Absolute magnitudes of semiregular variables in the solar vicinity from statistical parallaxes.
Abstract
Absolute magnitudes of SemiRegular and RV Tau variables have been determined from radial velocities and proper motions. I.Photographic absolute magnitudes of Mtype SRab variables vary with spectral type from 0m.0 at about M4 to + 2m.5 at M6 at mean brightness (Fig. 3). 2.Absolute magnitude of Mtype SRa and b variables without emission is a function of period. Mpg at mean and maximum brightness may be expressed asMpg(mean) = 06+39 (logp2o)andMpg(max) = Ol +28 (logp o), where p is the period in days. These variables are fainter than the Miras at a given period (Figs I and 2). 3.SRab variables with p <200 days showing emission lines fall on the extension of the periodabsolute magnitude relation for Mira variables. There is no significant difference between SRab M and SRab Me variables for p> 200 days. 4.The mean absolute magnitude of Ntype semiregular variables has also been determined from differential galactic rotation. The combined mean value is Mpg(max) = + 0m.7 j 0m.4 5.SRd variables have Mpg(mean) =  0m.9 j 0m.4 and Mpg(max) =  Im.7 I 0m.4. 6.RV Tau variables have Mpg(mean) =  0m.5 I o 6 and Mpg(max) =  Im.7 I om.6. The present results have been compared briefly with the absolute magnitudes of similar stars in clusters.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 1973
 DOI:
 10.1093/mnras/165.4.337
 Bibcode:
 1973MNRAS.165..337A