Messier 63, Sunflower Galaxy

Messier 63
Messier 63: Sunflower Galaxy in Canes Venatici; 500 mm Cassegrain 3625 mm f/7.2; SBIG STL11K; 120+40+40+40 min LRGB; Bernese Highlands; © 2011 Radek Chromik


This bright galaxy in the constellation of Canes Venaticy was discovered by the French astronomer Pierre Méchain (1744-1804) on June 14, 1779. Méchain was a friend of Charles Messier and worked with him. In Messier's «Catalog Nébuleuses et des Amas D'Étoiles» published in 1784, Messier wrote: «Nebula discovered by M. Méchain in hunting dogs. M. Messier looked for it; it is faint, it has about the same light as the nebula indicated under the number M 59: it does not contain a star, and the slightest light illuminating the wires of the micrometer makes it disappear: there is one nearby 8th magnitude star, which precedes the nebula clockwise. M. Messier reported his position on the map with the route comets from 1779.» [281]

Physical Properties

M 63 is a Hubble-type Sbc spiral galaxy. The designation Sb refers to the inner area where the spiral arms are tightly wound around the core. Sc describes the outer, less tightly wound spiral arms. There are also countless bright H-II regions, i. e. extensive emission nebulae, which are comparable to the Great Orion Nebula in our galaxy. This flaky appearance makes the M 63 the prototype of the so-called flocculent spirals.

Messier 63
Messier 63: Sunflower Galaxy in Canes Venatici; 500/2500 mm Newton + SBIG ST-6; Observatory Bülach; © 1996 Stefan Meister

Infrared observations showed that M 63 essentially has a two-armed spiral structure. Spectroscopic studies indicated a density in the core region of the galaxy that is around 150 times higher than the average value. In addition, a stream of matter emanating from the core was discovered. The gas flows in a westerly direction and spreads in a cone shape. This indicates that the galaxy core is only slightly active.

In May 1971 a type Ia supernova broke out near the core (SN 1971I) and reached a maximum brightness of 12.1 mag. Type Ia supernovae arise in very close binary star systems with mass transfer, one component being a white dwarf. If so much matter has flowed onto the white dwarf that its upper mass limit (1.4 solar masses, Chandrasekhar limit) has been exceeded, it comes to a collapse and if there is enough mass to an explosion, which appears to us as a type Ia supernova. This type of supernovae has a known absolute brightness and is therefore one of the most important means of extragalactic distance determination. Nevertheless, the distance from M 63 is still fraught with a great uncertainty factor. The generally assumed distance is 7 Mpc (23 million light years), although values of 20-40 million light years are also found in the literature. [4, 97]

— 1997, Philipp Reza Heck

«Catalogue of Principal Galaxies (PGC)», Paturel et al. 1989 [144]
DesignationsPGC 46153: NGC 5055, UGC 8334, MCG 7-27-54, M 63, CGCG 217-23
Right Ascension (J2000.0)13h 15m 49.2s
Declination (J2000.0)+42° 02' 05"
Morphological TypeS
Dimensions12.6' x 7.5'
Visual Magnitude9.3 mag
Radial Velocity (HRV)504 km/s
Position Angle105°

How to find a Sunflower?

The galaxy M 63 is located in the constellation Canes Venatici. It lies on the line connecting the stars Cor Caroli (α CVn) and Benetnasch or Alkaid (η UMa), the end star of the drawbar of the Big Dipper. A good third of the way from Cor Caroli you will then encounter the cosmic sunflower with a wide-field eyepiece.

Canes Venatici: Messier 63
Chart Messier 63
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

Visual Observation

Messier 63
Messier 63: Drawing, N top, W right; 200mm-SCT, 68-135fach; © 1997 Philipp Reza Heck

200mm aperture: The first thing you notice is the 'stellar' core of the galaxy. Even weak magnifications (68x) reveal two areas in the galaxy with different surface brightness. The lighter, inner area also has an oval shape and a spiral arm can be seen at its NNE edge. The brightness decreases almost abruptly towards the outer area. Even at 135x magnification, no structures were discernible there. A prominent star is located east of the galaxy. Even though you can't see too many details with a 200 mm telescope, the sunflower galaxy M 63 is an enjoyable sight!

— 1997, Philipp Reza Heck


4«Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System» by Robert Burnham; Dover Publications, Inc.; Voume I: ISBN 0-486-23567-X; Volume II: ISBN 0-486-23568-8; Volume III: ISBN 0-486-23673-0
97Objekte für lange Brennweiten: Die Galaxie M63 von Peter Riepe und Stefan Binnewies; Interstellarum2/96, S.60
144Catalogue of Principal Galaxies (PGC); Paturel G., Fouque P., Bottinelli L., Gouguenheim L.; Astron. Astrophys. Suppl. Ser. 80, 299 (1989); (2021-02-18)
149SkySafari 6 Pro, Simulation Curriculum;
160The STScI Digitized Sky Survey;
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; (2021-02-21)