Diffuse Reflection by an Inhomogeneous Planetary Atmosphere

Abstract The GJ 436 planetary system is an extraordinary system. The Neptune-size planet that orbits the M3 dwarf revealed in the Lyα line an extended neutral hydrogen atmosphere. This material fills a comet-like tail that obscures the stellar disc for more than 10 hours after the planetary transit. Here, we carry out a series of 3D radiation hydrodynamic simulations to model the interaction of the stellar wind with the escaping planetary atmosphere. With these models, we seek to reproduce the $\sim 56\%$ absorption found in Lyα transits, simultaneously with the lack of absorption in Hα transit. Varying the stellar wind strength and the EUV stellar luminosity, we search for a set of parameters that best fit the observational data. Based on Lyα observations, we found a stellar wind velocity at the position of the planet to be around [250-460] km s−1 with a temperature of [3 − 4] × 105 K. The stellar and planetary mass loss rates are found to be 2 × 10−15 M⊙ yr−1 and ∼[6 − 10] × 109 g s−1, respectively, for a stellar EUV luminosity of [0.8 − 1.6] × 1027 erg s−1. For the parameters explored in our simulations, none of our models present any significant absorption in the Hα line in agreement with the observations.

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Effect of atmosphere on recovery of diffuse reflection spectra of ZnO powder modified with nanoparticles upon irradiation in vacuum

Optical Materials ◽

10.1016/j.optmat.2021.111038 ◽

2021 ◽

Vol 115 ◽

pp. 111038

Author(s):

M.M. Mikhailov ◽

A.N. Lapin ◽

A.N. Sokolovskiy ◽

S.A. Yuryev

Keyword(s):

Diffuse Reflection ◽

Reflection Spectra ◽

Zno Powder

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Three Perceptual Dimensions for Specular and Diffuse Reflection

ACM Transactions on Applied Perception ◽

10.1145/3380741 ◽

2020 ◽

Vol 17 (2) ◽

pp. 1-26 ◽

Cited By ~ 2

Author(s):

Matteo Toscani ◽

Dar’ya Guarnera ◽

Giuseppe Claudio Guarnera ◽

Jon Yngve Hardeberg ◽

Karl R. Gegenfurtner

Keyword(s):

Diffuse Reflection

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Direct observation of long-lived cyanide anions in superexcited states

Communications Chemistry ◽

10.1038/s42004-021-00450-0 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Xiao-Fei Gao ◽

Jing-Chen Xie ◽

Hao Li ◽

Xin Meng ◽

Yong Wu ◽

...

Keyword(s):

Direct Observation ◽

Electron Attachment ◽

Planetary Atmosphere ◽

Interstellar Space ◽

Dissociative Electron Attachment ◽

Circumstellar Envelopes ◽

Vibrational States ◽

Cyanide Anion ◽

Exceptional Stability ◽

Electronic Ground

AbstractThe cyanide anion (CN−) has been identified in cometary coma, interstellar medium, planetary atmosphere and circumstellar envelopes, but its origin and abundance are still disputed. An isolated CN− is stabilized in the vibrational states up to ν = 17 of the electronic ground-state 1Σ+, but it is not thought to survive in the electronic or vibrational states above the electron autodetachment threshold, namely, in superexcited states. Here we report the direct observation of long-lived CN− yields of the dissociative electron attachment to cyanogen bromide (BrCN), and confirm that some of the CN− yields are distributed in the superexcited vibrational states ν ≥ 18 (1Σ+) or the superexcited electronic states 3Σ+ and 3Π. The triplet state can be accessed directly in the impulsive dissociation of BrCN− or by an intersystem transition from the superexcited vibrational states of CN−. The exceptional stability of CN− in the superexcited states profoundly influences its abundance and is potentially related to the production of other compounds in interstellar space.

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