Cigar Galaxy

Messier 82 (also known as NGC 3034 or the Cigar Galaxy) is the prototypenearby starburst galaxy about 12 million light-years away in the constellation Ursa Major. The starburst galaxy is five times as bright as the whole Milky Way and one hundred times as bright as our galaxy's center.

Messier 81 triggering starburst

Forming a striking pair in small telescopes with nearby spiral M81, M82 is being physically affected by its larger neighbor. Tidal forces caused by gravity have deformed this galaxy, a process that started about 100 million years ago. This interaction has caused star formation to increase 10 fold compared to "normal" galaxies.

Recently, M82 has undergone at least one tidal encounter with M81 resulting in a large amount of gas being funneled into the galaxy's core over the last 200 Myr.The most recent such encounter is thought to have happened around 2–5 × 108 years ago and resulted in a concentrated starburst together with a corresponding marked peak in the cluster age distribution.

Structure

M82 was previously believed to be an irregular galaxy. However, in 2005, two symmetric spiral arms were discovered in the near-infrared (NIR) images of M82. The arms were detected by subtracting an axisymmetric exponential disk from the NIR images.

. Assuming that the northern part of M82 is nearer to us, which most literature assumes, the observed sense of rotation implies trailing arms. Due to M82's high disk surface brightness, nearly edge-on orientation (~80°)with respect to us, and the presence of a complex network of dusty filaments in optical images, the arms were not previously detected.