Galaxy Messier 94

Messier 94
Messier 94: Galaxy in Canes Venatici; 500 mm Cassegrain 3625 mm f/7.2; SBIG STL11K; 60+20+20+20 min LRGB; Bernese Highlands; © 2011 Radek Chromik

History

M 94 was discovered by Pierre Méchain on March 22, 1781. Charles Messier observed him two nights later and wrote: «Nebula without a star, above the heart of Karl [Cor Caroli], on the parallels of star no. 8, sixth magnitude after Flamsteeed: the center is brilliant and the nebula a bit diffuse. It is like the nebula no. 79 below the hare; but this one is more beautiful and brighter. M. Méchain discovered it on March 22nd, 1781.» [281]

Physical Properties

Messier 94
Messier 94: Central region with starburst ring: Image taken with the Hubble space telescope [215]

M 94 is a spiral galaxy at a distance of 16 million light years. Around the center there is a ring-shaped arrangement of elevated star formation, a so-called starburst ring. The age of these newly formed stars is estimated to be around 10 million years. Due to the strong radiation in this ring, M 94 is classified as Seyfert Type 2. The cause of this ring of star formation is probably a shock wave, which migrates from the center outwards and compresses gas and dust in the outer regions. The gas then collapses into denser clouds until gravity has pulled the gas and dust together and condensed them enough that the temperature and pressure are high enough for nuclear fusion and a star is created.

In addition to the weaker outer ring, two weak spiral arms extend far out into the intergalactic space. Also noteworthy about M 94 is an obvious deficit of dark matter compared to other galaxies. The reason for this is still unknown and is the subject of further research. [196, 215]

«Catalogue of Principal Galaxies (PGC)», Paturel et al. 1989 [144]
DesignationsPGC 43495: NGC 4736, UGC 7996, MCG 7-26-58, M 94, CGCG 216-34, CGCG 217-1, IRAS 12485+4123
Right Ascension (J2000.0)12h 50m 53.5s
Declination (J2000.0)+41° 07' 09"
Morphological TypeS R
Dimensions12.3' x 10.8'
Visual Magnitude8.9 mag
Radial Velocity (HRV)308 km/s
Position Angle105°

Finder Chart

M 94 is located in the constellation Canes Venatici, about three degrees north of the star Cor Caroli (α Canum Venaticorum). The constellation is circumpolar and is highest in the night sky from February to July.

Chart M 94
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

References

144Catalogue of Principal Galaxies (PGC); Paturel G., Fouque P., Bottinelli L., Gouguenheim L.; Astron. Astrophys. Suppl. Ser. 80, 299 (1989); cdsarc.unistra.fr/viz-bin/cat/VII/119 (2021-02-18)
149SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
160The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
196Celestial Atlas by Curtney Seligman; cseligman.com/text/atlas.htm (2020-12-28)
215Explore - The Night Sky | Hubble’s Messier Catalog; nasa.gov/content/goddard/hubble-s-messier-catalog (2020-12-31)
281«Catalogue Nébuleuses et des Amas D'Étoiles» Observées à Paris, par M. Messier, à l'Observatoire de la Marine, hôtel de Clugni, rue des Mathurins. «Connoissance des temps ou connoissance des mouvements célestes, pour l'année bissextile 1784 » Page 227; gallica.bnf.fr/ark:/12148/bpt6k6514280n/f235 (2021-02-21)