To celebrate a new year, the NASA/ ESA Hubble Space Telescope published a montage of six beautiful galaxy mergers. Each of these fusion systems has been studied as part of the recent HiPEEC survey to examine the rate of new star formation within such systems. These interactions are an important aspect of galaxy evolution and are one of the most spectacular events in the life of a galaxy.
It is during rare mergers that galaxies change dramatically in their appearance and in their star content. These systems are excellent laboratories for detecting the formation of star clusters under extreme physical conditions.
The Milky Way usually form star clusters with masses that are 10 thousand times the mass of our sun. It can not be compared to the masses of galaxies that form in colliding galaxies, which can reach millions of times the mass of our sun.
These dense galaxies are also very bright. 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 host system, as long-term witnesses of merging events in the past.
By studying the six merger combinations shown here, the survey of the Hubble Image Probe of Extreme Environments and Bunches (HiPEEC) investigated how star clusters are affected during collisions by the rapid changes in the rate at which new stars in these galaxies formed is drastically increased.
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This image of NGC 3256 was taken with the Wide Field Camera 3 (WFC3) and the Advanced Camera for Surveys (ACS), both installed on the NASA / ESA Hubble Space Telescope. The galaxy is about 100 million light-years from Earth and is an ideal target for investigating stellar eruptions caused by melting of the galaxy. Credit: ESA / Hubble, NASA
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The galaxy NGC 1614 has a bright optical center and two distinct inner spiral arms that are fairly symmetrical. It also has a spectacular outer structure consisting mainly of a large one-sided curved extension of one of these arms at the bottom right, and a long, almost straight tail that appears from the core and crosses the extended arm to the top right. Credit: NASA, ESA, the Hubble Heritage Team (STScI / AURA) -ESA / Hubble Collaboration and A. Evans (University of Virginia, Charlottesville / NRAO / Stony Brook University)
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NGC 4194 is also known as the Medusa merger. An early galaxy consumed a smaller gaseous system that threw streams of stars and dust into space. These streams, seen rising from the top of the merging galaxy, resemble the meandering serpents that Medusa, a monster in ancient Greek mythology, famously wore on her head in place of hers, giving the object its interesting name. has. The merger of Medusa is about 130 million light-years away in the constellation Ursa Major (The Great Bear). Credit: ESA / Hubble & NASA, A. Adamo
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This system consists of a few galaxies, called IC 694 and NGC 3690, which made a good pass about 700 million years ago. As a result of this interaction, the system has undergone a severe eruption of star formation. In the last fifteen years, six supernovae have appeared in the outer parts of the galaxy, making this system an excellent supernova plant. Credit: NASA, ESA, the Hubble Heritage Team (STScI / AURA) -ESA / Hubble Collaboration and A. Evans (University of Virginia, Charlottesville / NRAO / Stony Brook University)
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NGC 6052, located in the constellation of Hercules, about 230 million light-years away, is a pair of colliding galaxies. They were first discovered in 1784 by William Herschel and were originally classified as a single irregular galaxy because of their strange shape. However, we now know that NGC 6052 actually consists of two galaxies that are colliding. This particular image of NGC 6052 was taken using Hubble’s Wide Field Camera 3. Credit: ESA / Hubble & NASA, A. Adamo et al.
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NGC 34’s outer region lies in the constellation Cetus (the sea monster) and looks almost translucent, spelled with stars and strange crater-like branches. This image shows the galaxy’s bright center, a result of this merging event that created an eruption of new star formation and illuminated the surrounding gas. As the galaxies intertwine and become one, the shape of NGC 34 will look more like that of a peculiar galaxy, without any distinct shape. Credit: ESA / Hubble & NASA, A. Adamo et al.
Hubble’s capabilities have made it possible to solve large star-forming ‘knots’ in numerous compact young star orbits. Hubble’s ultraviolet and near-infrared observations of these systems have been used to deduce star clusters, masses, and extinctions, and to analyze the rate of star formation in these six fusing galaxies.
The HiPEEC study shows that the star cluster populations undergo large and rapid variations in their characteristics, with the most massive clusters formed towards the end of the fusion phase.
Each of the merging systems shown here was previously published by Hubble, as early as 2008 and as recently as October 2020. To celebrate its 18th anniversary in 2008, the Hubble Space Telescope has released a collection of 59 images of merging galaxies , who explore here.
More information
Reference: “Star Clustering in the Most Extreme Environments: Insights from the HiPEEC Survey” 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 en G Östlin, 3 September 2020, Monthly notices from the Royal Astronomical Society.
DOI: 10.1093 / mnras / staa2380
The Hubble Space Telescope is a project of international collaboration between ESA and NASA.
The HiPEEC survey was completed as part of the Hubble Space Telescope Program GO 14066 (PI: A. Adamo). A repository with the final data and catalogs of the study 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.