| Issue |
A&A
Volume 684, April 2024
|
|
|---|---|---|
| Article Number | A72 | |
| Number of page(s) | 17 | |
| Section | Planets and planetary systems | |
| DOI | https://doi.org/10.1051/0004-6361/202348604 | |
| Published online | 09 April 2024 | |
The spectroastrometric detectability of nearby Solar System-like exomoons★
1
Leiden Observatory, Leiden University,
PO Box 9513,
2300 RA
Leiden,
The Netherlands
e-mail: woerkom@mail.strw.leidenuniv.nl
2
Faculty of Aerospace Engineering, Delft University of Technology,
Kluyverweg 1,
2629 HS
Delft,
The Netherlands
Received:
14
November
2023
Accepted:
31
January
2024
Context. Though efforts to detect them have been made with a variety of methods, no technique can claim a successful, confirmed detection of a moon outside the Solar System yet. Moon detection methods are restricted in capability to detecting moons of masses beyond what formation models would suggest, or they require surface temperatures exceeding what tidal heating simulations allow.
Aims. We expand upon spectroastrometry, a method that makes use of the variation of the centre of light with wavelength as the result of an unresolved companion, which has previously been shown to be capable of detecting Earth-analogue moons around nearby exo-Jupiters, with the aim to place bounds on the types of moons detectable using this method.
Methods. We derived a general, analytic expression for the spectroastrometric signal of a moon in any closed Keplerian orbit, as well as a new set of estimates on the noise due to photon noise, pointing inaccuracies, background and instrument noise, and a pixelated detector. This framework was consequently used to derive bounds on the temperature required for Solar System-like moons to be observable around super-Jupiters in nearby systems, with ∈ Indi Ab as an archetype.
Results. We show that such a detection is possible with the ELT for Solar System-like moons of moderate temperatures (150–300 K) in line with existing literature on tidal heating, and that the detection of large (Mars-sized or greater) icy moons of temperatures such as those observed in our Solar System in the very nearest systems may be feasible.
Key words: methods: observational / techniques: imaging spectroscopy / planets and satellites: detection / planets and satellites: general / infrared: planetary systems
The code used to generate the results and figures presented in this paper is publicly available at github.com/qui1712/spectroastrometry_pub.
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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