[M81, XMM Newton]
Striking ultraviolet image of spiral galaxy M81 from XMM-Newton. The Optical Monitor telescope onboard XMM-Newton has obtained one of the most striking ultraviolet pictures ever taken of the 'LINER' galaxy M81. Strong ultraviolet (UV) emission is a feature of star formation, supernova explosions and the accretion of matter by the supermassive central object.

This spectacular UV picture of the galaxy contains important evidence for the star-formation processes in M81. The image taken by the Optical Monitor is formed from three 1000 second exposures taken with different ultraviolet filters, centred on approximately 2000, 2300 and 2800 angstroms respectively. It covers a region one quarter of a degree square and frames the M81 galaxy which is at least 22 000 light years across. The project is led by Alice Breeveld of the Mullard Space Science Laboratory (MSSL), University College, London.

The coolest regions (those that are bright in the longest wavelength filter) are shown in red. These are concentrated in the central bulge of the galaxy, where most stars are older and less massive, and have reached the ends of their lives. The predominantly red-coloured and brightest point-like objects in the image are foreground stars in our own Galaxy.

The very bright, point-like, white heart revealed by XMM-Newton is the nucleus of the galaxy. The origin of the emission from the nucleus has prompted the 'starburst versus mini-quasar' debate amongst astrophysicists.

An investigation of the processes at work in a LINER galaxy is best made by combining images and spectra in the ultraviolet and X-rays. XMM-Newton is the only observatory with this capability.

The XMM ultraviolet image of M81, taken with the use of three UV filters, has given a M81 picture ten times more detailed than previous UV views, such as the UIT images of M81.

The observation of M81 was carried out in April 2001, using RGS guaranteed time. (MSSL is part of the RGS consortium as well as Optical Monitor principal investigator).

Image data courtesy of Alice Breeveld, Keith Mason (MSSL, United Kingdom) and the XMM-Newton RGS consortium led by A. Brinkman (SRON, the Netherlands).

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    Last Modification: December 23, 2003