M101: the Pinwheel Galaxy


The Pinwheel Galaxy (also known as Messier 101M101 or NGC 5457) is a face-on spiral galaxy distanced 21 million light-years (sixmegaparsecs) away in the constellation Ursa Major, 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. On August 24, 2011, a Type Ia supernova, SN 2011fe, was discovered in M101.

M101 is a relatively large galaxy compared to the Milky Way. With a diameter of 170,000 light-years it is seventy percent larger than 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 H II regions, of which a total of about 3,000 can be seen on photographs. H II regions usually accompany the enormous clouds of high density molecular hydrogen gas contracting under their own gravitational force where stars form. H II regions are ionized by large numbers of extremely bright and hot young stars.

Imaging telescopes or lenses: Explore Scientific ED102 APO
Imaging cameras: QSI 583 wsg
Mounts: Astro-Physics Mach 1 GTO
Guiding telescopes or lenses: Explore Scientific ED102 APO
Guiding cameras: SX Lodestar
Software: Maxim DL 5 MaximDL 5, Pleiades Astrophoto Pixinsight 1.8, Adobe Photoshop 6 CS
Filters: Astrodon LRGB CCD Imaging Filters (E-Series), Gen2

Autor: Daniele Malleo

AstroPhotography of the day by SPONLI

23 January 2014

We select the best works of amateur astrophotographers with details of equipment, shooting processing etc.