The β Pictoris b Hill sphere transit campaign

II. Searching for the signatures of the β Pictoris exoplanets through time delay analysis of the δ Scuti pulsations

¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
e-mail: zieba@mpia.de
² Leiden Observatory, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands
³ Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstraβe 25, 6020 Innsbruck, Austria
⁴ Institute for Astronomy, University of Hawai’i, Honolulu, HI 96822, USA
⁵ Centre for Astrophysics, University of Southern Queensland, Toowoomba, QLD 4350, Australia
⁶ Institut für Physik, Karl-Franzens Universität Graz, Universitätsplatz 5/II, NAWI Graz, 8010 Graz, Austria
⁷ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Bd de l’Observatoire, CS 34229, 06304 Nice Cedex 4, France
⁸ Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), via Anguillarese 301, Rome, Italy
⁹ Institut polaire français Paul Émile Victor and Programma Nazionale di Ricerche in Antartide, Concordia Station, Antarctica
¹⁰ Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Cagliari, Italy
¹¹ Department of Physics & Astronomy, University of Rochester, Rochester, NY 14627, USA
¹² Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
¹³ Department of Physics and Astronomy, Astronomy and Space Physics, Uppsala University, 751 20 Uppsala, Sweden
¹⁴ Department of Physics, University of Oxford, Oxford OX1 3RH, UK
¹⁵ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
¹⁶ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, M/S321-100, Pasadena, CA 91109, USA
¹⁷ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, 92195 Meudon, France
¹⁸ Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia
¹⁹ South African Astronomical Observatory, Observatory Rd, Observatory Cape Town, 7700 Cape Town, South Africa
²⁰ Department of Astronomy, University of Cape Town, Rondebosch, 7700 Cape Town, South Africa
²¹ Astronomy Department, University of California, Berkeley, CA 94720, USA
²² SETI Institute, Carl Sagan Center, 189 Bernardo Ave., Mountain View CA 94043, USA
²³ Institute of Astrophysics, FORTH, GR-71110 Heraklion, Greece
²⁴ Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
²⁵ Johns Hopkins APL, Laurel, MD, USA
²⁶ Johns Hopkins Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD, 20723, USA
²⁷ School of Physical Sciences and Centre for Astrophysics & Relativity, Dublin City University, Glasnevin, Dublin 9, Ireland
²⁸ IPAG, Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
²⁹ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
³⁰ European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748 Garching, Germany
³¹ Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK
³² Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
³³ Centre for Exoplanets and Habitability, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
³⁴ Shanghai Observatory, Chinese Academy of Sciences, PR China
³⁵ Purple Mountain Observatory, Chinese Academy of Science, Nanjing 210008, PR China

Received: 18 August 2023
Accepted: 12 March 2024

Abstract

The β Pictoris system is the closest known stellar system with directly detected gas giant planets, an edge-on circumstellar disc, and evidence of falling sublimating bodies and transiting exocomets. The inner planet, β Pictoris c, has also been indirectly detected with radial velocity (RV) measurements. The star is a known δ Scuti pulsator, and the long-term stability of these pulsations opens up the possibility of indirectly detecting the gas giant planets through time delays of the pulsations due to a varying light travel time. We search for phase shifts in the δ Scuti pulsations consistent with the known planets β Pictoris b and c and carry out an analysis of the stellar pulsations of β Pictoris over a multi-year timescale. We used photometric data collected by the BRITE-Constellation, bRing, ASTEP, and TESS to derive a list of the strongest and most significant δ Scuti pulsations. We carried out an analysis with the open-source python package maelstrom to study the stability of the pulsation modes of β Pictoris in order to determine the long-term trends in the observed pulsations. We did not detect the expected signal for β Pictoris b or β Pictoris c. The expected time delay is 6 s for β Pictoris c and 24 s for β Pictoris b. With simulations, we determined that the photometric noise in all the combined data sets cannot reach the sensitivity needed to detect the expected timing drifts. An analysis of the pulsational modes of β Pictoris using maelstrom showed that the modes themselves drift on the timescale of a year, fundamentally limiting our ability to detect exoplanets around β Pictoris via pulsation timing.