IC405 Flaming Star Nebula - Auriga

M101 - Galaxie in Ursa Major

  1. © Copyright 2014 by Lieven Persoons

M101 in Ursa Major, also know as the Pinwheel galaxy or NGC5427.
RK 14h 03’ 12” / DEC +54° 21’ 00”
22’ x 22‘ / Vis m9.6 / Abs m: -18.71
Distance: 15.000.000Lj / diam: 900Lj

The Pinwheel Galaxy is a face-on spral galaxy, first discovered by Pierre Méchain on March 27, 1781, and communicated to Charles Messier who verified its position for inclusion in the Messier Catalogue as one of its final entries. M101 is a relatively large galaxy compared to the Milky Way. It has a disk mass on the order of 100 billion solar masses, along with a small bulge of about 3 billion solar masses. Another remarkable property of this galaxy is its huge and extremely bright HII regions (red color on image), of which a total of about 3,000. HII regions usually accompany the enormous clouds of high density molecular hydrogen gas contracting under their own gravitational force where stars form. HII regions are ionized by large numbers of extremely bright and hot young stars. On photographs M101 can be seen to be asymmetrical on one side. It is thought that in the recent past (speaking in galactic terms) M101 underwent a near collision with another galaxy and the associated gravitational tidal forces caused the asymmetry. In addition, this encounter also amplified the density waves in the spiral arms of M101. The amplification of these waves leads to the compression of the interstellar hydrogen gas, which then triggers strong star formation activity.

M101 has five prominent companion galaxies: NGX5204, NGC5474, NGC5477, NGC5585 and Holmberg IV .As stated above, the gravitational interaction between M101 and its satellites may have triggered the formation of the grand design pattern in M101. M101 has also probably distorted the companion galaxy NGC 5474. M101 and its companion galaxies comprise most or possibly all of the M101 Group.
Supernova :
on August 24, 2011, a supernova,SN 2011fe, initially designated PTF 11kly, was discovered in M101. The supernova was visual magnitude 17.2 at discovery and reached magnitude 9.9 at its peak. This was the fourth supernova recorded in M101. The first, SN 1909A, was discovered by Max Wolf in January 1909 and reached magnitude 12.1. SN 1951H reached magnitude 17.5 in September 1951 and SN 1970G reached magnitude 11.5 in January 1970.


General Info

Ursa Major


Image Data

Optics : TMB 152 @ f/8
Mount : 10micron GM2000
Camera : SBig STL11000
Exposures : total, 19h20 - LRGB : 540:220:190:210 (1x1 bin)
Filters : Baader HaRGB 2”
Location : Verclause (France)
Date : 27, 28, 29/02/2012 & 1, 3, 13, 15, 26, 28/03/2012
Comments : First light! Data acquired remotely

Size :