| dc.description.abstract | In this study, we employ the random forest algorithm to classify Mira variables and investigate their properties in the Magellanic Clouds using the I-band light curves of these stars. Mira variables, as asymptotic giant branch pulsating stars, are well-known for their characteristic long pulsation periods and large amplitudes in optical bands
Our analysis resulted in the classification of the Miras into two distinct groups: regular Miras and non-regular Miras. The non-regular Miras, unlike the regular Miras, exhibited a more complex variation in their light curves, which included a long-term modulation in addition to their primary pulsation periods. Our results confirm the presence of a period-luminosity relation for maximum light, with a smaller dispersion found in the regular oxygen-rich (O-rich) Miras. This relation is deemed to be a valuable tool in future distance scale work and is recommended to be applied accordingly.
In addition to analyzing the multi-band photometry data was also collected for the Miras to enable spectral-energy-distribution (SED) fitting. The results of the SED fitting indi- cated that a significant fraction of dust is present around the non-regular Miras. Given the results of the SED fitting, it is suggested that the presence of dust may account for non-regular Miras.
Furthermore, we performed a systematic analysis to determine and improve the pulsation periods of 1637 known Mira variables in M33. This was accomplished by analyzing gri- band light curves spanning approximately 18 years from several surveys, including the M33 variability survey, Panoramic Survey Telescope and Rapid Response System (Pan- STARRs), Palomar Transient Factory (PTF), intermediate Palomar Transient Factory (iPTF), and Zwicky Transient Facility (ZTF). The results showed that complete optical band light curves are essential for determining the periods of distant Miras. In addition, machine learning techniques were used to classify the Miras into O-rich and C-rich based
on the (J − Ks) period–color plane.
Finally, we derived the distance modulus to M33 using O-rich Miras at maximum light and our improved periods. The distance modulus was found to be 24.67±0.06 mag, which agrees with the recommended value in the literature. This study provides a comprehensive understanding of the Mira variables in M33, and the results of this analysis will be helpful for future research in this field.understanding of the Mira variables in M33, and the results of this analysis will be helpful for future research in this field. | en_US |