Tag: stars

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

What do astronomers mean when they say that we are all "star stuff"? 

  1. that life would be impossible without energy from the Sun

  2. that life would be possible without energy from the Sun

  3. that the carbon, oxygen, and many elements essential to life were created by nucleosynthesis in stellar cores

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The phrase star stuff refers to the fact that the heavy elements (like carbon, oxygen, and iron) that make up our bodies and the Earth were synthesized through nuclear fusion in the cores of stars and later dispersed into space.

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

The brightness of a star which can be seen from earth is called

  1. absolute magnitude

  2. apparent magnitude

  3. light year

  4. parallax
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Apparent magnitude measures the brightness of a star as observed from Earth. Absolute magnitude measures intrinsic luminosity at a standard distance, while light year is a unit of distance.

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

What is the first stage of a stars life.

  1. Nebula collapsing under itself

  2. Supernova of old star

  3. Planets collapsing

  4. Fusion of atoms
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A star is a luminous globe of gas producing its own heat and light by nuclear reactions (nuclear fusion). They are born from the nebula and consist mostly of hydrogen and helium gas. Surface temperatures range from 2000 C to above 30,000 C, and the corresponding colors from red to blue-white. 

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

What happens during the Main Sequence phase of a star?

  1. Hydrogen atoms are fused into helium atoms

  2. The star explodes and releases energy

  3. Helium atoms are fused into heavy elements

  4. The star is born out of dust and gas
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Main sequence stars fuse hydrogen atoms to form helium atoms in their cores. About 90 percent of the stars in the universe, including the sun, are main sequence stars. 

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

A main sequence star is 

  1. A star that shines steadily due to nuclear fusion

  2. Several stars close together

  3. A star with planets orbiting it

  4. A Nebula that skips a protostar and is instantly turns into a star.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Main sequence stars are in the longest stage of their life cycle, where they fuse hydrogen into helium in their cores. This process releases the energy that makes them shine steadily.

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

What is a Star?

  1. A cloud of particles held together loosely by their own collective gravity

  2. A very big collection of matter, mostly gas compressed to incredible pressure and heat by gravity.

  3. A nuclear explosion caused by a growth of hydrogen onto the surface of a white dwarf star

  4. A ball of gas.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A star is a massive, luminous sphere of plasma held together by its own gravity. The intense pressure and heat at the core are necessary to sustain nuclear fusion.

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

A star in the main sequence will maintain a constant size

  1. as long as its helium supply holds out.

  2. because its tendency to contract is opposed by the pressure of the hot interior.

  3. until it is devoured by black holes.

  4. provided that gravitational collapse does not overwhelm its photosphere.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

All main sequence stars (including the Sun) are in hydrostatic equilibrium. That is, the inward force of gravity, which tends to compress the star, is balanced by the outward force due to the pressure.