Pub Date : 2024-11-07DOI: 10.1051/0004-6361/202451823
Pascal A. Noti, Elspeth K. H. Lee
Context. The vertical mixing in hot-Jupiter atmospheres plays a critical role in the formation and spacial distribution of cloud particles in their atmospheres. This affects the observed spectra of a planet through cloud opacity, which can be influenced by the degree of cold trapping of refractory species in the deep atmosphere.Aims. We aim to isolate the effects of the internal temperature on the mixing efficiency in the atmospheres of ultra-hot Jupiters (UHJs) and the spacial distribution of cloud particles across the planet.Methods. We combined a simplified tracer-based cloud model, a picket fence radiative-transfer scheme, and a mixing length theory to the Exo-FMS general circulation model. We ran the model for five different internal temperatures at typical UHJ atmosphere system parameters.Results. Our results show the convective eddy diffusion coefficient remains low throughout the vast majority of the atmosphere, with mixing dominated by advective flows. However, some regions can show convective mixing in the upper atmosphere for colder interior temperatures. The vertical extent of the clouds is reduced as the internal temperature is increased. Additionally, a global cloud layer gets formed below the radiative-convective boundary (RCB) in the cooler cases.Conclusions. Convection is generally strongly inhibited in UHJ atmospheres above the RCB due to their strong irradiation. Convective mixing plays a minor role compared to advective mixing in keeping cloud particles aloft in UHJs with warm interiors. Higher vertical turbulent heat fluxes and the advection of potential temperature inhibit convection in warmer interiors. Our results suggest that isolated upper atmosphere regions above cold interiors may exhibit strong convective mixing in isolated regions around Rossby gyres, allowing aerosols to be better retained in these areas.
{"title":"Effects of the internal temperature on vertical mixing and on cloud structures in ultra-hot Jupiters","authors":"Pascal A. Noti, Elspeth K. H. Lee","doi":"10.1051/0004-6361/202451823","DOIUrl":"https://doi.org/10.1051/0004-6361/202451823","url":null,"abstract":"<i>Context.<i/> The vertical mixing in hot-Jupiter atmospheres plays a critical role in the formation and spacial distribution of cloud particles in their atmospheres. This affects the observed spectra of a planet through cloud opacity, which can be influenced by the degree of cold trapping of refractory species in the deep atmosphere.<i>Aims.<i/> We aim to isolate the effects of the internal temperature on the mixing efficiency in the atmospheres of ultra-hot Jupiters (UHJs) and the spacial distribution of cloud particles across the planet.<i>Methods.<i/> We combined a simplified tracer-based cloud model, a picket fence radiative-transfer scheme, and a mixing length theory to the Exo-FMS general circulation model. We ran the model for five different internal temperatures at typical UHJ atmosphere system parameters.<i>Results.<i/> Our results show the convective eddy diffusion coefficient remains low throughout the vast majority of the atmosphere, with mixing dominated by advective flows. However, some regions can show convective mixing in the upper atmosphere for colder interior temperatures. The vertical extent of the clouds is reduced as the internal temperature is increased. Additionally, a global cloud layer gets formed below the radiative-convective boundary (RCB) in the cooler cases.<i>Conclusions.<i/> Convection is generally strongly inhibited in UHJ atmospheres above the RCB due to their strong irradiation. Convective mixing plays a minor role compared to advective mixing in keeping cloud particles aloft in UHJs with warm interiors. Higher vertical turbulent heat fluxes and the advection of potential temperature inhibit convection in warmer interiors. Our results suggest that isolated upper atmosphere regions above cold interiors may exhibit strong convective mixing in isolated regions around Rossby gyres, allowing aerosols to be better retained in these areas.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"2 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142596914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2024-11-07DOI: 10.1051/0004-6361/202347839
Henriette Wirth, František Dinnbier, Pavel Kroupa, Ladislav Šubr
Context. Unresolved binaries have a strong influence on the observed parameters of stellar clusters (SCs).Aims. We quantify this influence and compute the resulting mass underestimates and stellar mass function (MF).Methods. N-body simulations of realistic SCs were used to investigate the evolution of the binary population in a SC and its tidal tails. Together with an empirically gauged stellar mass-luminosity relation, the results were then used to determine how the presence of binaries changes the photometric mass and MF of the SC and its tails as deduced from observations.Results. Tail 1 (T1), which is the tidal tail caused by gas expulsion, contains a larger fraction of binaries than both the SC and Tail 2 (T2), which forms after gas expulsion. Additionally, T1 has a larger velocity dispersion. Using the luminosity of an unresolved binary, an observer would underestimate its mass. This bias sensitively depends on the companion masses due to the structure of the stellar mass-luminosity relation. Combining the effect of all binaries in the simulation, the total photometric mass of the SC is underestimated by 15%. Dark objects (black holes and neutron stars) increase the difference between the real and observed mass of the SC further. For both the SC and the tails, the observed power-law index of the MF between a stellar mass of 0.3 and 0.7 M⊙ is smaller by up to 0.2 than the real one, the real initial mass function (IMF) being steeper by this amount. This difference is larger for stars with a larger velocity dispersion or binary fraction.Conclusions. Since the stars formed in SCs are the progenitors of the Galactic field stars, this work suggests that the binary fractions of different populations of stars in the Galactic disc will differ as a function of the velocity dispersion. However, the direction of this correlation is currently unclear, and a complete population synthesis will be needed to investigate this effect. Variations in the binary fractions of different clusters can lead to perceived variations of the deduced stellar MFs.
{"title":"The masses of open star clusters and their tidal tails and the stellar initial mass function","authors":"Henriette Wirth, František Dinnbier, Pavel Kroupa, Ladislav Šubr","doi":"10.1051/0004-6361/202347839","DOIUrl":"https://doi.org/10.1051/0004-6361/202347839","url":null,"abstract":"<i>Context.<i/> Unresolved binaries have a strong influence on the observed parameters of stellar clusters (SCs).<i>Aims.<i/> We quantify this influence and compute the resulting mass underestimates and stellar mass function (MF).<i>Methods. N<i/>-body simulations of realistic SCs were used to investigate the evolution of the binary population in a SC and its tidal tails. Together with an empirically gauged stellar mass-luminosity relation, the results were then used to determine how the presence of binaries changes the photometric mass and MF of the SC and its tails as deduced from observations.<i>Results.<i/> Tail 1 (T1), which is the tidal tail caused by gas expulsion, contains a larger fraction of binaries than both the SC and Tail 2 (T2), which forms after gas expulsion. Additionally, T1 has a larger velocity dispersion. Using the luminosity of an unresolved binary, an observer would underestimate its mass. This bias sensitively depends on the companion masses due to the structure of the stellar mass-luminosity relation. Combining the effect of all binaries in the simulation, the total photometric mass of the SC is underestimated by 15%. Dark objects (black holes and neutron stars) increase the difference between the real and observed mass of the SC further. For both the SC and the tails, the observed power-law index of the MF between a stellar mass of 0.3 and 0.7 <i>M<i/><sub>⊙<sub/> is smaller by up to 0.2 than the real one, the real initial mass function (IMF) being steeper by this amount. This difference is larger for stars with a larger velocity dispersion or binary fraction.<i>Conclusions.<i/> Since the stars formed in SCs are the progenitors of the Galactic field stars, this work suggests that the binary fractions of different populations of stars in the Galactic disc will differ as a function of the velocity dispersion. However, the direction of this correlation is currently unclear, and a complete population synthesis will be needed to investigate this effect. Variations in the binary fractions of different clusters can lead to perceived variations of the deduced stellar MFs.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"196 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142597311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Coronal mass ejections (CMEs) are often associated with X-ray (SXR) flares powered by magnetic reconnection in the low corona, while the CME shocks in the upper corona and interplanetary (IP) space accelerate electrons often producing the type II radio bursts. The CME and the reconnection event are part of the same energy release process as highlighted by the correlation between reconnection flux (ϕrec) that quantifies the strength of the released magnetic free energy during the SXR flare, and the CME kinetic energy that drives the IP shocks leading to type II bursts. Unlike the Sun, these physical parameters cannot be directly inferred in stellar observations. Hence, scaling laws between unresolved sun-as-a-star observables, namely SXR luminosity (LX) and type II luminosity (LR), and the physical properties of the associated dynamical events are crucial. Such scaling laws also provide insights into the interconnections between the particle acceleration processes across low-corona to IP space during solar-stellar “flare-CME-type II” events. Using long-term solar data in the SXR to radio waveband, we derived a scaling law between two novel power metrics for the flare and CME-associated processes. The metrics of “flare power” ( ) and “CME power” ( ), where VCME is the CME speed, scale as . In addition, LX and ϕrec show power-law trends with PCME with indices of 1.12 ± 0.05 and 0.61 ± 0.05, respectively. These power laws help infer the spatially resolved physical parameters, VCME and ϕrec, from disk-averaged observables, LX and LR during solar-stellar flare-CME-type II events.
日冕物质抛射（CME）通常与由低日冕中的磁重联驱动的 X 射线（SXR）耀斑有关，而上日冕和行星际（IP）空间中的 CME 冲击会加速电子，通常会产生 II 型射电暴。CME和重联事件是同一能量释放过程的一部分，这一点从重联通量（ϕrec）与CME动能之间的相关性（CME动能可量化SXR耀斑期间释放的磁自由能的强度，而CME动能可驱动行星际冲击，从而产生II型射电暴）可以看出。与太阳不同，恒星观测无法直接推断出这些物理参数。因此，未解决的太阳-恒星观测值（即 SXR 光度（LX）和 II 型光度（LR））与相关动力学事件的物理特性之间的比例关系至关重要。这种缩放规律还有助于深入了解太阳-恒星 "耀斑-CME II 型 "事件期间从低日冕到 IP 空间的粒子加速过程之间的相互联系。利用从 SXR 到射电波段的长期太阳数据，我们得出了耀斑和 CME 相关过程的两个新功率指标之间的比例定律。耀斑功率"（ ）和 "CME 功率"（ ），其中 VCME 是 CME 速度，它们的比例为 。此外，LX 和 ϕrec 与 PCME 呈幂律趋势，指数分别为 1.12 ± 0.05 和 0.61 ± 0.05。这些幂律有助于从太阳-恒星耀斑-CME-II 型事件中的磁盘平均观测值 LX 和 LR 推断空间分辨物理参数 VCME 和 ϕrec。
{"title":"Novel scaling laws to derive spatially resolved flare and CME parameters from sun-as-a-star observables","authors":"Atul Mohan, Natchimuthuk Gopalswamy, Hemapriya Raju, Sachiko Akiyama","doi":"10.1051/0004-6361/202451072","DOIUrl":"https://doi.org/10.1051/0004-6361/202451072","url":null,"abstract":"Coronal mass ejections (CMEs) are often associated with X-ray (SXR) flares powered by magnetic reconnection in the low corona, while the CME shocks in the upper corona and interplanetary (IP) space accelerate electrons often producing the type II radio bursts. The CME and the reconnection event are part of the same energy release process as highlighted by the correlation between reconnection flux (<i>ϕ<i/><sub>rec<sub/>) that quantifies the strength of the released magnetic free energy during the SXR flare, and the CME kinetic energy that drives the IP shocks leading to type II bursts. Unlike the Sun, these physical parameters cannot be directly inferred in stellar observations. Hence, scaling laws between unresolved sun-as-a-star observables, namely SXR luminosity (<i>L<i/><sub>X<sub/>) and type II luminosity (<i>L<i/><sub>R<sub/>), and the physical properties of the associated dynamical events are crucial. Such scaling laws also provide insights into the interconnections between the particle acceleration processes across low-corona to IP space during solar-stellar “flare-CME-type II” events. Using long-term solar data in the SXR to radio waveband, we derived a scaling law between two novel power metrics for the flare and CME-associated processes. The metrics of “flare power” ( ) and “CME power” ( ), where <i>V<i/><sub>CME<sub/> is the CME speed, scale as . In addition, <i>L<i/><sub>X<sub/> and <i>ϕ<i/><sub>rec<sub/> show power-law trends with <i>P<i/><sub>CME<sub/> with indices of 1.12 ± 0.05 and 0.61 ± 0.05, respectively. These power laws help infer the spatially resolved physical parameters, <i>V<i/><sub>CME<sub/> and <i>ϕ<i/><sub>rec<sub/>, from disk-averaged observables, <i>L<i/><sub>X<sub/> and <i>L<i/><sub>R<sub/> during solar-stellar flare-CME-type II events.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"28 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142594702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Context. Lithium plays a crucial role in probing stellar physics, stellar and primordial nucleosynthesis, and the chemical evolution of the Galaxy. Stars are considered to be the main source of Li, yet the identity of its primary stellar producer has long been a matter of debate.Aims. In light of recent theoretical and observational results, we investigate in this study the role of two candidate sources of Li enrichment in the Milky Way, namely asymptotic giant branch (AGB) stars and, in particular, novae.Methods. We utilised a one-zone Galactic chemical evolution (GCE) model to assess the viability of AGB stars and novae as stellar sources of Li. We used recent theoretical Li yields for AGB stars, while for novae we adopted observationally inferred Li yields and recently derived delay time distributions (DTDs). Subsequently, we extended our analysis by using a multi-zone model with radial migration to investigate spatial variations in the evolution of Li across the Milky Way disc and compared the results with observational data for field stars and open clusters.Results. Our analysis shows that AGB stars clearly fail to reproduce the meteoritic Li abundance. In contrast, novae appear as promising candidates within the adopted framework, allowing us to quantify the contribution of each Li source at the Sun’s formation and today. Our multi-zone model reveals the role of the differences in the DTDs of Type Ia supernovae and novae in shaping the evolution of Li in the various galactic zones. Its results are in fair agreement with the observational data for most open clusters, but small discrepancies appear in the outer disc.
背景。锂在探测恒星物理学、恒星和原始核合成以及银河系的化学演化方面发挥着至关重要的作用。恒星被认为是锂的主要来源，然而锂的主要恒星生产者是谁一直是个争论不休的问题。 目的：根据最近的理论和观测结果，我们在本研究中调查了银河系中两个锂富集候选来源的作用，即渐近巨枝（AGB）恒星，特别是新星。我们利用单区银河化学演化（GCE）模型来评估AGB恒星和新星作为Li恒星来源的可行性。对于AGB恒星，我们采用了最新的理论锂产率；对于新星，我们采用了观测推断的锂产率和最新得出的延迟时间分布（DTD）。随后，我们通过使用具有径向迁移的多区模型扩展了我们的分析，研究了整个银河系圆盘中 Li 演变的空间变化，并将结果与野外恒星和疏散星团的观测数据进行了比较。我们的分析表明，AGB恒星显然无法再现陨星的Li丰度。与此相反，新星在所采用的框架内似乎是很有希望的候选者，使我们能够量化每个锂源在太阳形成和今天的贡献。我们的多区模型揭示了 Ia 型超新星和新星的 DTDs 差异在塑造不同星系区 Li 演变中的作用。其结果与大多数疏散星团的观测数据相当吻合，但在外层圆盘出现了微小的差异。
{"title":"Evolution of lithium in the disc of the Galaxy and the role of novae","authors":"Sviatoslav Borisov, Nikos Prantzos, Corinne Charbonnel","doi":"10.1051/0004-6361/202451321","DOIUrl":"https://doi.org/10.1051/0004-6361/202451321","url":null,"abstract":"<i>Context.<i/> Lithium plays a crucial role in probing stellar physics, stellar and primordial nucleosynthesis, and the chemical evolution of the Galaxy. Stars are considered to be the main source of Li, yet the identity of its primary stellar producer has long been a matter of debate.<i>Aims.<i/> In light of recent theoretical and observational results, we investigate in this study the role of two candidate sources of Li enrichment in the Milky Way, namely asymptotic giant branch (AGB) stars and, in particular, novae.<i>Methods.<i/> We utilised a one-zone Galactic chemical evolution (GCE) model to assess the viability of AGB stars and novae as stellar sources of Li. We used recent theoretical Li yields for AGB stars, while for novae we adopted observationally inferred Li yields and recently derived delay time distributions (DTDs). Subsequently, we extended our analysis by using a multi-zone model with radial migration to investigate spatial variations in the evolution of Li across the Milky Way disc and compared the results with observational data for field stars and open clusters.<i>Results.<i/> Our analysis shows that AGB stars clearly fail to reproduce the meteoritic Li abundance. In contrast, novae appear as promising candidates within the adopted framework, allowing us to quantify the contribution of each Li source at the Sun’s formation and today. Our multi-zone model reveals the role of the differences in the DTDs of Type Ia supernovae and novae in shaping the evolution of Li in the various galactic zones. Its results are in fair agreement with the observational data for most open clusters, but small discrepancies appear in the outer disc.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"3 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142594700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2024-11-06DOI: 10.1051/0004-6361/202451911
A. E. Volvach, L. N. Volvach, M. G. Larionov
Aims. A new method of determining the parameters of close binary systems of supermassive black holes (SMBHs) and the level of gravitational waves (GWs) on the Earth’s surface are proposed.Methods. Data are presented from long-term monitoring of possibly the most powerful emitter in the Universe, S 0528+134, at five frequencies in the radio range from 4.8 GHz to 37 GHz, obtained by the RT-22 radio telescope of the Radio Astronomy Laboratory CrAO in Simeiz, the RT-26 radio telescope at Michigan Observatory, and the 40 m radio telescope of the Owens Valley Radio Observatory.Results. The dynamics of powerful flares that have occurred in the object since its discovery in a sky survey in 1970 were considered. The main physical characteristics of binary SMBHs located in the central regions of the system were obtained. These data were used to find the masses of the SMBH companions, the parameters of their orbits, the energy reserve of the system, and the lifetime of the object before the SMBHs’ merger. The level of GWs on the Earth’s surface was determined and the possibility of their detection by International Pulsar Timing Array (IPTA) GW detectors was considered.
{"title":"Blazar S 0528+134 is possibly the most powerful emitter in the Universe, including in the range of gravitational waves","authors":"A. E. Volvach, L. N. Volvach, M. G. Larionov","doi":"10.1051/0004-6361/202451911","DOIUrl":"https://doi.org/10.1051/0004-6361/202451911","url":null,"abstract":"<i>Aims.<i/> A new method of determining the parameters of close binary systems of supermassive black holes (SMBHs) and the level of gravitational waves (GWs) on the Earth’s surface are proposed.<i>Methods.<i/> Data are presented from long-term monitoring of possibly the most powerful emitter in the Universe, S 0528+134, at five frequencies in the radio range from 4.8 GHz to 37 GHz, obtained by the RT-22 radio telescope of the Radio Astronomy Laboratory CrAO in Simeiz, the RT-26 radio telescope at Michigan Observatory, and the 40 m radio telescope of the Owens Valley Radio Observatory.<i>Results.<i/> The dynamics of powerful flares that have occurred in the object since its discovery in a sky survey in 1970 were considered. The main physical characteristics of binary SMBHs located in the central regions of the system were obtained. These data were used to find the masses of the SMBH companions, the parameters of their orbits, the energy reserve of the system, and the lifetime of the object before the SMBHs’ merger. The level of GWs on the Earth’s surface was determined and the possibility of their detection by International Pulsar Timing Array (IPTA) GW detectors was considered.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"95 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142594699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2024-11-05DOI: 10.1051/0004-6361/202347278
Ryszard Gabryszewski, Paweł Wajer, Ireneusz Włodarczyk
Aims. Most studies of the dynamics of main-belt objects describing the evolution of the bodies in inner Solar System have been carried with models that include weak nongravitational forces, such as the Yarkovsky and YORP effects. Only about 19 objects exhibit cometary-type activity, with sublimation being the principal mechanism. This paper presents a study of the influence of cometary- type nongravitational forces on the dynamics of main-belt comets, and the possible paths and timescales of evolution into other Solar System regions.Methods. We used the standard Marsden model for cometary-type activity. This model was designed for elongated orbits and the continuous ejection of mass, while the main-belt comets exhibit a different mode of activity. For this reason, we propose a simple model of nongravitational force activation that is consistent with observations. The dynamical evolution of objects was studied using a fifteenth-order RADAU integrator implemented in the REBOUND package.Results. The paper presents the dynamical routes of main-belt comets in the inner Solar System when cometary-type nongravitational forces are included in calculations. The forces significantly shorten the time of transition to other regions compared to the Yarkovsky effect, shortening this time to as little as a few thousand years depending on the frequency of the activity and the A1, A2, and A3 Marsden constants. There is a large probability of a transition to near-Earth object(NEO)-type orbits for bodies with A2 < 0, which means that cometary-type nongravitational forces can be a non-negligible mechanism increasing the number of bodies in that population. The forces can also deliver active main-belt objects into mean motion resonances but can equally eject bodies into outer planetary regions on far shorter timescales than the Yarkovsky and YORP effects. Cometary-type nongravitational effects should be included in dynamical studies of individual sublimating active asteroids.
{"title":"Main-belt comets as contributors to the near-Earth objects population","authors":"Ryszard Gabryszewski, Paweł Wajer, Ireneusz Włodarczyk","doi":"10.1051/0004-6361/202347278","DOIUrl":"https://doi.org/10.1051/0004-6361/202347278","url":null,"abstract":"<i>Aims<i/>. Most studies of the dynamics of main-belt objects describing the evolution of the bodies in inner Solar System have been carried with models that include weak nongravitational forces, such as the Yarkovsky and YORP effects. Only about 19 objects exhibit cometary-type activity, with sublimation being the principal mechanism. This paper presents a study of the influence of cometary- type nongravitational forces on the dynamics of main-belt comets, and the possible paths and timescales of evolution into other Solar System regions.<i>Methods<i/>. We used the standard Marsden model for cometary-type activity. This model was designed for elongated orbits and the continuous ejection of mass, while the main-belt comets exhibit a different mode of activity. For this reason, we propose a simple model of nongravitational force activation that is consistent with observations. The dynamical evolution of objects was studied using a fifteenth-order RADAU integrator implemented in the REBOUND package.<i>Results<i/>. The paper presents the dynamical routes of main-belt comets in the inner Solar System when cometary-type nongravitational forces are included in calculations. The forces significantly shorten the time of transition to other regions compared to the Yarkovsky effect, shortening this time to as little as a few thousand years depending on the frequency of the activity and the <i>A<i/><sub>1<sub/>, <i>A<i/><sub>2<sub/>, and <i>A<i/><sub>3<sub/> Marsden constants. There is a large probability of a transition to near-Earth object(NEO)-type orbits for bodies with <i>A<i/><sub>2<sub/> < 0, which means that cometary-type nongravitational forces can be a non-negligible mechanism increasing the number of bodies in that population. The forces can also deliver active main-belt objects into mean motion resonances but can equally eject bodies into outer planetary regions on far shorter timescales than the Yarkovsky and YORP effects. Cometary-type nongravitational effects should be included in dynamical studies of individual sublimating active asteroids.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"68 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142589028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2024-11-05DOI: 10.1051/0004-6361/202348285
J. Schwaak, F. Führer, D. E. Wolf, L. Posorski, L. Brendel, J. Teiser, G. Wurm
Context. The initial particle growth in protoplanetary disks is limited by a bouncing barrier at submillimeter wavelengths. Bouncing leads to tribocharging and the electrostatic attraction of tribocharged aggregates may eventually draw them into large clusters. A charge- mediated growth phase allows for the formation of larger entities, namely, clusters of aggregates that are more prone to further particle concentrations, such as the streaming instability.Aims. We aim to quantify the strength of the electrostatic forces.Methods. In laboratory experiments, we used an acoustic trap to levitate small aggregates of tribocharged submm grains. These aggregates spin up within the trap until they lose grains. Thus, we used the centrifugal force as a measure of the local force.Results. Grains are regularly bound strongly to their neighbors. In comparison, the force at ejection can be stronger than the attractive scattering forces of the trap and can therefore be several orders of magnitude larger than expected. We note that these forces are long- ranging, compared to van der Waals forces. Thus, charged aggregates are much more stable than uncharged ones.Conclusions. Particle aggregates in disks might grow to centimeter clusters or larger as tribocharging increases the effective binding forces. This allows for hydrodynamic concentration and planetesimal formation to eventually take place throughout a wide part of the disk.
{"title":"High stability of charged particle clusters in protoplanetary disks","authors":"J. Schwaak, F. Führer, D. E. Wolf, L. Posorski, L. Brendel, J. Teiser, G. Wurm","doi":"10.1051/0004-6361/202348285","DOIUrl":"https://doi.org/10.1051/0004-6361/202348285","url":null,"abstract":"<i>Context<i/>. The initial particle growth in protoplanetary disks is limited by a bouncing barrier at submillimeter wavelengths. Bouncing leads to tribocharging and the electrostatic attraction of tribocharged aggregates may eventually draw them into large clusters. A charge- mediated growth phase allows for the formation of larger entities, namely, clusters of aggregates that are more prone to further particle concentrations, such as the streaming instability.<i>Aims<i/>. We aim to quantify the strength of the electrostatic forces.<i>Methods<i/>. In laboratory experiments, we used an acoustic trap to levitate small aggregates of tribocharged submm grains. These aggregates spin up within the trap until they lose grains. Thus, we used the centrifugal force as a measure of the local force.<i>Results<i/>. Grains are regularly bound strongly to their neighbors. In comparison, the force at ejection can be stronger than the attractive scattering forces of the trap and can therefore be several orders of magnitude larger than expected. We note that these forces are long- ranging, compared to van der Waals forces. Thus, charged aggregates are much more stable than uncharged ones.<i>Conclusions<i/>. Particle aggregates in disks might grow to centimeter clusters or larger as tribocharging increases the effective binding forces. This allows for hydrodynamic concentration and planetesimal formation to eventually take place throughout a wide part of the disk.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"45 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142589029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2024-11-05DOI: 10.1051/0004-6361/202451643
Jia-Rui Li, Jacques Delabrouille, Yi-Fu Cai, Dongdong Zhang
Context. The extreme precision and accuracy of forthcoming observations of the cosmic microwave background (CMB) temperature and polarisation anisotropies, aiming to detect the tiny signatures of primordial gravitational waves or of light relic particles beyond the standard three light neutrinos, requires commensurate precision in the modelling of foreground Galactic emission that contaminates CMB observations.Aims. We evaluate the impact of second-order effects in Galactic foreground emission due to Thomson scattering off interstellar free electrons and to Rayleigh scattering off interstellar dust particles.Methods. We used existing sky survey data and models of the distribution of free electrons and dust within the Milky Way to estimate the amplitude and power spectra of the emission originating from radiation scattered either by free electrons or by dust grains at CMB frequencies.Results. Both processes generate corrections to the total emission that are small compared to direct emission and are small enough not to pose problems for current-generation observations.Conclusions. However, B modes generated by Thomson scattering of incoming radiation off interstellar free electrons at CMB frequencies are within an order of magnitude compared to the sensitivity of the most advanced forthcoming CMB telescopes, and might require more precise evaluation in the future.
背景。即将进行的宇宙微波背景（CMB）温度和极化各向异性观测具有极高的精度和准确性，其目的是探测原始引力波或标准三轻中微子以外的轻遗迹粒子的微小特征，这就要求对污染CMB观测的银河系前景发射进行相应精确的建模。我们评估了星际自由电子的汤姆逊散射和星际尘埃粒子的瑞利散射对银河系前景发射的二阶效应的影响。我们利用现有的巡天数据以及银河系内自由电子和尘埃的分布模型，估算了CMB频率下自由电子或尘埃颗粒散射的辐射的振幅和功率谱。与直接辐射相比，这两个过程对总辐射产生的修正都很小，不足以对目前的观测造成问题。然而，由星际自由电子在 CMB 频率上的汤姆逊散射所产生的 B 模式与即将到来的最先进的 CMB 望远镜的灵敏度相比，还在一个数量级之内，因此可能需要在未来进行更精确的评估。
{"title":"Implications of scattering for CMB foreground emission modelling","authors":"Jia-Rui Li, Jacques Delabrouille, Yi-Fu Cai, Dongdong Zhang","doi":"10.1051/0004-6361/202451643","DOIUrl":"https://doi.org/10.1051/0004-6361/202451643","url":null,"abstract":"<i>Context<i/>. The extreme precision and accuracy of forthcoming observations of the cosmic microwave background (CMB) temperature and polarisation anisotropies, aiming to detect the tiny signatures of primordial gravitational waves or of light relic particles beyond the standard three light neutrinos, requires commensurate precision in the modelling of foreground Galactic emission that contaminates CMB observations.<i>Aims<i/>. We evaluate the impact of second-order effects in Galactic foreground emission due to Thomson scattering off interstellar free electrons and to Rayleigh scattering off interstellar dust particles.<i>Methods<i/>. We used existing sky survey data and models of the distribution of free electrons and dust within the Milky Way to estimate the amplitude and power spectra of the emission originating from radiation scattered either by free electrons or by dust grains at CMB frequencies.<i>Results<i/>. Both processes generate corrections to the total emission that are small compared to direct emission and are small enough not to pose problems for current-generation observations.<i>Conclusions<i/>. However, B modes generated by Thomson scattering of incoming radiation off interstellar free electrons at CMB frequencies are within an order of magnitude compared to the sensitivity of the most advanced forthcoming CMB telescopes, and might require more precise evaluation in the future.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"127 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142589031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2024-11-05DOI: 10.1051/0004-6361/202451013
A. Choplin, L. Siess, S. Goriely
Context. J-type stars are a subclass of carbon stars that are generally Li-rich, not enriched in s-elements, and have low 12C/13C ratios. They were suggested to be the manufacturers of the pre-solar grains of type AB2 (having low 12C/13C and supersolar 14N/15N).Aims. In this Letter, we investigate the possibility that J-type stars are early asymptotic giant branch (AGB) stars that experienced a proton ingestion event (PIE).Methods. We used the stellar evolution code STAREVOL to compute AGB stellar models with initial masses of 1, 2, and 3M⊙ and metallicities [Fe/H] = − 0.5 and 0.0. We included overshooting above the thermal pulse and used a network of 1160 nuclei coupled to the transport equations. The outputs of these models were compared to observations of J-type stars and AB2 grains.Results. In solar-metallicity AGB stars, PIEs can be triggered if a sufficiently high overshoot is considered. These events lead to low 12C/13C ratios, high Li abundances, and no enrichment in s-elements. We find that the 2 − 3 M⊙ AGB models experiencing a PIE can account for most of the observational features of J-type stars and AB2 grains. The remaining tensions between models and observations are (1) the low 14N/15N ratio of some AB2 grains and of 2 out of 13 J-type stars, (2) the high 26Al/27Al of some AB2 grains, and (3) the J-type stars with A(Li) < 2. Extra mixing mechanisms can alleviate some of these tensions, such as thermohaline or rotation.Conclusions. This work highlights a possible match between AGB stellar models that undergo a PIE and J-type stars and AB2 grains. To account for other types of carbon stars, such as N-type stars, PIEs should only develop in a fraction of solar-metallicity AGB stars. Additional work is needed to assess how the occurrence of PIEs depends on mixing parameters and initial conditions, and therefore to further confirm or exclude the proposed scenario.
{"title":"Proton ingestion in asymptotic giant branch stars as a possible explanation for J-type stars and AB2 grains","authors":"A. Choplin, L. Siess, S. Goriely","doi":"10.1051/0004-6361/202451013","DOIUrl":"https://doi.org/10.1051/0004-6361/202451013","url":null,"abstract":"<i>Context.<i/> J-type stars are a subclass of carbon stars that are generally Li-rich, not enriched in s-elements, and have low <sup>12<sup/>C/<sup>13<sup/>C ratios. They were suggested to be the manufacturers of the pre-solar grains of type AB2 (having low <sup>12<sup/>C/<sup>13<sup/>C and supersolar <sup>14<sup/>N/<sup>15<sup/>N).<i>Aims.<i/> In this Letter, we investigate the possibility that J-type stars are early asymptotic giant branch (AGB) stars that experienced a proton ingestion event (PIE).<i>Methods.<i/> We used the stellar evolution code STAREVOL to compute AGB stellar models with initial masses of 1, 2, and 3<i>M<i/><sub>⊙<sub/> and metallicities [Fe/H] = − 0.5 and 0.0. We included overshooting above the thermal pulse and used a network of 1160 nuclei coupled to the transport equations. The outputs of these models were compared to observations of J-type stars and AB2 grains.<i>Results.<i/> In solar-metallicity AGB stars, PIEs can be triggered if a sufficiently high overshoot is considered. These events lead to low <sup>12<sup/>C/<sup>13<sup/>C ratios, high Li abundances, and no enrichment in s-elements. We find that the 2 − 3 <i>M<i/><sub>⊙<sub/> AGB models experiencing a PIE can account for most of the observational features of J-type stars and AB2 grains. The remaining tensions between models and observations are (1) the low <sup>14<sup/>N/<sup>15<sup/>N ratio of some AB2 grains and of 2 out of 13 J-type stars, (2) the high <sup>26<sup/>Al/<sup>27<sup/>Al of some AB2 grains, and (3) the J-type stars with A(Li) < 2. Extra mixing mechanisms can alleviate some of these tensions, such as thermohaline or rotation.<i>Conclusions.<i/> This work highlights a possible match between AGB stellar models that undergo a PIE and J-type stars and AB2 grains. To account for other types of carbon stars, such as N-type stars, PIEs should only develop in a fraction of solar-metallicity AGB stars. Additional work is needed to assess how the occurrence of PIEs depends on mixing parameters and initial conditions, and therefore to further confirm or exclude the proposed scenario.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"23 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142589026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2024-11-05DOI: 10.1051/0004-6361/202451488
Christina Konstantopoulou, Annalisa De Cia, Jens-Kristian Krogager, Cédric Ledoux, Julia Roman-Duval, Edward B. Jenkins, Tanita Ramburuth-Hurt, Anna Velichko
We present a novel method to characterize dust depletion, namely, the depletion of metals into dust grains. We used observed correlations among relative abundances combining a total of 17 metals in diverse galactic environments, including the Milky Way (MW), Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC), and damped Lyman-α absorbers (DLAs) towards quasars and gamma-ray bursts (GRBs). We only considered the relative abundances of metals that qualify as tracers of dust and we used all available dust tracers. We find linear correlations among all studied dust tracers in a multidimensional space, where each dimension corresponds to an individual dust tracer. The fit to the linear correlations among the dust tracers describes the tendencies of different elements when depleting into dust grains. We determined the overall strength of dust depletion, ∆, along individual lines of sight, based on the correlations among different dust tracers. We avoided any preference for specific dust tracers or any other assumptions by including all available dust tracers in this multidimensional space. We also determined the dust depletion of Kr, C, O, Cl, P, Zn, Ge, Mg, Cu, Si, Fe, Ni, and Ti. Finally, we offer simple guidelines for the application of the method to the study of the observed patterns of abundances and relative abundances. This has allowed for a straightforward determination of the overall strength of depletion and the dust depletion of individual elements. We also obtained an estimate for the gas-phase metallicity and identified any additional deviations due to the nucleosynthesis of specific stellar populations. Thus, we have established a unified methodology for characterizing dust depletion across cosmic time and diverse galactic environments, offering a valuable new approach to the study of dust depletion in studies of the chemical evolution of galaxies.
我们提出了一种新方法来描述尘埃耗竭，即尘埃颗粒中金属的耗竭。我们使用了在不同星系环境中观测到的相对丰度之间的相关性，这些星系环境包括银河系（MW）、大麦哲伦云（LMC）、小麦哲伦云（SMC）以及类星体和伽马射线暴（GRB）的阻尼莱曼-α吸收体（DLAs）。我们只考虑了作为尘埃示踪剂的金属的相对丰度，并使用了所有可用的尘埃示踪剂。我们发现在一个多维空间中，所有研究的尘埃示踪剂之间都存在线性相关关系，其中每个维度对应一个单独的尘埃示踪剂。尘埃示踪剂之间的线性相关拟合描述了不同元素在消耗到尘粒中时的倾向。根据不同尘埃示踪剂之间的相关性，我们确定了各条视线上尘埃损耗的总体强度 ∆。我们将所有可用的尘埃示踪剂都纳入了这个多维空间，从而避免了对特定尘埃示踪剂的偏好或任何其他假设。我们还确定了尘埃中 Kr、C、O、Cl、P、Zn、Ge、Mg、Cu、Si、Fe、Ni 和 Ti 的损耗。最后，我们提供了应用该方法研究观测到的丰度和相对丰度模式的简单指南。这样就可以直接确定耗损的总体强度和单个元素的尘埃耗损。我们还获得了气相金属度的估计值，并确定了由于特定恒星群的核合成而产生的任何额外偏差。因此，我们建立了一种统一的方法来描述宇宙时间和不同星系环境中的尘埃损耗，为研究星系化学演化中的尘埃损耗提供了一种宝贵的新方法。
{"title":"DUNE: Dust depletion UNified method across cosmic time and Environments","authors":"Christina Konstantopoulou, Annalisa De Cia, Jens-Kristian Krogager, Cédric Ledoux, Julia Roman-Duval, Edward B. Jenkins, Tanita Ramburuth-Hurt, Anna Velichko","doi":"10.1051/0004-6361/202451488","DOIUrl":"https://doi.org/10.1051/0004-6361/202451488","url":null,"abstract":"We present a novel method to characterize dust depletion, namely, the depletion of metals into dust grains. We used observed correlations among relative abundances combining a total of 17 metals in diverse galactic environments, including the Milky Way (MW), Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC), and damped Lyman-α absorbers (DLAs) towards quasars and gamma-ray bursts (GRBs). We only considered the relative abundances of metals that qualify as tracers of dust and we used all available dust tracers. We find linear correlations among all studied dust tracers in a multidimensional space, where each dimension corresponds to an individual dust tracer. The fit to the linear correlations among the dust tracers describes the tendencies of different elements when depleting into dust grains. We determined the overall strength of dust depletion, ∆, along individual lines of sight, based on the correlations among different dust tracers. We avoided any preference for specific dust tracers or any other assumptions by including all available dust tracers in this multidimensional space. We also determined the dust depletion of Kr, C, O, Cl, P, Zn, Ge, Mg, Cu, Si, Fe, Ni, and Ti. Finally, we offer simple guidelines for the application of the method to the study of the observed patterns of abundances and relative abundances. This has allowed for a straightforward determination of the overall strength of depletion and the dust depletion of individual elements. We also obtained an estimate for the gas-phase metallicity and identified any additional deviations due to the nucleosynthesis of specific stellar populations. Thus, we have established a unified methodology for characterizing dust depletion across cosmic time and diverse galactic environments, offering a valuable new approach to the study of dust depletion in studies of the chemical evolution of galaxies.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"90 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142589032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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