Amorphous materials are also distinguished from crystals by their thermal properties. The structural disorder seems to be responsible both for a significant increase in heat capacity compared to crystals of the same composition, but also for a significant decrease in thermal conductivity. The temperature dependence of thermal conductivity, unusual for common interpretations of solid-state physics, gave rise to a lot of debates. We review in this article different interpretations of thermal conductivity in amorphous materials. We show finally that the temperature dependence of thermal conductivity in dielectric materials can be understood by relating it to the disorder-dependent harmonic vibrational eigenmodes.
{"title":"Vibrations and Heat Transfer in Glasses: The Role Played by Disorder","authors":"Anne Tanguy","doi":"10.5802/crphys.162","DOIUrl":"https://doi.org/10.5802/crphys.162","url":null,"abstract":"Amorphous materials are also distinguished from crystals by their thermal properties. The structural disorder seems to be responsible both for a significant increase in heat capacity compared to crystals of the same composition, but also for a significant decrease in thermal conductivity. The temperature dependence of thermal conductivity, unusual for common interpretations of solid-state physics, gave rise to a lot of debates. We review in this article different interpretations of thermal conductivity in amorphous materials. We show finally that the temperature dependence of thermal conductivity in dielectric materials can be understood by relating it to the disorder-dependent harmonic vibrational eigenmodes.","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136347313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Astronomy, Atmospheres and Refraction: Foreword","authors":"L. Dettwiller, P. Léna, D. Gratias","doi":"10.5802/crphys.132","DOIUrl":"https://doi.org/10.5802/crphys.132","url":null,"abstract":"","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45425485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Up to now and probably for still a long time, the only support of information used to detect exoplanets has been the analysis of light, either visible or infrared. In the vast majority of cases it is the light from a star and not the light from the planet itself which is used, because the huge contrast in brightness between the star and a planet orbiting it as well as the extremely short angular distance between them makes direct imaging a real challenge. It is then a subtle effect detected on the starlight that in general indicates the planet’s presence and provides information on some of its characteristics: mass, radius, distance to the star, temperature, etc. As an introduction to the different contributions appearing in this volume, this article proposes a kind of brief review of the various methods imagined by astronomers to exploit one of the properties of the light to succeed in detecting and characterizing exoplanets. We’ll show that even direct detection became a reality and contributes to the more than 5000 exoplanets detected today. Résumé. Jusqu’à présent et probablement pour encore longtemps, le seul support d’information utilisé pour détecter les exoplanètes est l’analyse de la lumière, qu’elle soit visible ou infrarouge. Dans la grande majorité des cas, c’est la lumière d’une étoile et non celle de la planète elle-même qui est utilisée, car l’énorme contraste de luminosité entre l’étoile et une planète en orbite autour d’elle ainsi que la distance angulaire extrêmement courte qui les sépare font de l’imagerie directe un véritable défi. C’est alors un effet subtil détecté sur la lumière de l’étoile qui indique en général la présence de la planète et fournit des informations sur certaines de ses caractéristiques : masse, rayon, distance à l’étoile, température, etc. En guise d’introduction aux différentes contributions figurant dans ce volume, cet article propose une sorte de brève revue des différentes méthodes imaginées par les astronomes pour exploiter une des propriétés de la lumière afin de parvenir à détecter et caractériser des exoplanètes. Nous montrerons que même la détection directe est devenue une réalité et contribue aux plus de 5000 exoplanètes détectées aujourd’hui.
{"title":"Detection of exoplanets: exploiting each property of light","authors":"D. Rouan, A. Lagrange","doi":"10.5802/crphys.135","DOIUrl":"https://doi.org/10.5802/crphys.135","url":null,"abstract":"Up to now and probably for still a long time, the only support of information used to detect exoplanets has been the analysis of light, either visible or infrared. In the vast majority of cases it is the light from a star and not the light from the planet itself which is used, because the huge contrast in brightness between the star and a planet orbiting it as well as the extremely short angular distance between them makes direct imaging a real challenge. It is then a subtle effect detected on the starlight that in general indicates the planet’s presence and provides information on some of its characteristics: mass, radius, distance to the star, temperature, etc. As an introduction to the different contributions appearing in this volume, this article proposes a kind of brief review of the various methods imagined by astronomers to exploit one of the properties of the light to succeed in detecting and characterizing exoplanets. We’ll show that even direct detection became a reality and contributes to the more than 5000 exoplanets detected today. Résumé. Jusqu’à présent et probablement pour encore longtemps, le seul support d’information utilisé pour détecter les exoplanètes est l’analyse de la lumière, qu’elle soit visible ou infrarouge. Dans la grande majorité des cas, c’est la lumière d’une étoile et non celle de la planète elle-même qui est utilisée, car l’énorme contraste de luminosité entre l’étoile et une planète en orbite autour d’elle ainsi que la distance angulaire extrêmement courte qui les sépare font de l’imagerie directe un véritable défi. C’est alors un effet subtil détecté sur la lumière de l’étoile qui indique en général la présence de la planète et fournit des informations sur certaines de ses caractéristiques : masse, rayon, distance à l’étoile, température, etc. En guise d’introduction aux différentes contributions figurant dans ce volume, cet article propose une sorte de brève revue des différentes méthodes imaginées par les astronomes pour exploiter une des propriétés de la lumière afin de parvenir à détecter et caractériser des exoplanètes. Nous montrerons que même la détection directe est devenue une réalité et contribue aux plus de 5000 exoplanètes détectées aujourd’hui.","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46103546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An important category of glass-forming materials is organic; it includes molecular liquids, polymers, solutions, proteins that can be vitrified by cooling the liquid under standard conditions or after special thermal treatments. The range of applications is large from materials to life sciences and recently to electronics. To distinguish them from other systems described in this issue, some specific properties such as the range of their glass transition temperature (T g ), their ability to vitrify and some rules of thumb to locate T g are presented. The most remarkable property of these liquids is how fast in temperature their viscosity or structural relaxation time increases as approaching T g . To characterize this behavior and rank the liquids of different strength, C.A. Angell introduced the concept of Fragility nearly 40 years ago. He proposed to classify liquids as fragile or strong in an Arrhenius plot with T g scaling (the strongest ones have never being observed in organic glasses, except for water under specific conditions). The T g value and the fragility index of a given liquid can be changed by applying pressure, i.e. changing the density. One can then explore the properties of the supercooled/overcompressed liquid and the glass in a P-T phase diagram. The T g line corresponds to an isochronic line, i.e. a line at constant relaxation time for different pairs of density-temperature. We observe that all data can be placed on master-curves that depend only on a single density- and species-dependent and T-independent effective interaction energy, E ∞ (ρ). An isochoric fragility index is defined as an intrinsic property of a given liquid, that can help in rationalizing all the correlations between the glass properties below T g and the viscous slowing down just above T g from which they are made. Geometrical confinement of liquids is also a way to modify the dynamics of a liquid and the properties of a glass; it corresponds to a large number of situations encountered in nature. Another phase diagram T-d (d defining pore size) can be defined with a non-trivial pore size dependence of the glass transition, which is also strongly affected by surface interactions.
{"title":"Organic Glass-Forming Liquids and the Concept of Fragility","authors":"Christiane Alba-Simionesco","doi":"10.5802/crphys.148","DOIUrl":"https://doi.org/10.5802/crphys.148","url":null,"abstract":"An important category of glass-forming materials is organic; it includes molecular liquids, polymers, solutions, proteins that can be vitrified by cooling the liquid under standard conditions or after special thermal treatments. The range of applications is large from materials to life sciences and recently to electronics. To distinguish them from other systems described in this issue, some specific properties such as the range of their glass transition temperature (T g ), their ability to vitrify and some rules of thumb to locate T g are presented. The most remarkable property of these liquids is how fast in temperature their viscosity or structural relaxation time increases as approaching T g . To characterize this behavior and rank the liquids of different strength, C.A. Angell introduced the concept of Fragility nearly 40 years ago. He proposed to classify liquids as fragile or strong in an Arrhenius plot with T g scaling (the strongest ones have never being observed in organic glasses, except for water under specific conditions). The T g value and the fragility index of a given liquid can be changed by applying pressure, i.e. changing the density. One can then explore the properties of the supercooled/overcompressed liquid and the glass in a P-T phase diagram. The T g line corresponds to an isochronic line, i.e. a line at constant relaxation time for different pairs of density-temperature. We observe that all data can be placed on master-curves that depend only on a single density- and species-dependent and T-independent effective interaction energy, E ∞ (ρ). An isochoric fragility index is defined as an intrinsic property of a given liquid, that can help in rationalizing all the correlations between the glass properties below T g and the viscous slowing down just above T g from which they are made. Geometrical confinement of liquids is also a way to modify the dynamics of a liquid and the properties of a glass; it corresponds to a large number of situations encountered in nature. Another phase diagram T-d (d defining pore size) can be defined with a non-trivial pore size dependence of the glass transition, which is also strongly affected by surface interactions.","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136228725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Hunting for Cold Exoplanets via Microlensing","authors":"J. Beaulieu","doi":"10.5802/crphys.151","DOIUrl":"https://doi.org/10.5802/crphys.151","url":null,"abstract":"","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43840050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Corrigendum: What is measured when measuring a thermoelectric coefficient?","authors":"Kamran Behnia","doi":"10.5802/crphys.124","DOIUrl":"https://doi.org/10.5802/crphys.124","url":null,"abstract":"","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135287557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
. Understanding how giant and terrestrial planets form and evolve, what is their internal structure and that of their atmosphere, represents one of the major challenges of modern astronomy, which is directly connected to the ultimate search for life at the horizon 2030–2050. However, several astrophysical (under-standing of the formation and physics of giant and terrestrial exoplanets), biological (identification of the best biomarkers) and technological (technical innovations for the new generations of telescopes and instruments) obstacles must be overcome. From the astrophysical point of view, it is indeed crucial to understand the mechanisms of formation and evolution of giant planets, including planet and disk interactions, which will completely sculpt the planetary architectures and thus dominate the formation of terrestrial planets, es-pecially in regions around the host star capable of supporting life. It is also important to develop dedicated instrumentation and techniques to study in their totality the population of giant and terrestrial planets, but also to reveal in the near future the first biological markers of life in the atmospheres of terrestrial planets. In that perspective, direct imaging from ground-based observatories or in space is playing a central role in concert with other observing techniques. In this paper, I will briefly review the genesis of this observing tech-nique,themaininstrumentalinnovationandchallenges,stellartargetsandsurveys,tothenpresentthemain resultsobtainedsofaraboutthephysicsandthemechanismsofformationandevolutionofyounggiantplan-ets and planetary system architectures. I will then present the exciting perspectives o ff ered by the upcoming
{"title":"Direct imaging of exoplanets: Legacy and prospects","authors":"G. Chauvin","doi":"10.5802/crphys.139","DOIUrl":"https://doi.org/10.5802/crphys.139","url":null,"abstract":". Understanding how giant and terrestrial planets form and evolve, what is their internal structure and that of their atmosphere, represents one of the major challenges of modern astronomy, which is directly connected to the ultimate search for life at the horizon 2030–2050. However, several astrophysical (under-standing of the formation and physics of giant and terrestrial exoplanets), biological (identification of the best biomarkers) and technological (technical innovations for the new generations of telescopes and instruments) obstacles must be overcome. From the astrophysical point of view, it is indeed crucial to understand the mechanisms of formation and evolution of giant planets, including planet and disk interactions, which will completely sculpt the planetary architectures and thus dominate the formation of terrestrial planets, es-pecially in regions around the host star capable of supporting life. It is also important to develop dedicated instrumentation and techniques to study in their totality the population of giant and terrestrial planets, but also to reveal in the near future the first biological markers of life in the atmospheres of terrestrial planets. In that perspective, direct imaging from ground-based observatories or in space is playing a central role in concert with other observing techniques. In this paper, I will briefly review the genesis of this observing tech-nique,themaininstrumentalinnovationandchallenges,stellartargetsandsurveys,tothenpresentthemain resultsobtainedsofaraboutthephysicsandthemechanismsofformationandevolutionofyounggiantplan-ets and planetary system architectures. I will then present the exciting perspectives o ff ered by the upcoming","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44947682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Evaporation, from exoplanets to exocomets","authors":"Alain Lecavelier des Etangs","doi":"10.5802/crphys.142","DOIUrl":"https://doi.org/10.5802/crphys.142","url":null,"abstract":"Evaporation, from","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45642311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
. In the middle of the 20th century, a paradigm shift appeared concerning the expected frequency of planetary systems in the galaxy...a shift induced by the observation of the rotational velocities of low main sequence stars (Struve 1952)! Atthesametime,Fellgett(1955)proposedtoconcentratethedilutedDopplerinformationonseveraltens of thousands of absorption lines to allow the precise measurement of stellar velocities. This idea improved the e ffi ciency of radial velocity measurements by a factor of over 1000. Gradually the accuracy of the new generation of spectrographs using cross-correlation is improved from 300 m/s to 0.1 m/s....An idea that will contribute in an important way to the discovery of 51 Pegasi b and several hundreds of planetary systems. Will visible or infrared cross-correlation spectrographs today be able to detect rocky planets in the habitable zone associated with their host star?
{"title":"Doppler cross-correlation spectroscopy as a path to the detection of Earth-like planets","authors":"M. Mayor","doi":"10.5802/crphys.153","DOIUrl":"https://doi.org/10.5802/crphys.153","url":null,"abstract":". In the middle of the 20th century, a paradigm shift appeared concerning the expected frequency of planetary systems in the galaxy...a shift induced by the observation of the rotational velocities of low main sequence stars (Struve 1952)! Atthesametime,Fellgett(1955)proposedtoconcentratethedilutedDopplerinformationonseveraltens of thousands of absorption lines to allow the precise measurement of stellar velocities. This idea improved the e ffi ciency of radial velocity measurements by a factor of over 1000. Gradually the accuracy of the new generation of spectrographs using cross-correlation is improved from 300 m/s to 0.1 m/s....An idea that will contribute in an important way to the discovery of 51 Pegasi b and several hundreds of planetary systems. Will visible or infrared cross-correlation spectrographs today be able to detect rocky planets in the habitable zone associated with their host star?","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48791927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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