Volcanic Exoplanet Surfaces

Fortin, Marc-Antoine; Gazel, Esteban; Kaltenegger, Lisa; Holycross, Megan

doi:10.1093/mnras/stac2198

Cited by 7 publications

(4 citation statements)

References 26 publications

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“…The Christiansen Feature (CF) is common among silicates, both crystalline and glassy [11,18,25,55]; its wavelength position can be used as a proxy for chemical composition [13,79]. In our case, for SC samples (Figure 3), the CF does not appear to be shifting in wavelength position as the grain size of the samples varies, reasonably because samples are extremely homogeneous and, as pointed out by previous studies, its position is not influenced by the grain size of investigated samples, both glassy [40] and crystalline [13].…”

Section: Discussionmentioning

confidence: 99%

Mid-Infrared (MIR) Spectroscopy of Silicate Glasses as Analogs for Mercury’s Surface: The Influence of Grain Size

et al. 2023

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Volcanic products are widely present on Mercury: they occur as low-viscosity lava flows, but traces of ash deriving from explosive volcanism are also observed. Silicate glasses represent a major component in volcanic products, and it is likely that the fine-powdered regolith on Mercury contains a non-negligible fraction of glassy material. In the laboratory, we have reproduced a Mercury-like silicate glass, from which we have obtained 14 powdered samples with different granulometric characteristics: 8 samples are extremely sorted with grain sizes ranging from 25 to 425 µm, and 6 samples consist of less sorted powders with normal distributions, varying mean values (30, 95, and 160 µm) and standard deviation (40 and 80 µm). The reflectance of samples was investigated in the mid-infrared (MIR) region: we observe how the reflectance intensity increases with grain size, and the presence of extremely fine material defines the emergence of the transparency feature (TF). We provide reference data with qualitative observations and quantitative parameterization of spectral characteristics; in particular, we observe how a small fraction of fine material can greatly influence the spectral response of coarser powders. Results of this work will be crucial for the interpretation of data collected by the BepiColombo mission, but need to be integrated with other possible Mercurian compositions.

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Section: Discussionmentioning

confidence: 99%

Mid-Infrared (MIR) Spectroscopy of Silicate Glasses as Analogs for Mercury’s Surface: The Influence of Grain Size

et al. 2023

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“…Therefore, it may be possible to discern the presence of an underlying magma ocean if the presence of an atmosphere on a rocky exoplanet can be confirmed. This has been suggested to be done via (v) eclipse photometry (Koll et al 2019;Mansfield et al 2019) through the presence of a high albedo, which is expected to differ from the crystallized rock of a solidified magma ocean (Essack et al 2020;Fortin et al 2022). Spectral information from atmospheres of highly irradiated planets may also help to distinguish classical runaway greenhouse states from other climate regimes, such as a moist bistability (Leconte et al 2013a).…”

Section: Atmospheric Spectral Signaturesmentioning

confidence: 99%

Bioverse: The Habitable Zone Inner Edge Discontinuity as an Imprint of Runaway Greenhouse Climates on Exoplanet Demographics

Schlecker,

Apai,

Lichtenberg

et al. 2024

Planet. Sci. J.

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Long-term magma ocean phases on rocky exoplanets orbiting closer to their star than the runaway greenhouse threshold—the inner edge of the classical habitable zone—may offer insights into the physical and chemical processes that distinguish potentially habitable worlds from others. The thermal stratification of runaway planets is expected to significantly inflate their atmospheres, potentially providing observational access to the runaway greenhouse transition in the form of a habitable zone inner edge discontinuity in radius–density space. Here, we use Bioverse, a statistical framework combining contextual information from the overall planet population with a survey simulator, to assess the ability of ground- and space-based telescopes to test this hypothesis. We find that the demographic imprint of the runaway greenhouse transition is likely detectable with high-precision transit photometry for sample sizes ≳100 planets if at least ∼10% of those orbiting closer than the habitable zone inner edge harbor runaway climates. Our survey simulations suggest that, in the near future, ESA’s PLATO mission will be the most promising survey to probe the habitable zone inner edge discontinuity. We determine the survey strategies that maximize the diagnostic power of the obtained data and identify as key mission design drivers: (1) a follow-up campaign of planetary mass measurements and (2) the fraction of low-mass stars in the target sample. Observational constraints on the runaway greenhouse transition will provide crucial insights into the distribution of atmospheric volatiles among rocky exoplanets, which may help to identify the nearest potentially habitable worlds.

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“…demonstrated that SO 2 is a promising tracer of exoplanetary volcanism, given its high abundance from Earth's volcanic activity and that it is not typically in the atmospheres of normal planets. SO 2 has a variety of spectral features detectable in the infrared (IR), for example with JWST, (2.5, 4.05, 7.34, 8.68, and 19.30 μm) as does H 2 S (3.80 and 8.45 μm; Fortin et al 2022). In Section 4.2, we focus on the detectability of SO 2 .…”

Section: Observability With Jwstmentioning

confidence: 99%

Potential Melting of Extrasolar Planets by Tidal Dissipation

Seligman,

Feinstein,

Lai

et al. 2024

ApJ

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Tidal heating on Io due to its finite eccentricity was predicted to drive surface volcanic activity, which was subsequently confirmed by the Voyager spacecraft. Although the volcanic activity in Io is more complex, in theory volcanism can be driven by runaway melting in which the tidal heating increases as the mantle thickness decreases. We show that this runaway melting mechanism is generic for a composite planetary body with liquid core and solid mantle, provided that (i) the mantle rigidity, μ, is comparable to the central pressure, i.e., μ/(ρ gR P) ≳ 0.1 for a body with density ρ, surface gravitational acceleration g, and radius R P; (ii) the surface is not molten; (iii) tides deposit sufficient energy; and (iv) the planet has nonzero eccentricity. We calculate the approximate liquid core radius as a function of μ/(ρ gR P), and find that more than 90% of the core will melt due to this runaway for μ/(ρ gR P) ≳ 1. From all currently confirmed exoplanets, we find that the terrestrial planets in the L 98-59 system are the most promising candidates for sustaining active volcanism. However, uncertainties regarding the quality factors and the details of tidal heating and cooling mechanisms prohibit definitive claims of volcanism on any of these planets. We generate synthetic transmission spectra of these planets assuming Venus-like atmospheric compositions with an additional 5%, 50%, and 98% SO2 component, which is a tracer of volcanic activity. We find a ≳3σ preference for a model with SO2 with 5–10 transits with JWST for L 98-59bcd.

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Volcanic Exoplanet Surfaces

Cited by 7 publications

References 26 publications

Mid-Infrared (MIR) Spectroscopy of Silicate Glasses as Analogs for Mercury’s Surface: The Influence of Grain Size

Mid-Infrared (MIR) Spectroscopy of Silicate Glasses as Analogs for Mercury’s Surface: The Influence of Grain Size

Bioverse: The Habitable Zone Inner Edge Discontinuity as an Imprint of Runaway Greenhouse Climates on Exoplanet Demographics

Potential Melting of Extrasolar Planets by Tidal Dissipation

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