Ramos-Larios, G.; Guzmán, V. (2015). "WISE morphological study of Wolf-Rayet nebulae". Astronomy & Astrophysics. 578: A66. arXiv:1503.06878. Bibcode:2015A&A...578A..66T. doi:10.1051/0004-6361/201525706. ISSN 0004-6361. S2CID 55776698.
- ^ Hille, Karl (2017-04-21). "Hubble's Cosmic Bubbles". NASA. Retrieved 2017-04-30.
External links
- Sh 2-308 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
- APOD December 20, 2016