Peremennye Zvezdy (Variable Stars) 42, No. 5, 2022 Received 2 June; accepted 14 June.	Article in PDF
	DOI: 10.24412/2221-0474-2022-42-28-34

A Study of Double-mode High-amplitude Scuti Variable Stars Pulsating in the Fundamental and First Overtone Modes. II

A. V. Khruslov^1,2

1. Sternberg Astronomical Institute, Lomonosov Moscow State University, Universitetskij pr. 13, Moscow 119992, Russia; khruslov@bk.ru

2. Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya str. 48, Moscow 119017, Russia

1. Introduction

In the course of my study of high-amplitude Scuti variable stars (HADS) included in the ASAS-SN Variable Stars Database (Jayasinghe et al., 2018, 2019a, 2019b, 2020, 2021), I discovered 44 new double-mode HADS variables, pulsating in the fundamental and first overtone modes. This article continues my previous paper (Khruslov, 2021). Searching for double periodicity, I mainly used data available in the photometric archive of the All-Sky Automated Survey for Supernovae (ASAS-SN, Shappe et al., 2014, Kochanek et al., 2017). Additionally, I analyzed available data from other archives: the Wide Angle Search for Planets (SuperWASP, Butters et al., 2010), the Catalina Sky Surveys (Drake et al., 2009), the All Sky Automated Survey (ASAS-3, Pojmanski, 2002).

The SuperWASP observations are available as FITS tables, which were converted into ASCII tables using the OMC2ASCII¹program as described by Sokolovsky (2007).

The method used to search for multiperiodicity is similar to that described in my previous paper (Khruslov, 2021).

The light curves and data from the ASAS-SN survey are available online in the html version of this paper as a zip-archive. The light curves are given in the format displayed in Fig. 1.

The radial pulsation modes were identified by the period ratio ( ). The period ratio of pulsations in the fundamental and first-overtone modes typical of double-mode HADS stars (F/1O) is (Petersen & Christensen-Dalsgaard, 1996).

The stars were identified in the GSC 1.2 (Morrison et al., 2001) and USNO-B1.0 (Monet et al., 2003) catalogs. The tabulated coordinates of the variables were drawn from the Gaia DR2 catalog (Gaia Collaboration, Brown et al., 2018).

2. Results

In the right ascension interval, I detected 44 new HADS(B) stars pulsating in the fundamental and first-overtone modes. Their magnitudes are between 108 and 157 in the  band of the ASAS-SN photometric system. The highest peak-to-peak amplitude of light variations is 088. The fundamental-mode periods are between 0049 and 0198.

The light curves for one of the stars (No. 40) are displayed in Fig. 1. The top panels present data folded with the fundamental-mode and first overtone periods. The bottom panels show the same curves after prewhitening the other oscillation (if , and interaction frequencies or non-radial frequencies were excluded, it is also noted). Along with the light curves, we present power spectra of the double-mode variables, for the raw data and after subtraction of the dominant mode (fundamental or first-overtone oscillations). The structure of the power spectra shows that the secondary periods are real.

Information on these stars is presented in Tables 1 and 2. Table 1 contains equatorial coordinates (J2000); star numbers from the GSC and USNO-B1.0 catalogs; magnitudes at maximum and minimum in the  band of the ASAS-SN photometric system; number for comments on individual stars, which are given below the table.

Comments to Table 1.

1. The variability was detected in the ASAS-SN survey, type HADS.

2. The star is contained in the Gaia DR2 catalog as a variable, type DSCT or SXPHE.

3. The variable is contained in the Catalina surveys periodic variable star catalog (Drake et al., 2014), the type HADS and a wrong period, , are given. In the ASAS-SN Variable Stars Database, the type RRC and the period are given.

4. Data from the Catalina survey (CSS or SSS) were used to improve the light elements.

5. Data from 1SWASP were used to improve the light elements.

6. The variability was discovered by Denis Denisenko (announcement of May 17, 2017 in the AAVSO Variable Star Index, DDE110).

7. The variable is contained in the ZTF catalog (Chen et al., 2020), type DSCT.

8. The variability was detected by Palaversa et al. (2013), LINEAR 7834923, type  Sct or SX Phe is given.

9. Additional non-radial pulsation, .

10. The variability was announced in GALEX TDS Alerts (May 2008 archive²). Later, Patrick Wils (announcement of October 05, 2010 in the AAVSO Variable Star Index) classified this variable as a HADS star.

11. The variability was detected in the ASAS-SN survey, type RRc.

12. Additional non-radial pulsation, .

13. Data from the ASAS-3 survey were used to improve the light elements.

14. Better identification compared to GSC and USNO-B1.0: 2MASS15383724-2716085.

15. A close faint companion can somewhat influence the ASAS-SN photometry, amplitude is underestimated.

16. Light elements improved only for .

17. possibly varies.

18. The variability was detected in the ASAS-3 survey (Pojmanski, 2002), type DSCT.

Table 2 presents the light elements (period in days and epoch of maximum, ), semi-amplitude and asymmetry parameter for the fundamental mode (, , , and ) and first-overtone mode (, , and ) oscillations, and the period ratio .

The information on detected interaction frequencies is contained in Table 3: periods and semi-amplitudes of the frequencies , , and .

The Petersen diagram for double-mode HADS variables pulsating in the fundamental and first overtone modes, studied in this paper, is displayed in Fig. 2.

Acknowledgments: The author wishes to thank Dr. V.P. Goranskij for providing his software.

Erratum: In my previous paper (Khruslov, 2021), in Table 2, the epochs of maximum and should be understood in accordance with the rule , similar to designations in the present article.

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