M74 (NGC 628)
Distance: 32 million Light Years

Right Ascension: 01 : 36.7 (hours : minutes)
Declination: +15 : 47 (degrees : minutes)


M74 is the prototypical Grand Design spiral galaxy. Grand design spirals often have two symmetric large spiral arms. Its inclination from the direct face-on position by just 6 degrees gives earth observers a dramatic view of its two exquisitely symmetric spiral arms. Studies at ultraviolet wavelengths bear evidence of a higher than normal level of star formation over the last 500 million years. The abundant HII regions are related to this recent and prolonged epoch of star formation. In addition to the overall star formation activity M74 also possesses a weak nuclear starburst ring. Rings are believed to have a strong relationship to the presence of a central bar. M74 has a weak oval distortion at its core which although not a full fledged bar, has most likely triggered the formation of the circumnuclear starburst ring.

Supernova SN2002ap was discovered in M74 on January 29th 2002. As one of the nearest supernova events in the last few decades it raised great interest among astronomers. Based on the shape of light curves and variation in color indices, the supernova was classified as a type 1c supernova the result of the core collapse of a massive star at the end of their nuclear burning lifetime (similar to Supernovae types II and Ib). The energy distribution suggests that the progenitor star was a spectral class F5V although no visual evidence of the progenitor has been found in prediscovery images.

Recent observations at X-ray wavelengths revealed a remarkable ultraluminous x-ray source (ULX) within a spiral arm of M74. A ULX can release incredible amounts of x- radiation, 10 to 1000 times the energy released from a neutron star or stellar mass black holes and are believed to arise from accretion disks surrounding an intermediate sized black hole of about 10,000 solar masses. Although quite large, intermediate mass black holes fall short of the multimillion or billion solar mass black holes found within the cores of large spiral galaxies. How can the presence of a black hole of this magnitude located not in the core but within a spiral arm be explained? The answer may lie in the possible cannibalization of a smaller galaxy by M74 in its remote past.