Pub Date : 2021-07-14DOI: 10.1051/0004-6361/202140657
A. Kolodzig, N. Aghanim, M. Douspis, E. Pointecouteau, Edouard Lecoq
We conducted an X-ray analysis of one of the two Planck-detected triplet-cluster systems, PLCK G334.8-38.0, with a $sim100$~ks deep XMM-Newton data. We find that the system has a redshift of $z=0.37pm{0.01}$ but the precision of the X-ray spectroscopy for two members is too low to rule out a projected triplet system, demanding optical spectroscopy for further investigation. In projection, the system looks almost like an equilateral triangle with an edge length of $sim2.0,mathrm{Mpc}$, but masses are very unevenly distributed ($M_{500} sim [2.5,0.7,0.3] times 10^{14},mathrm{M_{odot}}$ from bright to faint). The brightest member appears to be a relaxed cool-core cluster and is more than twice as massive as both other members combined. The second brightest member appears to be a disturbed non-cool-core cluster and the third member was too faint to make any classification. None of the clusters have an overlapping $R_{500}$ region and no signs of cluster interaction were found; however, the XMM-Newton data alone are probably not sensitive enough to detect such signs, and a joint analysis of X-ray and the thermal Sunyaev-Zeldovich effect (tSZ) is needed for further investigation, which may also reveal the presence of the warm-hot intergalactic medium (WHIM) within the system. The comparison with the other Planck-detected triplet-cluster-system (PLCK G214.6+36.9) shows that they have rather different configurations, suggesting rather different merger scenarios, under the assumption that they are both not simply projected triplet systems.
我们利用$sim100$ ks深度的XMM-Newton数据对两个普朗克探测到的三重星团系统之一PLCK G334.8-38.0进行了x射线分析。我们发现该系统的红移为$z=0.37pm{0.01}$，但其中两个成员的x射线光谱精度太低，无法排除投影三重态系统，需要进一步的光学光谱研究。在投影中，该系统看起来几乎像一个边长为$sim2.0,mathrm{Mpc}$的等边三角形，但质量分布非常不均匀($M_{500} sim [2.5,0.7,0.3] times 10^{14},mathrm{M_{odot}}$从亮到暗)。最亮的成员似乎是一个松弛的冷核星团，其质量是其他两个成员质量总和的两倍多。第二个最亮的成员似乎是一个不受干扰的非冷核星团，第三个成员太暗而无法进行任何分类。没有一个星团有重叠的$R_{500}$区域，也没有发现星团相互作用的迹象;然而，单靠xmm -牛顿望远镜的数据可能不够灵敏，无法探测到这些迹象，进一步的研究需要对x射线和热Sunyaev-Zeldovich效应(tSZ)进行联合分析，这也可能揭示系统内温热星系际介质(WHIM)的存在。与普朗克探测到的其他三重星团系统(PLCK G214.6+36.9)的比较表明，在假设它们都不是简单的投影三重星团系统的情况下，它们具有相当不同的结构，表明相当不同的合并场景。
{"title":"X-ray analysis of the Planck-detected triplet-cluster-system PLCK G334.8-38","authors":"A. Kolodzig, N. Aghanim, M. Douspis, E. Pointecouteau, Edouard Lecoq","doi":"10.1051/0004-6361/202140657","DOIUrl":"https://doi.org/10.1051/0004-6361/202140657","url":null,"abstract":"We conducted an X-ray analysis of one of the two Planck-detected triplet-cluster systems, PLCK G334.8-38.0, with a $sim100$~ks deep XMM-Newton data. We find that the system has a redshift of $z=0.37pm{0.01}$ but the precision of the X-ray spectroscopy for two members is too low to rule out a projected triplet system, demanding optical spectroscopy for further investigation. In projection, the system looks almost like an equilateral triangle with an edge length of $sim2.0,mathrm{Mpc}$, but masses are very unevenly distributed ($M_{500} sim [2.5,0.7,0.3] times 10^{14},mathrm{M_{odot}}$ from bright to faint). The brightest member appears to be a relaxed cool-core cluster and is more than twice as massive as both other members combined. The second brightest member appears to be a disturbed non-cool-core cluster and the third member was too faint to make any classification. None of the clusters have an overlapping $R_{500}$ region and no signs of cluster interaction were found; however, the XMM-Newton data alone are probably not sensitive enough to detect such signs, and a joint analysis of X-ray and the thermal Sunyaev-Zeldovich effect (tSZ) is needed for further investigation, which may also reveal the presence of the warm-hot intergalactic medium (WHIM) within the system. The comparison with the other Planck-detected triplet-cluster-system (PLCK G214.6+36.9) shows that they have rather different configurations, suggesting rather different merger scenarios, under the assumption that they are both not simply projected triplet systems.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"84 5 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89329448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-07-14DOI: 10.1051/0004-6361/202141151
C. Moutou, J. Almenara, G. H'ebrard, N. Santos, K. Stassun, S. Deheuvels, S. Barros, P. Benni, A. Bieryla, I. Boisse, X. Bonfils, P. Boyd, K. Collins, D. Baker, P. Cort'es-Zuleta, S. Dalal, F. Debras, M. Deleuil, X. Delfosse, O. Demangeon, Z. Essack, T. Forveille, E. Girardin, P. Guerra, N. Heidari, K. Hesse, S. Hoyer, J. Jenkins, F. Kiefer, P. Konig, D. Laloum, D. Latham, T. Lopez, E. Martioli, H. Osborn, G. Ricker, S. Seager, R. Vanderspek, M. Vezie, J. Villaseñor, J. Winn, B. Wohler, C. Ziegler
We present the discovery of two new transiting extrasolar planet candidates identified as TOI-1296.01 and TOI-1298.01 by the Transiting Exoplanet Survey Satellite (TESS). The planetary nature of these candidates has been secured with the SOPHIE high-precision spectrograph through the measurement of the companion’s mass with the radial velocity method. Both planets are similar to Saturn in mass and have similar orbital periods of a few days. They, however, show discrepant radii and therefore different densities. The radius discrepancy might be explained by the different levels of irradiation by the host stars. The subgiant star TOI-1296 hosts a low-density planet with 1.2 RJup while the less luminous, lower-size star TOI-1298 hosts a much denser planet with a 0.84 RJup radius, resulting in bulk densities of 0.198 and 0.743 g.cm−3, respectively. In addition, both stars are strongly enriched in heavy elements, having metallicities of +0.44 and +0.49 dex, respectively. The planet masses and orbital periods are 0.298± 0.039 MJup and 3.9443715± 5.8 10−6 days for TOI-1296b, and 0.356± 0.032 MJup and 4.537164± 1.2 10−5 days for TOI-1298b. The mass measurements have a relative precision of better than 13%.
{"title":"TOI-1296b and TOI-1298b observed with TESS and SOPHIE: Two hot Saturn-mass exoplanets with different densities around metal-rich stars","authors":"C. Moutou, J. Almenara, G. H'ebrard, N. Santos, K. Stassun, S. Deheuvels, S. Barros, P. Benni, A. Bieryla, I. Boisse, X. Bonfils, P. Boyd, K. Collins, D. Baker, P. Cort'es-Zuleta, S. Dalal, F. Debras, M. Deleuil, X. Delfosse, O. Demangeon, Z. Essack, T. Forveille, E. Girardin, P. Guerra, N. Heidari, K. Hesse, S. Hoyer, J. Jenkins, F. Kiefer, P. Konig, D. Laloum, D. Latham, T. Lopez, E. Martioli, H. Osborn, G. Ricker, S. Seager, R. Vanderspek, M. Vezie, J. Villaseñor, J. Winn, B. Wohler, C. Ziegler","doi":"10.1051/0004-6361/202141151","DOIUrl":"https://doi.org/10.1051/0004-6361/202141151","url":null,"abstract":"We present the discovery of two new transiting extrasolar planet candidates identified as TOI-1296.01 and TOI-1298.01 by the Transiting Exoplanet Survey Satellite (TESS). The planetary nature of these candidates has been secured with the SOPHIE high-precision spectrograph through the measurement of the companion’s mass with the radial velocity method. Both planets are similar to Saturn in mass and have similar orbital periods of a few days. They, however, show discrepant radii and therefore different densities. The radius discrepancy might be explained by the different levels of irradiation by the host stars. The subgiant star TOI-1296 hosts a low-density planet with 1.2 RJup while the less luminous, lower-size star TOI-1298 hosts a much denser planet with a 0.84 RJup radius, resulting in bulk densities of 0.198 and 0.743 g.cm−3, respectively. In addition, both stars are strongly enriched in heavy elements, having metallicities of +0.44 and +0.49 dex, respectively. The planet masses and orbital periods are 0.298± 0.039 MJup and 3.9443715± 5.8 10−6 days for TOI-1296b, and 0.356± 0.032 MJup and 4.537164± 1.2 10−5 days for TOI-1298b. The mass measurements have a relative precision of better than 13%.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"3 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86626840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-07-13DOI: 10.1051/0004-6361/202040053
F. Louvet, P. Hennebelle, A. Men’shchikov, P. Didelon, E. Ntormousi, F. Motte
During the last decade in star formation research, many studies have targeted low- and high-mass star formation regions located at different distances, with different telescopes having specific angular resolution capabilities. We present a systematic investigation of the angular resolution effects, with special attention being paid to the derived masses of sources as well as the shape of the resulting source mass functions (SMFs). We tested the impact of angular resolution, from 0.6 down to 0.02 pc, in two star-forming regions observed with Herschel (NGC6334 and Aquila), and three (magneto)-hydrodynamical simulations. We detected and measured sources at each resolution using getsf and we analysed the derived masses and sizes of the sources. We find that the number of sources does not converge from 0.6 to 0.05 pc. It increases by about two when the angular resolution increases with a similar factor. Below 0.05 pc, the number of source still increases by about 1.3 when the angular resolution increases by two, suggesting that we are close to, but not yet at, convergence. We find that the measured sizes and masses of sources linearly depend on the angular resolution with no sign of convergence to a resolution-independent value. The corresponding SMF peak also shifts with angular resolution, while the slope of the high-mass tail of the SMFs remains almost invariant. If prestellar cores, physically distinct from their background, exist in cluster-forming molecular clouds, we conclude that their mass must be lower than reported so far in the literature. We discuss various implications for the studies of star formation: the problem of determining the mass reservoirs involved in the star-formation process; the inapplicability of the Gaussian beam deconvolution to infer source sizes; and the impossibility to determine the efficiency of the mass conversion from the cores to the stars.
{"title":"Strong dependence of the physical properties of cores on spatial resolution in observations and simulations","authors":"F. Louvet, P. Hennebelle, A. Men’shchikov, P. Didelon, E. Ntormousi, F. Motte","doi":"10.1051/0004-6361/202040053","DOIUrl":"https://doi.org/10.1051/0004-6361/202040053","url":null,"abstract":"During the last decade in star formation research, many studies have targeted low- and high-mass star formation regions located at different distances, with different telescopes having specific angular resolution capabilities. We present a systematic investigation of the angular resolution effects, with special attention being paid to the derived masses of sources as well as the shape of the resulting source mass functions (SMFs). We tested the impact of angular resolution, from 0.6 down to 0.02 pc, in two star-forming regions observed with Herschel (NGC6334 and Aquila), and three (magneto)-hydrodynamical simulations. We detected and measured sources at each resolution using getsf and we analysed the derived masses and sizes of the sources. We find that the number of sources does not converge from 0.6 to 0.05 pc. It increases by about two when the angular resolution increases with a similar factor. Below 0.05 pc, the number of source still increases by about 1.3 when the angular resolution increases by two, suggesting that we are close to, but not yet at, convergence. We find that the measured sizes and masses of sources linearly depend on the angular resolution with no sign of convergence to a resolution-independent value. The corresponding SMF peak also shifts with angular resolution, while the slope of the high-mass tail of the SMFs remains almost invariant. If prestellar cores, physically distinct from their background, exist in cluster-forming molecular clouds, we conclude that their mass must be lower than reported so far in the literature. We discuss various implications for the studies of star formation: the problem of determining the mass reservoirs involved in the star-formation process; the inapplicability of the Gaussian beam deconvolution to infer source sizes; and the impossibility to determine the efficiency of the mass conversion from the cores to the stars.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"1 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90841997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-07-08DOI: 10.1051/0004-6361/202141226
Y. Alonso, M. Krumpe, L. Wisotzki, T. Miyaji, T. Garel, K. Schmidt, C. Diener, T. Urrutia, J. Kerutt, E. C. Herenz, J. Schaye, G. Pezzulli, M. Maseda, L. Boogaard, J. Richard
We present an analysis of the spatial clustering of 695 Lyα-emitting galaxies (LAEs) in the MUSE-Wide survey. All objects have spectroscopically confirmed redshifts in the range 3.3 < z < 6. We employ the K-estimator of Adelberger et al. (2005), adapted and optimized for our sample. We also explore the standard two-point correlation function (2pcf) approach, which is however less suited for a pencil-beam survey such as ours. The results from both approaches are consistent. We parametrize the clustering properties in two ways, (i) following the standard approach of modelling the clustering signal with a power law (PL), and (ii) adopting a Halo Occupation Distribution (HOD) model of the 2-halo term. Using the K-estimator and applying HOD modeling, we infer a large-scale bias of bHOD = 2.80+0.38 −0.38 at a median redshift of the number of galaxy pairs 〈zpair〉 ' 3.82, while the best-fit power-law analysis gives bPL = 3.03+1.51 −0.52 (r0 = 3.60 +3.10 −0.90 comoving h −1Mpc and γ = 1.30+0.36 −0.45). The implied typical dark matter halo (DMH) mass is log(MDMH/[hM ]) = 11.34+0.23 −0.27 (adopting b = bHOD and assuming σ8 = 0.8). We study possible dependencies of the clustering signal on object properties by bisecting the sample into disjoint subsets, considering Lyα luminosity, UV absolute magnitude, Lyα equivalent width, and redshift as variables. We find no evidence for a strong dependence on the latter three variables but detect a suggestive trend of more luminous Lyα emitters clustering more strongly (thus residing in more massive DMHs) than their lower Lyα luminosity counterparts. We also compare our results to mock LAE catalogs based on a semi-analytic model of galaxy formation and find a stronger clustering signal than in our observed sample, driven by spikes in the simulated z-distributions. By adopting a galaxyconserving model we estimate that the Lyα-bright galaxies in the MUSE-Wide survey will typically evolve into galaxies hosted by halos of log(MDMH/[hM ]) ≈ 13.5 at redshift zero, suggesting that we observe the ancestors of present-day galaxy groups.
{"title":"The MUSE-Wide survey: Three-dimensional clustering analysis of Lyman-alpha emitters at 3.3 < z < 6","authors":"Y. Alonso, M. Krumpe, L. Wisotzki, T. Miyaji, T. Garel, K. Schmidt, C. Diener, T. Urrutia, J. Kerutt, E. C. Herenz, J. Schaye, G. Pezzulli, M. Maseda, L. Boogaard, J. Richard","doi":"10.1051/0004-6361/202141226","DOIUrl":"https://doi.org/10.1051/0004-6361/202141226","url":null,"abstract":"We present an analysis of the spatial clustering of 695 Lyα-emitting galaxies (LAEs) in the MUSE-Wide survey. All objects have spectroscopically confirmed redshifts in the range 3.3 < z < 6. We employ the K-estimator of Adelberger et al. (2005), adapted and optimized for our sample. We also explore the standard two-point correlation function (2pcf) approach, which is however less suited for a pencil-beam survey such as ours. The results from both approaches are consistent. We parametrize the clustering properties in two ways, (i) following the standard approach of modelling the clustering signal with a power law (PL), and (ii) adopting a Halo Occupation Distribution (HOD) model of the 2-halo term. Using the K-estimator and applying HOD modeling, we infer a large-scale bias of bHOD = 2.80+0.38 −0.38 at a median redshift of the number of galaxy pairs 〈zpair〉 ' 3.82, while the best-fit power-law analysis gives bPL = 3.03+1.51 −0.52 (r0 = 3.60 +3.10 −0.90 comoving h −1Mpc and γ = 1.30+0.36 −0.45). The implied typical dark matter halo (DMH) mass is log(MDMH/[hM ]) = 11.34+0.23 −0.27 (adopting b = bHOD and assuming σ8 = 0.8). We study possible dependencies of the clustering signal on object properties by bisecting the sample into disjoint subsets, considering Lyα luminosity, UV absolute magnitude, Lyα equivalent width, and redshift as variables. We find no evidence for a strong dependence on the latter three variables but detect a suggestive trend of more luminous Lyα emitters clustering more strongly (thus residing in more massive DMHs) than their lower Lyα luminosity counterparts. We also compare our results to mock LAE catalogs based on a semi-analytic model of galaxy formation and find a stronger clustering signal than in our observed sample, driven by spikes in the simulated z-distributions. By adopting a galaxyconserving model we estimate that the Lyα-bright galaxies in the MUSE-Wide survey will typically evolve into galaxies hosted by halos of log(MDMH/[hM ]) ≈ 13.5 at redshift zero, suggesting that we observe the ancestors of present-day galaxy groups.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"39 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84845389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-07-08DOI: 10.1051/0004-6361/202040047
P. O. Alcalaya, I. Zouganelis, J. Pacheco
Context. Some kinetic models of the solar wind, such as the exospheric ones, make certain assumptions about the solar plasma, which for modelling purposes is generally considered collisionless and quasi-neutral. They also assume specific distribution functions for the electron and proton populations from which the fundamental properties of the plasma, including the density, are calculated using the moment integrals. Imposing the quasi-neutrality condition leads to the presence of an ambipolar electrostatic field, which is responsible for the acceleration of the wind. Usually, the calculation of the moment integrals is complicated by the fact that most kinetic models assume di ff erent trajectories for the solar wind components, separating the integrals into chunks corresponding to the pitch angles defining the trajectories. Hence, up to now all these integrals and therefore the plasma fundamental quantities have been calculated numerically. Aims. A new model is presented that makes use of similar assumptions to other kinetic collisionless models but does not need to impose the separation of the populations in di ff erent trajectories for the calculation of the integrals. As a consequence, an analytic solution for the electrostatic potential of the solar wind valid for all distances is found. Methods. A kinetic collisionless approach was used to characterise the solar wind plasma. A single equation for the electrostatic potential function was found assuming certain distribution functions (Maxwellian or non-thermal such as Kappa), which include an unknown electrostatic potential, calculating the density integral for those distribution functions and making those densities equal for electrons and protons. Results. An analytic solution for the electrostatic potential as a function of radial distance is found (for the first time for all distances) and shown to produce a non-monotonic total potential, which is compatible with other models like the exospheric ones whose electrostatic potential drives the acceleration of the solar wind. This expression can now be used, in a straightforward way, to provide insight into the importance of the electron distribution functions to shape the electrostatic potential of thermal solar-like outflows.
{"title":"Analytic solution for the electrostatic potential of the solar wind","authors":"P. O. Alcalaya, I. Zouganelis, J. Pacheco","doi":"10.1051/0004-6361/202040047","DOIUrl":"https://doi.org/10.1051/0004-6361/202040047","url":null,"abstract":"Context. Some kinetic models of the solar wind, such as the exospheric ones, make certain assumptions about the solar plasma, which for modelling purposes is generally considered collisionless and quasi-neutral. They also assume specific distribution functions for the electron and proton populations from which the fundamental properties of the plasma, including the density, are calculated using the moment integrals. Imposing the quasi-neutrality condition leads to the presence of an ambipolar electrostatic field, which is responsible for the acceleration of the wind. Usually, the calculation of the moment integrals is complicated by the fact that most kinetic models assume di ff erent trajectories for the solar wind components, separating the integrals into chunks corresponding to the pitch angles defining the trajectories. Hence, up to now all these integrals and therefore the plasma fundamental quantities have been calculated numerically. Aims. A new model is presented that makes use of similar assumptions to other kinetic collisionless models but does not need to impose the separation of the populations in di ff erent trajectories for the calculation of the integrals. As a consequence, an analytic solution for the electrostatic potential of the solar wind valid for all distances is found. Methods. A kinetic collisionless approach was used to characterise the solar wind plasma. A single equation for the electrostatic potential function was found assuming certain distribution functions (Maxwellian or non-thermal such as Kappa), which include an unknown electrostatic potential, calculating the density integral for those distribution functions and making those densities equal for electrons and protons. Results. An analytic solution for the electrostatic potential as a function of radial distance is found (for the first time for all distances) and shown to produce a non-monotonic total potential, which is compatible with other models like the exospheric ones whose electrostatic potential drives the acceleration of the solar wind. This expression can now be used, in a straightforward way, to provide insight into the importance of the electron distribution functions to shape the electrostatic potential of thermal solar-like outflows.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"30 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89967039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-07-07DOI: 10.1051/0004-6361/202140284
Antonino Francesco Lanza
A new mechanism for the internal heating of ultra-short-period planets is proposed based on the gravitational perturbation by a non-axisymmetric quadrupole moment of their host stars. Such a quadrupole is due to the magnetic flux tubes in the stellar convection zone, unevenly distributed in longitude and persisting for many stellar rotations as observed in young late-type stars. The rotation period of the host star evolves from its shortest value on the zero-age main sequence to longer periods due to the loss of angular momentum through a magnetized wind. If the stellar rotation period comes close to twice the orbital period of the planet, the quadrupole leads to a spin-orbit resonance that excites oscillations of the star-planet separation. As a consequence, a strong tidal dissipation is produced inside the planet. We illustrate the operation of the mechanism by modeling the evolution of the stellar rotation and of the innermost planetary orbit in the cases of CoRoT-7, Kepler-78, and K2-141 whose present orbital periods range between 0.28 and 0.85 days. If the spin-orbit resonance occurs, the maximum power dissipated inside the planets ranges between $10^{18}$ and $10^{19}$ W, while the total dissipated energy is of the order of $10^{30}-10^{32}$ J over a time interval as short as $(1-4.5) times 10^{4}$ yr. Such a huge heating over a so short time interval produces a complete melting of the planetary interiors and may shut off their hydromagnetic dynamos. These may initiate a successive phase of intense internal heating owing to unipolar magnetic star-planet interactions and affect the composition and the escape of their atmospheres, producing effects that could be observable during the entire lifetime of the planets [abridged abstract].
{"title":"An internal heating mechanism operating in ultra-short-period planets orbiting magnetically active stars","authors":"Antonino Francesco Lanza","doi":"10.1051/0004-6361/202140284","DOIUrl":"https://doi.org/10.1051/0004-6361/202140284","url":null,"abstract":"A new mechanism for the internal heating of ultra-short-period planets is proposed based on the gravitational perturbation by a non-axisymmetric quadrupole moment of their host stars. Such a quadrupole is due to the magnetic flux tubes in the stellar convection zone, unevenly distributed in longitude and persisting for many stellar rotations as observed in young late-type stars. The rotation period of the host star evolves from its shortest value on the zero-age main sequence to longer periods due to the loss of angular momentum through a magnetized wind. If the stellar rotation period comes close to twice the orbital period of the planet, the quadrupole leads to a spin-orbit resonance that excites oscillations of the star-planet separation. As a consequence, a strong tidal dissipation is produced inside the planet. We illustrate the operation of the mechanism by modeling the evolution of the stellar rotation and of the innermost planetary orbit in the cases of CoRoT-7, Kepler-78, and K2-141 whose present orbital periods range between 0.28 and 0.85 days. If the spin-orbit resonance occurs, the maximum power dissipated inside the planets ranges between $10^{18}$ and $10^{19}$ W, while the total dissipated energy is of the order of $10^{30}-10^{32}$ J over a time interval as short as $(1-4.5) times 10^{4}$ yr. Such a huge heating over a so short time interval produces a complete melting of the planetary interiors and may shut off their hydromagnetic dynamos. These may initiate a successive phase of intense internal heating owing to unipolar magnetic star-planet interactions and affect the composition and the escape of their atmospheres, producing effects that could be observable during the entire lifetime of the planets [abridged abstract].","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"84 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73112959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-07-05DOI: 10.1051/0004-6361/202141333
B. Vandenbroucke, M. Baes, P. Camps, A. U. Kapoor, D. Barrientos, J. Bernard
(Aims) In this work, we predict the far-infrared polarisation signal emitted by non-spherical dust grains in nearby galaxies. We determine the angular resolution and sensitivity required to study the magnetic field configuration in these galaxies. (Methods) We post-process a set of Milky Way like galaxies from the Auriga project, assuming a dust mix consisting of spheroidal dust grains that are partially aligned with the model magnetic field. We constrain our dust model using Planck 353 GHz observations of the Milky Way. This model is then extrapolated to shorter wavelengths that cover the peak of interstellar dust emission and to observations of arbitrarily oriented nearby Milky Way like galaxies. (Results) Assuming an intrinsic linear polarisation fraction that does not vary significantly with wavelength for wavelengths longer than 50 micron, we predict a linear polarisation fraction with a maximum of $10-15%$ and a median value of $approx{}7%$ for face-on galaxies and $approx{}3%$ for edge-on galaxies. The polarisation fraction anti-correlates with the line of sight density and with the angular dispersion function which expresses the large scale order of the magnetic field perpendicular to the line of sight. The maximum linear polarisation fraction agrees well with the intrinsic properties of the dust model. The true magnetic field orientation can be traced along low density lines of sight when it is coherent along the line of sight. These results also hold for nearby galaxies, where a coherent magnetic field structure is recovered over a range of different broad bands. (Conclusions) Polarised emission from non-spherical dust grains accurately traces the large scale structure of the galactic magnetic field in Milky Way like galaxies, with expected maximum linear polarisation fractions of $10-15%$. To resolve this maximum, a spatial resolution of at least 1 kpc is required.
{"title":"Polarised emission from aligned dust grains in nearby galaxies: Predictions from the Auriga simulations","authors":"B. Vandenbroucke, M. Baes, P. Camps, A. U. Kapoor, D. Barrientos, J. Bernard","doi":"10.1051/0004-6361/202141333","DOIUrl":"https://doi.org/10.1051/0004-6361/202141333","url":null,"abstract":"(Aims) In this work, we predict the far-infrared polarisation signal emitted by non-spherical dust grains in nearby galaxies. We determine the angular resolution and sensitivity required to study the magnetic field configuration in these galaxies. (Methods) We post-process a set of Milky Way like galaxies from the Auriga project, assuming a dust mix consisting of spheroidal dust grains that are partially aligned with the model magnetic field. We constrain our dust model using Planck 353 GHz observations of the Milky Way. This model is then extrapolated to shorter wavelengths that cover the peak of interstellar dust emission and to observations of arbitrarily oriented nearby Milky Way like galaxies. (Results) Assuming an intrinsic linear polarisation fraction that does not vary significantly with wavelength for wavelengths longer than 50 micron, we predict a linear polarisation fraction with a maximum of $10-15%$ and a median value of $approx{}7%$ for face-on galaxies and $approx{}3%$ for edge-on galaxies. The polarisation fraction anti-correlates with the line of sight density and with the angular dispersion function which expresses the large scale order of the magnetic field perpendicular to the line of sight. The maximum linear polarisation fraction agrees well with the intrinsic properties of the dust model. The true magnetic field orientation can be traced along low density lines of sight when it is coherent along the line of sight. These results also hold for nearby galaxies, where a coherent magnetic field structure is recovered over a range of different broad bands. (Conclusions) Polarised emission from non-spherical dust grains accurately traces the large scale structure of the galactic magnetic field in Milky Way like galaxies, with expected maximum linear polarisation fractions of $10-15%$. To resolve this maximum, a spatial resolution of at least 1 kpc is required.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"13 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78187314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-07-05DOI: 10.1051/0004-6361/202140754
V. Cabedo, A. Maury, J. Girart, M. Padovani
Studying Class 0 objects is very important, as it allows to characterize dynamical processes at the onset of the star formation process, and to determine the physical mechanisms responsible for the outcome of the collapse. Observations of dense gas tracers allow the characterization of key kinematics of the gas directly involved in the star-formation process, such as infall, outflow or rotation. This work aims at investigating the molecular line velocity profiles of the Class 0 protostellar object B335 and attempts to put constraints on the infall motions happening in the circumstellar gas of the object.} Observations of C$^{17}$O (1-0), C$^{18}$O (1-0) and $^{12}CO$ (2-1) transitions are presented and the spectral profiles are analyzed at envelope radii between 100 and 860 au. C$^{17}$O emission presents a double peaked line profile distributed in a complex velocity field. Both peaks present an offset of 0.2 to 1 km s$^{-1}$ from the systemic velocity of the source in the probed area. The optical depth of the C$^{17}$O emission has been estimated and found to be less than 1, suggesting that the two velocity peaks trace two distinct velocity components of the gas in the inner envelope. After discarding possible motions that could produce the complex velocity pattern, such as rotation and outflow, it is concluded that infall is producing the velocity field. Because inside-out symmetric collapse cannot explain those observed profiles, it is suggested that those are produced by non-isotropic accretion from the envelope into the central source along the outflow cavity walls.
研究0级天体非常重要，因为它可以表征恒星形成过程开始时的动力学过程，并确定导致坍缩结果的物理机制。对致密气体示踪剂的观测，可以表征直接参与恒星形成过程的气体的关键运动学，如流入、流出或旋转。本工作旨在研究0级原恒星天体B335的分子线速度分布，并试图对该天体的星周气体中发生的落入运动施加约束。给出了C$^{17}$O(1-0)、C$^{18}$O(1-0)和$^{12}CO$(2-1)跃迁的观测结果，并分析了包络半径在100 ~ 860 au之间的光谱剖面。C$^{17}$O发射在复杂速度场中呈双峰线分布。这两个峰与探测区域内源的系统速度有0.2 ~ 1 km s$^{-1}$的偏移。C$^{17}$O发射的光学深度已被估计并发现小于1，这表明两个速度峰追踪了内包层中气体的两个不同的速度分量。在排除了可能产生复杂速度模式的运动，如旋转和流出后，得出了下降产生速度场的结论。由于由内而外对称塌缩不能解释这些观测到的轮廓，因此认为这些轮廓是由沿流出腔壁从包络层向中心源的非各向同性吸积产生的。
{"title":"Structured velocity field in the inner envelope of B335: ALMA observations of rare CO isotopologues","authors":"V. Cabedo, A. Maury, J. Girart, M. Padovani","doi":"10.1051/0004-6361/202140754","DOIUrl":"https://doi.org/10.1051/0004-6361/202140754","url":null,"abstract":"Studying Class 0 objects is very important, as it allows to characterize dynamical processes at the onset of the star formation process, and to determine the physical mechanisms responsible for the outcome of the collapse. Observations of dense gas tracers allow the characterization of key kinematics of the gas directly involved in the star-formation process, such as infall, outflow or rotation. This work aims at investigating the molecular line velocity profiles of the Class 0 protostellar object B335 and attempts to put constraints on the infall motions happening in the circumstellar gas of the object.} Observations of C$^{17}$O (1-0), C$^{18}$O (1-0) and $^{12}CO$ (2-1) transitions are presented and the spectral profiles are analyzed at envelope radii between 100 and 860 au. C$^{17}$O emission presents a double peaked line profile distributed in a complex velocity field. Both peaks present an offset of 0.2 to 1 km s$^{-1}$ from the systemic velocity of the source in the probed area. The optical depth of the C$^{17}$O emission has been estimated and found to be less than 1, suggesting that the two velocity peaks trace two distinct velocity components of the gas in the inner envelope. After discarding possible motions that could produce the complex velocity pattern, such as rotation and outflow, it is concluded that infall is producing the velocity field. Because inside-out symmetric collapse cannot explain those observed profiles, it is suggested that those are produced by non-isotropic accretion from the envelope into the central source along the outflow cavity walls.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"6 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74268008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-07-05DOI: 10.1051/0004-6361/202140527
V. Shalyapin, R. Gil-Merino, L. Goicoechea
We present a new and very fast method for producing microlensing magnification maps at high optical depths. It is based on the combination of two approaches: (a) the two-dimensional Poisson solver for a deflection potential and (b) inverse polygon mapping. With our method we extremely reduce the computing time for the generation of magnification patterns and avoid the use of highly demanding computer resources. For example, the generation of a magnification map of size 2000 x 2000 pixels, covering a region of 20 Einstein radii, takes a few seconds on a state-of-the-art laptop. The method presented here will facilitate the massive production of magnification maps for extragalactic microlensing studies within the forthcoming surveys without the need for large computer clusters. The modest demand of computer power and a fast execution time allow the code developed here to be placed on a standard server and thus provide the public online access through a web-based interface.
我们提出了一种在高光学深度下快速生成微透镜放大图的新方法。它基于两种方法的结合:(a)挠度势的二维泊松求解器和(b)逆多边形映射。我们的方法极大地减少了生成放大图形的计算时间，并且避免了使用高要求的计算机资源。例如，在一台最先进的笔记本电脑上，生成一张2000 x 2000像素的放大地图，覆盖20个爱因斯坦半径的区域，只需要几秒钟。这里提出的方法将有助于在即将到来的调查中大规模生产河外微透镜研究的放大地图，而不需要大型计算机集群。对计算机能力的适度要求和快速的执行时间允许在这里开发的代码放置在标准服务器上，从而通过基于web的界面向公众提供在线访问。
{"title":"Fast simulations of extragalactic microlensing","authors":"V. Shalyapin, R. Gil-Merino, L. Goicoechea","doi":"10.1051/0004-6361/202140527","DOIUrl":"https://doi.org/10.1051/0004-6361/202140527","url":null,"abstract":"We present a new and very fast method for producing microlensing magnification maps at high optical depths. It is based on the combination of two approaches: (a) the two-dimensional Poisson solver for a deflection potential and (b) inverse polygon mapping. With our method we extremely reduce the computing time for the generation of magnification patterns and avoid the use of highly demanding computer resources. For example, the generation of a magnification map of size 2000 x 2000 pixels, covering a region of 20 Einstein radii, takes a few seconds on a state-of-the-art laptop. The method presented here will facilitate the massive production of magnification maps for extragalactic microlensing studies within the forthcoming surveys without the need for large computer clusters. The modest demand of computer power and a fast execution time allow the code developed here to be placed on a standard server and thus provide the public online access through a web-based interface.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"23 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73742145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-06-29DOI: 10.1051/0004-6361/202039959
F. L. Johansson, A. Eriksson, E. Vigren, L. Bucciantini, P. Henri, H. Nilsson, S. Bergman, N. Edberg, G. S. Wieser, E. Odelstad
Context.During its two year mission at comet 67P, Rosetta nearly continuously monitored the inner coma plasma environment forgas production rates varying over three orders of magnitude, at distance ...
{"title":"Plasma densitites, flow and Solar EUV flux at comet 67P : A cross-calibration approach","authors":"F. L. Johansson, A. Eriksson, E. Vigren, L. Bucciantini, P. Henri, H. Nilsson, S. Bergman, N. Edberg, G. S. Wieser, E. Odelstad","doi":"10.1051/0004-6361/202039959","DOIUrl":"https://doi.org/10.1051/0004-6361/202039959","url":null,"abstract":"Context.During its two year mission at comet 67P, Rosetta nearly continuously monitored the inner coma plasma environment forgas production rates varying over three orders of magnitude, at distance ...","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"21 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85712207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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