Volume 374, Number 3, August II 2001
|Page(s)||1056 - 1070|
|Section||Interstellar and circumstellar matter|
|Published online||15 August 2001|
University of Brussels (VUB), Pleinlaan 2, 1050 Brussels, Belgium
2 South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa
3 Royal Observatory of Belgium, Ringlaan 3, 1180 Brussels, Belgium
4 Laboratório Nacional de Astrofísica, CP 21, 37500-000 Itajubá -MG, Brazil
5 Department of Astrophysics, Astronomy and Mechanics, University of Athens, 157 84 Zografos, Athens, Greece
6 Beersel Hills Observatory, Belgium
7 Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate, Italy
8 Department of Astronomy, San Diego State University, San Diego, California, USA
9 Department of Physics and Astronomy, Western Connecticut State University, Danbury, Connecticut 06810, USA
10 Beijing Astronomical Observatory, Chinese Academy of Sciences, Beijing 100012, PR China
11 Research School of Astronomy and Astrophysics, Australian National University, Weston Creek PO, ACT 2611, Australia
12 Instituto de Astrofisica de Andalucia, CSIC, Apdo. 3004, 18080 Granada, Spain
13 Braeside Observatory, Flagstaff, Arizona, USA
14 Ege University Observatory, Bornova 35100, Izmir, Turkey
15 Astrophysical Sciences Department, Princeton University, Princeton, New Jersey 08544, USA
16 Centre for Astrophysics, University of Central Lancashire, Preston PR1 2HE, UK
17 Department of Astronomy, University of Cape Town, Rondebosch 7701, South Africa
18 Laboratoire d'Astrophysique, Observatoire Midi-Pyrénées, 31400 Toulouse, France
Corresponding author: T. Arentoft, firstname.lastname@example.org
Accepted: 31 May 2001
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. ]
Key words: stars: variables: δ Scuti / stars: individual: V 1162 Orionis / techniques: photometric / methods: data analysis
Based on observations obtained at the South African Astronomical Observatory (SAAO), Athens University and Kryonerion Observatories, European Southern Observatories (ESO: applications ESO 62H-0110, 64H-0065 and 64L-0182), Laboratório Nacional de Astrofísica (Brazil), Xinglong, Beersel Hills, Ege University, San Pedro Martir, Merate, Mt. Laguna, Siding Spring, Sierra Nevada, Braeside and Lick Observatories.
© ESO, 2001
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