Light and colour variations of mira variables in the small magellanic cloud

Yoshifusa Ita, John W. Menzies, Patricia A. Whitelock, Noriyuki Matsunaga, Masaki Takayama, Yoshikazu Nakada, Toshihiko Tanabé, Michael W. Feast, Takahiro Nagayama

Research output: Contribution to journalArticlepeer-review

Abstract

The goal of this paper is to characterize the light variation properties of Mira variables in the Small Magellanic Cloud. We have investigated a combined optical and near-infrared multi-epoch data set of Mira variables based on our monitoring data obtained over 15 yr. Bolometric correction relations are formulated for various near-infrared colours. We find that the same bolometric correction equation holds for both the bolometricly brightest and faintest pulsation phases. Period–bolometric magnitude relations and period–colour relations were derived using time-averaged values. Phase lags between bolometric phase and optical and near-infrared phases were detected from the O-rich (the surface C/O number ratio is below unity) Mira variables, while no significant systematic lags were observed in most of the C-rich (the C/O ratio is over unity) ones. Some Miras show colour phase inversions, e.g. H–Ks at its bluest while J–H and J–Ks are at their reddest values at about the bolometricly brightest phase. Their occurrence conditions were studied but no clear direct or indirect trigger was found. A large NIR colour change unassociated with stellar pulsation was observed in Miras with long secondary periods, and its possible explanation is described.

Original languageEnglish
Pages (from-to)82-100
Number of pages19
JournalMonthly Notices of the Royal Astronomical Society
Volume500
Issue number1
DOIs
Publication statusPublished - 2021 Jan 1

Keywords

  • Infrared: stars
  • Stars: AGB and post-AGB
  • Stars: carbon
  • Stars: late-type

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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