Dirkx, D.

Kenworthy, M.

Kleisioti, E.

Rovira-Navarro, M.

Leiden University Scholary Publications

Could we observe exomoons around β Pictoris b?Kleisioti, E.; Dirkx, D.; Rovira-Navarro, M.; Kenworthy, M.CitationKleisioti, E., Dirkx, D., Rovira-Navarro, M., & Kenworthy, M. (2021). Could we observeexomoons around β Pictoris b? Epsc Abstracts, EPSC2021-546. Retrieved fromhttps://hdl.handle.net/1887/3263652 Version: Publisher's VersionLicense: Creative Commons CC BY 4.0 licenseDownloaded from: https://hdl.handle.net/1887/3263652 Note: To cite this publication please use the final published version (if applicable).EPSC AbstractsVol. 15, EPSC2021-546, 2021https://doi.org/10.5194/epsc2021-546Europlanet Science Congress 2021© Author(s) 2022. This work is distributed underthe Creative Commons Attribution 4.0 License.Could we observe exomoons around β Pictoris b?Evangelia Kleisioti1, Dominic Dirkx2, Marc Rovira-Navarro2,3, and Matthew Kenworthy11Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands (kleisioti@mail.strw.leidenuniv.nl)2Faculty of Aerospace Engineering, TU Delft, Building 62 Kluyverweg 1, 2629 HS Delft, the Netherlands3NIOZ Royal Netherlands Institute for Sea Research, Department of Estuarine and Delta Systems EDS, Utrecht University, P.O.Box 140, 4400 AC Yerseke, the NetherlandsIntroductionThe discovery of the first extrasolar planets demonstrated that planets can form around other starsand be detected with current instrumentation. Since more than 200 moons exist in the SolarSystem, it is expected that they orbit exoplanets as well. Detecting an exomoon could set the nextmilestone in observations of exoplanetary systems.   Tidal interactions between planets and their satellites can heat a satellite’s interior. The mostevident example is Io, which is the most tidally active body in the Solar System. Since tidaldissipation depends on the orbital and physical properties of the system, if tidal heating is vigorousenough in exoplanetary systems, there is a chance that Tidally Heated Exomoons (THEMs; Petersand Turner 2015) are detectable with current instrumentation and/or the JWST in infrared (IR)wavelengths. As a direct result of tidal heating, spectral signatures of volcanic activity could also bea method of detecting THEMs (Oza et al. 2019). Two of the gas giant planet moon systems are in long-lived mean motion resonances (MMR) and it isexpected that the latter would prevail in extrasolar systems as well. Taking the Jovian satellites asan archetype for an exomoon system around β Pictoris b, this would mean that an MMR betweentwo or more exomoons would make them detectable for larger timescales, maintaining tidal activityover the lifetime of the system.β Pictoris is a 23 Myr old star with a distance of 19.44 pc. A ≃10 Mj directly imaged planet isorbiting the star at 9.8 AU (Lagrange et al. 2020). The system is almost edge-on to our line of sight,making β Pictoris b a plausible candidate for the search of THEMs in the IR, through photocenterastrometry of the combined planet and moon (Agol 2015) or by looking for primary and secondarytransits of the exomoon. MethodsWe scale up a Galilean satellite system around β Pictoris b in order to investigate which propertiesmake a putative exomoon detectable. We use orbital-thermal coupled models that assume alayered, radially symmetric moon, consisting of a silicate mantle and a liquid core. We assume thatheat is transferred via melt advection (Moore 2003) and mantle convection from the interior to thesurface and we obtain equilibrium temperatures. We explore the parameter space of orbital andphysical properties of an exomoon around β Pictoris b by using different rheological models(Maxwell, Andrade). ResultsGiven a semi-major axis and eccentricity for an 8MIo mass exomoon, we obtain the correspondinginterior structure and heat flow through the moon, resulting in a calculated effective temperature atthe surface. We present our results for our Andrade rheology model and heat transfer mechanisms(Figure 1) and place constraints on the feasible interior models and orbital parameters for a putativesurface heat flux of an exomoon around β Pictoris b. At Io’s orbital eccentricity a 2RIo exomoonwould need to be close to the Roche radius of β Pictoris b to reach 600 K and be observed with theJWST (Figure 2), however this limit relaxes for higher eccentricities and bigger moons. We find thatthe Andrade rheology results in higher surface temperatures when compared to the basic Maxwellviscoelastic model.Figure 1: Equilibrium surface temperatures of a 2RIo exomoon (Super-Io) around β Pictoris b usingAndrade rheology and melt advection. The horizontal line shows Io’s orbital eccentricity. Figure 2: Fluxes at the β Pictoris system. The grey continuous line shows the modeled spectrum of aplanet with similar parameters as β Pictoris b (Morley et al. 2015), the dashed black line theblackbody curve of the star and the purple line the one of a Super-Io (2RIo). The horizontal lines arethe 5σ and 10,000s integration time detection limits of MIRI/JWST for various bands (Glasse 2010)). ReferencesAgol et al. (2015) The Astrophysical Journal, 812(1), p.5.Glasse (2010) SPIE, 7731, 77310K.Lagrange et al. (2020) Astronomy & Astrophysics, 642, p.A18.Moore  (2003) Journal of Geophysical Research, 108(E8).Morley et al. (2015) The Astrophysical Journal, 815(2), p.110.Oza et al. (2019) The Astrophysical Journal, 885(2), p.168.Peters and Turner (2013) The Astrophysical Journal, 769(2), p.98. Powered by TCPDF (www.tcpdf.org)

Could we observe exomoons around β Pictoris b?

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Could we observe exomoons around β Pictoris b?

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