New Models Provide Better Understanding of End Stages of Stars Like Our Sun

Sub : Sci

Sec: Space sector

Why in News

Astronomers have made advancements in understanding the final stages of stars like our Sun through improved models for dust behaviour in planetary nebulae. The study, based on observations from the Vainu Bappu Telescope and archival data, offers deeper insights into the formation, evolution, and chemical composition of hydrogen-deficient stars.

What is a Nebula?

A nebula is a vast cloud of gas and dust in space. Nebulae are often the birthplaces of stars, as they contain the materials necessary for star formation.
Types:
- Emission Nebulae: Emit light due to ionized gases.
- Reflection Nebulae: Reflect the light of nearby stars.
- Dark Nebulae: Block the light from stars and other objects behind them.
- Planetary Nebulae: Shells of gas and dust ejected by dying stars in the late stages of their evolution.

What is a Planetary Nebula?

A planetary nebula is a type of nebula formed when a medium or low-mass star (like the Sun) sheds its outer layers after exhausting its nuclear fuel.
Occurs in the final stages of a star’s life cycle when it transitions from a red giant to a white dwarf. The expelled gases form a shell around the stellar remnant.
Some planetary nebulae show characteristics of Wolf-Rayet stars, which display strong mass loss and emissions of ionized helium, carbon, and oxygen.
Characteristics:
- Primarily composed of hydrogen, helium, and other ionized gases.
- The central star of a planetary nebula is often a white dwarf, which is the leftover core of the dying star.
- Planetary nebulae are short-lived (about 10,000 to 20,000 years).

About Wolf-Rayet (WR) Characteristics:

Wolf-Rayet stars are massive, evolved stars that are in the late stages of their life cycle, exhibiting high luminosity and strong stellar winds.
Massive Stars: Typically, 20 times the mass of the Sun or more.
Strong Stellar Winds: WR stars lose mass rapidly due to intense stellar winds.
Hydrogen Deficiency: Unlike normal stars, WR stars are hydrogen-poor and often exhibit helium, carbon, and oxygen at their surfaces.
Emissions: WR stars show strong emission lines of ionized helium, carbon, and oxygen in their spectra.
These stars are the precursors to supernovae, which mark their explosive deaths. Their evolution is key to understanding the late stages of massive stars.

Observational Data and Equipment:

The study used data from the Vainu Bappu Telescope and archived data from the IUE satellite and IRAS satellite.
The astronomers employed the CLOUDY17.3 code, a one-dimensional dusty photo-ionization model, to simulate the data and match the observed characteristics of the nebula.

Vainu Bappu Telescope:

VBT was inaugurated in 1986.
The Vainu Bappu Telescope (VBT) is a prominent optical telescope located at the Vainu Bappu Observatory in Kavalur, Tamil Nadu, India. (at an altitude of 2,360 feet on the Srinivasapur Hills in Kavalur,).
It is one of the largest ground-based telescopes in India and plays a crucial role in astronomical research, particularly in the fields of stellar and galactic astronomy.
The VBT has a 2.3-meter (90-inch) diameter primary mirror, making it one of the largest optical telescopes in India.
The telescope is named after Dr. Vainu Bappu, a renowned Indian astronomer who was instrumental in the establishment of the observatory.