Context
Researchers from Aryabhatta Research Institute of Observational Sciences found that an unusual supernova SN 2015dj, in 2015,came from 2 stars, one of which wasan extremely rare Wolf-Rayet star.
About the finding
- Study:The study was conducted at the Aryabhatta Research Institute of Observational Sciences (ARIES) in Nainital, which is an autonomous institute under the Department of Science & Technology.
- Scientists calculated the mass of the star that resulted in the supernova along with the geometry of its ejection.
- Origin: They traced the origin of the type 1b supernova, a rare type of supernova to a binary star system.
Wolf-Rayet star
- Wolf-Rayet stars or WR starsare a rare group of stars with unusual spectral signatures.
- They are one of the hottest stars in the universe.
- Their surface temperatures range between 20,000 K and 2,00,000 K.
- These are highly luminous or bright because of the high temperature.
- These stars have shed their outer hydrogen layer.
- Some of the most massive stars known are WR stars and many are at the center of planetary nebulae, ejecting gas and dust into space around it.
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- Binary System: This Binary system (two stars orbiting each other) includes
- A type of massive and rare star called a Wolf-Rayet star witha mass of about 13 to 20 times that of the sun
- another star with a mass much less than that of the sun
Supernova
- It refers to the explosion of a massive star towards the end of its life.
- It is a powerful and luminous phenomenon that can often be brighter than the galaxy in which it is located.
- Types:Supernovae are of two primary types — type 1 and type 2.
- Type 1is without hydrogen absorption lines in their spectra and further categorized as type 1a, type 1b, and type 1c.
- Type 2, contains hydrogen absorption lines.
Subtypes
- Type 1a occurs in a binary star system where one star is a white dwarf that is remained of a supernovathat devours the other star.
- Type 1b and 1c supernovae occur by the collapse of the core of a massive star in itself.
- It also has an absorption line of silicon that 1a lacks.
Formation Process of Supernova
- Layers of gases:A massive star has layers of gas that include hydrogen as the outermost gas, followed by an inner layer of helium, carbon, neon, oxygen, silicon with iron in the core.
- Stars that result in a type 1b supernova typically shed their outermost hydrogen layer while type 1c progenitors also shed the subsequent helium layer.
- As iron accumulates in the core of the star, the process of fusion comes to a stop.
- This also ends the outward pressure from the core of the star which makes it unstable.
- The star then starts to collapse under its gravity and release a thermal shock as a supernova.
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