Tag: evolution and end stages of stars

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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.

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

During which of the following phases does the core of a massive star have so much gravity that even light can't escape?

  1. Neutron Star

  2. Supernova

  3. White Dwarf

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

Once a black hole has formed, it can continue to grow by absorbing mass from its surroundings. The gravitational force becomes so intense that even light cannot escape from it

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

Why do massive stars have shorter lifespans than average stars?

  1. They are excited to get through their lifecycles faster

  2. They have less steps in their lifecycles

  3. They burn their fuel faster

  4. They have less fuel to burn
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Massive stars live shorter lives than the common small stars because even though they have a larger amount of hydrogen for nuclear reactions, their rate of consuming their fuel is very much greater.