V 1162 Ori: A multiperiodicδScuti star with variable period and amplitude

Abstract

Abstract. We present the results of multisite observations of the δ Scuti star V 1162 Ori. The observations were done in the period October 1999 -May 2000, when 18 telescopes at 15 observatories were used to collect 253 light extrema during a total of 290 hours of time-series observations. The purpose of the observations was to investigate amplitude and period variability previously observed in this star, and to search for low-amplitude frequencies. We detect, apart from the main frequency and its two first harmonics, four additional frequencies in the light curves, all with low amplitudes (1-3 mmag). Combining the present data set with data obtained in 1998-99 at ESO confirms the new frequencies and reveals the probable presence of yet another pulsational frequency. All five low-amplitude frequencies are statistically significant in the data, but at least one of them (f5) suffers from uncertainty due to aliasing. Using colour photometry we find evidence for a radial main frequency (f1), while most or all low-amplitude frequencies are likely non-radial. We show that the main frequency of V 1162 Ori has variable amplitude and period/phase, the latter is also displayed in the O-C diagram from light extrema. The amplitude variability in our data is cyclic with a period of 282 d and a range of nearly 20 mmag, but earlier amplitude values quoted in the literature cannot be explained by this cyclic variation. O-C analysis including data from the literature show that the period of V 1162 Ori displays a linear period change as well as sudden or cyclic variations on a time scale similar to that of the amplitude variations.

A comprehensive study of the δ Scuti star AN Lyncis

“…1 and de-noised following the method used for XX Pyx by Handler et al (2000), it is possibly caused by intrinsic low frequencies or binarity as shown by Arentoft et al (2001a). We have noted a similar sinusoidal amplitude variation appearing in the δ Sct star V1162 Ori (Arentoft et al 2001b), for which binarity (Arentoft & Sterken 2000) and multiperiodicity were proposed and well discussed. Last, however, larger errors for the earlier values should be noted before giving any convincing explanations.…”

Long term behaviour of the double-mode high-amplitude δ Scuti star RV Arietis

“…Rodríguez et al (1997) confirmed that the amplitude of the main frequency of AN Lyn varies on a long time scale of several years, and changes in the amplitude are also present in the secondary frequencies. Arentoft et al (2001aArentoft et al ( , 2001b investigated the interesting medium amplitude δ Scuti star V1162 Ori and arrived at the remarkable result that the amplitude of the main frequency varies in a very complex way. Irregular variations are superimposed on a cyclic variation.…”

“…The variability may increase by ∼40 per cent over a decade. It was also shown that the light curve of the medium amplitude δ Scuti stars AN Lyn (Rodríguez et al 1997) and V1162 Ori (Arentoft et al 2001a(Arentoft et al , 2001b) underwent amplitude changes. The HADS may also be characterized by amplitude changes (e.g.…”

A search for period changes inδScuti stars with the super-LOTIS sky patrol system

“…There are relatively few discussions in the literature of observations of large amplitude, non-evolutionary period changes. In addition to the case already discussed of XX Pyx, period variations in V1162 Ori are presented by Arentoft et al (2001), and the peculiar behavior the one-time monoperiodic HADS star RY Lep is discussed by Laney & Schwendiman (2002). In both cases, changes in periodicity, similar in magnitude to those presented here, are found.…”