Credit: ESA/Hubble & NASA
Acknowledgement: Judy Schmidt
The subject of this NASA/ESA Hubble Space Telescope image is known as
NGC 3597. It is the product of a collision between two good-sized
galaxies, and is slowly evolving to become a giant elliptical galaxy.
This type of galaxy has grown more and more common as the Universe has
evolved, with initially small galaxies merging and progressively
building up into larger galactic structures over time.
NGC 3597 is
located approximately 150 million light-years away in the constellation
of Crater (The Cup). Astronomers study NGC 3597 to learn more about how
elliptical galaxies form — many ellipticals began their lives far
earlier in the history of the Universe. Older ellipticals are nicknamed
“red and dead” by astronomers because these bloated galaxies are not
anymore producing new, bluer, stars in ages, and are thus packed full of
old and redder stellar populations.
Before infirmity sets in,
some freshly formed elliptical galaxies experience a final flush of
youth, as is the case with NGC 3597. Galaxies smashing together pool
their available gas and dust, triggering new rounds of star birth. Some
of this material ends up in dense pockets initially called
proto-globular clusters, dozens of which festoon NGC 3597. These pockets
will go on to collapse and form fully-fledged globular clusters, large spheres that orbit the centres of galaxies like satellites, packed tightly full of millions of stars.
