Astr111 Photography Projects, Fall 2009

M94-Spiral Galaxy, Kayla Rosendale

Messier-94 is a spiral galaxy. Spiral galaxies have a central concentration of stars known as the bulge and consist of a flat rotating disc containing stars, gas and dust. It was discovered on March 22,1781 by Pierre Mechain and then was catalogued by Charles Messier on March 24. This spiral galaxy is considered a nearby galaxy, along with other nearby galaxies which are called the Canes Venatici Cloud of galaxies. M94 has a large outer ring of extremely hot stars which classifies it as a starburst galaxy. The stars in this outer ring formed relatively recently; within the last ten million years. M94 is known for its extremely bright inner region, and its 2 "waves" of star formation occurring; the inner ring and the outer ring.

The image above shows the extremely bright inner core of the galaxy. The spiral shape is also very evident. Because of the star formation which occurred, the bright outer edges appear bluish because there is so much bright energy there. The inner spiral pattern portrays the bright star formation, and there is another, very faint, ring of star formation occurring around the outer edges of the prominent spiral shape of the galaxy. These arms which form the spiral pattern that we see are caused by a density wave of gas and dust particles. These dense areas promote star formation, and thus the spiral arms are these density waves of stars and of stars being formed. This galaxy is estimated to be about 20 million light years away. The angular size of M94 is about 315 arcseconds wide and 235 arcseconds tall.The linear size is 30,000 light years across.

References:
K.H. Schmidt and T. Boller, 1992. Nearby Galaxies.
<http://www.seds.org/messier/m/m094.htmll>.

Ripples in Galactic Pond, Scientific American. October 2005.
<http://en.wikipedia.org/wiki/Spiral_galaxy>