Stability and Detectability of Exomoons Orbiting HIP 41378 f, a Temperate Jovian Planet with an Anomalously Low Apparent Density

Caleb K. Harada; Courtney D. Dressing; Munazza K. Alam; James Kirk; Mercedes López-Morales; Kazumasa Ohno; Babatunde Akinsanmi; Susana C. C. Barros; Lars A. Buchhave; Andrew C Collier Cameron; Ian J. M. Crossfield; Fei Dai; Peter Gao; Steven Giacalone; Salomé Grouffal; J. Lillo-Box; Andrew W. Mayo; Annelies Mortier; Alexandre Santerne; Nuno C. Santos; Sérgio G. Sousa; Emma V. Turtelboom; Andrew Vanderburg; Peter J. Wheatley

doi:10.3847/1538-3881/ad011c

Stability and Detectability of Exomoons Orbiting HIP 41378 f, a Temperate Jovian Planet with an Anomalously Low Apparent Density

Caleb K. Harada^*, Courtney D. Dressing, Munazza K. Alam, James Kirk, Mercedes López-Morales, Kazumasa Ohno, Babatunde Akinsanmi, Susana C. C. Barros, Lars A. Buchhave, Andrew C Collier Cameron, Ian J. M. Crossfield, Fei Dai, Peter Gao, Steven Giacalone, Salomé Grouffal, J. Lillo-Box, Andrew W. Mayo, Annelies Mortier, Alexandre Santerne, Nuno C. SantosSérgio G. Sousa, Emma V. Turtelboom, Andrew Vanderburg, Peter J. Wheatley

^*Corresponding author for this work

Physics and Astronomy

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Abstract

Moons orbiting exoplanets (“exomoons”) may hold clues about planet formation, migration, and habitability. In this work, we investigate the plausibility of exomoons orbiting the temperate (T_eq = 294 K) giant (R = 9.2 R_⊕) planet HIP 41378 f, which has been shown to have a low apparent bulk density of 0.09 g cm⁻³ and a flat near-infrared transmission spectrum, hinting that it may possess circumplanetary rings. Given this planet’s long orbital period (P ≈ 1.5 yr), it has been suggested that it may also host a large exomoon. Here, we analyze the orbital stability of a hypothetical exomoon with a satellite-to-planet mass ratio of 0.0123 orbiting HIP 41378 f. Combining a new software package, astroQTpy, with REBOUND and EqTide, we conduct a series of N-body and tidal migration simulations, demonstrating that satellites up to this size are largely stable against dynamical escape and collisions. We simulate the expected transit signal from this hypothetical exomoon and show that current transit observations likely cannot constrain the presence of exomoons orbiting HIP 41378 f, though future observations may be capable of detecting exomoons in other systems. Finally, we model the combined transmission spectrum of HIP 41378 f and a hypothetical moon with a low-metallicity atmosphere and show that the total effective spectrum would be contaminated at the ∼10 ppm level. Our work not only demonstrates the feasibility of exomoons orbiting HIP 41378 f but also shows that large exomoons may be a source of uncertainty in future high-precision measurements of exoplanet systems.

Original language	English
Article number	208
Number of pages	22
Journal	The Astronomical Journal
Volume	166
Issue number	5
Early online date	24 Oct 2023
DOIs	https://doi.org/10.3847/1538-3881/ad011c
Publication status	Published - 1 Nov 2023

Bibliographical note

Acknowledgments:
The authors thank Kristo Ment for helpful discussions regarding quadtree algorithms. This paper makes use of observations from the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 526555. These observations are associated with HST-GO program 16267 (PI: Dressing), and the analysis was supported by grant HST-GO-16267. This work was supported by the Programme National de Planétologie (PNP) of CNRS-INSU co-funded by CNES. This work was supported by FCT—Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020—Programa Operacional Competitividade e Internacionalização by these grants: UIDB/04434/2020; UIDP/04434/2020, 2022.06962.PTDC. This research has also been partly funded by the Spanish State Research Agency (AEI) Project No. PID2019-107061GB-C61. A.C.C. acknowledges support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant No. ST/R003203/1. C.K.H. acknowledges support from the National Science Foundation Graduate Research Fellowship Program under grant No. DGE 2146752. J.K. acknowledges financial support from Imperial College London through an Imperial College Research Fellowship grant. J.L.-B. acknowledges support from the Ramón y Cajal program (RYC2021-031640-I) supported by the MCIN/AEI/10.13039/501100011033 and the European Union "NextGenerationEU"/PRTR as well as partial financial support received from "la Caixa" Foundation (ID 100010434) and the European Unions Horizon 2020 research and innovation program No. 847648, with fellowship code LCF/BQ/PI20/11760023. N.C.S. acknowledges funding from the European Union (ERC, FIERCE, 101052347). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. S.G.S. acknowledges the support from FCT through Investigador FCT contract No. CEECIND/00826/2018 and POPH/FSE (EC). P.J.W. acknowledges support from the UK Science and Technology Facilities Council (STFC) under consolidated grant ST/T000406/1.

Keywords

Transmission spectroscopy
Natural satellites (Extrasolar)
Exoplanet systems
Exoplanet dynamics
Exoplanet astronomy
Exoplanet tides
Transits
astro-ph.EP

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Harada, C. K., Dressing, C. D., Alam, M. K., Kirk, J., López-Morales, M., Ohno, K., Akinsanmi, B., Barros, S. C. C., Buchhave, L. A., Collier Cameron, A. C., Crossfield, I. J. M., Dai, F., Gao, P., Giacalone, S., Grouffal, S., Lillo-Box, J., Mayo, A. W., Mortier, A., Santerne, A., ... Wheatley, P. J. (2023). Stability and Detectability of Exomoons Orbiting HIP 41378 f, a Temperate Jovian Planet with an Anomalously Low Apparent Density. The Astronomical Journal, 166(5), Article 208. https://doi.org/10.3847/1538-3881/ad011c

@article{cb8fbb61fb4c4055af3a3bcffc78cb85,

title = "Stability and Detectability of Exomoons Orbiting HIP 41378 f, a Temperate Jovian Planet with an Anomalously Low Apparent Density",

abstract = "Moons orbiting exoplanets (“exomoons”) may hold clues about planet formation, migration, and habitability. In this work, we investigate the plausibility of exomoons orbiting the temperate (Teq = 294 K) giant (R = 9.2 R⊕) planet HIP 41378 f, which has been shown to have a low apparent bulk density of 0.09 g cm−3 and a flat near-infrared transmission spectrum, hinting that it may possess circumplanetary rings. Given this planet{\textquoteright}s long orbital period (P ≈ 1.5 yr), it has been suggested that it may also host a large exomoon. Here, we analyze the orbital stability of a hypothetical exomoon with a satellite-to-planet mass ratio of 0.0123 orbiting HIP 41378 f. Combining a new software package, astroQTpy, with REBOUND and EqTide, we conduct a series of N-body and tidal migration simulations, demonstrating that satellites up to this size are largely stable against dynamical escape and collisions. We simulate the expected transit signal from this hypothetical exomoon and show that current transit observations likely cannot constrain the presence of exomoons orbiting HIP 41378 f, though future observations may be capable of detecting exomoons in other systems. Finally, we model the combined transmission spectrum of HIP 41378 f and a hypothetical moon with a low-metallicity atmosphere and show that the total effective spectrum would be contaminated at the ∼10 ppm level. Our work not only demonstrates the feasibility of exomoons orbiting HIP 41378 f but also shows that large exomoons may be a source of uncertainty in future high-precision measurements of exoplanet systems.",

keywords = "Transmission spectroscopy, Natural satellites (Extrasolar), Exoplanet systems, Exoplanet dynamics, Exoplanet astronomy, Exoplanet tides, Transits, astro-ph.EP",

author = "Harada, {Caleb K.} and Dressing, {Courtney D.} and Alam, {Munazza K.} and James Kirk and Mercedes L{\'o}pez-Morales and Kazumasa Ohno and Babatunde Akinsanmi and Barros, {Susana C. C.} and Buchhave, {Lars A.} and {Collier Cameron}, {Andrew C} and Crossfield, {Ian J. M.} and Fei Dai and Peter Gao and Steven Giacalone and Salom{\'e} Grouffal and J. Lillo-Box and Mayo, {Andrew W.} and Annelies Mortier and Alexandre Santerne and Santos, {Nuno C.} and Sousa, {S{\'e}rgio G.} and Turtelboom, {Emma V.} and Andrew Vanderburg and Wheatley, {Peter J.}",

note = "Acknowledgments: The authors thank Kristo Ment for helpful discussions regarding quadtree algorithms. This paper makes use of observations from the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 526555. These observations are associated with HST-GO program 16267 (PI: Dressing), and the analysis was supported by grant HST-GO-16267. This work was supported by the Programme National de Plan{\'e}tologie (PNP) of CNRS-INSU co-funded by CNES. This work was supported by FCT—Funda{\c c}{\~a}o para a Ci{\^e}ncia e a Tecnologia through national funds and by FEDER through COMPETE2020—Programa Operacional Competitividade e Internacionaliza{\c c}{\~a}o by these grants: UIDB/04434/2020; UIDP/04434/2020, 2022.06962.PTDC. This research has also been partly funded by the Spanish State Research Agency (AEI) Project No. PID2019-107061GB-C61. A.C.C. acknowledges support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant No. ST/R003203/1. C.K.H. acknowledges support from the National Science Foundation Graduate Research Fellowship Program under grant No. DGE 2146752. J.K. acknowledges financial support from Imperial College London through an Imperial College Research Fellowship grant. J.L.-B. acknowledges support from the Ram{\'o}n y Cajal program (RYC2021-031640-I) supported by the MCIN/AEI/10.13039/501100011033 and the European Union {"}NextGenerationEU{"}/PRTR as well as partial financial support received from {"}la Caixa{"} Foundation (ID 100010434) and the European Unions Horizon 2020 research and innovation program No. 847648, with fellowship code LCF/BQ/PI20/11760023. N.C.S. acknowledges funding from the European Union (ERC, FIERCE, 101052347). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. S.G.S. acknowledges the support from FCT through Investigador FCT contract No. CEECIND/00826/2018 and POPH/FSE (EC). P.J.W. acknowledges support from the UK Science and Technology Facilities Council (STFC) under consolidated grant ST/T000406/1.",

year = "2023",

month = nov,

day = "1",

doi = "10.3847/1538-3881/ad011c",

language = "English",

volume = "166",

journal = "The Astronomical Journal",

issn = "0004-6256",

publisher = "American Astronomical Society",

number = "5",

}

Harada, CK, Dressing, CD, Alam, MK, Kirk, J, López-Morales, M, Ohno, K, Akinsanmi, B, Barros, SCC, Buchhave, LA, Collier Cameron, AC, Crossfield, IJM, Dai, F, Gao, P, Giacalone, S, Grouffal, S, Lillo-Box, J, Mayo, AW, Mortier, A, Santerne, A, Santos, NC, Sousa, SG, Turtelboom, EV, Vanderburg, A & Wheatley, PJ 2023, 'Stability and Detectability of Exomoons Orbiting HIP 41378 f, a Temperate Jovian Planet with an Anomalously Low Apparent Density', The Astronomical Journal, vol. 166, no. 5, 208. https://doi.org/10.3847/1538-3881/ad011c

TY - JOUR

T1 - Stability and Detectability of Exomoons Orbiting HIP 41378 f, a Temperate Jovian Planet with an Anomalously Low Apparent Density

AU - Harada, Caleb K.

AU - Dressing, Courtney D.

AU - Alam, Munazza K.

AU - Kirk, James

AU - López-Morales, Mercedes

AU - Ohno, Kazumasa

AU - Akinsanmi, Babatunde

AU - Barros, Susana C. C.

AU - Buchhave, Lars A.

AU - Collier Cameron, Andrew C

AU - Crossfield, Ian J. M.

AU - Dai, Fei

AU - Gao, Peter

AU - Giacalone, Steven

AU - Grouffal, Salomé

AU - Lillo-Box, J.

AU - Mayo, Andrew W.

AU - Mortier, Annelies

AU - Santerne, Alexandre

AU - Santos, Nuno C.

AU - Sousa, Sérgio G.

AU - Turtelboom, Emma V.

AU - Vanderburg, Andrew

AU - Wheatley, Peter J.

N1 - Acknowledgments: The authors thank Kristo Ment for helpful discussions regarding quadtree algorithms. This paper makes use of observations from the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 526555. These observations are associated with HST-GO program 16267 (PI: Dressing), and the analysis was supported by grant HST-GO-16267. This work was supported by the Programme National de Planétologie (PNP) of CNRS-INSU co-funded by CNES. This work was supported by FCT—Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020—Programa Operacional Competitividade e Internacionalização by these grants: UIDB/04434/2020; UIDP/04434/2020, 2022.06962.PTDC. This research has also been partly funded by the Spanish State Research Agency (AEI) Project No. PID2019-107061GB-C61. A.C.C. acknowledges support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant No. ST/R003203/1. C.K.H. acknowledges support from the National Science Foundation Graduate Research Fellowship Program under grant No. DGE 2146752. J.K. acknowledges financial support from Imperial College London through an Imperial College Research Fellowship grant. J.L.-B. acknowledges support from the Ramón y Cajal program (RYC2021-031640-I) supported by the MCIN/AEI/10.13039/501100011033 and the European Union "NextGenerationEU"/PRTR as well as partial financial support received from "la Caixa" Foundation (ID 100010434) and the European Unions Horizon 2020 research and innovation program No. 847648, with fellowship code LCF/BQ/PI20/11760023. N.C.S. acknowledges funding from the European Union (ERC, FIERCE, 101052347). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. S.G.S. acknowledges the support from FCT through Investigador FCT contract No. CEECIND/00826/2018 and POPH/FSE (EC). P.J.W. acknowledges support from the UK Science and Technology Facilities Council (STFC) under consolidated grant ST/T000406/1.

PY - 2023/11/1

Y1 - 2023/11/1

N2 - Moons orbiting exoplanets (“exomoons”) may hold clues about planet formation, migration, and habitability. In this work, we investigate the plausibility of exomoons orbiting the temperate (Teq = 294 K) giant (R = 9.2 R⊕) planet HIP 41378 f, which has been shown to have a low apparent bulk density of 0.09 g cm−3 and a flat near-infrared transmission spectrum, hinting that it may possess circumplanetary rings. Given this planet’s long orbital period (P ≈ 1.5 yr), it has been suggested that it may also host a large exomoon. Here, we analyze the orbital stability of a hypothetical exomoon with a satellite-to-planet mass ratio of 0.0123 orbiting HIP 41378 f. Combining a new software package, astroQTpy, with REBOUND and EqTide, we conduct a series of N-body and tidal migration simulations, demonstrating that satellites up to this size are largely stable against dynamical escape and collisions. We simulate the expected transit signal from this hypothetical exomoon and show that current transit observations likely cannot constrain the presence of exomoons orbiting HIP 41378 f, though future observations may be capable of detecting exomoons in other systems. Finally, we model the combined transmission spectrum of HIP 41378 f and a hypothetical moon with a low-metallicity atmosphere and show that the total effective spectrum would be contaminated at the ∼10 ppm level. Our work not only demonstrates the feasibility of exomoons orbiting HIP 41378 f but also shows that large exomoons may be a source of uncertainty in future high-precision measurements of exoplanet systems.

AB - Moons orbiting exoplanets (“exomoons”) may hold clues about planet formation, migration, and habitability. In this work, we investigate the plausibility of exomoons orbiting the temperate (Teq = 294 K) giant (R = 9.2 R⊕) planet HIP 41378 f, which has been shown to have a low apparent bulk density of 0.09 g cm−3 and a flat near-infrared transmission spectrum, hinting that it may possess circumplanetary rings. Given this planet’s long orbital period (P ≈ 1.5 yr), it has been suggested that it may also host a large exomoon. Here, we analyze the orbital stability of a hypothetical exomoon with a satellite-to-planet mass ratio of 0.0123 orbiting HIP 41378 f. Combining a new software package, astroQTpy, with REBOUND and EqTide, we conduct a series of N-body and tidal migration simulations, demonstrating that satellites up to this size are largely stable against dynamical escape and collisions. We simulate the expected transit signal from this hypothetical exomoon and show that current transit observations likely cannot constrain the presence of exomoons orbiting HIP 41378 f, though future observations may be capable of detecting exomoons in other systems. Finally, we model the combined transmission spectrum of HIP 41378 f and a hypothetical moon with a low-metallicity atmosphere and show that the total effective spectrum would be contaminated at the ∼10 ppm level. Our work not only demonstrates the feasibility of exomoons orbiting HIP 41378 f but also shows that large exomoons may be a source of uncertainty in future high-precision measurements of exoplanet systems.

KW - Transmission spectroscopy

KW - Natural satellites (Extrasolar)

KW - Exoplanet systems

KW - Exoplanet dynamics

KW - Exoplanet astronomy

KW - Exoplanet tides

KW - Transits

KW - astro-ph.EP

U2 - 10.3847/1538-3881/ad011c

DO - 10.3847/1538-3881/ad011c

M3 - Article

SN - 0004-6256

VL - 166

JO - The Astronomical Journal

JF - The Astronomical Journal

IS - 5

M1 - 208

ER -

Stability and Detectability of Exomoons Orbiting HIP 41378 f, a Temperate Jovian Planet with an Anomalously Low Apparent Density

Abstract

Bibliographical note

Keywords

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