arXiv: Earth and Planetary Astrophysics最新文献

Revisiting The Averaged Problem in The Case of Mean-Motion Resonances of The Restricted Three-Body Problem. Global Rigorous Treatment and Application To The Co-Orbital Motion. 再论受限三体平均运动共振情况下的平均问题。共轨运动的全局严格处理及其应用。

arXiv: Earth and Planetary Astrophysics Pub Date : 2021-06-28 DOI: 10.21203/RS.3.RS-614015/V1

A. Pousse, E. Alessi

{"title":"Revisiting The Averaged Problem in The Case of Mean-Motion Resonances of The Restricted Three-Body Problem. Global Rigorous Treatment and Application To The Co-Orbital Motion.","authors":"A. Pousse, E. Alessi","doi":"10.21203/RS.3.RS-614015/V1","DOIUrl":"https://doi.org/10.21203/RS.3.RS-614015/V1","url":null,"abstract":"\u0000 A classical approach to the restricted three-body problem is to analyze the dynamics of the massless body in the synodic reference frame. A different approach is represented by the perturbative treatment: in particular the averaged problem of a mean-motion resonance allows to investigate the long-term behavior of the solutions through a suitable approximation that focuses on a particular region of the phase space.\u0000In this paper, we intend to bridge a gap between the two approaches in the specific case of mean-motion resonant dynamics, establish the limit of validity of the averaged problem, and take advantage of its results in order to compute trajectories in the synodic reference frame.\u0000After the description of each approach, we develop a rigorous treatment of the averaging process, estimate the size of the transformation and prove that the averaged problem is a suitable approximation of the restricted three-body problem as long as the solutions are located outside the Hill's sphere of the secondary. In such a case, a rigorous theorem of stability over finite but large timescales can be proven. We establish that a solution of the averaged problem provides an accurate approximation of the trajectories on the synodic reference frame within a finite time that depend on the minimal distance to the Hill's sphere of the secondary.\u0000The last part of this work is devoted to the co-orbital motion (i.e., the dynamics in 1:1 mean-motion resonance) in the circular-planar case. In this case, an interpretation of the solutions of the averaged problem in the synodic reference frame is detailed and a method that allows to compute co-orbital trajectories is displayed.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72880822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Automatic planetary defense Deflecting NEOs by missiles shot from L1 and L3 (Earth-Moon). 自动行星防御用从L1和L3(地月)发射的导弹偏转近地天体。

arXiv: Earth and Planetary Astrophysics Pub Date : 2021-03-22 DOI: 10.2514/6.iac-04-iaa.5.12.3.08

C. Maccone

{"title":"Automatic planetary defense Deflecting NEOs by missiles shot from L1 and L3 (Earth-Moon).","authors":"C. Maccone","doi":"10.2514/6.iac-04-iaa.5.12.3.08","DOIUrl":"https://doi.org/10.2514/6.iac-04-iaa.5.12.3.08","url":null,"abstract":"We develop the mathematical theory for an automatic, space-based system to deflect NEOs by virtue of missiles shot from the Earth-Moon L1 and L3 Lagrangian Points. A patent application has been filed for the relevant code dubbed AsterOFF (=Asteroids OFF !). This code was already implemented, and a copyright for it was registered. In a paper published in Acta Astronautica, this author proved mathematically the following theorem: \"Within the sphere of influence of the Earth, any NEO could be hit by a missile at just an angle of 90 degrees, was the missile shot from the Lagrangian Points L1 or L3 of the Earth-Moon system, rather than from the surface of the Earth\". As a consequence, the hitting missile would have to move along a \"confocal ellipse\" (centered at the Earth) uniquely determined by the NEO's incoming hyperbola. The author further shows in this paper that: 1) The proposed defense system would be ideal to deflect NEOs that are small, i.e. less than one kilometer in diameter. 2) The traditional theory of Keplerian orbits can successfully be applied to get an excellent first-order approximation of the mathematical formulae of the energy-momentum requested to achieve the NEO deflection. Many engineering details about the missiles shot from L1 and L3, however, still have to be implemented into our simulations. 3) Was one missile not enough to deflect the NEO completely, it is a great advantage of the \"confocal conics\" used here that the new, slightly deflected NEO's hyperbola would certainly be hit at nearly 90 degrees by another and slightly more eccentric elliptical missile trajectory. A sufficient number of missiles could thus be launched in a sequence from the Earth-Moon Lagrangian points L1 and L3 with the result that the SUM of all these small and repeated deflections will finally throw the NEO off its collision hyperbola with the Earth.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85699039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Modeling the nonaxisymmetric structure in the HD 163296 disk with planet-disk interaction 基于行星-圆盘相互作用的hd163296盘非轴对称结构建模

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-12-16 DOI: 10.1051/0004-6361/202038484

P. Rodenkirch, T. Rometsch, C. Dullemond, P. Weber, W. Kley

{"title":"Modeling the nonaxisymmetric structure in the HD 163296 disk with planet-disk interaction","authors":"P. Rodenkirch, T. Rometsch, C. Dullemond, P. Weber, W. Kley","doi":"10.1051/0004-6361/202038484","DOIUrl":"https://doi.org/10.1051/0004-6361/202038484","url":null,"abstract":"High resolution ALMA observations revealed a variety of rich substructures in numerous protoplanetary disks. These structures consist of rings, gaps and asymmetric features. It is debated whether planets can be accounted for these substructures in the dust continuum. Characterizing the origin of asymmetries as seen in HD 163296 might lead to a better understanding of planet formation and the underlying physical parameters of the system. We test the possibility of the formation of the crescent-shaped asymmetry in the HD 163296 disk through planet-disk interaction. The goal is to obtain constraints on planet masses and eccentricities and disk viscosities. Two dimensional, multi-fluid, hydrodynamical simulations are performed with the FARGO3D code including three embedded planets. Dust is described with the pressureless fluid approach and is distributed over eight size bins. Resulting grids are post-processed with the radiative transfer code RADMC-3D and the CASA software to model synthetic observations. We find that the crescent-shaped asymmetry can be qualitatively modeled with a Jupiter mass planet at a radial distance of 48 au. Dust is trapped preferably in the trailing Lagrange point L5 with a mass of 10 to 15 earth masses. Increased values of eccentricity of the innermost Jupiter mass planet damages the stability of the crescent-shaped feature and does not reproduce the observed radial proximity to the first prominent ring in the system. Generally, a low level of viscosity ($alpha leq 2cdot10^{-3}$) is necessary to allow the existence of such a feature. Including dust feedback the leading point L4 can dominantly capture dust for dust grains with an initial Stokes number $leq 3.6cdot 10^{-2}$. The observational results suggest a negligible effect of dust feedback since only one such feature has been detected so far.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89101017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Origin and dynamical evolution of the asteroid belt 小行星带的起源和动力学演化

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-12-14 DOI: 10.1017/9781108856324.019

S. Raymond, D. Nesvorný

{"title":"Origin and dynamical evolution of the asteroid belt","authors":"S. Raymond, D. Nesvorný","doi":"10.1017/9781108856324.019","DOIUrl":"https://doi.org/10.1017/9781108856324.019","url":null,"abstract":"The asteroid belt was dynamically shaped during and after planet formation. Despite representing a broad ring of stable orbits, the belt contains less than one one-thousandth of an Earth mass. The asteroid orbits are dynamically excited with a wide range in eccentricity and inclination and their compositions are diverse, with a general trend toward dry objects in the inner belt and more water-rich objects in the outer belt. Here we review models of the asteroid belt's origins and dynamical history. The classical view is that the belt was born with several Earth masses in planetesimals, then strongly depleted. However, it is possible that very few planetesimals ever formed in the asteroid region and that the belt's story is one of implantation rather than depletion. A number of processes may have implanted asteroids from different regions of the Solar System, dynamically removed them, and excited their orbits. During the gaseous disk phase these include the effects of giant planet growth and migration and sweeping secular resonances. After the gaseous disk phase these include scattering from resident planetary embryos, chaos in the giant planets' orbits, the giant planet instability, and long-term dynamical evolution. Different global models for Solar System formation imply contrasting dynamical histories of the asteroid belt. Vesta and Ceres may have been implanted from opposite regions of the Solar System -- Ceres from the Jupiter-Saturn region and Vesta from the terrestrial planet region -- and could therefore represent very different formation conditions.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82206098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9

Revised planet brightness temperatures using the Planck/LFI 2018 data release 使用普朗克/LFI 2018年发布的数据修订行星亮度温度

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-12-08 DOI: 10.1051/0004-6361/202037788

M. Maris, E. Romelli, M. Tomasi, A. Gregorio, M. Sandri, S. Galeotta, D. Tavagnacco, M. Frailis, G. Maggio, A. Zacchei

{"title":"Revised planet brightness temperatures using the Planck/LFI 2018 data release","authors":"M. Maris, E. Romelli, M. Tomasi, A. Gregorio, M. Sandri, S. Galeotta, D. Tavagnacco, M. Frailis, G. Maggio, A. Zacchei","doi":"10.1051/0004-6361/202037788","DOIUrl":"https://doi.org/10.1051/0004-6361/202037788","url":null,"abstract":"We present new estimates of the brightness temperatures of Jupiter, Saturn, Uranus, and Neptune based on the measurements carried in 2009--2013 by PLANCK/LFI at 30, 44, and 70 GHz and released to the public in 2018. This work extends the results presented in the 2013 and 2015 PLANCK/LFI Calibration Papers, based on the data acquired in 2009--2011. PLANCK observed each planet up to eight times during the nominal mission. We processed time-ordered data from the 22 LFI radiometers to derive planet antenna temperatures for each planet and transit. We accounted for the beam shape, radiometer bandpasses, and several systematic effects. We compared our results with the results from the ninth year of WMAP, PLANCK/HFI observations, and existing data and models for planetary microwave emissivity. For Jupiter, we obtain Tb = 144.9, 159.8, 170.5 K (+/- 0.2 K at 1 sigma, with temperatures expressed using the Rayleigh-Jeans scale) at 30, 44 and 70 GHz, respectively, or equivalently a band averaged Planck temperature TbBA=144.7$, 160.3, 171.2 K in good agreement with WMAP and existing models. A slight excess at 30 GHz with respect to models is interpreted as an effect of synchrotron emission. Our measures for Saturn agree with the results from WMAP for rings Tb = 9.2 +/- 1.4, 12.6 +/- 2.3, 16.2 +/- 0.8 K, while for the disc we obtain Tb = 140.0 +/- 1.4, 147.2 +/- 1.2, 150.2 +/- 0.4 K, or equivalently a TbBA=139.7, 147.8, 151.0 K. Our measures for Uranus (Tb = 152 +/- 6, 145 +/- 3, 132.0 +/- 2 K, or TbBA=152, 145, 133 K and Neptune Tb = 154 +/- 11, 148 +/- 9, 128 +/- 3 K, or TbBA=154 , 149, 128 K) agree closely with WMAP and previous data in literature.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89360611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

A Newtonian Model for the WASP-148 Exoplanetary System Enhanced with TESS and Ground-based Photometric Observations 基于TESS和地面光度观测的WASP-148系外行星系统牛顿模型

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-12-04 DOI: 10.32023/0001-5237/70.3.3

G. Maciejewski, Matilde Fernández, Alfredo Sota Ballano, A. J. G. Segura

{"title":"A Newtonian Model for the WASP-148 Exoplanetary System Enhanced with TESS and Ground-based Photometric Observations","authors":"G. Maciejewski, Matilde Fernández, Alfredo Sota Ballano, A. J. G. Segura","doi":"10.32023/0001-5237/70.3.3","DOIUrl":"https://doi.org/10.32023/0001-5237/70.3.3","url":null,"abstract":"GM acknowledges the financial support from the National Science Centre, Poland through grant no. 2016/23/B/ST9/00579. MF acknowledges financial support from grant AYA2016-79425-C3-3-P of the Spanish Ministry of Economy and Competitiveness (MINECO), co-funded with EU FEDER funds, and grant PID2019-109522GB-C5X/AEI/10.13039/501100011033 of the Spanish Ministry of Science and Innovation (MICINN). This paper includes data collected with the TESS mission, obtained from the MAST data archive at the Space Telescope Science Institute (STScI). MF, AS, and AGS acknowledge financial support from the State Agency for Research of the Spanish MCIU through the Center of Excellence Severo Ochoa award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709). Funding for the TESS mission is provided by the NASA Explorer Program. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. This research made use of Lightkurve, a Python package for Kepler and TESS data analysis (Lightkurve Collaboration, 2018). This research has made use of the SIMBAD database and the VizieR catalogue access tool, operated at CDS, Strasbourg, France, and NASA's Astrophysics Data System Bibliographic Services.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80693116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Size and structures of disks around very low mass stars in the Taurus star-forming region 金牛座恒星形成区非常低质量恒星周围圆盘的大小和结构

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-12-03 DOI: 10.1051/0004-6361/202038983

N. Kurtovic, P. Pinilla, F. Long, M. Benisty, C. Manara, A. Natta, I. Pascucci, L. Ricci, A. Scholz, L. Testi

{"title":"Size and structures of disks around very low mass stars in the Taurus star-forming region","authors":"N. Kurtovic, P. Pinilla, F. Long, M. Benisty, C. Manara, A. Natta, I. Pascucci, L. Ricci, A. Scholz, L. Testi","doi":"10.1051/0004-6361/202038983","DOIUrl":"https://doi.org/10.1051/0004-6361/202038983","url":null,"abstract":"We aim to estimate if structures, such as cavities, rings, and gaps, are common in disks around VLMS and to test models of structure formation in these disks. We also aim to compare the radial extent of the gas and dust emission in disks around VLMS, which can give us insight about radial drift. We studied six disks around VLMS in the Taurus star-forming region using ALMA Band 7 ($sim 340,$GHz) at a resolution of $sim0.1''$. The targets were selected because of their high disk dust content in their stellar mass regime. Our observations resolve the disk dust continuum in all disks. In addition, we detect the $^{12}$CO ($J=3-2$) emission line in all targets and $^{13}$CO ($J=3-2$) in five of the six sources. The angular resolution allows the detection of dust substructures in three out of the six disks, which we studied by using UV-modeling. Central cavities are observed in the disks around stars MHO,6 (M5.0) and CIDA,1 (M4.5), while we have a tentative detection of a multi-ringed disk around J0433. Single planets of masses $0.1sim0.4,M_{rm{Jup}}$ would be required. The other three disks with no observed structures are the most compact and faintest in our sample. The emission of $^{12}$CO and $^{13}$CO is more extended than the dust continuum emission in all disks of our sample. When using the $^{12}$CO emission to determine the gas disk extension $R_{rm{gas}}$, the ratio of $R_{rm{gas}}/R_{rm{dust}}$ in our sample varies from 2.3 to 6.0, which is consistent with models of radial drift being very efficient around VLMS in the absence of substructures. Our observations do not exclude giant planet formation on the substructures observed. A comparison of the size and luminosity of VLMS disks with their counterparts around higher mass stars shows that they follow a similar relation.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90676847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 19

TRAP: a temporal systematics model for improved direct detection of exoplanets at small angular separations TRAP:一种时间系统模型，用于在小角距离上改进对系外行星的直接探测

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-11-24 DOI: 10.1051/0004-6361/201937308

M. Samland, J. Bouwman, David W. Hogg, W. Brandner, T. Henning, M. Janson

{"title":"TRAP: a temporal systematics model for improved direct detection of exoplanets at small angular separations","authors":"M. Samland, J. Bouwman, David W. Hogg, W. Brandner, T. Henning, M. Janson","doi":"10.1051/0004-6361/201937308","DOIUrl":"https://doi.org/10.1051/0004-6361/201937308","url":null,"abstract":"High-contrast imaging surveys for exoplanet detection have shown giant planets at large separations to be rare. It is important to push towards detections at smaller separations, the part of the parameter space containing most planets. The performance of traditional methods for post-processing of pupil-stabilized observations decreases at smaller separations, due to the larger field-rotation required to displace a source on the detector in addition to the intrinsic difficulty of higher stellar contamination. We developed a method of extracting exoplanet signals that improves performance at small angular separations. A data-driven model of the temporal behavior of the systematics for each pixel can be created using reference pixels at a different position, assuming the underlying causes of the systematics are shared across multiple pixels. This is mostly true for the speckle pattern in high-contrast imaging. In our causal regression model, we simultaneously fit the model of a planet signal \"transiting\" over detector pixels and non-local reference lightcurves describing a basis of shared temporal trends of the speckle pattern to find the best fitting temporal model describing the signal. With our implementation of a spatially non-local, temporal systematics model, called TRAP, we show that it is possible to gain up to a factor of 6 in contrast at close separations ($<3lambda/D$) compared to a model based on spatial correlations between images displaced in time. We show that better temporal sampling resulting in significantly better contrasts. At short integration times for $beta$ Pic data, we increase the SNR of the planet by a factor of 4 compared to the spatial systematics model. Finally, we show that the temporal model can be used on unaligned data which has only been dark and flat corrected, without the need for further pre-processing.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91488435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 16

Dust delivery and entrainment in photoevaporative winds 光蒸发风中的粉尘输送和夹带

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-11-17 DOI: 10.1093/mnras/staa3608

M. Hutchison, C. Clarke

{"title":"Dust delivery and entrainment in photoevaporative winds","authors":"M. Hutchison, C. Clarke","doi":"10.1093/mnras/staa3608","DOIUrl":"https://doi.org/10.1093/mnras/staa3608","url":null,"abstract":"We model the gas and dust dynamics in a turbulent protoplanetary disc undergoing extreme-UV photoevaporation in order to better characterise the dust properties in thermal winds (e.g. size distribution, flux rate, trajectories). Our semi-analytic approach allows us to rapidly calculate these dust properties without resorting to expensive hydrodynamic simulations. We find that photoevaporation creates a vertical gas flow within the disc that assists turbulence in supplying dust to the ionisation front. We examine both the delivery of dust to the ionisation front and its subsequent entrainment in the overlying wind. We derive a simple analytic criterion for the maximum grain size that can be entrained and show that this is in good agreement with the results of previous simulations where photoevaporation is driven by a range of radiation types. We show that, in contrast to the case for magnetically driven winds, we do not expect large scale dust transport within the disc to be effected by photoevaporation. We also show that the maximum size of grains that can be entrained in the wind ($s_{rm max}$) is around an order of magnitude larger than the maximum size of grains that can be delivered to the front by advection alone ($s_{rm crit} lesssim 1$ $mu{rm m}$ for Herbig Ae/Be stars and $lesssim 0.01$ $mu{rm m}$ for T Tauri stars). We further investigate how larger grains, up to a limiting size $s_{rm limit}$, can be delivered to the front by turbulent diffusion alone. In all cases, we find $s_{rm max} gtrsim s_{rm limit}$ so that we expect that any dust that is delivered to the front can be entrained in the wind and that most entrained dust follows trajectories close to that of the gas.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85768924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Modelling heterogeneous dust particles: an application to cometary polarization 模拟非均匀尘埃粒子:应用于彗星极化

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-11-16 DOI: 10.1093/mnras/staa3647

P. Halder, S. Ganesh

{"title":"Modelling heterogeneous dust particles: an application to cometary polarization","authors":"P. Halder, S. Ganesh","doi":"10.1093/mnras/staa3647","DOIUrl":"https://doi.org/10.1093/mnras/staa3647","url":null,"abstract":"In this work, we introduce a comet dust model that incorporates multiple dust morphologies along with inhomogeneous mixture of silicate minerals and carbonaceous materials under power-law size distribution, to replicate the standard polarization-phase curve observed in several comets in the narrow-band continuum. Following the results from Rosetta/MIDAS and COSIMA, we create high porosity Hierarchical Aggregates (HA) and low porosity (< 10$%$) Solids in the form of agglomerated debris. We also introduce a moderate porosity structure with solids in the core, surrounded by fluffy aggregates called Fluffy Solids (FS). We study the mixing combinations, (HA and Solids), (HA and FS) and (HA, FS and Solids) for a range of power-law index n=2.0 to 3.0 for different sets of mixing percentage of silicate minerals and carbonaceous materials. Polarimetry of the short period comets 1P/Halley and 67P/Churyumov-Gerasimenko match best with the polarisation resulting from the combination of HA and Solids while the combinations (HA and FS) and (HA, FS and Solids) provide the best fit results for the long period comets C/1995 O1 (Hale-Bopp) and C/1996 B2 (Hyakutake). The best fit model results also recreate the observed wavelength dependence of polarization. Our dust model agree with the idea that the long period comets may have high percentage of loose particles (HA and FS) compared to those in the case of short period comets as the short period comets experience more frequent and/or higher magnitude of weathering.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82962351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7