To celebrate the new year, NASA/ TH Hubble Space Telescope published an installation of six beautiful mergers of galaxies. Each of these fusion systems has been studied as part of a recent HiPEEC study to investigate the rate of star formation in such systems. These interactions are a key aspect of the evolution of galaxies and are one of the most spectacular events in the life of the galaxy.
During rare merging events, galaxies undergo dramatic changes in their appearance and star content. These systems are excellent laboratories for tracking the formation of star clusters in extreme physical conditions.
The Milky Way it usually forms star clusters with masses that are 10,000 times the mass of our Sun. This is not comparable to the masses of star clusters formed in colliding galaxies that can reach the mass of our Sun millions of times.
These dense star systems are also very luminous. Even after the collision, when the resulting galactic system begins to fade into a calmer phase, these very massive star clusters will shine throughout their galaxy as long-term witnesses to past merging events.
By studying the six mergers of galaxies shown here, Hubble’s study of the extreme environment and clusters (HiPEEC) examines how stellar clusters are affected during collisions by rapid changes that dramatically increase the rate at which new stars form in these galaxies.
Hubble’s capabilities made it possible to resolve large star-forming “nodes” in a number of compact young star clusters. Ultraviolet and Hubble’s near-infrared observations of these systems have been used to extract the age, mass, and disappearance of star clusters and to analyze the rate of star formation in these six merging galaxies.
The HiPEEC study reveals that populations of stellar clusters undergo large and rapid variations in their properties, with the most massive clusters forming towards the end of the fusion phase.
Each of the fusion systems shown here was previously published by Hubble back in 2008 and most recently in October 2020. To celebrate its 18th anniversary in 2008, the Hubble Space Telescope released a collection of 59 images of merging galaxies that can be explored here.
Reference: “Formation of star clusters in the most extreme environments: insights from the HiPEEC study” by A Adamo, K Hollyhead, M Messa, JE Ryon, V Bajaj, A Runnholm, S Aalto, D Calzetti, JS Gallagher, MJ Hayes, JMD Kruijssen, S König, SS Larsen, J Melinder, E Sabbi, LJ Smith and G Östlin, 3 September 2020, Monthly notices of the Royal Astronomical Society.
DOI: 10.1093 / mnras / staa2380
The Hubble Space Telescope is a project for international cooperation between ESA and NASA.
The HiPEEC study was completed as part of the Hubble Space Telescope GO 14066 program (PI: A. Adamo). A repository with the final data and catalogs of the survey is available here in the MAST archive.
The international team of astronomers in this study consists of A. Adamo, K. Hollyhead, M. Messa, JE Ryon, V. Bajaj, A. Runholm, A. Aalto, D. Calzeti, JS Gallagher, MJ Hayes, JMD Kruijssen, S. König, SS Larsen, J. Melinder, E. Sabbi, LJ Smith, and G. Östlin.