Messier 100 (M100)

Also Known as: NGC 4321

Object Type: Grand Design Spiral Galaxy

Constellation: Coma Berenices

Distance from Earth: 55 million light years

Apparent Magnitude: 10.1

Coordinates: RA 12H 22M 54.9S DEC 15 deg 49 min 21 sec

Actual Size: 107,000 light years in diameter

Apparent Dimensions: 7.4 arc-minutes x 6.3 arc-minutes

Discovered by: M100 was discovered by Pierre Méchain on March 15, 1781, along with the nearby galaxies Messier 98 and Messier 99.
Charles Messier determined the position for the object and added it to his catalogue on April 13, 1781, just before he completed the third and final edition. Messier noted: Nebula without star, of the same light as the preceding [Messier 99], situated in the ear of Virgo.
Seen by Méchain on March 15, 1781. The three nebulae, nos. 98, 99 & 100, are very difficult to recognize, because of the faintness of their light: one can observe them only in good weather, and near their passage of the Meridian.

Description: M100 is a grand-design spiral galaxy and is part of the Virgo Cluster.
It is one of the largest and brightest members of the Virgo Cluster. M100 is a starburst galaxy with strongest burst of star formation concentrated within a ring in the center of the galaxy.
The ring is 2 tightly wound spiral arms connected to a small bar. Star formation has been taking place in this region for at least 500 million years in several bursts.
The galaxy is estimated to contain 400 billion stars. M100 is seen almost face-on. It has 2 prominent spiral arms and several fainter arms. The arms are dotted with star forming regions.
The southern side of the galaxy contains more young stars, giving M100 a slightly asymmetric appearance.
The galaxy is considerably larger than it appears in conventional photographs. Deep images have revealed that a lot of the galaxy’s mass is contained in its fainter outer regions. The ring is in fact two tightly wound spiral arms connected to a small bar with a radius of 1 kiloparsec.
Like most spiral galaxies in the Virgo Cluster, M100 is deficient in neutral hydrogen compared to similar galaxies that are isolated. As a result, M100 is not showing signs of star formation in the rest of the disk. The galaxy is experiencing ram pressure stripping as it moves through the Virgo Cluster and the process is leaving it without gas. Star formation has been taking place in this region for at least 500 million years in several bursts.
M100 has 2 satellite galaxies, NGC 4323 and NGC 4328 connected by a bridge of luminous material.

Click Below Image(s) for Full Size:

Due to low surface brightness, it is difficult to see in small binoculars.
In large binoculars and small telescopes, it appears as a dim patch of light. An 8-inch scope reveals the bright core surrounded by nebulosity.

The best time to observe M100 is March-May.

Platesolve

M100 Spiral Galaxy

Imaging Details
Click to Return to Home Page