WD 0141−675: a case study on how to follow-up astrometric planet candidates around white dwarfs

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Date
2023-10-28
Authors
Rogers, Laura K.
Debes, John
Anslow, Richard J.
Bonsor, Amy
Casewell, S.L.
Dos Santos, Leonardo A.
Dufour, Patrick
T. Gänsicke, Boris
Gentile Fusillo, Nicola
Koester, Detlev
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Published version
OA Version
Citation
L.K. Rogers, J. Debes, R.J. Anslow, A. Bonsor, S.L. Casewell, L.A. Dos Santos, P. Dufour, B. T. Gänsicke, N. Gentile Fusillo, D. Koester, L.D. Nielsen, Z. Penoyre, E.L. Rickman, J. Sahlmann, P.-E. Tremblay, A. Vanderburg, S. Xu, E. Dennihy, J. Farihi, J.J. Hermes, S. Hodgkin, M. Kilic, P.M. Kowalski, H. Sanderson, S. Toonen. 2023. "WD 0141−675: a case study on how to follow-up astrometric planet candidates around white dwarfs" Monthly Notices of the Royal Astronomical Society, Volume 527, Issue 1, pp.977-990. https://doi.org/10.1093/mnras/stad3098
Abstract
This work combines spectroscopic and photometric data of the polluted white dwarf WD 0141−675, which has a now retracted astrometric super-Jupiter candidate, and investigates the most promising ways to confirm Gaia astrometric planetary candidates and obtain follow-up data. Obtaining precise radial velocity measurements for white dwarfs is challenging due to their intrinsic faint magnitudes, lack of spectral absorption lines, and broad spectral features. However, dedicated radial velocity campaigns are capable of confirming close-in giant exoplanets (a few MJup) around polluted white dwarfs, where additional metal lines aid radial velocity measurements. Infrared emission from these giant exoplanets is shown to be detectable with JWST Mid-Infrared Instrument (MIRI) and will provide constraints on the formation of the planet. Using the initial Gaia astrometric solution for WD 0141−675 as a case study, if there were a planet with a 33.65 d period or less with a nearly edge-on orbit, (1) ground-based radial velocity monitoring limits the mass to <15.4 MJup, and (2) space-based infrared photometry shows a lack of infrared excess and in a cloud-free planetary cooling scenario, a substellar companion would have to be <16 MJup and be older than 3.7 Gyr. These results demonstrate how radial velocities and infrared photometry can probe the mass of the objects producing some of the astrometric signals, and rule out parts of the brown dwarf and planet mass parameter space. Therefore, combining astrometric data with spectroscopic and photometric data is crucial to both confirm and characterize astrometric planet candidates around white dwarfs.
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© The Author(s) 2023. Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.