Period Analysis of All-Sky Automated Survey for Supernovae (ASAS-SN) Data on Pulsating Red Giants

• Main Authors: Percy, John R, Fenaux, Lucas
• Format: Journal Article
• Language: English
• Published: 08-05-2019
• Subjects: Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.1905.03279

The All-Sky Automated Survey for Supernovae (ASAS-SN) has recently used over
2000 days of data to identify more than 50,000 variable stars, automatically
classify these, determine periods and amplitudes for those that are periodic --
part of a remarkable project to classify 412,000 known variable stars, and
determine their basic properties. This information about the newly-discovered
variables, along with the photometric data is freely available on-line. In this
paper, we analyze ASAS-SN data on two small random samples of pulsating red
giants (PRGs) in detail, and compare our results with those found by ASAS-SN.
For the majority of a sample of 29 mostly semi-regular (SR) PRGs, the ASAS-SN
results are incorrect or incomplete: either the ASAS-SN periods are 2, 3, or 4
times the actual period, or the ASAS-SN period is a "long secondary period"
with a shorter pulsation present, or the star is multi-periodic or otherwise
complex, or the star's data are contaminated by instrumental effects. For
almost all of a sample of 20 of the longest-period Mira stars (period 640 days
or more), the ASAS-SN period is actually 2 or more times the actual period. Our
results are not surprising, given the very complex behavior of PRGs.