Messier 33, also known as the Pinwheel or Triangulum Galaxy, is the third-largest
galaxy in the Local Group, after Messier 31 and the Milky Way.
It provides a unique laboratory for the study of star formation.
Nearly all the star formation in the modern Universe occurs in large,
cold clouds of molecular hydrogen known as Giant Molecular Clouds
(GMCs). Typical GMCs are nearly a million times as massive as the sun
and are frequently seen to be the formation site of large stellar
clusters and high mass stars. The intense winds and radiation from
newly-formed high mass stars ultimately destroys the parent GMC,
returning the clouds material to the diffuse interstellar medium. Using
the 45-meter radio telescope in Nobeyama, Japan in conjunction with the
BIMA millimeter interferometer in Hat Creek, California, scientists at
the CfA have studied GMCs in Messier 33. This study has revealed
how the ongoing star formation
changes the galactic environment. In addition, the study also
demonstrates that the different parts of the galaxy have different types
of molecular clouds. This variation will control the numbers and types
of stars and star clusters formed in the galaxy. In turn, the
differences in the newly formed stars will be ultimately responsible for
a galaxy's evolution over its lifetime.
High Resolution Molecular Gas Maps of M33 .pdf
The Giant Molecular Clouds (GMCs) in M33 are shown as blue dots
with the size of the dot representing the mass of the molecular cloud.
The background (red) emission traces gas ionized by young, massive stars
that were formed in GMCs and is therefore the hallmark of recent star
formation. GMCs are often seen associated with young, massive stars in
the center of M33, but there are fewer GMCs in the outer portions of the
galaxy. Photo Credit: CO (Rosolowsky et al. 2007), Ha (Massey et al. 2006)
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