When the star shines:
a) due to the energy of gravitational compression?
b) due to the energy of thermonuclear fusion?
c) due to the energy of radioactive decay?
d) due to thermal energy?
e) due to the neighboring star?
a) At the stage of a protostar. The gas-dust cloud, compressed, radiates in the infrared region of the spectrum.
b) The star emits due to the energy of thermonuclear fusion when it is on the main sequence, in the giant or supergiant stage.
c) Type I supernovae, after the maximum brightness, maintain the glow due to the decay of radioactive nuclides.
d) Due to thermal energy, a white dwarf shines while cooling.
e) In close binary systems, a hot star illuminates the surface of a cooler component
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.