AstroSat discovers new group of stars
The Indian multi-wavelength space observatory AstroSat, launched in September 2015, continues to yield exciting results. Using this observatory, astronomers from Thiruvananthapuram and Mumbai have identified a new population of ultraviolet stars in the globular cluster NGC 2808.
Globular clusters are collections of thousands to millions of stars, moving as one unit. These stars are tightly held together by gravity of the cluster itself, and are believed to have formed together at roughly the same time. Some globular clusters could be among the oldest objects in our Milky Way, which hosts over 150 of them.
NGC 2808 is one of the most massive globular clusters that we know of, and is located at a distance of 47,000 light years from us. This cluster was observed by the team of researchers using the UltraViolet Imaging Telescope (UVIT) on-board AstroSat.
The Milky Way Galaxy
Our galaxy is considered to be a typical spiral galaxy about 75,000 light years in diameter. It is a member of the so-called ‘Local Group’ of about 20 galaxies, which is about 6 million light years in extent and which is dominated at one end by our own galaxy and at the other by the much larger Andromeda galaxy.
- Astrosat is India’s first dedicated multi-wavelength space observatory launched on a PSLV-XL on 28 September 2015.
- It is a multi-wavelength astronomy mission on an IRS-class satellite into a near-Earth, equatorial orbit.
- On board ASTROSAT are five astronomy payloads for simultaneous multi-band observations.
- The assembly is placed on a rotating platform to scan the available sky once every six hours in order to locate transient X-ray sources. They are:
- Twin 38-cm Ultraviolet Imaging Telescopes (UVIT) covering Far-UV to optical bands.
- Large Area Xenon Proportional Counters (LAXPC) covering medium energy X-rays.
- Soft X-ray Telescope (SXT) with conical foil mirrors and X-ray CCD detector
- A Cadmium-Zinc-Telluride coded-mask imager (CZTI)
- A Scanning Sky Monitor (SSM) consisting of three one-dimensional position-sensitive proportional counters with coded masks.