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A search for transiting planets around hot subdwarfs : I. Methods and performance tests on light curves from Kepler, K2, TESS, and CHEOPS

Van Grootel, V. ; Davies, M.B. ; Mustill, Alexander J LU orcid and Wilson, T. G. (2021) In Astronomy and Astrophysics 650.
Abstract
Context. Hot subdwarfs experienced strong mass loss on the red giant branch (RGB) and are now hot and small He-burning objects. These stars constitute excellent opportunities for addressing the question of the evolution of exoplanetary systems directly after the RGB phase of evolution.

Aims. In this project we aim to perform a transit survey in all available light curves of hot subdwarfs from space-based telescopes (Kepler, K2, TESS, and CHEOPS) with our custom-made pipeline SHERLOCK in order to determine the occurrence rate of planets around these stars as a function of orbital period and planetary radius. We also aim to determine whether planets that were previously engulfed in the envelope of their red giant host star can... (More)
Context. Hot subdwarfs experienced strong mass loss on the red giant branch (RGB) and are now hot and small He-burning objects. These stars constitute excellent opportunities for addressing the question of the evolution of exoplanetary systems directly after the RGB phase of evolution.

Aims. In this project we aim to perform a transit survey in all available light curves of hot subdwarfs from space-based telescopes (Kepler, K2, TESS, and CHEOPS) with our custom-made pipeline SHERLOCK in order to determine the occurrence rate of planets around these stars as a function of orbital period and planetary radius. We also aim to determine whether planets that were previously engulfed in the envelope of their red giant host star can survive, even partially, as a planetary remnant.

Methods. For this first paper, we performed injection-and-recovery tests of synthetic transits for a selection of representative Kepler, K2, and TESS light curves to determine which transiting bodies in terms of object radius and orbital period we will be able to detect with our tools. We also provide estimates for CHEOPS data, which we analyzed with the pycheops package.

Results. Transiting objects with a radius ≲1.0 R⊕ can be detected in most of the Kepler, K2, and CHEOPS targets for the shortest orbital periods (1 d and shorter), reaching values as low as ~0.3 R⊕ in the best cases. Sub-Earth-sized bodies are only reached for the brightest TESS targets and for those that were observed in a significant number of sectors. We also give a series of representative results for larger planets at greater distances, which strongly depend on the target magnitude and on the length and quality of the data.

Conclusions. The TESS sample will provide the most important statistics for the global aim of measuring the planet occurrence rate around hot subdwarfs. The Kepler, K2, and CHEOPS data will allow us to search for planetary remnants, that is, very close and small (possibly disintegrating) objects. (Less)
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author
; ; and
author collaboration
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Astronomy and Astrophysics
volume
650
article number
A205
pages
19 pages
publisher
EDP Sciences
external identifiers
  • scopus:85108975914
ISSN
1432-0746
DOI
10.1051/0004-6361/202140381
project
Consolidating CHEOPS and preparing for PLATO: Exoplanet studies in the 2020s
A unified picture of white dwarf planetary systems
language
English
LU publication?
yes
id
1d6815cb-14ff-4b00-be90-bcbd97119896
alternative location
https://arxiv.org/abs/2104.10462
date added to LUP
2022-01-27 10:39:04
date last changed
2024-04-20 20:36:49
@article{1d6815cb-14ff-4b00-be90-bcbd97119896,
  abstract     = {{Context. Hot subdwarfs experienced strong mass loss on the red giant branch (RGB) and are now hot and small He-burning objects. These stars constitute excellent opportunities for addressing the question of the evolution of exoplanetary systems directly after the RGB phase of evolution.<br/><br/>Aims. In this project we aim to perform a transit survey in all available light curves of hot subdwarfs from space-based telescopes (Kepler, K2, TESS, and CHEOPS) with our custom-made pipeline SHERLOCK in order to determine the occurrence rate of planets around these stars as a function of orbital period and planetary radius. We also aim to determine whether planets that were previously engulfed in the envelope of their red giant host star can survive, even partially, as a planetary remnant.<br/><br/>Methods. For this first paper, we performed injection-and-recovery tests of synthetic transits for a selection of representative Kepler, K2, and TESS light curves to determine which transiting bodies in terms of object radius and orbital period we will be able to detect with our tools. We also provide estimates for CHEOPS data, which we analyzed with the pycheops package.<br/><br/>Results. Transiting objects with a radius ≲1.0 R⊕ can be detected in most of the Kepler, K2, and CHEOPS targets for the shortest orbital periods (1 d and shorter), reaching values as low as ~0.3 R⊕ in the best cases. Sub-Earth-sized bodies are only reached for the brightest TESS targets and for those that were observed in a significant number of sectors. We also give a series of representative results for larger planets at greater distances, which strongly depend on the target magnitude and on the length and quality of the data.<br/><br/>Conclusions. The TESS sample will provide the most important statistics for the global aim of measuring the planet occurrence rate around hot subdwarfs. The Kepler, K2, and CHEOPS data will allow us to search for planetary remnants, that is, very close and small (possibly disintegrating) objects.}},
  author       = {{Van Grootel, V. and Davies, M.B. and Mustill, Alexander J and Wilson, T. G.}},
  issn         = {{1432-0746}},
  language     = {{eng}},
  publisher    = {{EDP Sciences}},
  series       = {{Astronomy and Astrophysics}},
  title        = {{A search for transiting planets around hot subdwarfs : I. Methods and performance tests on light curves from Kepler, K2, TESS, and CHEOPS}},
  url          = {{http://dx.doi.org/10.1051/0004-6361/202140381}},
  doi          = {{10.1051/0004-6361/202140381}},
  volume       = {{650}},
  year         = {{2021}},
}