Umeå University's logo

umu.sePublikasjoner
Endre søk
Begrens søket
1 - 4 of 4
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Fatemi, Shahab
    et al.
    Swedish Institute of Space Physics, Kiruna, Sweden.
    Poirier, Nicolas
    École nationale supérieure de mécanique et d’aérotechnique, Chasseneuil-du-Poitou, France .
    Holmström, Mats
    Swedish Institute of Space Physics, Kiruna, Sweden.
    Lindkvist, Jesper
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wieser, Martin
    Swedish Institute of Space Physics, Kiruna, Sweden.
    Barabash, Stas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Swedish Institute of Space Physics, Kiruna, Sweden.
    A modelling approach to infer the solar wind dynamic pressure from magnetic field observations inside Mercury's magnetosphere2018Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 614, artikkel-id A132Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aims: The lack of an upstream solar wind plasma monitor when a spacecraft is inside the highly dynamic magnetosphere of Mercury limits interpretations of observed magnetospheric phenomena and their correlations with upstream solar wind variations.

    Methods: We used AMITIS, a three-dimensional GPU-based hybrid model of plasma (particle ions and fluid electrons) to infer the solar wind dynamic pressure and Alfvén Mach number upstream of Mercury by comparing our simulation results with MESSENGER magnetic field observations inside the magnetosphere of Mercury. We selected a few orbits of MESSENGER that have been analysed and compared with hybrid simulations before. Then we ran a number of simulations for each orbit (~30–50 runs) and examined the effects of the upstream solar wind plasma variations on the magnetic fields observed along the trajectory of MESSENGER to find the best agreement between our simulations and observations.

    Results: We show that, on average, the solar wind dynamic pressure for the selected orbits is slightly lower than the typical estimated dynamic pressure near the orbit of Mercury. However, we show that there is a good agreement between our hybrid simulation results and MESSENGER observations for our estimated solar wind parameters. We also compare the solar wind dynamic pressure inferred from our model with those predicted previously by the WSA-ENLIL model upstream of Mercury, and discuss the agreements and disagreements between the two model predictions. We show that the magnetosphere of Mercury is highly dynamic and controlled by the solar wind plasma and interplanetary magnetic field. In addition, in agreement with previous observations, our simulations show that there are quasi-trapped particles and a partial ring current-like structure in the nightside magnetosphere of Mercury, more evident during a northward interplanetary magnetic field (IMF). We also use our simulations to examine the correlation between the solar wind dynamic pressure and stand-off distance of the magnetopause and compare it with MESSENGER observations. We show that our model results are in good agreement with the response of the magnetopause to the solar wind dynamic pressure, even during extreme solar events. We also show that our model can be used as a virtual solar wind monitor near the orbit of Mercury and this has important implications for interpretation of observations by MESSENGER and the future ESA/JAXA mission to Mercury, BepiColombo.

    Fulltekst (pdf)
    fulltext
  • 2.
    Lindkvist, Jesper
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Swedish Institute of Space Physics, Kiruna.
    Holmström, Mats
    Swedish Institute of Space Physics, Kiruna.
    Fatemi, Shahab
    Space Sciences Laboratory, UC Berkeley.
    Wieser, Martin
    Swedish Institute of Space Physics, Kiruna.
    Barabash, Stas
    Swedish Institute of Space Physics, Kiruna.
    Ceres interaction with the solar wind2017Inngår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 44, nr 5, s. 2070-2077Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The solar wind interaction with Ceres is studied for a high water vapor release from its surface using a hybrid model including photoionization. We use a water vapor production rate of 6 kg/s, thought to be due to subsurface sublimation, corresponding to a detection on 6 March 2013 by the Herschel Space Observatory. We present the general morphology of the plasma interactions, both close to Ceres and on a larger scale. Mass loading of water ions causes a magnetic pileup region in front of Ceres, where the solar wind deflects up to 15 ∘ and slows down by 15%. The global plasma interaction with Ceres is not greatly affected by the source location of water vapor nor on gravity, only on the production rate of water vapor. On a global scale, Ceres has a comet-like interaction with the solar wind with observable perturbations farther than 250 Ceres radii downstream of the body.

  • 3.
    Nilsson, Hans
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Swedish Institute of Space Physics, Kiruna, Sweden.
    Zhang, Qi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Swedish Institute of Space Physics, Kiruna, Sweden.
    Stenberg Wieser, Gabriella
    Umeå universitet. Swedish Institute of Space Physics, Kiruna, Sweden.
    Holmström, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Swedish Institute of Space Physics, Kiruna, Sweden.
    Barabash, Stas
    Swedish Institute of Space Physics, Kiruna, Sweden.
    Futaana, Yoshifumi
    Swedish Institute of Space Physics, Kiruna, Sweden.
    Fedorov, Andrey
    Institut de Recherche en Astrophysique et Planétologie, Toulouse, France.
    Persson, Moa
    Swedish Institute of Space Physics, Kiruna, Sweden; Institut de Recherche en Astrophysique et Planétologie, 9 avenue du Colonel Roche BP 44346 31028 Toulouse Cedex 4, France.
    Wieser, Martin
    Swedish Institute of Space Physics, Kiruna, Sweden.
    Solar cycle variation of ion escape from Mars2023Inngår i: Icarus, ISSN 0019-1035, E-ISSN 1090-2643, Vol. 393, artikkel-id 114610Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using Mars Express data from 2007 until 2020 we show how ion outflow from Mars varied over more than a solar cycle, from one solar minimum to another. The data was divided into intervals with a length of one Martian year, starting from 30 April 2007 and ending 13 July 2020. The net escape rate was about 5×1024s−1 in the first covered minimum, and 2−3×1024s−1 in the most recent minimum. Ion escape peaked at 1×1025s−1 during the intervening solar maximum. The outflow is a clear function of the solar cycle, in agreement with previous studies which found a clear relationship between solar EUV flux and ion escape at Mars. The outflow during solar maximum is 2.5 to 3 times higher than in the surrounding solar minima. The average solar wind dynamic pressure over a Martian year was investigated, but does not vary much with the solar cycle. The escape rate at solar maximum is in good agreement with some recent MAVEN studies, and dominated by low energy ions at most sampled locations. A simple linear fit to the data gives a prediction of the escape rate for the much stronger solar maximum during the Phobos mission in 1989 that is consistent with observations. The fit also implies a non-linear response of ion escape for low solar EUV, with a lower initial escape response for lower solar EUV levels than those of the studied data set.

    Fulltekst (pdf)
    fulltext
  • 4.
    Pontoni, Angèle
    et al.
    Swedish Institute of Space Physics, Kiruna, Sweden.
    Shimoyama, Manabu
    Swedish Institute of Space Physics, Kiruna, Sweden.
    Futaana, Yoshifumi
    Swedish Institute of Space Physics, Kiruna, Sweden.
    Fatemi, Shahab
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Poppe, A.R.
    Space Sciences Laboratory, University of California, CA, Berkeley, United States.
    Wieser, Martin
    Swedish Institute of Space Physics, Kiruna, Sweden.
    Barabash, Stas
    Swedish Institute of Space Physics, Kiruna, Sweden.
    Simulations of Energetic Neutral Atom Sputtering From Ganymede in Preparation for the JUICE Mission2022Inngår i: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 127, nr 1, artikkel-id e2021JA029439Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Jovian magnetospheric plasma irradiates the surface of Ganymede and is postulated to be the primary agent that changes the surface brightness of Ganymede, leading to asymmetries between polar and equatorial regions as well as between the trailing and leading hemispheres. As impinging ions sputter surface constituents as neutrals, ion precipitation patterns can be remotely imaged using the Energetic Neutral Atoms (ENA) measurement technique. Here we calculate the expected sputtered ENA flux from the surface of Ganymede to help interpret future observations by ENA instruments, particularly the Jovian Neutrals Analyzer (JNA) onboard the JUpiter ICy moon Explorer (JUICE) spacecraft. We use sputtering models developed based on laboratory experiments to calculate sputtered fluxes of H2O, O2, and H2. The input ion population used in this study is the result of test particle simulations using electric and magnetic fields from a hybrid simulation of Ganymede's environment. This population includes a thermal component (H+ and O+ from 10 eV to 10 keV) and an energetic component (H+, O++, and S+++ from 10 keV to 10 MeV). We find a global ENA sputtering rate from Ganymede of 1.42 × 1027 s−1, with contributions from H2, O2, and H2O of 34%, 17%, and 49% respectively. We also calculate the energy distribution of sputtered Energetic Neutral Atoms (ENAs), give an estimate of a typical JNA count rate at Ganymede, and investigate latitudinal variations of sputtered fluxes along a simulated orbit track of the JUICE spacecraft. Our results demonstrate the capability of the JNA sensor to remotely map ion precipitation at Ganymede.

1 - 4 of 4
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf