UGC 9749 Ursa minor Dwarf Galaxy

This dwarf spheroidal galaxy is a satellite of our Milk Way galaxy and is approx 220,000 lightyears distant. This class of galaxy is much more diffuse and ill-defined than any other galaxy type, UGC 9749 only being discovered in 1955. The surface brightness is very low at magnitude 17.8, so is only slightly brighter than the floor on detectability imposed by light pollution.

In this image, it is only visible as a slight brightening – the dashes indicate the rough outline. It is only around 1900 x 1200 lightyears in size.

The stars in the galaxy are ancient and were formed over a 2 billion year period early in the universe's history. Such dwarf galaxies are thought to have proportionally much more dark matter than normal galaxies – if dark matter exists of course, as cosmologists have found it to be maddeningly elusive so far. These galaxies may be the relics of the first condensations of normal matter around conglomerations of dark matter.

The image is the result of just under 5h of data capture, over 7 evenings in March-May 2020.

ZWO ASI294MC Pro through an 8-inch Teleskop-Service Ritchey-Chretien reflector.

Date: 24/05/2020

Photographer: Graham Wilcock

UGC 9749 Ursa minor Dwarf Galaxy

This dwarf spheroidal galaxy is a satellite of our Milk Way galaxy and is approx 220,000 lightyears distant. This class of galaxy is much more diffuse and ill-defined than any other galaxy type, UGC 9749 only being discovered in 1955. The surface brightness is very low at magnitude 17.8, so is only slightly brighter than the floor on detectability imposed by light pollution.

In this image, it is only visible as a slight brightening – the dashes indicate the rough outline. It is only around 1900 x 1200 lightyears in size.

The stars in the galaxy are ancient and were formed over a 2 billion year period early in the universe's history. Such dwarf galaxies are thought to have proportionally much more dark matter than normal galaxies – if dark matter exists of course, as cosmologists have found it to be maddeningly elusive so far. These galaxies may be the relics of the first condensations of normal matter around conglomerations of dark matter.

The image is the result of just under 5h of data capture, over 7 evenings in March-May 2020.

ZWO ASI294MC Pro through an 8-inch Teleskop-Service Ritchey-Chretien reflector.

Date: 24/05/2020

Photographer: Graham Wilcock