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Title: Estimating the Magnetic Field Strength in Hot Jupiters

Abstract

A large fraction of known Jupiter-like exoplanets are inflated as compared to Jupiter. These “hot” Jupiters orbit close to their parent star and are bombarded with intense starlight. Many theories have been proposed to explain their radius inflation and several suggest that a small fraction of the incident starlight is injected into the planetary interior, which helps to puff up the planet. How will such energy injection affect the planetary dynamo? In this Letter, we estimate the surface magnetic field strength of hot Jupiters using scaling arguments that relate energy available in planetary interiors to the dynamo-generated magnetic fields. We find that if we take into account the energy injected in the planetary interior that is sufficient to inflate hot Jupiters to observed radii, then the resulting dynamo should be able generate magnetic fields that are more than an order of magnitude stronger than the Jovian values. Our analysis highlights the potential fundamental role of the stellar light in setting the field strength in hot Jupiters.

Authors:
 [1];  [2]
  1. Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138 (United States)
  2. Department of Physics, University of California, Santa Cruz, CA (United States)
Publication Date:
OSTI Identifier:
22654357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 849; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; INJECTION; JUPITER PLANET; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; ORBITS; SATELLITES; STARS; SURFACES; VISIBLE RADIATION

Citation Formats

Yadav, Rakesh K., and Thorngren, Daniel P., E-mail: rakesh_yadav@fas.harvard.edu. Estimating the Magnetic Field Strength in Hot Jupiters. United States: N. p., 2017. Web. doi:10.3847/2041-8213/AA93FD.
Yadav, Rakesh K., & Thorngren, Daniel P., E-mail: rakesh_yadav@fas.harvard.edu. Estimating the Magnetic Field Strength in Hot Jupiters. United States. doi:10.3847/2041-8213/AA93FD.
Yadav, Rakesh K., and Thorngren, Daniel P., E-mail: rakesh_yadav@fas.harvard.edu. 2017. "Estimating the Magnetic Field Strength in Hot Jupiters". United States. doi:10.3847/2041-8213/AA93FD.
@article{osti_22654357,
title = {Estimating the Magnetic Field Strength in Hot Jupiters},
author = {Yadav, Rakesh K. and Thorngren, Daniel P., E-mail: rakesh_yadav@fas.harvard.edu},
abstractNote = {A large fraction of known Jupiter-like exoplanets are inflated as compared to Jupiter. These “hot” Jupiters orbit close to their parent star and are bombarded with intense starlight. Many theories have been proposed to explain their radius inflation and several suggest that a small fraction of the incident starlight is injected into the planetary interior, which helps to puff up the planet. How will such energy injection affect the planetary dynamo? In this Letter, we estimate the surface magnetic field strength of hot Jupiters using scaling arguments that relate energy available in planetary interiors to the dynamo-generated magnetic fields. We find that if we take into account the energy injected in the planetary interior that is sufficient to inflate hot Jupiters to observed radii, then the resulting dynamo should be able generate magnetic fields that are more than an order of magnitude stronger than the Jovian values. Our analysis highlights the potential fundamental role of the stellar light in setting the field strength in hot Jupiters.},
doi = {10.3847/2041-8213/AA93FD},
journal = {Astrophysical Journal Letters},
number = 1,
volume = 849,
place = {United States},
year = 2017,
month =
}
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