985 research outputs found
Semi-quantitative characterisation of binary salt mixtures with static secondary ion mass spectrometry (S-SIMS)
Metamorphic constraints on the character and displacement of the South Tibetan fault system, central Bhutanese Himalaya
Static secondary ion mass spectrometry (S-SIMS) for the characterization of surface components in mineral particulates
A Coupled Analysis of Atmospheric Mass Loss and Tidal Evolution in XUV Irradiated Exoplanets: The TRAPPIST-1 Case Study
Exoplanets residing close to their stars can experience evolution of both their physical structures and their orbits due to the influence of their host stars. In this work, we present a coupled analysis of dynamical tidal dissipation and atmospheric mass loss for exoplanets in X-ray and ultraviolet (XUV) irradiated environments. As our primary application, we use this model to study the TRAPPIST-1 system and place constraints on the interior structure and orbital evolution of the planets. We start by reporting on an ultraviolet continuum flux measurement (centered around ~1900 Å) for the star TRAPPIST-1, based on 300 ks of Neil Gehrels Swift Observatory data, and which enables an estimate of the XUV-driven thermal escape arising from XUV photodissociation for each planet. We find that the X-ray flaring luminosity, measured from our X-ray detections, of TRAPPIST-1 is 5.6 × 10⁻⁴ L*, while the full flux including non-flaring periods is 6.1 × 10⁻⁵ L*, when L* is TRAPPIST-1's bolometric luminosity. We then construct a model that includes both atmospheric mass loss and tidal evolution and requires the planets to attain their present-day orbital elements during this coupled evolution. We use this model to constrain the ratio
Q′ = 3Q/2k₂ for each planet. Finally, we use additional numerical models implemented with the Virtual Planet Simulator VPLanet to study ocean retention for these planets using our derived system parameters
In situ development of high-elevation, low-relief landscapes via duplex deformation in the Eastern Himalayan hinterland, Bhutan
Constraints on the tectonic and landscape evolution of the Bhutan Himalaya from thermochronometry
The observed geomorphology and calculated thermal histories of the Bhutan Himalaya provide
an excellent platform to test ideas regarding the influence of tectonics and climate on the evolution of a
convergentmountain range. However, little consensus has been reached regarding the late Cenozoic history of
the Bhutan Himalaya. Some researchers have argued that observed geologic relationships show slowing
deformation rates, such that the range is decaying from a geomorphic perspective, while others see the range
as growing and steepening. We suggest that a better understanding is possible through the integrated
interpretation of geomorphic and thermochronometric data from the comparison of predictions from models
of landscape evolution and thermal-kinematic models of orogenic systems. New thermochronometric data
throughout Bhutan aremost consistent with a significant decrease in erosion rates, from2 to 3 km/Ma down to
0.1–0.3 km/Ma, around 6–4Ma. We interpret this pattern as a decrease in rock uplift rates due to the activation
of contractional structures of the Shillong Plateau, an uplifted region approximately 100 km south of Bhutan.
However, low-relief, fluvial landscapes throughout the Bhutanese hinterland record a late pulse of surface uplift
likely due to a recent increase in rock uplift rates. Constraints from our youngest thermochronometers suggest
that this increase in rock uplift and surface uplift occurred within the last 1.75Ma. These results imply that
the dynamics of the Bhutan Himalaya and Shillong Plateau have been linked during the late Cenozoic, with
structural elements of both regions active in variable ways and times over that interval
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