Hubble Space Telescope Discovers Clusters of Newborn Stars in Galaxy Collisions
In a groundbreaking discovery, NASA’s Hubble Space Telescope has captured images of 12 interacting galaxies, unveiling long tidal tails filled with gas, dust, and stars. These tidal tails have revealed the presence of 425 clusters of newborn stars, each containing up to 1 million blue, newborn stars. This finding challenges the common belief that galaxy collisions lead to destruction rather than creation.
When galaxies collide, a gravitational tug-of-war occurs, causing gas and dust to be drawn out into large streamers. The Hubble Space Telescope’s exceptional vision has allowed scientists to observe clusters of newborn stars along these tidal tails. These clusters form when knots of gas collapse under gravitational forces, resulting in the birth of approximately 1 million stars per cluster. These stunning “string of pearls” features were likely more prevalent in the early universe when galaxy collisions were more frequent.
One example of this phenomenon is galaxy AM 1054-325, which has been distorted into an S-shape from its original pancake-like spiral shape due to the gravitational pull of a neighboring galaxy. As a consequence, clusters of newborn stars have formed along a stretched-out tidal tail, resembling a string of pearls.
Contrary to popular belief, galaxy collisions do not destroy stars. Instead, they trigger the formation of new generations of stars and potentially accompanying planets. The Hubble Space Telescope has now focused on 12 interacting galaxies with long, tadpole-like tidal tails composed of gas, dust, and a multitude of stars. Its sharpness and sensitivity to ultraviolet light have allowed scientists to identify 425 clusters of newborn stars along these tails, resembling strings of holiday lights. Each cluster boasts up to 1 million blue, newborn stars.
The discovery of these star clusters in tidal tails is not entirely new. Astronomers have been aware of their existence for decades. When galaxies interact, gravitational tidal forces pull out long streamers of gas and dust, resulting in these clusters. Two well-known examples are the Antennae and Mice galaxies, which exhibit long, narrow, finger-like projections.
To gain a deeper understanding of these tidal tail star clusters, a team of astronomers combined new observations with archival data to determine their ages and masses. They found that these clusters are remarkably young, only 10 million years old. Furthermore, they appear to be forming at a consistent rate along tails that stretch for thousands of light-years.
Lead author Michael Rodruck of Randolph-Macon College in Ashland, Virginia, expressed surprise at the abundance of young objects in the tails. He stated, “It tells us a lot about cluster formation efficiency. With tidal tails, you will build up new generations of stars that otherwise might not have existed.”
The appearance of these tails resembles a galaxy’s spiral arm being stretched out into space. The outer part of the arm experiences a taffy-like stretching due to the gravitational tug-of-war between interacting galaxies.
Prior to the mergers, the galaxies contained dusty clouds of molecular hydrogen that may have remained inert. However, during the encounters, these clouds collided and compressed, resulting in a firestorm of star birth.
The fate of these star clusters is uncertain. They may remain gravitationally intact and evolve into globular star clusters similar to those orbiting outside the plane of our Milky Way galaxy. Alternatively, they may disperse and form a halo of stars around their host galaxy or become wandering intergalactic stars.
This string-of-pearls star formation may have been more prevalent in the early universe when galaxy collisions occurred more frequently. The nearby galaxies observed by the Hubble Space Telescope serve as proxies for understanding what transpired in the distant past, making them invaluable laboratories for studying cosmic history.
The discovery of these clusters of newborn stars in tidal tails opens up new avenues for research and provides insights into the mechanisms behind star formation. The Hubble Space Telescope continues to revolutionize our understanding of the universe, uncovering hidden wonders and unraveling the mysteries of the cosmos.
The Hubble Space Telescope is a remarkable project of international cooperation between NASA and the European Space Agency (ESA). Managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, the telescope’s science operations are conducted by the Space Telescope Science Institute (STScI) in Baltimore, Maryland. STScI, operated for NASA by the Association of Universities for Research in Astronomy, plays a crucial role in advancing our knowledge of the universe through Hubble and the upcoming James Webb Space Telescope.
