 Very low mass stars , with masses below 0 @.@ 5 M ☉ , are fully convective and distribute helium evenly throughout the whole star while on the main sequence . Therefore , they never undergo shell burning , never become red giants , which cease fusing and become helium white dwarfs and slowly cool after exhausting their hydrogen . However , as the lifetime of 0 @.@ 5 M ☉ stars is longer than the age of the universe , no such star has yet reached the white dwarf stage . 
 Very low mass stars , with masses below 0 @.@ 5 M ☉ , <a href='drop_aux' title='1'><mark>are</mark></a>fully convective and distribute helium evenly throughout the whole star while on the main sequence . Therefore , they never undergo shell burning , never become red giants , which cease fusing and become helium white dwarfs and slowly cool after exhausting their hydrogen . However , as the lifetime of 0 @.@ 5 M ☉ stars is longer than the age of the universe , no such star <a href='been_done' title='2'><mark>has</mark></a> yet reached the white dwarf stage . 
Very low mass stars , wit masses below 0 @.@ 5 M ☉ , fully convective and distribute helium evenly throughout da whole star while on the main sequence . Therefore , they never undergo shell burnin , never become red giants , which cease fusing and become helium white dwarfs and slowly cool after exhausting their hydrogen . However , as tdalifetime of 0 @.@ 5 M ☉ stars is longer den thdage of the universe , no such star done yet reached thedaite dwarf stage .