Ramanakumar Sankar, Shawn Brueshaber, Lucy Fortson, Candice Hansen-Koharcheck, Chris Lintott, Cooper Nesmith, Glenn Orton
The Jovian atmosphere contains a wide diversity of vortices, which have a large range of sizes, colors and forms in different dynamical regimes. The formation processes for these vortices is poorly understood, and aside from a few known, long-lived ovals, such as the Great Red Spot, and Oval BA, vortex stability and their temporal evolution are currently largely unknown. In this study, we use JunoCam data and a citizen-science project on Zooniverse to derive a catalog of vortices, some with repeated observations, through May 2018 to Sep 2021, and analyze their associated properties, such as size, location and color. We find that different colored vortices (binned as white, red, brown and dark), follow vastly different distributions in terms of their sizes and where they are found on the planet. We employ a simplified stability criterion using these vortices as a proxy, to derive a minimum Rossby deformation length for the planet of $sim1800$ km. We find that this value of $L_d$ is largely constant throughout the atmosphere, and does not have an appreciable meridional gradient.
{"title":"Jovian Vortex Hunter: a citizen science project to study Jupiter's vortices","authors":"Ramanakumar Sankar, Shawn Brueshaber, Lucy Fortson, Candice Hansen-Koharcheck, Chris Lintott, Cooper Nesmith, Glenn Orton","doi":"arxiv-2408.04772","DOIUrl":"https://doi.org/arxiv-2408.04772","url":null,"abstract":"The Jovian atmosphere contains a wide diversity of vortices, which have a\u0000large range of sizes, colors and forms in different dynamical regimes. The\u0000formation processes for these vortices is poorly understood, and aside from a\u0000few known, long-lived ovals, such as the Great Red Spot, and Oval BA, vortex\u0000stability and their temporal evolution are currently largely unknown. In this\u0000study, we use JunoCam data and a citizen-science project on Zooniverse to\u0000derive a catalog of vortices, some with repeated observations, through May 2018\u0000to Sep 2021, and analyze their associated properties, such as size, location\u0000and color. We find that different colored vortices (binned as white, red, brown\u0000and dark), follow vastly different distributions in terms of their sizes and\u0000where they are found on the planet. We employ a simplified stability criterion\u0000using these vortices as a proxy, to derive a minimum Rossby deformation length\u0000for the planet of $sim1800$ km. We find that this value of $L_d$ is largely\u0000constant throughout the atmosphere, and does not have an appreciable meridional\u0000gradient.","PeriodicalId":501209,"journal":{"name":"arXiv - PHYS - Earth and Planetary Astrophysics","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141931829","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}
Linear equations with periodic coefficients describe the behavior of various dynamical systems. This studying is devoted to their applications to the planetary restricted three-body problem (RTBP). Here we consider the Laplace method for determining perturbation in coordinates. We show that classical theory of perturbation leads to a linear equation with periodic coefficients. Than we present a modification of Laplace method. This modification allows us to study motion over a longer time interval.
{"title":"Mathieu equation as a result of Laplace perturbation theory in the restricted three body problem","authors":"Alexey Rosaev, Eva Plavalova","doi":"arxiv-2408.04298","DOIUrl":"https://doi.org/arxiv-2408.04298","url":null,"abstract":"Linear equations with periodic coefficients describe the behavior of various\u0000dynamical systems. This studying is devoted to their applications to the\u0000planetary restricted three-body problem (RTBP). Here we consider the Laplace\u0000method for determining perturbation in coordinates. We show that classical\u0000theory of perturbation leads to a linear equation with periodic coefficients.\u0000Than we present a modification of Laplace method. This modification allows us\u0000to study motion over a longer time interval.","PeriodicalId":501209,"journal":{"name":"arXiv - PHYS - Earth and Planetary Astrophysics","volume":"192 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141931833","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}
Alvaro Francisco Gil, Walther Litteri, Victor Rodriguez-Fernandez, David Camacho, Massimiliano Vasile
The Three-Body Problem has fascinated scientists for centuries and it has been crucial in the design of modern space missions. Recent developments in Generative Artificial Intelligence hold transformative promise for addressing this longstanding problem. This work investigates the use of Variational Autoencoder (VAE) and its internal representation to generate periodic orbits. We utilize a comprehensive dataset of periodic orbits in the Circular Restricted Three-Body Problem (CR3BP) to train deep-learning architectures that capture key orbital characteristics, and we set up physical evaluation metrics for the generated trajectories. Through this investigation, we seek to enhance the understanding of how Generative AI can improve space mission planning and astrodynamics research, leading to novel, data-driven approaches in the field.
{"title":"Generative Design of Periodic Orbits in the Restricted Three-Body Problem","authors":"Alvaro Francisco Gil, Walther Litteri, Victor Rodriguez-Fernandez, David Camacho, Massimiliano Vasile","doi":"arxiv-2408.03691","DOIUrl":"https://doi.org/arxiv-2408.03691","url":null,"abstract":"The Three-Body Problem has fascinated scientists for centuries and it has\u0000been crucial in the design of modern space missions. Recent developments in\u0000Generative Artificial Intelligence hold transformative promise for addressing\u0000this longstanding problem. This work investigates the use of Variational\u0000Autoencoder (VAE) and its internal representation to generate periodic orbits.\u0000We utilize a comprehensive dataset of periodic orbits in the Circular\u0000Restricted Three-Body Problem (CR3BP) to train deep-learning architectures that\u0000capture key orbital characteristics, and we set up physical evaluation metrics\u0000for the generated trajectories. Through this investigation, we seek to enhance\u0000the understanding of how Generative AI can improve space mission planning and\u0000astrodynamics research, leading to novel, data-driven approaches in the field.","PeriodicalId":501209,"journal":{"name":"arXiv - PHYS - Earth and Planetary Astrophysics","volume":"129 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141931832","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}
Corey Beard, Paul Robertson, Mark R. Giovinazzi, Joseph M. Akana Murphy, Eric B. Ford, Samuel Halverson, Te Han, Rae Holcomb, Jack Lubin, Rafael Luque, Pranav Premnath, Chad F. Bender, Cullen H. Blake, Qian Gong, Howard Isaacson, Shubham Kanodia, Dan Li, Andrea S. J. Lin, 5 Sarah E. Logsdon, Emily Lubar, Michael W. McElwain, Andrew Monson, Joe P. Ninan, Jayadev Rajagopal, Arpita Roy, Christian Schwab, Gudmundur Stefansson, Ryan C. Terrien, Jason T. Wright
We present a new analysis of Kepler-21, the brightest (V = 8.5) Kepler system with a known transiting exoplanet, Kepler-21 b. Kepler-21 b is a radius valley planet ($R = 1.6pm 0.2 R_{oplus}$) with an Earth-like composition (8.38$pm$1.62 g/cc), though its mass and radius fall in the regime of possible "water worlds." We utilize new Keck/HIRES and WIYN/NEID radial velocity (RV) data in conjunction with Kepler and TESS photometry to perform a detailed study of activity mitigation between photometry and RVs. We additionally refine the system parameters, and we utilize Gaia astrometry to place constraints on a long-term RV trend. Our activity analysis affirms the quality of Kepler photometry for removing correlated noise from RVs, despite its temporal distance, though we reveal some cases where TESS may be superior. Using refined orbital parameters and updated composition curves, we rule out a ``water world" scenario for Kepler-21 b, and we identify a long period super-Jupiter planetary candidate, Kepler-21 (c).
{"title":"Utilizing Photometry from Multiple Sources to Mitigate Stellar Variability in Precise Radial Velocities: A Case Study of Kepler-21","authors":"Corey Beard, Paul Robertson, Mark R. Giovinazzi, Joseph M. Akana Murphy, Eric B. Ford, Samuel Halverson, Te Han, Rae Holcomb, Jack Lubin, Rafael Luque, Pranav Premnath, Chad F. Bender, Cullen H. Blake, Qian Gong, Howard Isaacson, Shubham Kanodia, Dan Li, Andrea S. J. Lin, 5 Sarah E. Logsdon, Emily Lubar, Michael W. McElwain, Andrew Monson, Joe P. Ninan, Jayadev Rajagopal, Arpita Roy, Christian Schwab, Gudmundur Stefansson, Ryan C. Terrien, Jason T. Wright","doi":"arxiv-2408.02873","DOIUrl":"https://doi.org/arxiv-2408.02873","url":null,"abstract":"We present a new analysis of Kepler-21, the brightest (V = 8.5) Kepler system\u0000with a known transiting exoplanet, Kepler-21 b. Kepler-21 b is a radius valley\u0000planet ($R = 1.6pm 0.2 R_{oplus}$) with an Earth-like composition\u0000(8.38$pm$1.62 g/cc), though its mass and radius fall in the regime of possible\u0000\"water worlds.\" We utilize new Keck/HIRES and WIYN/NEID radial velocity (RV)\u0000data in conjunction with Kepler and TESS photometry to perform a detailed study\u0000of activity mitigation between photometry and RVs. We additionally refine the\u0000system parameters, and we utilize Gaia astrometry to place constraints on a\u0000long-term RV trend. Our activity analysis affirms the quality of Kepler\u0000photometry for removing correlated noise from RVs, despite its temporal\u0000distance, though we reveal some cases where TESS may be superior. Using refined\u0000orbital parameters and updated composition curves, we rule out a ``water world\"\u0000scenario for Kepler-21 b, and we identify a long period super-Jupiter planetary\u0000candidate, Kepler-21 (c).","PeriodicalId":501209,"journal":{"name":"arXiv - PHYS - Earth and Planetary Astrophysics","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141968667","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}
One of the most serious limitations of current astrochemical models with the rate equation (RE) approach is that only a single type of binding site is considered in grain surface chemistry, although laboratory and quantum chemical studies have found that surfaces contain various binding sites with different potential energy depths. When various sites exist, adsorbed species can be trapped in deep potential sites, increasing the resident time on the surface. On the other hand, adsorbed species can be populated in shallow sites, activating thermal hopping and thus two-body reactions even at low temperatures, where the thermal hopping from deeper sites is not activated. Such behavior cannot be described by the conventional RE approach. In this work, I present a framework for incorporating various binding sites (i.e., binding energy distribution) in gas-ice astrochemical models as an extension of the conventional RE approach. I propose a simple method to estimate the probability density function for the occupation of various sites by adsorbed species, assuming a quasi-steady state. By using thermal desorption and hopping rates weighted by the probability density functions, the effect of binding energy distribution is incorporated into the RE approach without increasing the number of ordinary differential equations to be solved. This method is found to be accurate and computationally efficient and enables us to consider binding energy distribution even for a large gas-ice chemical network, which contains hundreds of icy species. The impact of the binding energy distribution on interstellar ice composition is discussed quantitatively for the first time.
目前采用速率方程（RE）方法的天体化学模型的一个最严重的局限性是在晶粒表面化学中只考虑了单一类型的结合位点，尽管实验室和量子化学研究已经发现，表面含有不同势能深度的各种结合位点。另一方面，被吸附的物种可以填充在浅层位点，激活热跳变，从而发生二体反应，即使在低温条件下，来自深层位点的热跳变也不会被激活。在这项工作中，我提出了一个将各种结合位点（即结合能分布）纳入气冰天体化学模型的框架，作为传统 RE 方法的扩展。我提出了一种简单的方法来估算吸附物种占据各种位点的概率密度函数，并假设其处于准稳态。通过使用由概率密度函数加权的热解吸附和跳板，结合能分布的影响被纳入 RE 方法，而无需增加需要求解的常微分方程的数量。该方法精确且计算效率高，使我们能够考虑结合能分布，即使是包含数百种冰物种的大型气冰化学网络。首次定量讨论了结合能分布对星际冰成分的影响。
{"title":"A framework for incorporating binding energy distribution in gas-ice astrochemical models","authors":"Kenji Furuya","doi":"arxiv-2408.02958","DOIUrl":"https://doi.org/arxiv-2408.02958","url":null,"abstract":"One of the most serious limitations of current astrochemical models with the\u0000rate equation (RE) approach is that only a single type of binding site is\u0000considered in grain surface chemistry, although laboratory and quantum chemical\u0000studies have found that surfaces contain various binding sites with different\u0000potential energy depths. When various sites exist, adsorbed species can be\u0000trapped in deep potential sites, increasing the resident time on the surface.\u0000On the other hand, adsorbed species can be populated in shallow sites,\u0000activating thermal hopping and thus two-body reactions even at low\u0000temperatures, where the thermal hopping from deeper sites is not activated.\u0000Such behavior cannot be described by the conventional RE approach. In this\u0000work, I present a framework for incorporating various binding sites (i.e.,\u0000binding energy distribution) in gas-ice astrochemical models as an extension of\u0000the conventional RE approach. I propose a simple method to estimate the\u0000probability density function for the occupation of various sites by adsorbed\u0000species, assuming a quasi-steady state. By using thermal desorption and hopping\u0000rates weighted by the probability density functions, the effect of binding\u0000energy distribution is incorporated into the RE approach without increasing the\u0000number of ordinary differential equations to be solved. This method is found to\u0000be accurate and computationally efficient and enables us to consider binding\u0000energy distribution even for a large gas-ice chemical network, which contains\u0000hundreds of icy species. The impact of the binding energy distribution on\u0000interstellar ice composition is discussed quantitatively for the first time.","PeriodicalId":501209,"journal":{"name":"arXiv - PHYS - Earth and Planetary Astrophysics","volume":"95 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141931836","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}
Ava Morrissey, George Zhou, Chelsea X. Huang, Duncan Wright, Caitlin Auger, Keighley E. Rockcliffe, Elisabeth R. Newton, James G. Rogers, Neale Gibson, Nataliea Lowson, Laura C. Mayorga, Robert A. Wittenmyer
HIP94235 b, a 120 Myr old sub-Neptune, provides us the unique opportunity to study mass loss at a pivotal stage of the system's evolution: the end of a 100 million year (Myr) old phase of intense XUV irradiation. We present two observations of HIP94235 b using the Hubble Space Telescope's Space Telescope Imaging Spectrograph (HST/STIS) in the Ly-alpha wavelength region. We do not observe discernible differences across either the blue and red wings of the Ly-alpha line profile in and out of transit, and report no significant detection of outflowing neutral hydrogen around the planet. We constrain the rate of neutral hydrogen escaping HIP94235 b to an upper limit of 10^13 g/s, which remains consistent with energy-limited model predictions of 10^11 g/s. The Ly-alpha non-detection is likely due to the extremely short photoionization timescale of the neutral hydrogen escaping the planet's atmosphere. This timescale, approximately 15 minutes, is significantly shorter than that of any other planets with STIS observations. Through energy-limited mass loss models, we anticipate that HIP94235 b will transition into a super-Earth within a timescale of 1 Gyr.
HIP94235 b是一颗120 Myr岁的亚海王星，它为我们提供了一个独特的机会来研究该系统演化关键阶段的质量损失情况：一个1亿年（Myr）的强烈XUV辐照阶段即将结束。我们利用哈勃太空望远镜的太空望远镜成像摄谱仪（HST/STIS）在 Ly-alpha 波长区域对 HIP94235 b 进行了两次观测。我们在Ly-alpha线剖面的蓝翼和红翼上都没有观测到过境时和非过境时的明显差异，也没有发现行星周围有明显的中性氢外流现象。我们将逸出HIP94235 b的中性氢的速率限制在10^13克/秒的上限，这与能量限制模型预测的10^11克/秒一致。这个时间尺度大约为 15 分钟，大大短于 STIS 观测到的其他行星的时间尺度。通过能量限制质量损失模型，我们预计 HIP94235 b 将在 1 Gyr 的时间尺度内转变为一颗超级地球。
{"title":"Searching for Neutral Hydrogen Escape from the 120 Myr Old Sub-Neptune HIP94235b using HST","authors":"Ava Morrissey, George Zhou, Chelsea X. Huang, Duncan Wright, Caitlin Auger, Keighley E. Rockcliffe, Elisabeth R. Newton, James G. Rogers, Neale Gibson, Nataliea Lowson, Laura C. Mayorga, Robert A. Wittenmyer","doi":"arxiv-2408.02170","DOIUrl":"https://doi.org/arxiv-2408.02170","url":null,"abstract":"HIP94235 b, a 120 Myr old sub-Neptune, provides us the unique opportunity to\u0000study mass loss at a pivotal stage of the system's evolution: the end of a 100\u0000million year (Myr) old phase of intense XUV irradiation. We present two\u0000observations of HIP94235 b using the Hubble Space Telescope's Space Telescope\u0000Imaging Spectrograph (HST/STIS) in the Ly-alpha wavelength region. We do not\u0000observe discernible differences across either the blue and red wings of the\u0000Ly-alpha line profile in and out of transit, and report no significant\u0000detection of outflowing neutral hydrogen around the planet. We constrain the\u0000rate of neutral hydrogen escaping HIP94235 b to an upper limit of 10^13 g/s,\u0000which remains consistent with energy-limited model predictions of 10^11 g/s.\u0000The Ly-alpha non-detection is likely due to the extremely short photoionization\u0000timescale of the neutral hydrogen escaping the planet's atmosphere. This\u0000timescale, approximately 15 minutes, is significantly shorter than that of any\u0000other planets with STIS observations. Through energy-limited mass loss models,\u0000we anticipate that HIP94235 b will transition into a super-Earth within a\u0000timescale of 1 Gyr.","PeriodicalId":501209,"journal":{"name":"arXiv - PHYS - Earth and Planetary Astrophysics","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141931835","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}
Eloy Peña-Asensio, Michael Küppers, Josep M. Trigo-Rodríguez, Albert Rimola
NASA's DART and ESA's Hera missions offer a unique opportunity to investigate the delivery of impact ejecta to other celestial bodies. We performed ejecta dynamical simulations using 3 million particles categorized into three size populations (10 cm, 0.5 cm, and 30 $mu$m) and constrained by early post-impact LICIACube observations. The main simulation explored ejecta velocities ranging from 1 to 1,000 m/s, while a secondary simulation focused on faster ejecta with velocities from 1 to 2 km/s. We identified DART ejecta orbits compatible with the delivery of meteor-producing particles to Mars and Earth. Our results indicate the possibility of ejecta reaching the Mars Hill sphere in 13 years for launch velocities around 450 m/s, which is within the observed range. Some ejecta particles launched at 770 m/s could reach Mars's vicinity in 7 years. Faster ejecta resulted in a higher flux delivery towards Mars and particles impacting the Earth Hill sphere above 1.5 km/s. The delivery process is slightly sensitive to the initial observed cone range and driven by synodic periods. The launch locations for material delivery to Mars were predominantly northern the DART impact site, while they displayed a southwestern tendency for the Earth-Moon system. Larger particles exhibit a marginally greater likelihood of reaching Mars, while smaller particles favor delivery to Earth-Moon, although this effect is insignificant. To support observational campaigns for DART-created meteors, we provide comprehensive information on the encounter characteristics (orbital elements and radiants) and quantify the orbital decoherence degree of the released meteoroids.
{"title":"Delivery of DART Impact Ejecta to Mars and Earth: Opportunity for Meteor Observations","authors":"Eloy Peña-Asensio, Michael Küppers, Josep M. Trigo-Rodríguez, Albert Rimola","doi":"arxiv-2408.02836","DOIUrl":"https://doi.org/arxiv-2408.02836","url":null,"abstract":"NASA's DART and ESA's Hera missions offer a unique opportunity to investigate\u0000the delivery of impact ejecta to other celestial bodies. We performed ejecta\u0000dynamical simulations using 3 million particles categorized into three size\u0000populations (10 cm, 0.5 cm, and 30 $mu$m) and constrained by early post-impact\u0000LICIACube observations. The main simulation explored ejecta velocities ranging\u0000from 1 to 1,000 m/s, while a secondary simulation focused on faster ejecta with\u0000velocities from 1 to 2 km/s. We identified DART ejecta orbits compatible with\u0000the delivery of meteor-producing particles to Mars and Earth. Our results\u0000indicate the possibility of ejecta reaching the Mars Hill sphere in 13 years\u0000for launch velocities around 450 m/s, which is within the observed range. Some\u0000ejecta particles launched at 770 m/s could reach Mars's vicinity in 7 years.\u0000Faster ejecta resulted in a higher flux delivery towards Mars and particles\u0000impacting the Earth Hill sphere above 1.5 km/s. The delivery process is\u0000slightly sensitive to the initial observed cone range and driven by synodic\u0000periods. The launch locations for material delivery to Mars were predominantly\u0000northern the DART impact site, while they displayed a southwestern tendency for\u0000the Earth-Moon system. Larger particles exhibit a marginally greater likelihood\u0000of reaching Mars, while smaller particles favor delivery to Earth-Moon,\u0000although this effect is insignificant. To support observational campaigns for\u0000DART-created meteors, we provide comprehensive information on the encounter\u0000characteristics (orbital elements and radiants) and quantify the orbital\u0000decoherence degree of the released meteoroids.","PeriodicalId":501209,"journal":{"name":"arXiv - PHYS - Earth and Planetary Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141968669","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}
Building on our first paper in this series, we investigate the impact of radial magnetic fields and non-ideal magnetohydrodynamic (MHD) effects - specifically, Ohmic resistivity, Hall drift, and ambipolar diffusion - on RWI unstable modes. The presence of a radial field is linked to the disk's vertical shear and vertical magnetic field. We perform radially global linear analyses and utilize the spectral code textsc{Dedalus} to solve the matrix eigenvalue problems. Our findings reveal that radial fields exhibit behavior similar to vertical fields. In the ideal MHD limit, radial fields enhance the effect of vertical fields in reducing growth rates, with significant reductions starting at relatively weak field strengths, around $beta sim 10^3 - 10^4$, which are relevant to protoplanetary disks. In the non-ideal MHD limit, all three non-ideal effects, when sufficiently strong, cause the growth rates to closely resemble those observed in hydrodynamic models.
{"title":"Rossby wave instability in weakly ionized protoplanetary disks. II. radial B-fields","authors":"Can Cui, Zijin Wang","doi":"arxiv-2408.02556","DOIUrl":"https://doi.org/arxiv-2408.02556","url":null,"abstract":"Building on our first paper in this series, we investigate the impact of\u0000radial magnetic fields and non-ideal magnetohydrodynamic (MHD) effects -\u0000specifically, Ohmic resistivity, Hall drift, and ambipolar diffusion - on RWI\u0000unstable modes. The presence of a radial field is linked to the disk's vertical\u0000shear and vertical magnetic field. We perform radially global linear analyses\u0000and utilize the spectral code textsc{Dedalus} to solve the matrix eigenvalue\u0000problems. Our findings reveal that radial fields exhibit behavior similar to\u0000vertical fields. In the ideal MHD limit, radial fields enhance the effect of\u0000vertical fields in reducing growth rates, with significant reductions starting\u0000at relatively weak field strengths, around $beta sim 10^3 - 10^4$, which are\u0000relevant to protoplanetary disks. In the non-ideal MHD limit, all three\u0000non-ideal effects, when sufficiently strong, cause the growth rates to closely\u0000resemble those observed in hydrodynamic models.","PeriodicalId":501209,"journal":{"name":"arXiv - PHYS - Earth and Planetary Astrophysics","volume":"73 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141931834","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}
Jupiter and Saturn exhibit alternating east-west jet streams as seen from surface. The origin of these zonal flows has been debated for decades. The high-precision gravity measurements by Juno mission and the grand finale of Cassini mission have revealed that the zonal flows observed at the surface may extend several thousand kilometres deep and stop around the transition region from molecular to metallic hydrogen, suggesting the magnetic braking effect on zonal flows. In this study, we perform a set of magnetohydrodynamic simulations in a spherical shell with radially variable electrical conductivity to investigate the interaction between magnetic fields and zonal flows. A key feature of our numerical models is that we impose a background dipole magnetic field on the anelastic rotating convection. By varying the strength of the imposed magnetic field and the vigor of convection, we investigate how the magnetic field interacts with the convective motions and the convection-driven zonal flows. Our simulations reveal that the magnetic field tends to destroy zonal flows in the metallic hydrogen and suppress zonal flows in the molecular envelope, while the magnetic field may enhance the radial convective motions. We extract a quantitative relation between the magnetic field strength and the amplitude of zonal flows at the surface through our simulations, which roughly matches the observed magnetic field and zonal wind speed of Jupiter and Saturn. This discovery provides support from a new perspective for the scenario of deep convection-driven zonal winds which are confined to the molecular hydrogen layers in giant planets.
{"title":"Numerical Simulations of Magnetic Effects on Zonal Flows in Giant Planets","authors":"Shanshan Xue, Yufeng Lin","doi":"arxiv-2408.01650","DOIUrl":"https://doi.org/arxiv-2408.01650","url":null,"abstract":"Jupiter and Saturn exhibit alternating east-west jet streams as seen from\u0000surface. The origin of these zonal flows has been debated for decades. The\u0000high-precision gravity measurements by Juno mission and the grand finale of\u0000Cassini mission have revealed that the zonal flows observed at the surface may\u0000extend several thousand kilometres deep and stop around the transition region\u0000from molecular to metallic hydrogen, suggesting the magnetic braking effect on\u0000zonal flows. In this study, we perform a set of magnetohydrodynamic simulations\u0000in a spherical shell with radially variable electrical conductivity to\u0000investigate the interaction between magnetic fields and zonal flows. A key\u0000feature of our numerical models is that we impose a background dipole magnetic\u0000field on the anelastic rotating convection. By varying the strength of the\u0000imposed magnetic field and the vigor of convection, we investigate how the\u0000magnetic field interacts with the convective motions and the convection-driven\u0000zonal flows. Our simulations reveal that the magnetic field tends to destroy\u0000zonal flows in the metallic hydrogen and suppress zonal flows in the molecular\u0000envelope, while the magnetic field may enhance the radial convective motions.\u0000We extract a quantitative relation between the magnetic field strength and the\u0000amplitude of zonal flows at the surface through our simulations, which roughly\u0000matches the observed magnetic field and zonal wind speed of Jupiter and Saturn.\u0000This discovery provides support from a new perspective for the scenario of deep\u0000convection-driven zonal winds which are confined to the molecular hydrogen\u0000layers in giant planets.","PeriodicalId":501209,"journal":{"name":"arXiv - PHYS - Earth and Planetary Astrophysics","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141968668","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}
Yuna G. Kwon, Stefano Bagnulo, Johannes Markkanen, Ludmilla Kolokolova, Jessica Agarwal, Manuela Lippi, Zuri Gray
Comets, relics from the early solar system, consist of dust and ice. The ice sublimates as comets approach the Sun, ejecting dust from their nuclei seen as activity. Different volatiles sublimate at different Sun-comet distances and eject dust of unique sizes, structures, and compositions. In this study, we present new polarimetric observations of Oort-cloud comet C/2017 K2 (PANSTARRS) in R and I-filter domains before, during, and after its crossover of the water-ice sublimation regime at phase angles of 15.9arcdeg, 10.5arcdeg, and 20.0arcdeg, respectively. Combining multiband optical imaging data covering a wide range of heliocentric distances ($sim$14$-$2.3 au), we aim to characterize the preperihelion evolution of cometary activity as well as the properties of its coma dust. Two discontinuous brightening events were observed: at $sim$6 au presumably associated with changes in CO-like supervolatile ice activity, and at $sim$2.9 au when water ice took over. Particularly, the latter activation is accompanied by changes in coma morphology and color whose trends differ between the inner ($sim$10$^3$-km) and outer ($sim$10$^4$-km) parts of the coma. No polarimetric discontinuities on the comet were observed over the inner coma region, all epochs showing phase-angle and wavelength dependencies compatible with those of active comets observed in similar observing geometry. During this period, the underlying dust continuum overwhelmed H$alpha$ emission at around 656.3 nm, suggesting less water ice on the comet's surface than expected. We discuss K2's coma environment by combining numerical simulations of light scattered by dust and place the observations within the context of the comet's evolution.
{"title":"The pre-perihelion evolution of the activity of comet C/2017 K2 (PANSTARRS) during the water ice-line crossover","authors":"Yuna G. Kwon, Stefano Bagnulo, Johannes Markkanen, Ludmilla Kolokolova, Jessica Agarwal, Manuela Lippi, Zuri Gray","doi":"arxiv-2408.01636","DOIUrl":"https://doi.org/arxiv-2408.01636","url":null,"abstract":"Comets, relics from the early solar system, consist of dust and ice. The ice\u0000sublimates as comets approach the Sun, ejecting dust from their nuclei seen as\u0000activity. Different volatiles sublimate at different Sun-comet distances and\u0000eject dust of unique sizes, structures, and compositions. In this study, we\u0000present new polarimetric observations of Oort-cloud comet C/2017 K2 (PANSTARRS)\u0000in R and I-filter domains before, during, and after its crossover of the\u0000water-ice sublimation regime at phase angles of 15.9arcdeg, 10.5arcdeg, and\u000020.0arcdeg, respectively. Combining multiband optical imaging data covering a\u0000wide range of heliocentric distances ($sim$14$-$2.3 au), we aim to\u0000characterize the preperihelion evolution of cometary activity as well as the\u0000properties of its coma dust. Two discontinuous brightening events were\u0000observed: at $sim$6 au presumably associated with changes in CO-like\u0000supervolatile ice activity, and at $sim$2.9 au when water ice took over.\u0000Particularly, the latter activation is accompanied by changes in coma\u0000morphology and color whose trends differ between the inner ($sim$10$^3$-km)\u0000and outer ($sim$10$^4$-km) parts of the coma. No polarimetric discontinuities\u0000on the comet were observed over the inner coma region, all epochs showing\u0000phase-angle and wavelength dependencies compatible with those of active comets\u0000observed in similar observing geometry. During this period, the underlying dust\u0000continuum overwhelmed H$alpha$ emission at around 656.3 nm, suggesting less\u0000water ice on the comet's surface than expected. We discuss K2's coma\u0000environment by combining numerical simulations of light scattered by dust and\u0000place the observations within the context of the comet's evolution.","PeriodicalId":501209,"journal":{"name":"arXiv - PHYS - Earth and Planetary Astrophysics","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141968670","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}
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