About Astronomical transients:
- Astronomical transients are brief and often dramatic astronomical events that can vary in brightness over relatively short timescales, ranging from fractions of a second to several months or even years.
- Understanding these violent and energetic phenomena helps us learn more about the universe, including the birth and death of stars, the formation of black holes, and the nature of dark matter and dark energy.
Types of Astronomical Transients:
1. Supernovae: When the outer layers of large stars blow up while their cores implode (collapse) because the stars have run out of elements to fuse. Many supernovae have been known to become so bright that they emit light more intensely than the stars in the rest of its host galaxy combined.
- Type Ia Supernovae: These occur in binary systems where a white dwarf accretes material from a companion star until it reaches a critical mass and undergoes a thermonuclear explosion.
- Core-Collapse Supernovae: These result from the collapse of massive stars (greater than 8 solar masses) at the end of their life cycles.
2. Active galactic nucleus (AGN): When the supermassive black hole at the heart of a galaxy is actively accreting material, it is called an Active Galactic Nucleus. As matter spirals inward due to the black hole's gravity, it heats up and releases tremendous energy through friction. This energy is what makes AGNs so luminous and glows with a changing brightness.
3. Fast Radio Bursts (FRBs): Millisecond-duration bursts of radio waves from distant galaxies. Their origin is still a mystery, but they are thought to be associated with highly energetic processes like neutron star mergers or magnetars. They can emit more than 10-times as much energy as the Sun in a few milliseconds.
4. Gamma-Ray Bursts (GRBs):
- Short GRBs: Typically lasting less than 2 seconds, often associated with the merger of compact objects like neutron stars.
- Long GRBs: Lasting more than 2 seconds, usually linked to the collapse of massive stars and associated with supernovae.