Take a look at the essential concepts, terms and phenomena of the static and current parts of the UPSC-CSE.

Word: white dwarf

Subject: Science (Space)

(Relevance: High value for foreplay. General questions, as well as conceptual ones, can be asked as in the news due to a phenomenon observed for the first time from “cosmic cannibalism”.)

Why in the news?

—Astronomers have observed for the first time a phenomenon, called, “cosmic cannibalism”, a dead star tears apart its planetary system. A star ends its life so violently that the dead star left behind, called a white dwarf, disrupts an entire planetary system by sucking debris both in and out.

— The white dwarf star consumes rock-metallic and icy matter, both of which are the “ingredients of planets.”

What is a white dwarf?

—A white dwarf forms when a low-mass star like our sun exhausts most of its nuclear fuel. It is usually very dense, weak, and planet-sized. It is the last observable stage in the evolution of low and medium mass stars.

—Compared to our sun, a white dwarf has a similar mass of carbon and oxygen although it is much smaller in size — similar to Earth. White dwarf temperatures can exceed 100,000 Kelvin according to NASA. Despite too high a temperature, white dwarfs have low luminosity because they are small in size.

— Where a star ends up at the end of its life depends on the mass it was born with. Stars that have a lot of mass can end their lives as black holes or neutron stars. A low or medium mass star (with a mass less than about 8 times the mass of our Sun) will become a white dwarf. A typical white dwarf is about as massive as the Sun, but only slightly larger than Earth. This makes white dwarfs one of the densest forms of matter, surpassed only by neutron stars and black holes.

What else do you need to know?

—This case of cosmic cannibalism was diagnosed using archival data from the The Hubble Space Telescope and other NASA observatories.

—Researchers got the results based on analysis of material captured by the atmosphere of the nearby white dwarf star G238-44.

(source: nasa.gov)

Point to ponder: What does the new study confirm about cosmic cannibalism and why do scientists find the research results interesting?

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