According to ISRO, this is the most distant Astrosat Picture of the Month so far.
AstroSat, India’s first dedicated multi-wavelength space observatory, has captured an image of a special galaxy cluster that is more than 800 million light-years away from Earth, developed by ISRO.
ASTROSAT observes the universe in the optical, Ultraviolet, low and high energy X-ray regions of the electromagnetic spectrum, whereas most other scientific satellites are capable of observing a narrow range of wavelength band. Multi-wavelength observations of ASTROSAT can be further extended with co-ordinated observations using other spacecraft and ground-based observations. All major astronomy Institutions and some Universities in India are participating in these observations.
The galaxy cluster is made of three separate clusters of galaxies that are all merging with one another to eventually form a single massive cluster in the future.
- Abell 2256 is actually three merging clusters.
- It contains more than 500 galaxies.
- Almost 100 times larger and more than 1,500 times massive as Milky Way.
ISRO says the merger of this extremely well-studied galaxy cluster has produced a rich diversity of structures that have been imaged in radio wavelengths by every radio telescope in the world.
The cluster contains galaxies spread over a large area, astronomers zoomed in on six of these galaxies to capture ultraviolet images. Astronomers used Ultra Violet Imaging Telescope (UVIT), one of the five instruments onboard Astrosat, launched in September 2015, to capture images of these galaxies.
The brightest objects in the full image are stars in our galaxy which happen to lie in the same direction as Abell 2256.
Astronomers explain that galaxy clusters are places where many spiral galaxies transform slowly into lenticular and elliptical galaxies. Spiral galaxies, like our own Milky Way, are bluer in colour and are forming stars constantly. Elliptical and lenticular galaxies, however, are redder and have mainly old stars in them. Abell 2256 is one such galaxy cluster where astronomers believe many galaxies are going through this metamorphosis.
Astronomers watched Abell 2256 for five hours using the UVIT to image these star-forming spiral galaxies, using the ultraviolet light emitted by their hot young stars.
“The fine detail with which the entire galaxy cluster could be imaged out to its edges by UVIT is keeping astronomers busy over the last few months. They are investigating the nature of individual galaxies in Abell 2256. They also hope to understand how these galaxies will transform into lenticular and elliptical galaxies in the future,” the post on the ISRO website said.
Earlier, Astrosat captured images of individual galaxies, two galaxies merging with each other, and even a lone galaxy falling into a cluster of other galaxies.