[vsnet-chat 3510] The difference between Mira and SRa

["Dahm, Michael" <marvin.siriuscorp@planet-interkom.de>]

Hallo!

As byproduct of an investigation of EF Aql I have a question about the
difference between Mira and SRa stars. EF Aql is a red longperiod variable
with a period of 300 days. But the classification is rather difficult.

SRa and Mira stars are red longperiodic variables and the borderline between
them is the amplitude of 2,5 magnitude (mean amplitude or the observed
extrem values?). There is also no definition about the passband but the
amplitude is greater at shorter wavelength and rather small in the infrared.

A further question : Does it make sense do separate between SRa and Mira
stars or do these stars have the same physical parameters except of their
amplitude? I read once that stars evolve up and down the AGB (Lb > SRb > SRa
> Mira > SRa > SRb > Lb and again and again)


Michael Dahm
Email : marvin.siriuscorp@planet-interkom.de
Homepage : www.planet-interkom.de/marvin.siriuscorp/

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