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arXiv · 2105.09018

Search for period changes in Mira stars

Roberto Nesci·Gianni Rocchi
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Abstract

We reobserved in the $R_C$ and $i'_{Sloan}$ bands, during the years 2020-2021, seven Mira variables in Cassiopeia, for which historical $i'_{Sloan}$ light curves were available from Asiago Observatory plates taken in the years 1967-84. The aim was to check if any of them had undergone a substantial change in the period or in the light curve shape. Very recent public data form ZTF-DR5 were also used to expand our time base window. A marked color change was detected for all the stars along their variability cycle. The star V890 Cas showed a significant period decrease of 12\% from 483 to 428 days, one of the largest known to date. All the stars, save AV Cas, showed a smaller variation amplitude in the recent CCD data, possibly due to a photometric accuracy higher than that of the photographic plates.

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Roberto Nesci, Gianni Rocchi. 2021-05-19. Search for period changes in Mira stars. https://doi.org/10.5817/oejv2021-0216

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