National Astronomical Observatory of Japan

Complete Map of Molecular Gas and Interstellar Dust of M33

| Science

A research group lead by Shinya KOMUGI (NAOJ) and Tomoka TOSAKI (Joetsu University of Education), has succeeded in completing a wide-field, precision map of the materials which give birth to stars in the Triangulum galaxy (M33, distance of 2.7 million light years), one of the closest galaxies to our own Milky Way Galaxy where we live.

The group invested more than one thousand hours of observing time at the Nobeyama 45m radio telescope, and at the 10m ASTE telescope located at an altitude of 4800m in the Chilean Andes of South America, to observe the distribution of molecular gas and interstellar dust in M33. Molecular gas is the main ingredient of stars, while interstellar dust works as the "factory" of molecular gas. The observation of molecular gas accomplished a three-fold improvement in spatial resolution compared to previous studies, whereas the observation of dust became the first of its kind.

Galaxies contain structures called "giant molecular clouds", which can be as massive as one hundred thousand suns and as large as several hundred light years. These giant molecular clouds are important in understanding the mechanism of how stars form. The study succeeded in completing a map of the distribution of molecular gas and interstellar dust over the full extent of M33, an area on the sky corresponding to two full moons. This research, for the first time, revealed the distribution of molecular gas and dust at a precision of individual molecular clouds in a galaxy other than our Milky Way.

The resulting map of gas and dust is expected to give important clues to understanding the questions of how molecular gas is formed and transformed into stars in a galaxy, one of the most outstanding questions of modern astronomy.