A galactic cloud is a vast collection of interstellar gas and dust within a galaxy. These clouds are denser than the average interstellar medium, the material between star systems. They are often described by different names depending on their composition and location.
Types of Galactic Clouds
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Infrared Cirrus: These are giant clouds of interstellar gas and warm dust. They obscure the light of stars behind them, similar to how clouds obscure our view on Earth. [Reference: In a dark clear night you can see our home galaxy the milkyway in the sky. You can notice that there are parts obscured as there would be clouds blocking the light of the stars behind. This are actually giant clouds of interstellar gas and warm dust called infrared cirrus.]
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Interstellar Clouds: This is a general term for any denser-than-average region of the interstellar medium. They are found throughout galaxies and play a crucial role in star formation. [Reference: An interstellar cloud is a denser-than-average region of the interstellar medium, the matter and radiation that exists in the space between the star systems in ...]
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Molecular Clouds: These are dense clouds composed primarily of molecules, like hydrogen. They are the birthplaces of stars. The physical conditions within these clouds can vary significantly depending on their location within the galaxy. [Reference: The physical conditions of the CMZ molecular clouds therefore differ substantially from the rest of the Galaxy. Indeed, the average H2 gas density (∼104 cm−3; ...]
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Clouds in specific galaxies: Galaxies like the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) are themselves often described in terms of their constituent clouds and the star formation processes within them. [References: Nearly 200000 light-years from Earth, the Large Magellanic Cloud, a satellite galaxy of the Milky Way, floats in space, in a long and slow ... We present a new model for the SMC by comparing the kinematics of young, massive stars with the structure of the ISM traced by high-resolution observations.]
Importance of Galactic Clouds
Galactic clouds are not merely obscurations; they are vital components of galactic evolution. They are the sites where stars are born from the collapse of dense regions within these clouds. The ongoing study of galactic clouds helps us understand the processes of star formation, galactic structure, and the evolution of galaxies themselves. Simulations, such as those described in 'Cloud Factory' research, aim to model the complex dynamics of these clouds within galactic environments. [Reference: The 'Cloud Factory' simulations we present here include: a galactic potential with differential rotation in the disc, spiral arms, clustered and random ...]
