M101 observed with the WSRT (again)

© Astron

The spiral galaxy M101 belongs to a small and select group of galaxies that are the HI icons of the WSRT. M101 is one of the largest nearby late-type galaxies and, because it is seen fairly face-on, offers one of the most detailed views of the complex structure and kinematics of spiral galaxies. Because of this, it was one of the first galaxies observed with the WSRT in the 21-cm line of atomic hydrogen (Allen, Goss & van Woerden 1973) and over the years, every time the performance of the WSRT improved, the galaxy has been observed again (now five times in total).

The latest observations were done last year. Twenty days of observation were used to cover the entire extent of the galaxy (about 1 degree). Compared to the observations of the early 70's, the new data reveal features that are about hundred times fainter than the weakest HI clouds in the first observations. The main aim of the observations is to study, in the greatest possible detail, the effects of star formation and of gas accretion on the disk of a spiral galaxy. For this purpose, these HI data will be combined with WSRT and LOFAR observations of the (polarised) continuum emission of M101 (also involving George Heald and Sarrvesh Sridhar).

The blue (but less beautiful) version of the poster above won 1st prize in the Astronomy Pretty Poster Pageant (APPP) 2014. This poster I was able to make thanks to the lessons of Jayanne English, who visited ASTRON recently