The δ Scuti pulsations of β Pictoris as observed by ASTEP from Antarctica

¹ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, CS 34229, 06304 Nice Cedex 4, France
e-mail: mekarnia@oca.eu
² Concordia Station, Dome C, Antarctica
³ Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstrasse 25/8, 6020 Innsbruck, Austria
⁴ Space Telescope Science Institute, Baltimore, MD 21218, USA
⁵ Astronomy Department, University of California, Berkeley, Berkeley, CA 94720, USA
⁶ Université Grenoble Alpes, CNRS, IPAG, 38 000 Grenoble, France
⁷ Instituto de Astrofisica de Canarias, C/via Lactea s/n, 38200 La Laguna, Spain
⁸ Fondazione Clément Fillietroz ONLUS, Astron. Observatory of the Autonomous region Aosta Valley, NUS, 11020 (AO), Italy
⁹ SETI Institute, Carl Sagan Center, 189 Bernardo Avenue, Mountain View, CA 94043, USA

Received: 18 October 2017
Accepted: 11 November 2017

Abstract

Aims. The Antarctica Search for Transiting Extrasolar Planets (ASTEP), an automatized 400 mm telescope located at Concordia station in Antarctica, monitored β Pictoris continuously to detect any variability linked to the transit of the Hill sphere of its planet β Pictoris b. The long observation sequence, from March to September 2017, combined with the quality and high level duty cycle of our data, enables us to detect and analyse the δ Scuti pulsations of the star.

Methods. Time series photometric data were obtained using aperture photometry by telescope defocussing. The 66 418 data points were analysed using the software package Period04. We only selected frequencies with amplitudes that exceed four times the local noise level in the amplitude spectrum.

Results. We detect 31 δ Scuti pulsation frequencies, 28 of which are new detections. All the frequencies detected are in the interval 34.76−75.68 d^-1. We also find that β Pictoris exhibits at least one pulsation mode that varies in amplitude over our monitoring duration of seven months.