Frontiers in Astronomy and Space Sciences最新文献_第6页

Dense gas star formation efficiency and the LHCN (4−3)′/LHCO+(4−3)′ ratio: insights from a statistical study of infrared bright star-forming galaxies 致密气体恒星形成效率和LHCN(4−3)' /LHCO+(4−3)'比值:来自红外明亮恒星形成星系统计研究的见解

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-10-03 DOI: 10.3389/fspas.2023.1246978

Qian Jiao, Yu Gao, Qinghua Tan, Yang Gao

引用次数: 0

The multi-point assessment of the kinematics of shocks (MAKOS) 冲击运动学的多点评估(MAKOS)

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-10-02 DOI: 10.3389/fspas.2023.1199711

Katherine Goodrich, Ian J. Cohen, Steven Schwartz, Lynn B. Wilson, Drew Turner, Amir Caspi, Keith Smith, Randall Rose, Phyllis Whittlesey, Ferdinand Plaschke

{"title":"The multi-point assessment of the kinematics of shocks (MAKOS)","authors":"Katherine Goodrich, Ian J. Cohen, Steven Schwartz, Lynn B. Wilson, Drew Turner, Amir Caspi, Keith Smith, Randall Rose, Phyllis Whittlesey, Ferdinand Plaschke","doi":"10.3389/fspas.2023.1199711","DOIUrl":"https://doi.org/10.3389/fspas.2023.1199711","url":null,"abstract":"Collisionless shock waves are one of the main mechanisms of energy conversion in space plasmas. They can directly or indirectly drive other universal plasma processes such as magnetic reconnection, turbulence, particle acceleration and wave phenomena. Collisionless shocks employ a myriad of kinetic plasma mechanisms to convert the kinetic energy of supersonic flows in space to other forms of energy (e.g., thermal plasma, energetic particles, or electromagnetic energy) in order for the flow to pass an immovable obstacle. The partitioning of energy downstream of collisionless shocks is not well understood, nor are the processes which perform energy conversion. While we, as the heliophysics community, have collected an abundance of observations of the terrestrial bow shock, instrument and mission-level limitations have made it impossible to quantify this partition, to establish the physics within the shock layer responsible for it, and to understand its dependence on upstream conditions. This paper stresses the need for the first ever spacecraft mission specifically designed and dedicated to the observation of both the terrestrial bow shock as well as Interplanetary shocks in the solar wind. Our mission concept, the Multi-point Assessment of the Kinematics of Shocks (MAKOS), will greatly improve on previous observations of the terrestrial bow shock with instrumentation specifically tailored to observe the evolution of the solar wind through the shock.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135894793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}

引用次数: 0

Longitudinal variability of thermospheric zonal winds near dawn and dusk 黎明和黄昏附近热层纬向风的纵向变率

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-09-29 DOI: 10.3389/fspas.2023.1214612

Ivana Molina, Ludger Scherliess

{"title":"Longitudinal variability of thermospheric zonal winds near dawn and dusk","authors":"Ivana Molina, Ludger Scherliess","doi":"10.3389/fspas.2023.1214612","DOIUrl":"https://doi.org/10.3389/fspas.2023.1214612","url":null,"abstract":"Understanding the morphology and dynamics of the thermosphere is key to understanding the Earth’s upper atmosphere as a whole. Thermospheric winds play an important role in this process by transporting momentum and energy and affecting the composition, dynamics and morphology of not only the thermosphere but also of the ionosphere. The general morphology of the winds has been well established over the past decades, but we are only starting to understand its variability. In this process the lower atmosphere plays an important role due to direct penetration of waves from the lower atmosphere into the ionosphere/thermosphere, secondary waves generated on the way, or internal feedback mechanisms in the coupled ionosphere-thermosphere system. Therefore, knowledge about thermospheric variability and its causes is critical for an improved understanding of the global ionosphere-thermosphere system and its coupling to the lower atmosphere. We have used low-to mid-latitude zonal wind observations obtained by the Gravity Field and Steady-State Ocean Explorer (GOCE) satellite near 260 km altitude during geomagnetically quiet times to investigate the interannual and spatial zonal wind variability near dawn and dusk, during December solstice. The temporal and spatial variability is presented as a variation about the zonal mean values and decomposed into its underlying wavenumbers using a Fourier analysis. The obtained wave features are compared between different years and clear interannual changes are observed in the individual wave components, which appear to align with changes in the solar flux but do not correlate with variations in either El Niño Southern Oscillation or the Quasi Biennial Oscillation. The obtained wave features are compared and contrasted with results from the Climatological Tidal Model of the Thermosphere (CTMT) and revealed a very good agreement between CTMT and the 2009 and 2010 December GOCE zonal wind perturbations at dawn. However, during dusk, the CTMT zonal wind perturbations and in particular the zonal wave-1 component show significant differences with those observed by GOCE.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135245969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}

引用次数: 1

Resolving the tidal weather of the thermosphere using GDC 利用GDC解析热层潮汐天气

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-09-29 DOI: 10.3389/fspas.2023.1282261

Jens Oberheide, Stone M. Gardner, Mukta Neogi

{"title":"Resolving the tidal weather of the thermosphere using GDC","authors":"Jens Oberheide, Stone M. Gardner, Mukta Neogi","doi":"10.3389/fspas.2023.1282261","DOIUrl":"https://doi.org/10.3389/fspas.2023.1282261","url":null,"abstract":"NASA’s Geospace Dynamics Constellation (GDC) mission is a six satellite constellation to make in situ measurements of important ionospheric and thermospheric variables to better understand the processes that govern Earth’s near space environment. Scheduled for a 2029 launch into high inclination orbits <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" id=\"m1\"><mml:mo>∼</mml:mo><mml:mn>82</mml:mn><mml:mo>°</mml:mo></mml:math> at <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" id=\"m2\"><mml:mo>∼</mml:mo><mml:mn>380</mml:mn></mml:math> km, the satellite orbit planes will separate over time to provide almost continuous local solar time coverage every day towards the end of the 3 year baseline GDC mission. As such, the neutral temperature and neutral wind measurements of GDC will likely allow the heliophysics community to make significant progress towards resolving the tidal weather of the thermosphere, that is, day-to-day tidal variability, and how it is driven by meteorological processes near the surface and in situ forcing in the ionosphere-thermosphere system. To assess the GDC ability to accurately resolve the tides each day and when in the mission this can be achieved, we conduct an Observational Simulation System Experiment (OSSE) using SD-WACCM-X and the predicted GDC orbits. Our results show that GDC can provide closure on the tidal variability (mean, diurnal and semidiurnal, migrating and nonmigrating) at orbit height in mission phase 4 and throughout most parts of mission phase 3. We also perform Hough Mode Extension fitting of relevant tidal components to study possible connections between the GDC observations and the tides at 200 km, to assess synergies between GDC and the forthcoming DYNAMIC mission (scheduled to be co-launched with GDC) that will measure altitude-resolved winds and temperatures in the ∼100–200 km height range.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135193316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}

引用次数: 0

Recent insights on CME deflections at low heights 最近对低高度CME偏转的见解

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-09-27 DOI: 10.3389/fspas.2023.1260432

M. Cécere, A. Costa, H. Cremades, G. Stenborg

引用次数: 0

Structural properties of a new class of stellar structures in modified teleparallel gravity 修正遥平行引力下一类新的恒星结构的结构特性

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-09-27 DOI: 10.3389/fspas.2023.1203777

Aylin Caliskan, Rana Muhammad Zulqarnain, Ertan Güdekli, Imran Siddique, Hijaz Ahmad, Sameh Askar

{"title":"Structural properties of a new class of stellar structures in modified teleparallel gravity","authors":"Aylin Caliskan, Rana Muhammad Zulqarnain, Ertan Güdekli, Imran Siddique, Hijaz Ahmad, Sameh Askar","doi":"10.3389/fspas.2023.1203777","DOIUrl":"https://doi.org/10.3389/fspas.2023.1203777","url":null,"abstract":"This paper explores new neutron star models based on spherically symmetric space–time. We take into account the gravitational effects of <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" id=\"m1\"><mml:mi>f</mml:mi><mml:mrow><mml:mo stretchy=\"false\">(</mml:mo><mml:mrow><mml:mi>T</mml:mi><mml:mo>,</mml:mo><mml:mi mathvariant=\"script\">T</mml:mi></mml:mrow><mml:mo stretchy=\"false\">)</mml:mo></mml:mrow></mml:math> gravity, in which T is the torsion and <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" id=\"m2\"><mml:mi mathvariant=\"script\">T</mml:mi></mml:math> is the trace of the energy–momentum tensor. Field equations are evaluated by incorporating the off-diagonal tetrad. In this paper, we discuss the detailed properties of compact star candidates 4 U 1538–52, J 0437–4,715, J 0030 + 0451, and 4 U 1820–30, like energy density, pressure profiles, gradients, anisotropy, energy conditions, equation of state, speeds of sound, TOV equation, and compactification parameters. We discuss all these characteristics using the quadratic cosmological model of <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" id=\"m3\"><mml:mi>f</mml:mi><mml:mrow><mml:mo stretchy=\"false\">(</mml:mo><mml:mrow><mml:mi>T</mml:mi><mml:mo>,</mml:mo><mml:mi mathvariant=\"script\">T</mml:mi></mml:mrow><mml:mo stretchy=\"false\">)</mml:mo></mml:mrow></mml:math> gravity. We use the well-famed junction equations to evaluate the unknown parameters. Our detailed and comprehensive graphical analysis ensures that the model containing the anisotropic nature of stellar structures is physically acceptable, regular, and stable.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135579268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}

引用次数: 0

Simulation of radiation belt wave-particle interactions in an MHD-particle framework mhd -粒子框架下辐射带波粒相互作用的模拟

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-09-26 DOI: 10.3389/fspas.2023.1239160

Anthony A. Chan, Scot R. Elkington, William J. Longley, Suhail A. Aldhurais, Shah S. Alam, Jay M. Albert, Allison N. Jaynes, David M. Malaspina, Qianli Ma, Wen Li

{"title":"Simulation of radiation belt wave-particle interactions in an MHD-particle framework","authors":"Anthony A. Chan, Scot R. Elkington, William J. Longley, Suhail A. Aldhurais, Shah S. Alam, Jay M. Albert, Allison N. Jaynes, David M. Malaspina, Qianli Ma, Wen Li","doi":"10.3389/fspas.2023.1239160","DOIUrl":"https://doi.org/10.3389/fspas.2023.1239160","url":null,"abstract":"In this paper we describe K2, a comprehensive simulation model of Earth’s radiation belts that includes a wide range of relevant physical processes. Global MHD simulations are combined with guiding-center test-particle methods to model interactions with ultra low-frequency (ULF) waves, substorm injections, convective transport, drift-shell splitting, drift-orbit bifurcations, and magnetopause shadowing, all in self-consistent MHD fields. Simulation of local acceleration and pitch-angle scattering due to cyclotron-scale interactions is incorporated by including stochastic differential equation (SDE) methods in the MHD-particle framework. The SDEs are driven by event-specific bounce-averaged energy and pitch-angle diffusion coefficients. We present simulations of electron phase-space densities during a simplified particle acceleration event based on the 17 March 2013 event observed by the Van Allen Probes, with a focus on demonstrating the capabilities of the K2 model. The relative wave-particle effects of global scale ULF waves and very-low frequency (VLF) whistler-mode chorus waves are compared, and we show that the primary acceleration appears to be from the latter. We also show that the enhancement with both ULF and VLF processes included exceeds that of VLF waves alone, indicating a synergistic combination of energization and transport processes may be important.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135718982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}

引用次数: 1

The outer dusty edge of accretion disks in active galactic nuclei 活动星系核中吸积盘的外尘埃边缘

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-09-25 DOI: 10.3389/fspas.2023.1256088

Hermine Landt

{"title":"The outer dusty edge of accretion disks in active galactic nuclei","authors":"Hermine Landt","doi":"10.3389/fspas.2023.1256088","DOIUrl":"https://doi.org/10.3389/fspas.2023.1256088","url":null,"abstract":"Recent models for the inner structure of active galactic nuclei (AGN) aim at connecting the outer region of the accretion disk with the broad-line region and dusty torus through a radiatively accelerated, dusty outflow. Such an outflow not only requires the outer disk to be dusty and thus predicts disk sizes beyond the self-gravity limit but requires the presence of nuclear dust with favorable properties. Here, we investigate a large sample of type 1 AGN by near-infrared (near-IR) cross-dispersed spectroscopy with the aim to constrain the astrochemistry, location, and geometry of the nuclear hot dust region. Assuming a thermal equilibrium for optically thin dust, we derive the luminosity-based dust radius for different grain properties using our measurement of the temperature. We combine our results with independent dust radius measurements from reverberation mapping and interferometry, and show that large dust grains that can provide the necessary opacity for the outflow are ubiquitous in AGN. Using our estimates of the dust covering factor, we investigate the dust geometry using the effects of the accretion disk anisotropy. A flared disk-like structure for the hot dust is favored. Finally, we discuss the implication of our results for the dust radius-luminosity plane.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135864507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}

引用次数: 0

Human-microbes symbiosis in health and disease, on earth and beyond planetary boundaries 人类-微生物在健康和疾病方面的共生关系，在地球上和超越地球边界

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-09-22 DOI: 10.3389/fspas.2023.1180522

Joel Doré, Sandra Ortega Ugalde

引用次数: 0

Surface contamination rates at different spatial scales in the Columbus module (ISS) during the MATISS campaigns 在MATISS活动期间，哥伦布太空舱(ISS)不同空间尺度的表面污染率

3区物理与天体物理

Frontiers in Astronomy and Space Sciences Pub Date : 2023-09-21 DOI: 10.3389/fspas.2023.1229022

Laurence Lemelle, Eléonore Mottin, Denis Le Tourneau, Sébastien Rouquette, Lucie Campagnolo, Cécile Thévenot, Alain Maillet, Sébastien Barde, Emmanuel Garre, Jérémie Teisseire, Caroline Fontelaye, Vincent Jousseaume, Catherine Pudda, Olivier Constantin, Pierre Marcoux, Guillaume Nonglaton, Christophe Place

{"title":"Surface contamination rates at different spatial scales in the Columbus module (ISS) during the MATISS campaigns","authors":"Laurence Lemelle, Eléonore Mottin, Denis Le Tourneau, Sébastien Rouquette, Lucie Campagnolo, Cécile Thévenot, Alain Maillet, Sébastien Barde, Emmanuel Garre, Jérémie Teisseire, Caroline Fontelaye, Vincent Jousseaume, Catherine Pudda, Olivier Constantin, Pierre Marcoux, Guillaume Nonglaton, Christophe Place","doi":"10.3389/fspas.2023.1229022","DOIUrl":"https://doi.org/10.3389/fspas.2023.1229022","url":null,"abstract":"Future long-duration human spaceflights require developments to limit biocontamination of surface habitats. The three MATISS (Microbial Aerosol Tethering on Innovative Surfaces in the International Space Station) campaigns exposed surface treatments over several months in the ISS. To this end, eight sample holders designed were mounted with lamella-bearing FDTS ((1 H , 1 H , 2 H , 2 H )-perfluorodecyltrichlorosilane), SiOCH, and parylene hydrophobic coatings, at two different locations, for several months, during three distinct periods from 2016 to 2020. Tile scanning optical microscopy (×3 and ×30 magnifications) detected several thousand particles, indicating a relatively clean environment (a few particles per mm 2 ). In previous studies, exposure rates were analyzed for all the coarse and fine particles detected on the largest total area of the integrated FDTS area exposed in the ISS (several cm 2 ). Here, the contamination rates observed for a smaller constant area unit (the 0.66-cm 2 window area of the holder) were statistically analyzed. Therefore, a statistical difference in rate distributions between RGSH (Return Grid Sensor House) and EDR (European Drawer Rack) and between FDTS and either SiOCH or parylene was shown for the coarse particles but not for the fine particles. The contamination rates were found to be low, confirming the efficiency of the long-term air purification system. The rates tend to vary with the astronaut occupancy rates. Surfaces of spacecraft for long-duration exploration left unmanned during dormancy periods can be considered safe from biocontamination.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136130865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}

引用次数: 0