scholarly journals Young planets under extreme UV irradiation

2018 ◽  
Vol 612 ◽  
pp. A25 ◽  
Author(s):  
D. Kubyshkina ◽  
M. Lendl ◽  
L. Fossati ◽  
P. E. Cubillos ◽  
H. Lammer ◽  
...  
Keyword(s):  
Equilibrium Temperature ◽  
High Energy ◽  
High Energy Radiation ◽  
Hydrodynamic Simulations ◽  
Planetary Evolution ◽  
Atmospheric Escape ◽  
Stellar Radiation ◽  
Extreme Uv ◽  
High Level ◽  
Increasing Temperature

The K2-33 planetary system hosts one transiting ~5 R⊕ planet orbiting the young M-type host star. The planet’s mass is still unknown, with an estimated upper limit of 5.4 MJ. The extreme youth of the system (<20 Myr) gives the unprecedented opportunity to study the earliest phases of planetary evolution, at a stage when the planet is exposed to an extremely high level of high-energy radiation emitted by the host star. We perform a series of 1D hydrodynamic simulations of the planet’s upper atmosphere considering a range of possible planetary masses, from 2 to 40 M⊕, and equilibrium temperatures, from 850 to 1300 K, to account for internal heating as a result of contraction. We obtain temperature profiles mostly controlled by the planet’s mass, while the equilibrium temperature has a secondary effect. For planetary masses below 7–10 M⊕, the atmosphere is subject to extremely high escape rates, driven by the planet’s weak gravity and high thermal energy, which increase with decreasing mass and/or increasing temperature. For higher masses, the escape is instead driven by the absorption of the high-energy stellar radiation. A rough comparison of the timescales for complete atmospheric escape and age of the system indicates that the planet is more massive than 10 M⊕.

scholarly journals Effects of radiation pressure on the evaporative wind of HD 209458b

2020 ◽  
Vol 493 (1) ◽  
pp. 1292-1305 ◽  
Author(s):  
Alex Debrecht ◽  
Jonathan Carroll-Nellenback ◽  
Adam Frank ◽  
Eric G Blackman ◽  
Luca Fossati ◽  
...  
Keyword(s):  
Radiation Pressure ◽  
High Energy ◽  
Line Of Sight ◽  
Hydrodynamic Simulation ◽  
High Energy Radiation ◽  
Hydrodynamic Simulations ◽  
Cometary Tail ◽  
Effects Of Radiation ◽  
Simplified Calculation

ABSTRACT The role of radiation pressure in shaping exoplanet photoevaporation remains a topic of contention. Radiation pressure from the exoplanet’s host star has been proposed as a mechanism to drive the escaping atmosphere into a ‘cometary’ tail and explain the high velocities observed in systems where mass-loss is occurring. In this paper, we present results from high-resolution 3D hydrodynamic simulations of a planet similar to HD 209458b. We self-consistently launch a wind flowing outwards from the planet by calculating the ionization and heating resulting from incident high-energy radiation, and account for radiation pressure. We first present a simplified calculation, setting a limit on the Lyman-α flux required to drive the photoevaporated planetary material to larger radii and line-of-sight velocities. We then present the results of our simulations, which confirm the limits determined by our analytic calculation. We thus demonstrate that, within the limits of our hydrodynamic simulation and for the Lyman-α fluxes expected for HD 209458, radiation pressure is unlikely to significantly affect photoevaporative winds or to explain the high velocities at which wind material is observed, though further possibilities remain to be investigated.

scholarly journals The Posttransit Tail of WASP-107b Observed at 10830 Å

2021 ◽  
Vol 162 (6) ◽  
pp. 284
Author(s):  
J. J. Spake ◽  
A. Oklopčić ◽  
L. A. Hillenbrand
Keyword(s):  
Three Dimensional ◽  
High Energy ◽  
Stellar Winds ◽  
High Energy Radiation ◽  
Absorption Signal ◽  
Metastable Helium ◽  
Atmospheric Escape ◽  
First Time ◽  
Excess Absorption ◽  
Three Dimensional Simulations

Abstract Understanding the effects of high-energy radiation and stellar winds on planetary atmospheres is vital for explaining the observed properties of close-in exoplanets. Observations of transiting exoplanets in the triplet of metastable helium lines at 10830 Å allow extended atmospheres and escape processes to be studied for individual planets. We observed one transit of WASP-107b with NIRSPEC on Keck at 10830 Å. Our observations, for the first time, had significant posttransit phase coverage, and we detected excess absorption for over an hour after fourth contact. The data can be explained by a comet-like tail extending out to ∼7 planet radii, which corresponds to roughly twice the Roche lobe radius of the planet. Planetary tails are expected based on three-dimensional simulations of escaping exoplanet atmospheres, particularly those including the interaction between the escaped material and strong stellar winds, and have been previously observed at 10830 Å in at least one other exoplanet. With both the largest midtransit absorption signal and the most extended tail observed at 10830 Å, WASP-107b remains a keystone exoplanet for atmospheric escape studies.

scholarly journals Grid of upper atmosphere models for 1–40 M⊕ planets: application to CoRoT-7 b and HD 219134 b,c

2018 ◽  
Vol 619 ◽  
pp. A151 ◽  
Author(s):  
D. Kubyshkina ◽  
L. Fossati ◽  
N. V. Erkaev ◽  
C. P. Johnstone ◽  
P. E. Cubillos ◽  
...  
Keyword(s):  
Mass Loss Rate ◽  
Atmospheric Temperature ◽  
High Energy ◽  
Physical Models ◽  
Upper Atmosphere ◽  
Heating Rates ◽  
Planetary Evolution ◽  
Atmospheric Escape ◽  
Theoretical Evidence ◽  
Atmospheric Loss

There is growing observational and theoretical evidence suggesting that atmospheric escape is a key driver of planetary evolution. Commonly, planetary evolution models employ simple analytic formulae (e.g. energy limited escape) that are often inaccurate, and more detailed physical models of atmospheric loss usually only give snapshots of an atmosphere’s structure and are difficult to use for evolutionary studies. To overcome this problem, we have upgraded and employed an existing upper atmosphere hydrodynamic code to produce a large grid of about 7000 models covering planets with masses 1–39 M⊕ with hydrogen-dominated atmospheres and orbiting late-type stars. The modelled planets have equilibrium temperatures ranging between 300 and 2000 K. For each considered stellar mass, we account for three different values of the high-energy stellar flux (i.e. low, moderate, and high activity). For each computed model, we derived the atmospheric temperature, number density, bulk velocity, X-ray and EUV (XUV) volume heating rates, and abundance of the considered species as a function of distance from the planetary centre. From these quantities, we estimate the positions of the maximum dissociation and ionisation, the mass-loss rate, and the effective radius of the XUV absorption. We show that our results are in good agreement with previously published studies employing similar codes. We further present an interpolation routine capable to extract the modelling output parameters for any planet lying within the grid boundaries. We used the grid to identify the connection between the system parameters and the resulting atmospheric properties. We finally applied the grid and the interpolation routine to estimate atmospheric evolutionary tracks for the close-in, high-density planets CoRoT-7 b and HD 219134 b,c. Assuming that the planets ever accreted primary, hydrogen-dominated atmospheres, we find that the three planets must have lost them within a few Myr.

scholarly journals Influence of the Sun-like magnetic cycle on exoplanetary atmospheric escape

2020 ◽  
Vol 496 (3) ◽  
pp. 4017-4031
Author(s):  
Gopal Hazra ◽  
Aline A Vidotto ◽  
Carolina Villarreal D’Angelo
Keyword(s):  
Magnetic Flux ◽  
Extreme Ultraviolet ◽  
High Energy ◽  
Doppler Imaging ◽  
The Sun ◽  
Solar Cycles ◽  
Atmospheric Escape ◽  
Stellar Radiation ◽  
Cyclic Variations ◽  
Hydrogen Lines

ABSTRACT Stellar high-energy radiation (X-ray and extreme ultraviolet, XUV) drives atmospheric escape in close-in exoplanets. Given that stellar irradiation depends on the stellar magnetism and that stars have magnetic cycles, we investigate how cycles affect the evolution of exoplanetary atmospheric escape. First, we consider a hypothetical HD209458b-like planet orbiting the Sun. For that, we implement the observed solar XUV radiation available over one and a half solar cycles in a 1D hydrodynamic escape model of HD209458b. We find that atmospheric escape rates show a cyclic variation (from 7.6 to 18.5 × 1010 g s−1), almost proportional to the incident stellar radiation. To compare this with observations, we compute spectroscopic transits in two hydrogen lines. We find non-detectable cyclic variations in Ly α transits. Given the temperature sensitiveness of the H α line, its equivalent width has an amplitude of 1.9 mÅ variation over the cycle, which could be detectable in exoplanets such as HD209458b. We demonstrate that the XUV flux is linearly proportional to the magnetic flux during the solar cycle. Secondly, we apply this relation to derive the cyclic evolution of the XUV flux of HD189733 using the star’s available magnetic flux observations from Zeeman Doppler Imaging over nearly a decade. The XUV fluxes are then used to model escape in HD189733b, which shows escape rate varying from 2.8 to 6.5 × 1010 g s−1. Like in the HD209458b case, this introduces variations in Ly α and H α transits, with H α variations more likely to be observable. Finally, we show that a strong stellar flare would enhance significantly Ly α and H α transit depths.

Photo-degradation of monoazo dye blue 13 using advanced oxidation process

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Aqueous Solution ◽  
Advanced Oxidation Process ◽  
Oxidation Process ◽  
High Energy ◽  
Uv Exposure ◽  
H2o2 Concentration ◽  
Oxidizing Agent ◽  
Photo Degradation ◽  
High Energy Radiation ◽  
Uv Lamp

The high energy radiation overcome the bonding of solute in a solution and H2O2 acts as an oxidizing agent and generates a free radical in the solution which results in photo-degradation by converting the solute in to simple form and resultantly, colored substance under the effect of photo-degradation becomes colorless. The photo-degradation of monoazo dye Blue 13 in an aqueous solution was investigated using a laboratory scale UV lamp in the presence of H2O2 and for maximum degradation of dye, the independent parameter UV power, UV exposure time, pH and H2O2 concentration were optimized. It was found that neither UV in the presence of H2O2 is able to degrade Blue 13 under optimum condition. The results revealed that the use of both UV and H2O2 have pronounced effect on the discoloration of dyes which could be used for management of textile effluents contain waste dyes.

scholarly journals Challenges and Opportunities for CsPbBr3 Perovskites in Low- and High-Energy Radiation Detection

2021 ◽  
pp. 1290-1314
Author(s):  
Lotte Clinckemalie ◽  
Donato Valli ◽  
Maarten B. J. Roeffaers ◽  
Johan Hofkens ◽  
Bapi Pradhan ◽  
...  
Keyword(s):  
Radiation Detection ◽  
High Energy ◽  
High Energy Radiation ◽  
Energy Radiation ◽  
Challenges And Opportunities

scholarly journals Signatures of the Carrier Envelope Phase in Nonlinear Thomson Scattering

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 528
Author(s):  
Marcel Ruijter ◽  
Vittoria Petrillo ◽  
Thomas C. Teter ◽  
Maksim Valialshchikov ◽  
Sergey Rykovanov
Keyword(s):  
Laser Pulse ◽  
Radiation Spectrum ◽  
Thomson Scattering ◽  
High Energy ◽  
Phase Changes ◽  
High Energy Radiation ◽  
Carrier Envelope Phase ◽  
High Intensity Laser ◽  
Experimental Parameters ◽  
Intensity Laser

High-energy radiation can be generated by colliding a relativistic electron bunch with a high-intensity laser pulse—a process known as Thomson scattering. In the nonlinear regime the emitted radiation contains harmonics. For a laser pulse whose length is comparable to its wavelength, the carrier envelope phase changes the behavior of the motion of the electron and therefore the radiation spectrum. Here we show theoretically and numerically the dependency of the spectrum on the intensity of the laser and the carrier envelope phase. Additionally, we also discuss what experimental parameters are required to measure the effects for a beamed pulse.

Ultrasmall Gd@Cdots as a Radiosensitizing Agent for Non-Small Cell Lung Cancer

Nanoscale ◽  
2021 ◽  
Author(s):  
Chaebin Lee ◽  
Xiangji Liu ◽  
Weizhong Zhang ◽  
M. A. Duncan ◽  
Fangchao Jiang ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Small Cell Lung Cancer ◽  
Cross Section ◽  
Cell Lung Cancer ◽  
High Energy ◽  
Small Cell ◽  
Small Cell Lung ◽  
High Energy Radiation ◽  
Energy Radiation

High-Z nanoparticles (HZNPs) afford high cross-section for high energy radiation and have attracted wide attention as a novel type of radiosensizers. However, conventional HZNPs are often associated with issues such...

scholarly journals Recent advances in radiation detection technologies enabled by metal-halide perovskites

2021 ◽  
Author(s):  
Tiebin Yang ◽  
Feng Li ◽  
Rongkun Zheng
Keyword(s):  
Gamma Rays ◽  
Performance Optimization ◽  
Radiation Detection ◽  
High Energy ◽  
Device Performance ◽  
High Energy Radiation ◽  
Energy Radiation ◽  
Halide Perovskites ◽  
Alpha Beta ◽  
Detection Technologies

Perovskite halides hold great potential for high-energy radiation detection. Recent advancements in detecting alpha-, beta-, X-, and gamma-rays by perovskite halides are reviewed and an outlook on the device performance optimization is provided.

scholarly journals The interstellar medium in young supernova remnants: key to the production of cosmic X-rays and $\gamma $-rays

2021 ◽  
Vol 366 (6) ◽  
Author(s):  
Hidetoshi Sano ◽  
Yasuo Fukui
Keyword(s):  
Interstellar Medium ◽  
Supernova Remnants ◽  
Cosmic Ray ◽  
High Energy ◽  
X Rays ◽  
Interstellar Gas ◽  
High Energy Radiation ◽  
Dense Cores ◽  
The Relationship ◽  
Turbulent Velocity Field

AbstractWe review recent progress in elucidating the relationship between high-energy radiation and the interstellar medium (ISM) in young supernova remnants (SNRs) with ages of ∼2000 yr, focusing in particular on RX J1713.7−3946 and RCW 86. Both SNRs emit strong nonthermal X-rays and TeV $\gamma $ γ -rays, and they contain clumpy distributions of interstellar gas that includes both atomic and molecular hydrogen. We find that shock–cloud interactions provide a viable explanation for the spatial correlation between the X-rays and ISM. In these interactions, the supernova shocks hit the typically pc-scale dense cores, generating a highly turbulent velocity field that amplifies the magnetic field up to 0.1–1 mG. This amplification leads to enhanced nonthermal synchrotron emission around the clumps, whereas the cosmic-ray electrons do not penetrate the clumps. Accordingly, the nonthermal X-rays exhibit a spatial distribution similar to that of the ISM on the pc scale, while they are anticorrelated at sub-pc scales. These results predict that hadronic $\gamma $ γ -rays can be emitted from the dense cores, resulting in a spatial correspondence between the $\gamma $ γ -rays and the ISM. The current pc-scale resolution of $\gamma $ γ -ray observations is too low to resolve this correspondence. Future $\gamma $ γ -ray observations with the Cherenkov Telescope Array will be able to resolve the sub-pc-scale $\gamma $ γ -ray distribution and provide clues to the origin of these cosmic $\gamma $ γ -rays.

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