The inset optical images show the Eagle Nebula and [DBS2003]179, where shining nebulae and newly born star clusters can be seen. Credit: Nagoya University, National Astronomical Observatory of
Japan, NASA, JPL-Caltech, R. Hurt (SSC/Caltech), Robert Gendler, Subaru
Telescope, ESA, The Hubble Heritage Team (STScI/AURA), Hubble
Collaboration, and 2MASS) - Hi-res image
Japanese researchers have found that collisions of gas clouds hovering in space bring about the birth of star clusters.
Stars form by the gravitational contraction of clouds of gas in space
and can have various masses. Massive stars, together with many other
stars, may form a huge star cluster (a group of more than 10,000 stars).
The formation of such a star cluster requires the rapid packing of
enormous amounts of gas and other materials into a small space, but the
mechanism by which this occurs has yet to be clarified.
A research team led by Associate Professor Kengo Tachihara and
Emeritus Professor Yasuo Fukui of Nagoya University focused on a
hypothesis in which multiple gas clouds collide, which allows them to
gather efficiently and thereby form a star cluster. To verify this
hypothesis, the team, in collaboration with researchers from Osaka
Prefecture University and the National Astronomical Observatory of
Japan, conducted observational studies of a vast amount of data obtained
as a result of more than a decade of research, as well as theoretical
studies of numerical simulations with the data. As a result, they found
that collisions of gas clouds hovering in space do, in fact, induce the
birth of a star cluster.
They observed many collisions of gas clouds in our Milky Way Galaxy
and also in other galaxies, suggesting that these collisions are a
universal phenomenon. From this perspective, there is an increasingly
likely possibility that the Milky Way Galaxy collided with other
galaxies soon after its birth, which caused gas clouds in the galaxies
to collide frequently, resulting in the formation of many globular
clusters (groups of more than one million stars). Their findings have
contributed to a deeper understanding of the formation of massive stars
and the birth of globular clusters.
The studies were published in the peer-reviewed journal Publications of the Astronomical Society of Japan in January 2021 as a special issue titled "Star Formation Triggered by Cloud-Cloud Collision Ⅱ," which contains a collection of 20 original papers based on elaborate verifications of individual astronomical bodies, as well as a review paper summarizing the latest understandings of star formation by collisions of gas clouds.
Contact:
Kengo Tachihara
Graduate School of Science, Nagoya University
Email: k.tachihara@a.phys.nagoya-u.ac.jp
