DETECTION OF EXO-MOONS OR DEBRIS ORBITING EXOPLANETS. A.V. Oza1,
S. Charnoz2, and R.E. Johnson3 1Physikalisches Institut, University
of Bern, Gesellschaftsstrasse 6, CH-3012 Bern, Switzerland,
[email protected], 2IPGP, Sorbonne Universités, Paris,
France, [email protected], 3U. of Virginia, Char-lottesville, 22904
& Physics, NYU, NY, NY 10012, [email protected]
Introduction: Extrasolar satellites, ring material or plasma
tori, features generally too small to be directly detected at
present by nominal searches of close in planets, can in principle
be detected using our under-standing and modeling of solar system
observations [1,2,3]. For instance, as is the case at the most
active body in the solar system, Io (Fig.1), we describe how alkali
gas transmission spectra could be a signature of the geological
activity venting from an exo-Io orbiting a hot Jupiter or the
sputtering of orbiting debris [2]. Alternatively, a dusty exoring
fueled by the disintegra-tion of a small satellite might account
for the large rates thought to be due to escape at a close-in
system [2]. At present, extended absorption features at several
systems have been interpreted as features of a gas giant atmosphere
.
Although planets orbiting at larger distances from their stars
are more likely to exhibit such features [1], analyzing a number of
close-in gas giants hosting ro-bust alkaline detections, we confirm
that an Io-sized satellite can be stable against orbital decay [4]
with the tidal energy driving mass-loss rates order of magnitude
higher than Io’s supply to Jupiter’s Na exosphere [2]. The
consequence is that potential exo-Io column densi-ties or, possibly
dusty exoring column densities, can be more than sufficient to
account for the observed equiv-alent width of an exoplanet
transmission spectrum with the high-altitude Na observations at
WASP-49b used as an example [2]. Furthermore, the requirements for
tidal stability, situate a putative rocky exomoon dan-gerously
close to the gas giant’s Roche limit [2,4]. Ongoing tidal
disintegration of a rocky core may then be revealed as a metallic
gas signature in transit [5]. Therefore, comparative planetology,
using the solar system observations to infer the presence of
satellites or rings, can be critical to understanding exoplanet
observations [1,2].
Fig. 1 Architecture of a sodium exosphere imaged at the Jupiter
system can be used as a guide to understand the presence of a moon
or a toroidal feature around an exoplanet [2].
References: [1] Johnson, R.E., & P.J. Huggins, Toroidal
Atmospheres around Extrasolar Planets. Pub.Astron.Soc.Pacific
(PASP) 118, 1136-1143 (2006) [2] Oza, A.V. R.E. Johnson, E.
Lellouch, & 12 authors. Sodium and Potassium Signatures of
Volcanic Satel-lites Orbiting Close-in Gas Giant Exoplanets. ApJ.
885:168 https://doi.org/10.3847/1538-4357/ab40cc (2019). [3]
Charnoz, S, R.M. Canup, A. Crida, L. Dones. The Origin of Planetary
Ring Systems, in Planetary Rings Systems, M. S. Tiscareno and C.D.
Murray Eds, Cambridge University Press (2018). [4] Cassidy, T.A.,
R. Mendez, P. Arras, R.E. Johnson, M.F. Skrutskie, Massive
Satellites of Close-In Gas Giant Exoplanets ApJ. 704, 1341-1348
(2009). [5] Hoeijmakers, H.J., D. Ehrenreich, D. Kitzmann & 16
co-authors. A spectral survey of an ultra-hot Jupiter. A&A,
627, A165 (2019)
3047.pdfExoplanets in our Backyard 2020 (LPI Contrib. No.
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