2.2.2 Life Cycle of Stars

• A dark nebula absorbs light from stars behind
• Arrange the stages of protostar formation in the correct order:

  1️⃣ Cloud Compression

  2️⃣ Protostar Formation

  3️⃣ Nuclear Ignition
• Match the atom with its atomic composition:

  Hydrogen ↔️ 1 proton, 0 neutrons

  Helium ↔️ 2 protons, 2 neutrons
• What two atoms combine in hydrogen fusion?

  Hydrogen and helium
• What force balances the inward pull of gravity in main sequence stars?

  Energy from hydrogen fusion
• A supernova is a powerful and luminous stellar explosion
• What type of star is involved in a thermonuclear supernova?

  White dwarf
• Stages in the formation of a protostar

  1️⃣ Gravity causes cloud compression

  2️⃣ Material heats up and forms spinning sphere

  3️⃣ Core temperature reaches fusion threshold

  4️⃣ Nuclear fusion begins
• What is the net product of hydrogen fusion in main sequence stars?

  Helium
• Hydrogen fusion involves combining four hydrogen nuclei into one helium
• What happens to a main sequence star when it exhausts its hydrogen fuel?

  Begins helium fusion
• Core collapse supernovae release more energy than thermonuclear supernovae.
• Match the stellar remnant with its characteristic:

  Neutron Star ↔️ Dense composition of neutrons

  Black Hole ↔️ Infinite density at singularity
• What force causes stars to form within nebulae?

  Gravity
• When the core temperature of a protostar reaches the fusion threshold, hydrogen atoms combine to form helium
• Hydrogen fusion in main sequence stars combines four hydrogen nuclei into one helium nucleus, releasing energy
• Main sequence stars are the most common type of stars in the universe.
• Helium fusion in red giants produces carbon and releases less energy than hydrogen fusion.
• Match the type of supernova with its cause:

  Core Collapse Supernova ↔️ Massive star runs out of fuel

  Thermonuclear Supernova ↔️ White dwarf accretes too much mass
• A nebula is a vast cloud of gas and dust in space
• What marks the birth of a star in protostar formation?

  Nuclear fusion begins
• Helium fusion in red giants releases more energy than hydrogen fusion.

  False
• A supernova is a powerful and luminous stellar explosion
• Neutron stars are composed almost entirely of densely packed neutrons
• Over billions of years, white dwarfs cool and become black
• What is a nebula?

  Vast cloud of gas and dust
• Protostars form within nebulae due to gravitational collapse.
• Main sequence stars, like our Sun, sustain their energy through hydrogen fusion.
• What force does hydrogen fusion balance in main sequence stars to maintain stability?

  Gravity
• Main sequence stars convert hydrogen into helium
• Why does a red giant expand when it switches to helium fusion?

  Energy is insufficient to balance gravity
• What triggers a core collapse supernova?

  Core collapses under gravity
• Dark nebulae absorb light from stars behind them.
• Main sequence stars maintain stability through hydrogen fusion.
• What is the process that converts hydrogen into helium in a star's core called?

  Hydrogen fusion
• Main sequence stars, including our Sun, are sustained by hydrogen fusion.
• Match the type of supernova with its cause:

  Core Collapse Supernova ↔️ Massive stars run out of fuel

  Thermonuclear Supernova ↔️ White dwarf accretes too much mass
• What creates a black hole?

  Collapse of a massive star