Anne’s Image of the Day: Spiral Galaxy Messier 61

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July 24, 2013

Messier 61, a barred spiral galaxy in Virgo

Image Credit & Copyright: Robert Gendler (http://www.robgendlerastropics.com)

Messier 61 (also known as NGC 4303) is a very bright barred spiral galaxy of some 100,000 light-years across, located only about 52.5 million light-years away from Earth in the constellation of Virgo (the Virgin), while it is receding from us at about 1566 kilometers per second.

This grand design galaxy spiral (a spiral galaxy with prominent and well-defined spiral arms that extend clearly around the galaxy) is one of the largest members of the Virgo Cluster, a cluster of approximately 1300 (and possibly up to 2000) galaxies held together by gravity. This cluster forms the central region of the Virgo Supercluster (or Local Supercluster), an even bigger gathering of galaxies.

Messier 61 is classified as a starburst galaxy and has an Active Galactic Nucleus. The energy source of an Active Galactic Nucleus is believed to originate in mass accretion by a supermassive black hole within the nucleus of the galaxy. Messier 61 probably has a supermassive black hole with a mass around 5 million times that of our Sun on its center.

In this image, its spiral arms can be seen in stunning detail, swirling inwards to the very center of the galaxy, where they form a smaller, intensely bright spiral. In the outer regions, these vast arms are sprinkled with bright blue regions where new stars are being formed from hot, dense clouds of gas. The high star formation across Messier 61′s disk is perhaps due to interactions with her satellite galaxies NGC 4292 and NGC 4303B.

The intensely bright spiral is a nuclear starburst ring some 730 light years from the nucleus, formed by several massive star-forming regions which contain massive hot stars with an age range between 5 and 25 million years old. The starburst ring may be associated with a second bar much smaller than the main one of this galaxy.

Six supernovae have been observed in this galaxy: SN 2008in; SN 2006ov; SN 1999gn; SN 1964F; SN 1961I; SN 1926A. All have been found to be of Type II, except for SN 1964F, which was a Type I supernova. This total places Messier 61 in the top handful of galaxies alongside Messier 83, also with six, and NGC 6946, with a total of nine observed supernovae.

This image was acquired from Moorook Obervatory, Australia (an affiliation of New Mexico Skies), the image data were acquired by Ryan Hannahoe and the image was processed by Robert Gendler.

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