Dark Energy Camera Captures Galaxies in Lopsided Tug of War, a Prelude to Merger
Galaxies grow and evolve over billions of years by absorbing nearby companions and merging with other galaxies. The early stages of this galactic growth process are showcased in a new image taken with the US Department of Energy’s (DOE) Dark Energy Camera (DECam) mounted on the National Science Foundation’s (NSF) Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO), a Program of NSF’s NOIRLab.
The massive barred spiral galaxy NGC 1532, also known as Haley’s Coronet, is located about 55 million light-years away in the direction of the southern constellation Eridanus (the river). Its sweeping spiral arms are seen edge-on from Earth, with the nearer arm dipping downward and the receding arm lurching upward as it tugs upon its smaller, dwarf companion galaxy NGC 1531. These gravitationally bound galaxies will eventually become one, as NGC 1532 completely consumes its smaller companion.
Despite its small stature, however, the dwarf galaxy has also been
exerting a noticeable gravitational influence on its larger companion,
distorting one of its spiral arms, which can be seen rising above the
galactic plane. Additionally, plumes of gas and dust can be seen between
the two galaxies, like a bridge of stellar matter held in place by the
competing tidal forces. This interaction has also triggered bursts of
star formation within both galaxies.
This lopsided cosmic tug of war is a snapshot of how large galaxies
grow and evolve by devouring smaller galaxies, absorbing their stars and
star-forming material. A similar process has happened in the Milky Way,
possibly six times in the past, leaving vast streams of stars and other signs in the halo of the Milky Way.
The process of absorbing a smaller companion galaxy is starkly
different from the cataclysmic merger of two spiral galaxies of
comparable size. In the latter case, two massive galaxies collide to
form an entirely distinct galaxy with its own shape and characteristics.
This type of galactic merger will happen to the Milky Way when it
merges with the Andromeda Galaxy four billion years from now.
DECam, with its unparalleled wide-field imaging capabilities, gives
astronomers highly detailed views of these large-scale galactic
interactions. It also has the remarkable sensitivity, with the help of
the 4-meter Blanco telescope, needed to detect faint objects in our
Solar System and to trace the influence of dark matter on galaxies
across the visible Universe. Currently, DECam is used for programs
covering a wide range of science.
More Information
Links
- Photos of the Víctor M. Blanco 4-meter Telescope
- Videos of the Víctor M. Blanco 4-meter Telescope
- Photos of DECam
Contacts:
Charles Blue
NSF’s NOIRLab
Tel: +1 202-236-6324
Email: charles.blue@noirlab.edu
Josie Fenske
NSF's NIORLab
Email: josie.fenske@noirlab.edu
