The Influence of Thermal Evolution in the Magnetic Protection of Terrestrial Planets

Zuluaga, Jorge I.; Bustamante, Sebastián; Cuartas, Pablo A.; Hoyos, J.

doi:10.1088/0004-637x/770/1/23

Cited by 78 publications

(70 citation statements)

References 105 publications

(183 reference statements)

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“…Similar calculations have been presented in Siscoe & Chen (1975), Tarduno et al (2010), Vidotto et al (2011a), and Zuluaga et al (2013). As in those works, here we took the colatitude of the open-closed field line boundary to be the colatitude of the auroral oval ring (first-order approximation), but we recall that these two colatitudes may not match exactly (e.g.…”

Section: Active M-dwarf Planet Hostsmentioning

confidence: 97%

“…Because Ro l is almost linearly proportional to the planetary rotation period 2 , a tidally locked Earth-like planet in the HZ of dM stars would probably have Ro l > 1 and, therefore, a weak dipolar field (Zuluaga & Cuartas 2012). In that case, these planets would lack a protective magnetic field, potentially losing a significant fraction of their atmospheres (Zuluaga et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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Effects of M dwarf magnetic fields on potentially habitable planets

Vidotto

Jardine

Morin

et al. 2013

A&A

152

161

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We investigate the effect of the magnetic fields of M dwarf (dM) stars on potentially habitable Earth-like planets. These fields can reduce the size of planetary magnetospheres to such an extent that a significant fraction of the planet's atmosphere may be exposed to erosion by the stellar wind. We used a sample of 15 active dM stars, for which surface magnetic-field maps were reconstructed, to determine the magnetic pressure at the planet orbit and hence the largest size of its magnetosphere, which would only be decreased by considering the stellar wind. Our method provides a fast means to assess which planets are most affected by the stellar magnetic field, which can be used as a first study to be followed by more sophisticated models. We show that hypothetical Earth-like planets with similar terrestrial magnetisation (∼1 G) orbiting at the inner (outer) edge of the habitable zone of these stars would present magnetospheres that extend at most up to 6 (11.7) planetary radii. To be able to sustain an Earth-sized magnetosphere, with the exception of only a few cases, the terrestrial planet would either (1) need to orbit significantly farther out than the traditional limits of the habitable zone; or else, (2) if it were orbiting within the habitable zone, it would require at least a magnetic field ranging from a few G to up to a few thousand G. By assuming a magnetospheric size that is more appropriate for the young-Earth (3.4 Gyr ago), the required planetary magnetic fields are one order of magnitude weaker. However, in this case, the polar-cap area of the planet, which is unprotected from transport of particles to/from interplanetary space, is twice as large. At present, we do not know how small the smallest area of the planetary surface is that could be exposed and would still not affect the potential for formation and development of life in a planet. As the star becomes older and, therefore, its rotation rate and magnetic field reduce, the interplanetary magnetic pressure decreases and the magnetosphere of planets probably expands. Using an empirically derived rotation-activity/magnetism relation, we provide an analytical expression for estimating the shortest stellar rotation period for which an Earth-analogue in the habitable zone could sustain an Earth-sized magnetosphere. We find that the required rotation rate of the early-and mid-dM stars (with periods 37-202 days) is slower than the solar one, and even slower for the late-dM stars ( 63-263 days). Planets orbiting in the habitable zone of dM stars that rotate faster than this have smaller magnetospheric sizes than that of the Earth magnetosphere. Because many late-dM stars are fast rotators, conditions for terrestrial planets to harbour Earth-sized magnetospheres are more easily achieved for planets orbiting slowly rotating early-and mid-dM stars.

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Section: Active M-dwarf Planet Hostsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Effects of M dwarf magnetic fields on potentially habitable planets

Vidotto

Jardine

Morin

et al. 2013

A&A

152

161

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“…In spite of the most common recipes used to estimate XUV levels as a function of stellar age (see, e.g., Zuluaga et al 2012), which will not be applicable in the case of binaries for the reasons given above, we use here an approach consistent with the methods used to calculate mass-loss rates, i.e., using the activity proxies provided by the models of Cranmer & Saar (2011).…”

Section: Xuv Emissionmentioning

confidence: 99%

“…These planets and putative moons are expected to experience harsh environments from aggressive host stars. Thus, understanding the radiation and plasma environment experienced by these bodies is a key effort to accessing their potential habitability (Zuluaga et al 2012;Heller & Zuluaga 2013).…”

Section: Introductionmentioning

confidence: 99%

Constraining the Radiation and Plasma Environment of the Kepler Circumbinary Habitable-Zone Planets

Zuluaga

Mason

Cuartas-Restrepo

2016

ApJ

Self Cite

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The discovery of many planets using the Kepler telescope includes 10planets orbiting eight binary stars. Three binaries, , have at least one planet in the circumbinary habitable zone (BHZ). We constrain the level of high-energy radiation and the plasma environment in the BHZ of these systems. With this aim, BHZ limits in these Kepler binaries are calculated as a function of time, and the habitability lifetimes are estimated for hypothetical terrestrial planets and/or moons within the BHZ. With the time-dependent BHZ limits established, a self-consistent model is developed describing the evolution of stellar activity and radiation properties as proxies for stellar aggression toward planetary atmospheres. Modeling binary stellar rotation evolution, including the effect of tidal interaction between stars in binaries, is key to establishing the environment around these systems. We find that Kepler-16 and its binary analogsprovide a plasma environment favorable for the survival of atmospheres of putative Mars-sized planets and exomoons. Tides have modified the rotation of the stars in Kepler-47, making its radiation environment less harsh in comparison to the solar system. This is a good example of the mechanism first proposed by has an environment similar to that of the solar system with slightly better than Earth radiation conditions at the inner edge of the BHZ. These results can be reproduced and even reparameterized as stellar evolution and binary tidal models progress, using our online tool http://bhmcalc.net.

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“…The mass-loss rate and wind speed both increase with increasing EUV and X-ray flux reachingṀ ≈ 6 × 10 12 for the EUV and X-ray flux values estimated for young T Tauri stars. Exoplanet mass-loss rates also depend on Roche-lobe overflow as well as charge exchange and ion pickup (and other erosion processes) when the stellar wind interacts with the outer atmosphere of exoplanets with weak magnetic fields [25][26][27].…”

Section: Why the Exoplanet's Radiation Environment Is Importantmentioning

confidence: 99%

The Radiation Environment of Exoplanet Atmospheres

Linsky

2014

Challenges

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Exoplanets are born and evolve in the radiation and particle environment created by their host star. The host star's optical and infrared radiation heats the exoplanet's lower atmosphere and surface, while the ultraviolet, extreme ultraviolet and X-radiation control the photochemistry and mass loss from the exoplanet's upper atmosphere. Stellar radiation, especially at the shorter wavelengths, changes dramatically as a host star evolves leading to changes in the planet's atmosphere and habitability. This paper reviews the present state of our knowledge concerning the time-dependent radiation emitted by stars with convective zones, that is stars with spectral types F, G, K, and M, which comprise nearly all of the host stars of detected exoplanets.

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The Influence of Thermal Evolution in the Magnetic Protection of Terrestrial Planets

Cited by 78 publications

References 105 publications

Effects of M dwarf magnetic fields on potentially habitable planets

Effects of M dwarf magnetic fields on potentially habitable planets

Constraining the Radiation and Plasma Environment of the Kepler Circumbinary Habitable-Zone Planets

The Radiation Environment of Exoplanet Atmospheres

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