The prevailing evidence suggests that most large-amplitude AGB variables follow the period luminosity ( PL ) relation that has been established for Miras in the LMC and galactic globular clusters .
Hipparcos observations indicate that most Miras in the solar neighbourhood are consistent with such a relation .
There are two groups of stars with luminosities that are apparently greater than the PL relation would predict : ( 1 ) in the LMC and SMC there are large amplitude variables , with long periods , P > 420 days , which are probably undergoing hot bottom burning , but which are very clearly more luminous than the PL relation ( these are visually bright and are likely to be among the first stars discovered in more distant intermediate age populations ) ; ( 2 ) in the solar neighbourhood there are short period , P < 235 days , red stars which are probably more luminous than the PL relation .
Similar short-period red stars , with high luminosities , have not been identified in the Magellanic Clouds .