Discovery of {delta} Sct type pulsations in the eclipsing binary IK Vir

Abstract

We report the detection of δ Sct type variations in the eclipsing binary system, IK Vir (V=11.54 mag, A6, P orb = 0.72 d, Velichko et al. 1991 andKazarovets et al. 1993), in our V-band photometry. The observations were carried out with Moravian G2-1600 CCD camera attached to 28 cm Schmidt-Cassegrain telescope at Akazawa Funao Observatory. Total observational runs are twenty one nights from March 26 to May 26 in 2015. IK Vir is measured differentially to BD+02 2522 = GSC 0281-0223 as the comparison star. BD+02 2522 is measured to GSC 0281-0255 as the check star. All the data in this observational season are shown in the lower light curve in Figure 1. To highlight short period (about 30 minutes) variations, data from only five observing runs, chosen so that there is no overlap in the same phase range, are plotted in the upper light curve in Figure 1. All the V-band photometric data obtained for this study are available as electronic tables(6211-t3.txt) from IBVS website.The light curves in Fig. 2 for three individual nights show beat phenomena, which suggests that the variations are multiply periodic. In order to extract short period variations, third-order polynomials are fitted and subtracted from data for eight nights runs which covered out-of-eclipse phases.The residuals are analysed by the Period4 program (Lenz and Breger, 2005). The first six dominant frequencies are listed in Table 1 and their power spectra at each subtraction phase are shown in Fig. 3. The over-plotted solid line in Fig. 2 shows the light curve synthesized from the detected multiple periods.When we tried to subtract the synthesized light curve from observational data, the short period variations were naturally cancelled in the residuals out-of-eclipse. However, in the period between the phase of about -0.15 to 0.15 covering the primary eclipse, the short period variations could not well cancelled (Fig. 4). This indicates that the pulsating component is the primary and it might indicates that nonradial oscillations of a specific low order mode are emphasized by the eclipse and that some phase shift has occurred (Unno et al. 1989). The new times of minima obtained in 2015 are listed in Table 2. Together with the times of minima listed in the O-C Gateway 1 since 1999, a new ephemeris for primary minimum could be calculated as follows:HJD Min = 2451275.3649312(1) + 0.7236021(2) × E

Spectroscopic long-term monitoring of RZ Cas

“…The latter authors obtained simultaneous Strömgren uvby light curves of RZ Cas. These authors present a detailed photometric analysis for both binarity and pulsation, deriving WD (Wilson & Devinney 1971) solutions in the four mentioned passbands as well as absolute parameters of both components, and confirming the pulsational behaviour of the primary component as found by Ohshima et al (1998). We use the radii and flux ratios between the components derived by Rodríguez et al (2004) as a reference in our spectroscopic investigation.…”

“…A partial eclipse is observed during primary minimum (Narusawa et al 1994). The primary was found by Ohshima et al (1998Ohshima et al ( , 2001 to exhibit short-period light variability with a dominant oscillation mode of a frequency of 64.2 c d −1 . This finding was later confirmed from dedicated multi-site photometric campaigns by both Mkrtichian et al (2003) and Rodríguez et al (2004).…”

The Ubv Color Evolution of Classical Novae. Ii. Color–magnitude Diagram

“…The V light curve fit gives a relation of (m − M) V = 14.8 for OS And. We plot the distance-reddening relations in Figure 25 Ohshima (1988) and IAU Circular Nos. 4493, 4511, and 4524, and the visual data are from the AAVSO archive.…”

“…4493, 4511, and 4524, and the visual data are from the AAVSO archive. We shift the B − V and U − B data of IAU Circulars down by 0.1 and 0.2 mag, respectively, to match these data to those of Ohshima (1988). QV Vul is a dust-blackout type moderately fast nova with t 2 = 50 and t 3 = 53 days (Downes & Duerbeck 2000).…”

Explaining Prolonged Fluctuations in Light Curves of Classical Novae via Modeling

“…Obtaining observations of PMHs are rare and often up to chance since they are usually very short lived -only a fraction of the rise time, which in itself is short (e.g., Starrfield et al 1972;Prialnik et al 1978;Prialnik 1986;Shara 1989;Prialnik & Kovetz 1995;Bode & Evans 2012). The rise time is relatively longer for slower developing novae, thus PMHs, in the form of a short plateau, are more commonly found in slow novae, such as V1548 Aql (Kato & Takamizawa 2001;Primak & Pavlenko 2003), HR Del (Terzan 1970;Drechsel et al 1977;Friedjung 1992), V723 Cas (Hirosawa et al 1995;Ohsima et al 1996;Iijima et al 1998) and V5558 Sgr (Munari et al 2007;Naito et al 2007;Poggiani 2008;Tanaka et al 2011). A PMH was also observed in the fast nova, V463 Sct (Kato et al 2002;Poggiani 2018), which is rarely observed.…”