Tag: stars

Questions Related to stars

Which of the following sequences correctly describes the stages of life for a low-mass star? 

physics life cycle of stars evolution and end stages of stars the stars stars

  1. red giant, protostar, main-sequence, white dwarf

  2. protostar, main-sequence, red giant, white dwarf

  3. protostar, red giant, main-sequence, white dwarf

  4. protostar, main-sequence, white dwarf, red giant

Show answer
Correct Option: C

Why is iron significant to understanding how a supernova occurs? 

physics life cycle of stars evolution and end stages of stars the stars stars

  1. Iron is the heaviest of all atomic nuclei, and thus no heavier elements can be made.

  2. Supernovae often leave behind neutron stars, which are made mostly of iron.

  3. The fusion of iron into uranium is the reaction that drives a supernova explosion.

  4. Iron cannot release energy either by fission or fusion.

Show answer
Correct Option: D

What happens after a helium flash?

physics life cycle of stars evolution and end stages of stars the stars stars

  1. The core quickly heats up and expands.

  2. The star breaks apart in a violent explosion.

  3. The core suddenly contracts.

  4. The core stops fusing helium.

Show answer
Correct Option: A
Explanation:

A helium flash is a very brief thermal runaway nuclear fusion of large quantities of helium into carbon through the triple-alpha process in the core of low mass stars (between 0.8 solar masses ( M ) and 2.0 M ) during their red giant phase . This results in heating up the core and expansion of the core takes place as a result

How many helium nuclei fuse together when making carbon?

physics life cycle of stars evolution and end stages of stars the stars stars

  1. 2

  2. 3

  3. 4

  4. None of the above

Show answer
Correct Option: B
Explanation:

At sufficiently high temperatures and densities, a 3-body reaction called the triple alpha process can occur: Two helium nuclei ("alpha particles") fuse to form unstable beryllium.

If another helium nucleus can fuse with the beryllium nucleus before it decays, stable carbon is formed along with a gamma ray.

Which of the following stars will certainly end its life in a supernova? 

physics life cycle of stars evolution and end stages of stars the stars stars

  1. the Sun

  2. a red giant star

  3. a 10-solar-mass star

  4. a neutron star

Show answer
Correct Option: C
Explanation:

Supernova being the last stages of a star, will happen only if the mass of the star exceeds the solar mass and hence a 10 solar mass star will have a high probability of becoming a supernova

What is a carbon star? 

physics life cycle of stars evolution and end stages of stars the stars stars

  1. a red giant star whose atmosphere becomes carbon-rich through convection from the core

  2. a star that fuses carbon in its core

  3. another name for a white dwarf, a remnant of a star made mainly of carbon

  4. a star that is made at least 50 percent of carbon

Show answer
Correct Option: A
Explanation:

Due to triple helium process, helium fusion takes place and carbon is formed due to convection from the core

What is a planetary nebula

physics life cycle of stars evolution and end stages of stars the stars stars

  1. a disk of gas surrounding a protostar that may form into planets

  2. what is left of the planets around a star after a low-mass star has ended its life

  3. the expanding shell of gas that is no longer gravitationally held to the remnant of a low-mass star

  4. the molecular cloud from which protostars form

Show answer
Correct Option: C
Explanation:

A ring-shaped gaseous structure formed by an expanding shell of gas round an ageing star is known as nebula

Why does a star grow larger after it exhausts its core hydrogen?

physics life cycle of stars evolution and end stages of stars the stars stars

  1. The outer layers of the star are no longer gravitationally attracted to the core.

  2. Hydrogen fusion in a shell outside the core generates enough thermal pressure to push the upper layers outward.

  3. Helium fusion in the core generates enough thermal pressure to push the upper layers outward.

  4. Helium fusion in a shell outside the core generates enough thermal pressure to push the upper layers outward.

Show answer
Correct Option: A,C

Compared to the star it evolved from, a white dwarf is 

physics life cycle of stars evolution and end stages of stars the stars stars

  1. hotter and brighter.

  2. hotter and dimmer.

  3. cooler and brighter.

  4. cooler and dimmer.

Show answer
Correct Option: B
Explanation:

A star's temperature is only 5,800 K, while a white dwarf has a temperature of 100,000 K. A white dwarf's faint luminosity comes from the emission of stored thermal energy; no fusion takes place in a white dwarf wherein mass is converted to energy. Hence it is dimmer than star

What happens to the core of a star after a planetary nebula occurs? 

physics life cycle of stars evolution and end stages of stars the stars stars

  1. It contracts from a protostar to a main-sequence star.

  2. It breaks apart in a violent explosion.

  3. It becomes a white dwarf.

  4. It becomes a neutron star.

Show answer
Correct Option: C