Pub Date : 2024-06-28DOI: 10.1051/0004-6361/202450011
Shishir Sankhyayan, Pratik Dabhade
We investigated the prevalence of giant radio galaxies (GRGs), some of the largest structures powered by supermassive black holes, within supercluster environments, and the influence of such environments on their properties. Utilising two large catalogues of superclusters (401) and GRGs (1446), we established the existence of 77 GRGs (5.3%) residing in 64 superclusters (16%) within 0.05 ≤ z ≤ 0.42. Among the 77 GRGs found in superclusters, we identified ∼70% as residing within galaxy clusters. Within the subset of GRGs not located in superclusters, which constitutes 94.7% of the sample, a mere 21% are associated with galaxy clusters, while the remaining majority are situated in sparser environments. We examined the influence of differing environments, such as cluster versus non-cluster and supercluster versus non-supercluster regions, on the size of GRGs, while also exploring the driving factors behind their overall growth. Our findings show that the largest GRGs (≳3 Mpc) grow in underdense environments beyond the confines of dense environments. Moreover, we show that ∼24% of 1446 GRGs reside in galaxy clusters. We conclude that GRGs preferentially grow in sparser regions of the cosmic web and have a significantly larger median size. Finally, we demonstrate the potential of GRGs as astrophysical probes with specific cases where GRGs, exhibiting polarised emissions and located behind superclusters (acting as natural Faraday screens), were used to estimate magnetic field strengths of the supercluster environment at sub-microgauss levels.
{"title":"Search and analysis of giant radio galaxies with associated nuclei (SAGAN)","authors":"Shishir Sankhyayan, Pratik Dabhade","doi":"10.1051/0004-6361/202450011","DOIUrl":"https://doi.org/10.1051/0004-6361/202450011","url":null,"abstract":"We investigated the prevalence of giant radio galaxies (GRGs), some of the largest structures powered by supermassive black holes, within supercluster environments, and the influence of such environments on their properties. Utilising two large catalogues of superclusters (401) and GRGs (1446), we established the existence of 77 GRGs (5.3%) residing in 64 superclusters (16%) within 0.05 ≤ <i>z<i/> ≤ 0.42. Among the 77 GRGs found in superclusters, we identified ∼70% as residing within galaxy clusters. Within the subset of GRGs not located in superclusters, which constitutes 94.7% of the sample, a mere 21% are associated with galaxy clusters, while the remaining majority are situated in sparser environments. We examined the influence of differing environments, such as cluster versus non-cluster and supercluster versus non-supercluster regions, on the size of GRGs, while also exploring the driving factors behind their overall growth. Our findings show that the largest GRGs (≳3 Mpc) grow in underdense environments beyond the confines of dense environments. Moreover, we show that ∼24% of 1446 GRGs reside in galaxy clusters. We conclude that GRGs preferentially grow in sparser regions of the cosmic web and have a significantly larger median size. Finally, we demonstrate the potential of GRGs as astrophysical probes with specific cases where GRGs, exhibiting polarised emissions and located behind superclusters (acting as natural Faraday screens), were used to estimate magnetic field strengths of the supercluster environment at sub-microgauss levels.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141462572","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 : 2024-06-27DOI: 10.1051/0004-6361/202449371
Di-Chang Chen, Christoph Mordasini, Ji-Wei Xie, Ji-Lin Zhou, Alexandre Emsenhuber
Context. The Kepler high-precision planetary sample has revealed a ‘radius valley’ separating compact super-Earths from sub-Neptunes with lower densities. Super-Earths are generally assumed to be rocky planets that were probably born in situ, while the composition and formation of sub-Neptunes remains debated. Numerous statistical studies have explored planetary and stellar properties and their correlations to provide observational clues. However, no conclusive result on the origin of the radius valley or the composition of sub-Neptunes has been derived to date.Aims. To provide more constraints, our aim is to investigate the distributions of the orbital spacing of sub-Neptunes and super-Earth planets in Kepler systems and compare their distributions with theoretical predictions of planet pairs of different formation pathways and compositions in synthetic planetary systems.Methods. Based on the Kepler planetary sample, we derived the distributions of period ratios of sub-Neptune and super-Earth planet pairs. Using synthetic planetary systems generated by the Generation III Bern Model, we also obtained theoretical predictions of period ratio distributions of planet pairs of different compositions and origins.Results. We find that Kepler sub-Neptune pairs show a significant preference to be near first-order mean motion resonances by a factor of 1.7−0.3+0.3. This is smaller than the model predictions for ‘water-rich’ pairs but larger than that of ‘water-poor’ pairs by confidence levels of ~2σ. Kepler super-Earth pairs show no significant preference for mean motion resonances from a random distribution. The derived normalised fraction of near first-order resonances of actual Kepler super-Earth pairs is consistent with that of synthetic water-poor planet pairs but significantly (≳3σ) smaller than that of synthetic water-rich planet pairs.Conclusions. The orbital migration has been more important for sub-Neptunes than for super-Earths, suggesting a partial ex situ formation of the former and an origin of the radius valley caused in part by distinct formation pathways. However, the model comparisons also show that sub-Neptunes in Kepler multiple systems are not likely (~2σ) to all be water-rich planets born ex situ but a mixture of the two (in situ and ex situ) pathways. Whereas, Kepler super-Earth planets are predominantly composed of water-poor planets that were born inside the ice line, likely through a series of giant impacts without large-scale migration.
{"title":"Constraints on the formation history and composition of Kepler planets from their distribution of orbital period ratios","authors":"Di-Chang Chen, Christoph Mordasini, Ji-Wei Xie, Ji-Lin Zhou, Alexandre Emsenhuber","doi":"10.1051/0004-6361/202449371","DOIUrl":"https://doi.org/10.1051/0004-6361/202449371","url":null,"abstract":"<i>Context<i/>. The <i>Kepler<i/> high-precision planetary sample has revealed a ‘radius valley’ separating compact super-Earths from sub-Neptunes with lower densities. Super-Earths are generally assumed to be rocky planets that were probably born in situ, while the composition and formation of sub-Neptunes remains debated. Numerous statistical studies have explored planetary and stellar properties and their correlations to provide observational clues. However, no conclusive result on the origin of the radius valley or the composition of sub-Neptunes has been derived to date.<i>Aims<i/>. To provide more constraints, our aim is to investigate the distributions of the orbital spacing of sub-Neptunes and super-Earth planets in <i>Kepler<i/> systems and compare their distributions with theoretical predictions of planet pairs of different formation pathways and compositions in synthetic planetary systems.<i>Methods<i/>. Based on the <i>Kepler<i/> planetary sample, we derived the distributions of period ratios of sub-Neptune and super-Earth planet pairs. Using synthetic planetary systems generated by the Generation III Bern Model, we also obtained theoretical predictions of period ratio distributions of planet pairs of different compositions and origins.<i>Results<i/>. We find that <i>Kepler<i/> sub-Neptune pairs show a significant preference to be near first-order mean motion resonances by a factor of 1.7<sub>−0.3<sub/><sup>+0.3<sup/>. This is smaller than the model predictions for ‘water-rich’ pairs but larger than that of ‘water-poor’ pairs by confidence levels of ~2<i>σ<i/>. <i>Kepler<i/> super-Earth pairs show no significant preference for mean motion resonances from a random distribution. The derived normalised fraction of near first-order resonances of actual <i>Kepler<i/> super-Earth pairs is consistent with that of synthetic water-poor planet pairs but significantly (≳3<i>σ<i/>) smaller than that of synthetic water-rich planet pairs.<i>Conclusions<i/>. The orbital migration has been more important for sub-Neptunes than for super-Earths, suggesting a partial ex situ formation of the former and an origin of the radius valley caused in part by distinct formation pathways. However, the model comparisons also show that sub-Neptunes in <i>Kepler<i/> multiple systems are not likely (~2<i>σ<i/>) to all be water-rich planets born ex situ but a mixture of the two (in situ and ex situ) pathways. Whereas, <i>Kepler<i/> super-Earth planets are predominantly composed of water-poor planets that were born inside the ice line, likely through a series of giant impacts without large-scale migration.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141461978","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 : 2024-06-27DOI: 10.1051/0004-6361/202450587
Adrien Leleu, Jean-Baptiste Delisle, Remo Burn, André Izidoro, Stéphane Udry, Xavier Dumusque, Christophe Lovis, Sarah Millholland, Léna Parc, François Bouchy, Vincent Bourrier, Yann Alibert, João Faria, Christoph Mordasini, Damien Ségransan
A systematic, population-level discrepancy exists between the densities of exoplanets whose masses have been measured with transit timing variations (TTVs) versus those measured with radial velocities (RVs). Since the TTV planets are predominantly nearly resonant, it is still unclear whether the discrepancy is attributed to detection biases or to astrophysical differences between the nearly resonant and non resonant planet populations. We defined a controlled, unbiased sample of 36 sub-Neptunes characterised by Kepler, TESS, HARPS, and ESPRESSO. We found that their density depends mostly on the resonant state of the system, with a low probability (of ) that the mass of (nearly) resonant planets is drawn from the same underlying population as the bulk of sub-Neptunes. Increasing the sample to 133 sub-Neptunes reveals finer details: the densities of resonant planets are similar and lower than non-resonant planets, and both the mean and spread in density increase for planets that are away from resonance. This trend is also present in RV-characterised planets alone. In addition, TTVs and RVs have consistent density distributions for a given distance to resonance. We also show that systems closer to resonances tend to be more co-planar than their spread-out counterparts. These observational trends are also found in synthetic populations, where planets that survived in their original resonant configuration retain a lower density; whereas less compact systems have undergone post-disc giant collisions that increased the planet’s density, while expanding their orbits. Our findings reinforce the claim that resonant systems are archetypes of planetary systems at their birth.
{"title":"Resonant sub-Neptunes are puffier","authors":"Adrien Leleu, Jean-Baptiste Delisle, Remo Burn, André Izidoro, Stéphane Udry, Xavier Dumusque, Christophe Lovis, Sarah Millholland, Léna Parc, François Bouchy, Vincent Bourrier, Yann Alibert, João Faria, Christoph Mordasini, Damien Ségransan","doi":"10.1051/0004-6361/202450587","DOIUrl":"https://doi.org/10.1051/0004-6361/202450587","url":null,"abstract":"A systematic, population-level discrepancy exists between the densities of exoplanets whose masses have been measured with transit timing variations (TTVs) versus those measured with radial velocities (RVs). Since the TTV planets are predominantly nearly resonant, it is still unclear whether the discrepancy is attributed to detection biases or to astrophysical differences between the nearly resonant and non resonant planet populations. We defined a controlled, unbiased sample of 36 sub-Neptunes characterised by <i>Kepler<i/>, TESS, HARPS, and ESPRESSO. We found that their density depends mostly on the resonant state of the system, with a low probability (of ) that the mass of (nearly) resonant planets is drawn from the same underlying population as the bulk of sub-Neptunes. Increasing the sample to 133 sub-Neptunes reveals finer details: the densities of resonant planets are similar and lower than non-resonant planets, and both the mean and spread in density increase for planets that are away from resonance. This trend is also present in RV-characterised planets alone. In addition, TTVs and RVs have consistent density distributions for a given distance to resonance. We also show that systems closer to resonances tend to be more co-planar than their spread-out counterparts. These observational trends are also found in synthetic populations, where planets that survived in their original resonant configuration retain a lower density; whereas less compact systems have undergone post-disc giant collisions that increased the planet’s density, while expanding their orbits. Our findings reinforce the claim that resonant systems are archetypes of planetary systems at their birth.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141461855","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 : 2024-06-27DOI: 10.1051/0004-6361/202348701
S. Dupourqué, N. Clerc, E. Pointecouteau, D. Eckert, M. Gaspari, L. Lovisari, G. W. Pratt, E. Rasia, M. Rossetti, F. Vazza, M. Balboni, I. Bartalucci, H. Bourdin, F. De Luca, M. De Petris, S. Ettori, S. Ghizzardi, P. Mazzotta
The intra-cluster medium is prone to turbulent motion that will contribute to the non-thermal heating of the gas, complicating the use of galaxy clusters as cosmological probes. Indirect approaches can estimate the intensity and structure of turbulent motions by studying the associated fluctuations in gas density and X-ray surface brightness. In this work, we aim to constrain the gas density fluctuations occurring in the CHEX-MATE sample to obtain a detailed view of their properties in a large population of clusters. To do so, we use a simulation-based approach to constrain the parameters of the power spectrum of density fluctuations, assuming a Kolmogorov-like spectrum and including the stochastic nature of the fluctuation-related observables in the error budget. Using a machine-learning approach, we learn an approximate likelihood for each cluster. This method requires clusters not to be too disturbed, as fluctuations can originate from dynamic processes such as merging. Accordingly, we removed the less relaxed clusters (centroid shift w > 0.02) from our sample, resulting in a sample of 64 clusters. We defined different subsets of CHEX-MATE to determine properties of density fluctuations as a function of dynamical state, mass, and redshift, and we investigated the correlation with the presence or not of a radio halo. We found a positive correlation between the dynamical state and density fluctuation variance, a non-trivial behaviour with mass, and no specific trend with redshift or the presence of a radio halo. The injection scale is mostly constrained by the core region. The slope in the inertial range is consistent with the Kolmogorov theory. When interpreted as originating from turbulent motion, the density fluctuations in R500 yield an average Mach number of ℳ3D ≃ 0.4 ± 0.2, an associated non-thermal pressure support of Pturb/Ptot ≃ (9 ± 6)%, or a hydrostatic mass bias bturb ≃ 0.09 ± 0.06. These findings align with expectations from existing literature.
{"title":"CHEX-MATE: Turbulence in the intra-cluster medium from X-ray surface brightness fluctuations","authors":"S. Dupourqué, N. Clerc, E. Pointecouteau, D. Eckert, M. Gaspari, L. Lovisari, G. W. Pratt, E. Rasia, M. Rossetti, F. Vazza, M. Balboni, I. Bartalucci, H. Bourdin, F. De Luca, M. De Petris, S. Ettori, S. Ghizzardi, P. Mazzotta","doi":"10.1051/0004-6361/202348701","DOIUrl":"https://doi.org/10.1051/0004-6361/202348701","url":null,"abstract":"The intra-cluster medium is prone to turbulent motion that will contribute to the non-thermal heating of the gas, complicating the use of galaxy clusters as cosmological probes. Indirect approaches can estimate the intensity and structure of turbulent motions by studying the associated fluctuations in gas density and X-ray surface brightness. In this work, we aim to constrain the gas density fluctuations occurring in the CHEX-MATE sample to obtain a detailed view of their properties in a large population of clusters. To do so, we use a simulation-based approach to constrain the parameters of the power spectrum of density fluctuations, assuming a Kolmogorov-like spectrum and including the stochastic nature of the fluctuation-related observables in the error budget. Using a machine-learning approach, we learn an approximate likelihood for each cluster. This method requires clusters not to be too disturbed, as fluctuations can originate from dynamic processes such as merging. Accordingly, we removed the less relaxed clusters (centroid shift <i>w<i/> > 0.02) from our sample, resulting in a sample of 64 clusters. We defined different subsets of CHEX-MATE to determine properties of density fluctuations as a function of dynamical state, mass, and redshift, and we investigated the correlation with the presence or not of a radio halo. We found a positive correlation between the dynamical state and density fluctuation variance, a non-trivial behaviour with mass, and no specific trend with redshift or the presence of a radio halo. The injection scale is mostly constrained by the core region. The slope in the inertial range is consistent with the Kolmogorov theory. When interpreted as originating from turbulent motion, the density fluctuations in <i>R<i/><sub>500<sub/> yield an average Mach number of ℳ<sub>3D<sub/> ≃ 0.4 ± 0.2, an associated non-thermal pressure support of <i>P<i/><sub>turb<sub/>/<i>P<i/><sub>tot<sub/> ≃ (9 ± 6)%, or a hydrostatic mass bias <i>b<i/><sub>turb<sub/> ≃ 0.09 ± 0.06. These findings align with expectations from existing literature.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141461872","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 : 2024-06-26DOI: 10.1051/0004-6361/202449323
Thomas Pfeil, Til Birnstiel, Hubert Klahr
Context. Gas in protoplanetary disks mostly cools via thermal accommodation with dust particles. Thermal relaxation is thus highly sensitive to the local dust size distributions and the spatial distribution of the grains. So far, the interplay between thermal relaxation and gas turbulence has not been dynamically modeled in hydrodynamic simulations of protoplanetary disks with dust.Aims. We aim to study the effects of the vertical shear instability (VSI) on the thermal relaxation times, and vice versa. We are particularly interested in the influence of the initial dust grain size on the VSI and whether the emerging turbulence is sustained over long timescales.Methods. We ran three axisymmetric hydrodynamic simulations of a protoplanetary disk including four dust fluids that initially resemble MRN size distributions of different initial grain sizes. From the local dust densities, we calculated the thermal accommodation timescale of dust and gas and used the result as the thermal relaxation time of the gas in our simulation. We included the effect of dust growth by applying the monodisperse dust growth rate and the typical growth limits.Results. We find that the emergence of the VSI is strongly dependent on the initial dust grain size. Coagulation also counteracts the emergence of hydrodynamic turbulence in our simulations, as shown by others before. Starting a simulation with larger grains (100 μm) generally leads to a less turbulent outcome. While the inner disk regions (within ∼70 au) develop turbulence in all three simulations, we find that the simulations with larger particles do not develop VSI in the outer disk.Conclusions. Our simulations with dynamically calculated thermal accommodation times based on the drifting and settling dust distribution show that the VSI, once developed in a disk, can be sustained over long timescales, even if grain growth is occurring. The VSI corrugates the dust layer and even diffuses the smaller grains into the upper atmosphere, where they can cool the gas. Whether the instability can emerge for a specific stratification depends on the initial dust grain sizes and the initial dust scale height. If the grains are initially ≳100 μm and if the level of turbulence is initially assumed to be low, we find no VSI turbulence in the outer disk regions.
背景原行星盘中的气体主要是通过与尘埃粒子的热容来冷却的。因此，热弛豫对当地尘埃大小分布和颗粒的空间分布非常敏感。迄今为止，在对有尘埃的原行星盘进行流体力学模拟时，尚未对热弛豫与气体湍流之间的相互作用进行动态建模。我们旨在研究垂直剪切不稳定性（VSI）对热弛豫时间的影响，反之亦然。我们尤其感兴趣的是初始尘粒大小对垂直剪切不稳定性的影响，以及新出现的湍流是否会在长时间尺度上持续。我们对一个原行星盘进行了三次轴对称流体力学模拟，其中包括四种尘埃流体，它们最初类似于不同初始粒度的 MRN 粒度分布。根据局部尘埃密度，我们计算了尘埃和气体的热容纳时间尺度，并将计算结果作为模拟中气体的热弛豫时间。我们采用单分散尘埃生长率和典型生长极限来计算尘埃生长的影响。我们发现，VSI 的出现与初始粉尘粒度密切相关。在我们的模拟中，凝结也会抵消流体动力湍流的出现，这与之前其他人的研究结果一致。以较大的颗粒（100 μm）开始模拟通常会导致较小的湍流结果。在所有三种模拟中，内盘区域（70au以内）都出现了湍流，但我们发现使用较大颗粒的模拟在外盘区没有出现VSI。我们根据漂移和沉降尘埃分布动态计算热容纳时间的模拟结果表明，VSI 一旦在圆盘中形成，就可以在较长的时间尺度内持续下去，即使颗粒正在生长。VSI 会使尘埃层呈波纹状，甚至会将较小的颗粒扩散到高层大气中，从而冷却气体。特定分层是否会出现不稳定性取决于初始尘粒大小和初始尘粒尺度高度。如果初始尘粒大小为≳100 μm，并且假设初始湍流水平较低，我们就会发现外盘区域没有 VSI 湍流。
{"title":"Vertical shear instability with dust evolution and consistent cooling times","authors":"Thomas Pfeil, Til Birnstiel, Hubert Klahr","doi":"10.1051/0004-6361/202449323","DOIUrl":"https://doi.org/10.1051/0004-6361/202449323","url":null,"abstract":"<i>Context.<i/> Gas in protoplanetary disks mostly cools via thermal accommodation with dust particles. Thermal relaxation is thus highly sensitive to the local dust size distributions and the spatial distribution of the grains. So far, the interplay between thermal relaxation and gas turbulence has not been dynamically modeled in hydrodynamic simulations of protoplanetary disks with dust.<i>Aims.<i/> We aim to study the effects of the vertical shear instability (VSI) on the thermal relaxation times, and vice versa. We are particularly interested in the influence of the initial dust grain size on the VSI and whether the emerging turbulence is sustained over long timescales.<i>Methods.<i/> We ran three axisymmetric hydrodynamic simulations of a protoplanetary disk including four dust fluids that initially resemble MRN size distributions of different initial grain sizes. From the local dust densities, we calculated the thermal accommodation timescale of dust and gas and used the result as the thermal relaxation time of the gas in our simulation. We included the effect of dust growth by applying the monodisperse dust growth rate and the typical growth limits.<i>Results.<i/> We find that the emergence of the VSI is strongly dependent on the initial dust grain size. Coagulation also counteracts the emergence of hydrodynamic turbulence in our simulations, as shown by others before. Starting a simulation with larger grains (100 μm) generally leads to a less turbulent outcome. While the inner disk regions (within ∼70 au) develop turbulence in all three simulations, we find that the simulations with larger particles do not develop VSI in the outer disk.<i>Conclusions.<i/> Our simulations with dynamically calculated thermal accommodation times based on the drifting and settling dust distribution show that the VSI, once developed in a disk, can be sustained over long timescales, even if grain growth is occurring. The VSI corrugates the dust layer and even diffuses the smaller grains into the upper atmosphere, where they can cool the gas. Whether the instability can emerge for a specific stratification depends on the initial dust grain sizes and the initial dust scale height. If the grains are initially ≳100 μm and if the level of turbulence is initially assumed to be low, we find no VSI turbulence in the outer disk regions.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141453127","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 : 2024-06-25DOI: 10.1051/0004-6361/202450257
E. A. Godenko, V. V. Izmodenov
Aims. Interstellar dust (ISD) particles penetrate the heliosphere because of the relative motion of the local interstellar cloud and the Sun. The penetrated particles pass through the heliospheric interface, that is, the region in which solar wind and interstellar plasma interact. As a result, the ISD flow is modified after the passage through this region under the influence of electromagnetic force. The main goal of this work is to show how the heliospheric interface affects the distribution of ISD particles near the Sun.Methods. We have developed a Monte Carlo model of the ISD distribution in the heliosphere. It first takes the effects of the heliospheric interface and the rotating heliospheric current sheet into account. The effects of the heliospheric interface were probed using a global heliospheric model.Results. The computation results show that the heliospheric interface strongly influences the distribution of relatively small (radius a = 150 − 250 nm) astronomical silicates. The unexpected finding is that the heliospheric interface facilitates the penetration of a = 150 nm particles at small heliocentric distances and, particularly, to the Ulysses orbit (1 − 5 AU). We demonstrate that the deflection of ISD particles in the outer heliosheath is the principal mechanism that causes the effects of the heliospheric interface on the distribution near the Sun. The computations with different heliospheric models show that the distribution near the Sun is sensitive to the plasma parameters in the pristine local interstellar medium. Thus, we demonstrated that being measured near the Sun, the ISD may serve as a new independent diagnostics of the local interstellar medium and the heliospheric boundaries.
{"title":"The unexpected role of heliospheric boundaries in facilitating interstellar dust penetration at 1–5 AU","authors":"E. A. Godenko, V. V. Izmodenov","doi":"10.1051/0004-6361/202450257","DOIUrl":"https://doi.org/10.1051/0004-6361/202450257","url":null,"abstract":"<i>Aims.<i/> Interstellar dust (ISD) particles penetrate the heliosphere because of the relative motion of the local interstellar cloud and the Sun. The penetrated particles pass through the heliospheric interface, that is, the region in which solar wind and interstellar plasma interact. As a result, the ISD flow is modified after the passage through this region under the influence of electromagnetic force. The main goal of this work is to show how the heliospheric interface affects the distribution of ISD particles near the Sun.<i>Methods.<i/> We have developed a Monte Carlo model of the ISD distribution in the heliosphere. It first takes the effects of the heliospheric interface and the rotating heliospheric current sheet into account. The effects of the heliospheric interface were probed using a global heliospheric model.<i>Results.<i/> The computation results show that the heliospheric interface strongly influences the distribution of relatively small (radius <i>a<i/> = 150 − 250 nm) astronomical silicates. The unexpected finding is that the heliospheric interface facilitates the penetration of <i>a<i/> = 150 nm particles at small heliocentric distances and, particularly, to the Ulysses orbit (1 − 5 AU). We demonstrate that the deflection of ISD particles in the outer heliosheath is the principal mechanism that causes the effects of the heliospheric interface on the distribution near the Sun. The computations with different heliospheric models show that the distribution near the Sun is sensitive to the plasma parameters in the pristine local interstellar medium. Thus, we demonstrated that being measured near the Sun, the ISD may serve as a new independent diagnostics of the local interstellar medium and the heliospheric boundaries.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141448304","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 : 2024-06-21DOI: 10.1051/0004-6361/202449689
S. Sulis, L. Borsato, S. Grouffal, H. P. Osborn, A. Santerne, A. Brandeker, M. N. Günther, A. Heitzmann, M. Lendl, M. Fridlund, D. Gandolfi, Y. Alibert, R. Alonso, T. Bárczy, D. Barrado Navascues, S. C. C. Barros, W. Baumjohann, T. Beck, W. Benz, M. Bergomi, N. Billot, A. Bonfanti, C. Broeg, A. Collier Cameron, C. Corral van Damme, A. C. M. Correia, Sz. Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, A. Deline, L. Delrez, O. D. S. Demangeon, B.-O. Demory, A. Derekas, B. Edwards, D. Ehrenreich, A. Erikson, A. Fortier, L. Fossati, K. Gazeas, M. Gillon, M. Güdel, Ch. Helling, S. Hoyer, K. G. Isaak, L. L. Kiss, J. Korth, K. W. F. Lam, J. Laskar, A. Lecavelier des Etangs, D. Magrin, P. F. L. Maxted, C. Mordasini, V. Nascimbeni, G. Olofsson, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, D. Piazza, G. Piotto, D. Pollacco, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, N. C. Santos, G. Scandariato, D. Ségransan, A. E. Simon, A. M. S. Smith, S. G. Sousa, M. Stalport, M. Steinberger, Gy. M. Szabó, A. Tuson, S. Udry, S. Ulmer-Moll, V. Van Grootel, J. Venturini, E. Villaver, N. A. Walton, T. G. Wilson, D. Wolter, T. Zingales
HIP 41378 d is a long-period planet that has only been observed to transit twice, three years apart, with K2. According to stability considerations and a partial detection of the Rossiter–McLaughlin effect, Pd = 278.36 d has been determined to be the most likely orbital period. We targeted HIP 41378 d with CHEOPS at the predicted transit timing based on Pd = 278.36 d, but the observations show no transit. We find that large (> 22.4 h) transit timing variations (TTVs) could explain this non-detection during the CHEOPS observation window. We also investigated the possibility of an incorrect orbital solution, which would have major implications for our knowledge of this system. If Pd ≠ 278.36 d, the periods that minimize the eccentricity would be 101.22 d and 371.14 d. The shortest orbital period will be tested by TESS, which will observe HIP 41378 in Sector 88 starting in January 2025. Our study shows the importance of a mission like CHEOPS, which today is the only mission able to make long observations (i.e., from space) to track the ephemeris of long-period planets possibly affected by large TTVs.
HIP 41378 d 是一颗长周期行星，只观测到它与 K2 相隔三年两次凌日。根据稳定性方面的考虑和对 Rossiter-McLaughlin 效应的部分探测，Pd = 278.36 d 被确定为最有可能的轨道周期。我们在根据 Pd = 278.36 d 预测的凌日时间用 CHEOPS 观测了 HIP 41378 d，但观测结果显示没有凌日。我们发现，巨大的（> 22.4 h）凌日时间变化（TTVs）可以解释在 CHEOPS 观测窗口期间未发现凌日的原因。我们还研究了错误轨道解的可能性，这将对我们了解这个系统产生重大影响。如果 Pd ≠ 278.36 d，那么偏心率最小的周期将是 101.22 d 和 371.14 d。最短的轨道周期将由 TESS 进行测试，TESS 将于 2025 年 1 月开始在 88 扇区观测 HIP 41378。我们的研究表明了像CHEOPS这样的任务的重要性，它是目前唯一能够进行长时间观测（即从太空）以跟踪可能受到大TTV影响的长周期行星星历表的任务。
{"title":"HIP 41378 observed by CHEOPS: Where is planet d?⋆⋆⋆","authors":"S. Sulis, L. Borsato, S. Grouffal, H. P. Osborn, A. Santerne, A. Brandeker, M. N. Günther, A. Heitzmann, M. Lendl, M. Fridlund, D. Gandolfi, Y. Alibert, R. Alonso, T. Bárczy, D. Barrado Navascues, S. C. C. Barros, W. Baumjohann, T. Beck, W. Benz, M. Bergomi, N. Billot, A. Bonfanti, C. Broeg, A. Collier Cameron, C. Corral van Damme, A. C. M. Correia, Sz. Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, A. Deline, L. Delrez, O. D. S. Demangeon, B.-O. Demory, A. Derekas, B. Edwards, D. Ehrenreich, A. Erikson, A. Fortier, L. Fossati, K. Gazeas, M. Gillon, M. Güdel, Ch. Helling, S. Hoyer, K. G. Isaak, L. L. Kiss, J. Korth, K. W. F. Lam, J. Laskar, A. Lecavelier des Etangs, D. Magrin, P. F. L. Maxted, C. Mordasini, V. Nascimbeni, G. Olofsson, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, D. Piazza, G. Piotto, D. Pollacco, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, N. C. Santos, G. Scandariato, D. Ségransan, A. E. Simon, A. M. S. Smith, S. G. Sousa, M. Stalport, M. Steinberger, Gy. M. Szabó, A. Tuson, S. Udry, S. Ulmer-Moll, V. Van Grootel, J. Venturini, E. Villaver, N. A. Walton, T. G. Wilson, D. Wolter, T. Zingales","doi":"10.1051/0004-6361/202449689","DOIUrl":"https://doi.org/10.1051/0004-6361/202449689","url":null,"abstract":"HIP 41378 d is a long-period planet that has only been observed to transit twice, three years apart, with K2. According to stability considerations and a partial detection of the Rossiter–McLaughlin effect, <i>P<i/><sub>d<sub/> = 278.36 d has been determined to be the most likely orbital period. We targeted HIP 41378 d with CHEOPS at the predicted transit timing based on <i>P<i/><sub>d<sub/> = 278.36 d, but the observations show no transit. We find that large (> 22.4 h) transit timing variations (TTVs) could explain this non-detection during the CHEOPS observation window. We also investigated the possibility of an incorrect orbital solution, which would have major implications for our knowledge of this system. If <i>P<i/><sub>d<sub/> ≠ 278.36 d, the periods that minimize the eccentricity would be 101.22 d and 371.14 d. The shortest orbital period will be tested by TESS, which will observe HIP 41378 in Sector 88 starting in January 2025. Our study shows the importance of a mission like CHEOPS, which today is the only mission able to make long observations (i.e., from space) to track the ephemeris of long-period planets possibly affected by large TTVs.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141435877","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 : 2024-06-21DOI: 10.1051/0004-6361/202449539
P. François, G. Cescutti, P. Bonifacio, E. Caffau, L. Monaco, M. Steffen, J. Puschnig, F. Calura, S. Cristallo, P. Di Marcantonio, V. Dobrovolskas, M. Franchini, A. J. Gallagher, C. J. Hansen, A. Korn, A. Kučinskas, R. Lallement, L. Lombardo, F. Lucertini, L. Magrini, A. M. Matas Pinto, F. Matteucci, A. Mucciarelli, L. Sbordone, M. Spite, E. Spitoni, M. Valentini
Context. Most of the studies on the determination of the chemical composition of metal-poor stars have been focused on the search of the most pristine stars, searching for the imprints of the ejecta of the first supernovae. Apart from the rare and very interesting r-enriched stars, few elements are measurable in the very metal-poor stars. On the other hand, a lot of work has been done also on the thin-disc and thick-disc abundance ratios in a metallicity range from [Fe/H]> −1.5 dex to solar. In the available literature, the intermediate metal-poor stars (−2.5<[Fe/H]< −1.5) have been frequently overlooked. The MINCE (Measuring at Intermediate metallicity Neutron-Capture Elements) project aims to gather the abundances of neutron-capture elements but also of light elements and iron peak elements in a large sample of giant stars in this metallicity range. The missing information has consequences for the precise study of the chemical enrichment of our Galaxy in particular for what concerns neutron-capture elements and it will be only partially covered by future multi object spectroscopic surveys such as WEAVE and 4MOST.Aims. The aim of this work is to study the chemical evolution of galactic sub-components recently identified (i.e. Gaia Sausage Enceladus (GSE), Sequoia).Methods. We used high signal-to-noise ratios, high-resolution spectra and standard 1D LTE spectrum synthesis to determine the detailed abundances.Results. We could determine the abundances for up to 10 neutron-capture elements (Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm and Eu) in 33 stars. The general trends of abundance ratios [n-capture element/Fe] versus [Fe/H] are in agreement with the results found in the literature. When our sample is divided in sub-groups depending on their kinematics, we found that the run of [Sr/Ba] versus [Ba/H] for the stars belonging to the GSE accretion event shows a tight anti-correlation. The results for the Sequoia stars, although based on a very limited sample, shows a [Sr/Ba] systematically higher than the [Sr/Ba] found in the GSE stars at a given [Ba/H] hinting at a different nucleosynthetic history. Stochastic chemical evolution models have been computed to understand the evolution of the GSE chemical composition of Sr and Ba. The first conclusions are that the GSE chemical evolution is similar to the evolution of a dwarf galaxy with galactic winds and inefficient star formation.Conclusions. Detailed abundances of neutron-capture elements have been measured in high-resolution, high signal-to-noise spectra of intermediate metal-poor stars, the metallicity range covered by the MINCE project. These abundances have been compared to detailed stochastic models of galactic chemical evolution.
{"title":"MINCE","authors":"P. François, G. Cescutti, P. Bonifacio, E. Caffau, L. Monaco, M. Steffen, J. Puschnig, F. Calura, S. Cristallo, P. Di Marcantonio, V. Dobrovolskas, M. Franchini, A. J. Gallagher, C. J. Hansen, A. Korn, A. Kučinskas, R. Lallement, L. Lombardo, F. Lucertini, L. Magrini, A. M. Matas Pinto, F. Matteucci, A. Mucciarelli, L. Sbordone, M. Spite, E. Spitoni, M. Valentini","doi":"10.1051/0004-6361/202449539","DOIUrl":"https://doi.org/10.1051/0004-6361/202449539","url":null,"abstract":"<i>Context<i/>. Most of the studies on the determination of the chemical composition of metal-poor stars have been focused on the search of the most pristine stars, searching for the imprints of the ejecta of the first supernovae. Apart from the rare and very interesting r-enriched stars, few elements are measurable in the very metal-poor stars. On the other hand, a lot of work has been done also on the thin-disc and thick-disc abundance ratios in a metallicity range from [Fe/H]> −1.5 dex to solar. In the available literature, the intermediate metal-poor stars (−2.5<[Fe/H]< −1.5) have been frequently overlooked. The MINCE (Measuring at Intermediate metallicity Neutron-Capture Elements) project aims to gather the abundances of neutron-capture elements but also of light elements and iron peak elements in a large sample of giant stars in this metallicity range. The missing information has consequences for the precise study of the chemical enrichment of our Galaxy in particular for what concerns neutron-capture elements and it will be only partially covered by future multi object spectroscopic surveys such as WEAVE and 4MOST.<i>Aims<i/>. The aim of this work is to study the chemical evolution of galactic sub-components recently identified (i.e. <i>Gaia<i/> Sausage Enceladus (GSE), Sequoia).<i>Methods<i/>. We used high signal-to-noise ratios, high-resolution spectra and standard 1D LTE spectrum synthesis to determine the detailed abundances.<i>Results<i/>. We could determine the abundances for up to 10 neutron-capture elements (Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm and Eu) in 33 stars. The general trends of abundance ratios [n-capture element/Fe] versus [Fe/H] are in agreement with the results found in the literature. When our sample is divided in sub-groups depending on their kinematics, we found that the run of [Sr/Ba] versus [Ba/H] for the stars belonging to the GSE accretion event shows a tight anti-correlation. The results for the Sequoia stars, although based on a very limited sample, shows a [Sr/Ba] systematically higher than the [Sr/Ba] found in the GSE stars at a given [Ba/H] hinting at a different nucleosynthetic history. Stochastic chemical evolution models have been computed to understand the evolution of the GSE chemical composition of Sr and Ba. The first conclusions are that the GSE chemical evolution is similar to the evolution of a dwarf galaxy with galactic winds and inefficient star formation.<i>Conclusions<i/>. Detailed abundances of neutron-capture elements have been measured in high-resolution, high signal-to-noise spectra of intermediate metal-poor stars, the metallicity range covered by the MINCE project. These abundances have been compared to detailed stochastic models of galactic chemical evolution.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141435943","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 : 2024-06-21DOI: 10.1051/0004-6361/202450322
Jingyi Mah, Sofia Savvidou, Bertram Bitsch
Improved observational technologies have enabled the resolution of substructures and the measurement of chemical abundances in protoplanetary discs. Understanding the chemical composition of the inner disc allows us to infer the building blocks available for planet formation. Recently, the depletion of water in the inner disc has been suggested to be linked to the presence of substructures, such as gaps and rings, further out in the disc. We investigate this hypothesis further by running 1D semi-analytical models of a protoplanetary disc with a gap to understand the combined effects of disc viscosity, gap depth, gap location, and gap formation timescales on the composition of the inner disc (water abundance, C/O, O/H, and C/H ratios). Our results show that for a specific value of disc viscosity, the simulation outcome can be classified into three regimes: shallow gap, “traffic jam”, and deep gap. While deep gaps may already be distinguishable with moderate-resolution (FWHM ∼ 10 AU) techniques, it is still challenging to resolve shallow gaps with the current capabilities. On the other hand, discs with traffic jams have a higher chance of being resolved when observed with a high resolution (FWHM ≲ 5 AU), but they may appear as an intensity enhancement or even featureless when observed with moderate to low angular resolution (FWHM ≳ 10 AU). In this regard, information on the inner disc composition is useful because it can help to infer the existence of traffic jams or distinguish them from deep gaps: discs with deep gaps are expected to have a low water content – and thus high C/O ratio in the inner disc due to the effective blocking of pebbles – while discs with shallow gaps would demonstrate the opposite trend (water-rich and low C/O ratio). Furthermore, discs with a traffic jam would have a constant (albeit low) inward flux of water-rich pebbles resulting in a moderate water content and sub-stellar C/O ratios. Finally, we find that the effectiveness of gaps as pebble barriers diminishes quickly when they form late (tgap ≳ 0.1 Myr), as most of the pebbles have already drifted inwards.
{"title":"Mind the gap: Distinguishing disc substructures and their impact on the inner disc composition","authors":"Jingyi Mah, Sofia Savvidou, Bertram Bitsch","doi":"10.1051/0004-6361/202450322","DOIUrl":"https://doi.org/10.1051/0004-6361/202450322","url":null,"abstract":"Improved observational technologies have enabled the resolution of substructures and the measurement of chemical abundances in protoplanetary discs. Understanding the chemical composition of the inner disc allows us to infer the building blocks available for planet formation. Recently, the depletion of water in the inner disc has been suggested to be linked to the presence of substructures, such as gaps and rings, further out in the disc. We investigate this hypothesis further by running 1D semi-analytical models of a protoplanetary disc with a gap to understand the combined effects of disc viscosity, gap depth, gap location, and gap formation timescales on the composition of the inner disc (water abundance, C/O, O/H, and C/H ratios). Our results show that for a specific value of disc viscosity, the simulation outcome can be classified into three regimes: shallow gap, “traffic jam”, and deep gap. While deep gaps may already be distinguishable with moderate-resolution (<i>FWHM<i/> ∼ 10 AU) techniques, it is still challenging to resolve shallow gaps with the current capabilities. On the other hand, discs with traffic jams have a higher chance of being resolved when observed with a high resolution (<i>FWHM<i/> ≲ 5 AU), but they may appear as an intensity enhancement or even featureless when observed with moderate to low angular resolution (<i>FWHM<i/> ≳ 10 AU). In this regard, information on the inner disc composition is useful because it can help to infer the existence of traffic jams or distinguish them from deep gaps: discs with deep gaps are expected to have a low water content – and thus high C/O ratio in the inner disc due to the effective blocking of pebbles – while discs with shallow gaps would demonstrate the opposite trend (water-rich and low C/O ratio). Furthermore, discs with a traffic jam would have a constant (albeit low) inward flux of water-rich pebbles resulting in a moderate water content and sub-stellar C/O ratios. Finally, we find that the effectiveness of gaps as pebble barriers diminishes quickly when they form late (<i>t<i/><sub>gap<sub/> ≳ 0.1 Myr), as most of the pebbles have already drifted inwards.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141436044","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 : 2024-06-19DOI: 10.1051/0004-6361/202449377
Fanpeng Shi, Dong Li, Zongjun Ning, Jun Xu, Yuxiang Song, Yuzhi Yang
Context. Solar jets play a role in coronal heating and the supply of solar wind.Aims. In this study, we calculate the energies of 23 small-scale jets emerging from a quiet-Sun region in order to investigate their contributions to coronal heating.Methods. We used data from the High-Resolution Imager (HRI) of the Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter. Small-scale jets were observed by the HRIEUV 174 Å passband in the high cadence of 6 s. These events were identified by the time–distance stacks along the trajectories of jets. Using the simultaneous observation from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO), we also performed a differential emission measure (DEM) analysis on these small-scale jets to obtain the physical parameters of plasma, which enabled us to estimate the kinetic and thermal energies of the jets.Results. We find that most of the jets exhibit common unidirectional or bidirectional motions, while some show more complex behaviors; namely, a mixture of unidirection and bidirection. A majority of jets also present repeated eruption blobs (plasmoids), which may be signatures of the quasi-periodic magnetic reconnection that has been observed in solar flares. The inverted Y-shaped structure can be recognized in several jets. These small-scale jets typically have a width of ∼0.3 Mm, a temperature of ∼1.7 MK, an electron number density of ≳109 cm−3, with speeds in a wide range from ∼20–170 km s−1. Most of these jets have an energy of 1023–1024 erg, which is marginally smaller than the energy of typical nanoflares. The thermal energy fluxes of 23 jets are estimated to be (0.74–2.96)×105 erg cm−2 s−1, which is almost on the same order of magnitude as the energy flow required to heat the quiet-Sun corona, although the kinetic energy fluxes vary over a wide range because of their strong dependence on velocity. Furthermore, the frequency distribution of thermal energy and kinetic energy both follow the power-law distribution N(E)∝E−α.Conclusions. Our observations suggest that although these jets cannot provide sufficient energy to heat the whole quiet-Sun coronal region, they are likely to account for a significant portion of the energy demand in the local regions where the jets occur.
背景：太阳射流在日冕加热和太阳风供应中发挥作用。太阳射流在日冕加热和太阳风供应中扮演着重要角色。 在这项研究中，我们计算了从静止太阳区域出现的23个小规模射流的能量，以研究它们对日冕加热的贡献。我们使用了太阳轨道器（Solar Orbiter）上的极紫外成像仪（Extreme Ultraviolet Imager，EUI）的高分辨率成像仪（High-Resolution Imager，HRI）提供的数据。HRIEUV 174 Å 通带以 6 秒的高频率观测到了小规模喷流。利用太阳动力学天文台（SDO）上的大气成像组件（AIA）的同步观测，我们还对这些小尺度喷流进行了差分发射测量（DEM）分析，以获得等离子体的物理参数，从而估算出喷流的动能和热能。我们发现，大多数喷流表现出常见的单向或双向运动，而有些则表现得更为复杂，即单向和双向混合运动。大多数喷流还呈现出重复喷发的小球（plasmoids），这可能是太阳耀斑中观测到的准周期磁性再连接的特征。在一些喷流中可以看到倒 Y 形结构。这些小尺度喷流的宽度通常为 ∼0.3 Mm，温度为 ∼1.7 MK，电子数密度为 ≳109 cm-3，速度范围为 ∼20-170 km s-1。这些射流的能量大多为 1023-1024 尔格，略小于典型纳米火花的能量。据估计，23 个喷流的热能通量为（0.74-2.96）×105 erg cm-2 s-1，这几乎与加热静日日冕所需的能量流量处于同一数量级，不过由于动能通量与速度有很大关系，其变化范围很大。此外，热能和动能的频率分布都遵循幂律分布N(E)∝E-α。我们的观测结果表明，虽然这些喷流不能提供足够的能量来加热整个静日日冕区域，但它们很可能在喷流发生的局部区域内提供了相当一部分的能量需求。
{"title":"Energy estimation of small-scale jets from the quiet-Sun region⋆","authors":"Fanpeng Shi, Dong Li, Zongjun Ning, Jun Xu, Yuxiang Song, Yuzhi Yang","doi":"10.1051/0004-6361/202449377","DOIUrl":"https://doi.org/10.1051/0004-6361/202449377","url":null,"abstract":"<i>Context.<i/> Solar jets play a role in coronal heating and the supply of solar wind.<i>Aims.<i/> In this study, we calculate the energies of 23 small-scale jets emerging from a quiet-Sun region in order to investigate their contributions to coronal heating.<i>Methods.<i/> We used data from the High-Resolution Imager (HRI) of the Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter. Small-scale jets were observed by the HRI<sub>EUV<sub/> 174 Å passband in the high cadence of 6 s. These events were identified by the time–distance stacks along the trajectories of jets. Using the simultaneous observation from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO), we also performed a differential emission measure (DEM) analysis on these small-scale jets to obtain the physical parameters of plasma, which enabled us to estimate the kinetic and thermal energies of the jets.<i>Results.<i/> We find that most of the jets exhibit common unidirectional or bidirectional motions, while some show more complex behaviors; namely, a mixture of unidirection and bidirection. A majority of jets also present repeated eruption blobs (plasmoids), which may be signatures of the quasi-periodic magnetic reconnection that has been observed in solar flares. The inverted Y-shaped structure can be recognized in several jets. These small-scale jets typically have a width of ∼0.3 Mm, a temperature of ∼1.7 MK, an electron number density of ≳10<sup>9<sup/> cm<sup>−3<sup/>, with speeds in a wide range from ∼20–170 km s<sup>−1<sup/>. Most of these jets have an energy of 10<sup>23<sup/>–10<sup>24<sup/> erg, which is marginally smaller than the energy of typical nanoflares. The thermal energy fluxes of 23 jets are estimated to be (0.74–2.96)×10<sup>5<sup/> erg cm<sup>−2<sup/> s<sup>−1<sup/>, which is almost on the same order of magnitude as the energy flow required to heat the quiet-Sun corona, although the kinetic energy fluxes vary over a wide range because of their strong dependence on velocity. Furthermore, the frequency distribution of thermal energy and kinetic energy both follow the power-law distribution <i>N<i/>(<i>E<i/>)∝<i>E<i/><sup>−<i>α<i/><sup/>.<i>Conclusions.<i/> Our observations suggest that although these jets cannot provide sufficient energy to heat the whole quiet-Sun coronal region, they are likely to account for a significant portion of the energy demand in the local regions where the jets occur.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141425504","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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