<P> After a star has formed , it generates thermal energy in the dense core region through nuclear fusion of hydrogen atoms into helium . During this stage of the star 's lifetime , it is located along the main sequence at a position determined primarily by its mass , but also based upon its chemical composition and other factors . All main - sequence stars are in hydrostatic equilibrium , where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers . The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance . Energy generated at the core makes its way to the surface and is radiated away at the photosphere . The energy is carried by either radiation or convection , with the latter occurring in regions with steeper temperature gradients , higher opacity or both . </P>
<P> After a star has formed , it generates thermal energy in the dense core region through nuclear fusion of hydrogen atoms into helium . During this stage of the star 's lifetime , it is located along the main sequence at a position determined primarily by its mass , but also based upon its chemical composition and other factors . All main - sequence stars are in hydrostatic equilibrium , where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers . The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance . Energy generated at the core makes its way to the surface and is radiated away at the photosphere . The energy is carried by either radiation or convection , with the latter occurring in regions with steeper temperature gradients , higher opacity or both . </P>
an astronomical object that generates energy through nuclear fusion is a
an astronomical object that generates energy through nuclear fusion is a
star
star