Tag: stars

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Questions Related to stars

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

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

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice physics life cycle of stars evolution and end stages of stars the stars stars

Why is iron significant to understanding how a supernova occurs? 

  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.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Iron has the highest binding energy per nucleon of any element. Consequently, fusing iron consumes energy rather than releasing it, which removes the outward thermal pressure supporting a massive star's core, leading to gravitational collapse.

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

What happens after a helium flash?

  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.
Reveal answer Fill a bubble to check yourself
A Correct answer
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

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

How many helium nuclei fuse together when making carbon?

  1. 2

  2. 3

  3. 4

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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

  1. the Sun

  2. a red giant star

  3. a 10-solar-mass star

  4. a neutron star
Reveal answer Fill a bubble to check yourself
C Correct answer
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

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

What is a carbon star? 

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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

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

What is a planetary nebula

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

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

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

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

  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.
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Multiple choice physics life cycle of stars evolution and end stages of stars the stars stars

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

  1. hotter and brighter.

  2. hotter and dimmer.

  3. cooler and brighter.

  4. cooler and dimmer.
Reveal answer Fill a bubble to check yourself
B Correct answer
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

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

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

  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.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

After a low-to-medium mass star sheds its outer layers as a planetary nebula, the remaining core, which is no longer undergoing fusion, becomes a dense, hot object known as a white dwarf.