Molecular clouds and star formation

• Evidence for star formation in molecular clouds
• Why does a cloud collapse?
• The Jeans Mass: WHEN will a cloud collapse?
• A recently discovered GMC in the Milky Way
• For more information

The topic today is how giant clouds of cold molecular hydrogen (H₂) can contribute to the birth of new stars.

Table 1 taken from Ferriere, K. M., Reviews of Modern Physics, 73, 1031 (2001)

Cosmic abundances of the elements

Figure 1 taken from Sahu, Liu, and Liu, Frontiers in Astronomy and Space Sciences, 8, 672893 (2021)

Figure 2 taken from Sahu, Liu, and Liu, Frontiers in Astronomy and Space Sciences, 8, 672893 (2021)

Figure 6a taken from Sahu, Liu, and Liu, Frontiers in Astronomy and Space Sciences, 8, 672893 (2021)

Image courtesy of NASA, ESA, Hubble Space Telescope, J. Hester, P. Scowen (ASU)

A recently discovered GMC in the Milky Way

Figure 2a from Butterfield, Morgan, and Barnes, ApJ 988, 99 (2025)

Figure 8, showing thermal emission from dust, from Butterfield, Morgan, and Barnes, ApJ 988, 99 (2025)

Figure 11, showing temperature of dust, from Butterfield, Morgan, and Barnes, ApJ 988, 99 (2025)

Figure 14 from Butterfield, Morgan, and Barnes, ApJ 988, 99 (2025)

For more information

• Ferriere, K. M., Reviews of Modern Physics, 73, 1031 (2001) is a good review of the ISM
• Discovery of a Giant Molecular Cloud at the Midpoint of the Galactic Bar Dust Lanes: M4.7–0.8 by Butterfield, Morgan and Barnes, ApJ 988, 99 (2025)
• Anatomy of Orion Molecular Clouds—The Astrochemistry Perspective/Approach by Sahu, Liu, and Liu, Frontiers in Astronomy and Space Sciences, 8, 672893 (2021), provides a multiwavelength view of the ISM around the entire constellation of Orion.

Copyright © Michael Richmond. This work is licensed under a Creative Commons License.