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Variable Red Giants Exploration with MASTER Robotic Net: Main Algorithms and Study of Three Mira-type Targets

Alexander N. Tarasenkov, Vladimir M. Lipunov, Artem S. Kuznetsov, Gleb A. Antipov, Pavel V. Balanutsa, Nataly V. Tyurina, Yakov Yu. Kechin

Abstract

We are discussing the capabilities of MASTER network of robotic telescopes to study variable red giant stars. We report the discovery and present archival light curves for three optical transients, connected with long period variable red giants, based on MASTER Robotic Net all-sky survey observations and archival MASTER light curves at Lomonosov database storage. We demonstrate transient detection frames and light curves for three Mira-type variables: MASTER OT $J083717.54-573411.1$, MASTER OT $J190436.33+192828.7$ and MASTER OT $J07010810-6818548$. Spectroscopically validated carbon star MASTER OT $J07010810-6818548$ shows mean magnitude growth but constant pulsation period which may indicate the presence of a long secondary period. As the result of MASTER wide-field images analysis at Lomonosov supercomputer data storage we present the 8-years historical light curves for all three objects with period calculations for all three Mira-type variables. We estimated fundamental astrophysical parameters for all three Mira-type variables: luminosities, radii, and zero age main sequence (ZAMS) masses.

Variable Red Giants Exploration with MASTER Robotic Net: Main Algorithms and Study of Three Mira-type Targets

Abstract

We are discussing the capabilities of MASTER network of robotic telescopes to study variable red giant stars. We report the discovery and present archival light curves for three optical transients, connected with long period variable red giants, based on MASTER Robotic Net all-sky survey observations and archival MASTER light curves at Lomonosov database storage. We demonstrate transient detection frames and light curves for three Mira-type variables: MASTER OT , MASTER OT and MASTER OT . Spectroscopically validated carbon star MASTER OT shows mean magnitude growth but constant pulsation period which may indicate the presence of a long secondary period. As the result of MASTER wide-field images analysis at Lomonosov supercomputer data storage we present the 8-years historical light curves for all three objects with period calculations for all three Mira-type variables. We estimated fundamental astrophysical parameters for all three Mira-type variables: luminosities, radii, and zero age main sequence (ZAMS) masses.
Paper Structure (11 sections, 4 equations, 5 figures, 4 tables)

This paper contains 11 sections, 4 equations, 5 figures, 4 tables.

Table of Contents

  1. Introduction
  2. MASTER global network and main principles of its operation
  3. MASTER observation algorithms
  4. Data reduction and transient detection system
  5. MASTER archive at Lomonosov database storage
  6. Variable stars detection by MASTER online reduction
  7. Mira-type Optical Transient MASTER OT J083717.54-573411.1
  8. Mira-type Optical Transient MASTER OT J190436.33+192828.7
  9. MASTER OT J07010810-6818548: Carbon Mira variable brightening
  10. Astrophysical parameters estimation
  11. Results and conclusions

Figures (5)

  • Figure 1: An archive light curve of J0837 (upper panel, the red circles are from MASTER-SAAO, the green ones are from MASTER-OAFA in unfiltered band) and the OT discovery and confirming images with reference one - lower panels. Here and further, discovery and reference frames have a size of 6' by 6'.
  • Figure 2: An archive light curve of MASTER OT MASTER OT J190436.33+192828.7 (upper panel). The different colored circles are from MASTER-Amur (red), -Tunka (green), -Kislovodsk (orange), -SAAO (blue) in unfiltered band and the OT discovery and confirming images with reference one (lower panels).
  • Figure 3: Archive MASTER-SAAO light curve of MASTER OT J07010810-681854 in unfiltered band and discovery images in February and reference one in 2015.
  • Figure 4: Master Net archive light curve of J0701 (black dots) in unfilered band with sinusoidal fit of long term trend with period of 5785 days (blue line).
  • Figure 5: Lomb-Scargle periodograms for Mira variables under study (lower panels, green and red dashed lines correspond to false alarm level of 1 and 10 percent respectively) and light curves folded with highest power periods (upper panels). For J0701, detrended data was used.