Astronomers have captured a stunning image of Centaurus A, a galaxy in close proximity to our own. The portrait—captured with the Dark Energy Camera at the Cerro Tololo Inter-American Observatory, Chile— shows in exceptional detail the Centaurus A's extraordinary features, particularly the lanes of dust around it, which is the result of a collision with another galaxy.
The portrait was obtained by astronomer Monika Soraisam of the University of Illinois at Urbana-Champaign during a long-term monitoring campaign that observed the Centaurus A—the fifth brightest galaxy in the sky—from 2018 to 2021.
Centaurus A lies in the direction of the southern-hemisphere constellation. The fact that the galaxy is so bright, located just over 12 light-years from Earth, and is massive in size, means it has become one of the most widely studied cosmic objects by professional and amateur astronomers alike.
"Centaurus A is the nearest giant elliptical galaxy hosting an active supermassive black hole. It has had recent star formation triggered by a merger with another gas-rich spiral galaxy," Soraisam told Newsweek. "The main driver for our observations of this galaxy is to probe its population of brightness-variable stars."
Because it is the location of a large number of newly formed stars Centaurus A hosts a wide variety of different star types. This includes many whose brightness changes over time, according to Soraisam.
Previous observations of the galaxy have revealed that Centaurus A is host to a number of extraordinary features. These include powerful jets that are launched from its central region at near light speed by a supermassive black hole with a mass 55 million times that of the Sun.
Even though the galaxy has been extensively studied and its most powerful and energetic features have been well-mapped, previous images have failed to capture the curling tendrils of dust and gas that obscure its bright central region in such detail.
Visible within the lanes of dust are red clouds of hydrogen and the faint blue stars within them. This indicates that these tendrils hide regions of intense star-formation.
Researchers believe that these dust lanes and the star-forming regions they partially obscure were both created by a collision and merger with another galaxy that occurred 100 million years ago. This collision is believed to have influenced a number of Centaurus A's other features, as well as contorting it into a distinctive "s" shape.
The two galaxies that merged to form Centaurus A are believed to have been of differing shapes, with one being a massive elliptical galaxy with a long stretched out shape, and the other a much smaller spiral galaxy, similar to our own Milky Way.
Researchers are currently studying how this collision could have influenced the magnetic fields around Centaurus A. It is believed that galactic mergers and their gravitational influence could majorly amplify such magnetic fields and these could in turn influence star formation. This means that galactic mergers, such as this one and one observed recently by the Hubble Space Telescope, could play a significant role in the evolution of the Universe.
The purpose of the three-year program of observations with the Dark Energy Camera, which is mounted on the Víctor M. Blanco 4-meter Telescope, did not concern the galaxy's magnetic fields but was to identify and monitor objects within Centaraus A that vary over long timescales. These include pulsating cool stars, supergiant stars, and clouds of gas and dust called nebulae.
The campaign is a pathfinder mission that will be followed up by the Vera C Rubin Observatory, home to the world's largest digital camera, set to monitor the night sky over the entire southern hemisphere when it begins operations in either late 2022 or early 2023.
"Work is in progress to analyze the time-varying aspects of this data set," said Soraisam. "Ultimately we will use the results from this campaign to form expectations for variability that will be detectable in the upcoming Vera Rubin Observatory's Legacy Survey of Space and Time."
This article has been updated with comment from Monika Soraisam.
