Canis Major dwarf
|Canis Major dwarf|
|Observation data (J2000 epoch)|
|Right ascension||07h 12m 35.0s|
|Declination||-27° 40′ 00″|
|Apparent dimensions (V)||12 degrees × 12 degrees|
|CMa Dwarf, PGC 5065047|
|See also: Galaxy, List of galaxies|
The Canis Major dwarf galaxy (CMa dwarf) or Canis Major overdensity (CMa overdensity) is a disputed dwarf irregular galaxy in the Local Group. It is in the same part of the sky as the constellation Canis Major.
The Canis Major dwarf is classified as an irregular galaxy. It is now thought to be the closest neighbouring galaxy to our position in the Milky Way. It is about 25,000 light-years away from the Solar System, and 52,000 light-years from the Galactic centre. It has a roughly elliptical shape and is thought to contain as many stars as the Sagittarius dwarf elliptical galaxy, the previous contender for closest galaxy to us.
Discussion[change | change source]
The dwarf was discovered in 2003.
Several studies cast doubts on the true nature of this overdensity. Investigation of the area in 2009 showed only ten RR Lyrae variable stars. This is consistent with the Milky Way's halo and thick disk populations, rather than a separate dwarf spheroidal galaxy.
References[change | change source]
- "NASA/IPAC extragalactic database". Results for Canis Major dwarf. http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=Canis+Major+Dwarf#ObjNo1. Retrieved 2007-03-16.
- "Astronomers find nearest galaxy to the Milky Way". Archived from the original on May 27, 2008. http://web.archive.org/web/20080527020725/http://astro.u-strasbg.fr/images_ri/canm-e.html. Retrieved 2009-09-24.
- Martin N.F. et al (Nov 2003). "A dwarf galaxy remnant in Canis Major: the fossil of an in-plane accretion onto the Milky Way". http://arxiv.org/abs/astro-ph/0311010.
- "Comments on the "Monoceros" affair". Jul 2012. http://arxiv.org/abs/1207.2749.
- "Probing the Canis Major stellar over-density as due to the Galactic warp". July 2004. http://adsabs.harvard.edu/abs/2004A%26A...421L..29M.
- Mateu, Cecilia et al (2009). "No excess of RR Lyrae stars in the Canis Major Overdensity". The Astronomical Journal 37 (5): 4412–23. http://iopscience.iop.org/1538-3881/137/5/4412/article.