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Barabash, Stas
Publications (10 of 21) Show all publications
Nilsson, H., Wieser, G. S., Behar, E., Wedlund, C. S., Gunell, H., Yamauchi, M., . . . Rubin, M. (2015). Birth of a comet magnetosphere: A spring of water ions (ed.). Science, 347(6220), Article ID aaa0571.
Open this publication in new window or tab >>Birth of a comet magnetosphere: A spring of water ions
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2015 (English)In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 347, no 6220, article id aaa0571Article in journal (Refereed) Published
Abstract [en]

The Rosetta mission shall accompany comet 67P/Churyumov-Gerasimenko from a heliocentric distance of >3.6 astronomical units through perihelion passage at 1.25 astronomical units, spanning low and maximum activity levels. Initially, the solar wind permeates the thin comet atmosphere formed from sublimation, until the size and plasma pressure of the ionized atmosphere define its boundaries: A magnetosphere is born. Using the Rosetta Plasma Consortium ion composition analyzer, we trace the evolution from the first detection of water ions to when the atmosphere begins repelling the solar wind (~3.3 astronomical units), and we report the spatial structure of this early interaction. The near-comet water population comprises accelerated ions (

National Category
Aerospace Engineering
Research subject
Space Technology; Atmospheric science
Identifiers
urn:nbn:se:ltu:diva-3136 (URN)10.1126/science.aaa0571 (DOI)000348225800033 ()25613894 (PubMedID)2-s2.0-84921808746 (Scopus ID)0eb80de3-affe-418a-a246-d47cfd5661a1 (Local ID)0eb80de3-affe-418a-a246-d47cfd5661a1 (Archive number)0eb80de3-affe-418a-a246-d47cfd5661a1 (OAI)
Note

Validerad; 2015; Nivå 2; 20150127 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Fatemi, S., Holmström, M., Futaana, Y., Lue, C., Collier, M. R., Barabash, S. & Stenberg, G. (2014). Effects of protons deflected by lunar crustal magnetic fields on the global lunar plasma environment (ed.). Paper presented at . Journal of Geophysical Research, 119(8), 6095-6105
Open this publication in new window or tab >>Effects of protons deflected by lunar crustal magnetic fields on the global lunar plasma environment
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2014 (English)In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 119, no 8, p. 6095-6105Article in journal (Refereed) Published
Abstract [en]

Solar wind plasma interaction with lunar crustal magnetic fields is different than that of magnetized bodies like the Earth. Lunar crustal fields are, for typical solar wind conditions, not strong enough to form a (bow)shock upstream but rather deflect and perturb plasma and fields. Here we study the global effects of protons reflected from lunar crustal magnetic fields on the lunar plasma environment when the Moon is in the unperturbed solar wind. We employ a three-dimensional hybrid model of plasma and an observed map of reflected protons from lunar magnetic anomalies over the lunar farside. We observe that magnetic fields and plasma upstream over the lunar crustal fields compress to nearly 120% and 160% of the solar wind, respectively. We find that these disturbances convect downstream in the vicinity of the lunar wake, while their relative magnitudes decrease. In addition, solar wind protons are disturbed and heated at compression regions and their velocity distribution changes from Maxwellian to a non-Maxwellian. Finally, we show that these features persists, independent of the details of the ion reflection by the magnetic fields.

National Category
Aerospace Engineering
Research subject
Atmospheric science; Space Technology
Identifiers
urn:nbn:se:ltu:diva-4347 (URN)10.1002/2014JA019900 (DOI)000344809600006 ()2482743f-c727-41ba-9349-fba7a339e9b2 (Local ID)2482743f-c727-41ba-9349-fba7a339e9b2 (Archive number)2482743f-c727-41ba-9349-fba7a339e9b2 (OAI)
Note
Validerad; 2014; 20140513 (shafat)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Dieval, C., Stenberg, G., Nilsson, H. & Barabash, S. (2013). A statistical study of proton precipitation onto the Martian upper atmosphere: Mars Express observations (ed.). Paper presented at . Journal of Geophysical Research, 1972-1983
Open this publication in new window or tab >>A statistical study of proton precipitation onto the Martian upper atmosphere: Mars Express observations
2013 (English)In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, p. 1972-1983Article in journal (Refereed) Published
Abstract [en]

Due to the small size of the Martian magnetic pile-up region, especially at the subsolar point, heated protons with high enough energy can penetrate the induced magnetosphere boundary (IMB) without being backscattered, i.e., they precipitate. We present a statistical study of the downgoing ~ keV proton fluxes measured in the Martian ionosphere by the Analyzer of Space Plasma and Energetic Atoms (ASPERA-3) experiment onboard the Mars Express spacecraft. We find that on the dayside, the events of proton penetration occur during 3% of the observation time: the precipitation is an intermittent phenomenon. The proton events carry on average ~0.2% of the incident solar wind flux. Therefore, the induced magnetosphere is an effective shield against the magnetosheath protons. The events are more frequent during fast solar wind conditions than during slow solar wind conditions. The sporadic proton penetration is thought to be caused by transient increases in the magnetosheath temperature. The precipitating flux is higher on the dayside than on the nightside, and its spatial deposition is controlled by the solar wind convective electric field. The largest crustal magnetic anomalies tend to decrease the proton precipitation in the Southern hemisphere. The particle and energy fluxes vary in the range 104-106 cm-2 s-1 and 107-109 eVcm-2 s-1, respectively. The corresponding heating for the dayside atmosphere is on average negligible compared to the solar extreme ultraviolet heating, although the intermittent penetration may cause local ionization. The net precipitating proton particle flux input to the dayside ionosphere is estimated as 1.2 · 1021 s-1.

National Category
Aerospace Engineering
Research subject
Space Technology
Identifiers
urn:nbn:se:ltu:diva-12223 (URN)10.1002/jgra.50229 (DOI)000325215800017 ()2-s2.0-84882787403 (Scopus ID)b52e75da-88f5-4b37-b4b9-c3b3693cf7bb (Local ID)b52e75da-88f5-4b37-b4b9-c3b3693cf7bb (Archive number)b52e75da-88f5-4b37-b4b9-c3b3693cf7bb (OAI)
Note
Validerad; 2013; 20130320 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Shematovich, V., Bisikalo, D., Stenberg, G., Barabash, S., Dieval, C. & Gérard, J.-C. (2013). He2+ transport in the Martian upper atmosphere with an induced magnetic field (ed.). Paper presented at . Journal of Geophysical Research, 118(3), 1231-1242
Open this publication in new window or tab >>He2+ transport in the Martian upper atmosphere with an induced magnetic field
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2013 (English)In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 118, no 3, p. 1231-1242Article in journal (Refereed) Published
Abstract [en]

Solar wind helium may be a significant source of neutral helium in the Martian atmosphere. The precipitating particles also transfer mass, energy, and momentum. To investigate the transport of He2+ in the upper atmosphere of Mars, we have applied the direct simulation Monte Carlo method to solve the kinetic equation. We calculate the upward He, He+, and He2+ fluxes, resulting from energy spectra of the downgoing He2+ observed below 500 km altitude by the Analyzer of Space Plasmas and Energetic Atoms 3 instrument onboard Mars Express. The particle flux of the downward moving He2+ ions was 1–2 × 106 cm–2 s–1, and the energy flux is equal to 9–10 × 10–3 erg cm–2 s–1. The calculations of the upward flux have been made for the Martian atmosphere during solar minimum. It was found, that if the induced magnetic field is not introduced in the simulations the precipitating He2+ ions are not backscattered at all by the Martian upper atmosphere. If we include a 20 nT horizontal magnetic field, a typical field measured by Mars Global Surveyor in the altitude range of 85–500 km, we find that up to 30%–40% of the energy flux of the precipitating He2+ ions is backscattered depending on the velocity distribution of the precipitating particles. We thus conclude that the induced magnetic field plays a crucial role in the transport of charged particles in the upper atmosphere of Mars and, therefore, that it determines the energy deposition of the solar wind.

National Category
Aerospace Engineering
Research subject
Space Technology
Identifiers
urn:nbn:se:ltu:diva-10450 (URN)10.1002/jgra.50184 (DOI)000318274000026 ()2-s2.0-84876938379 (Scopus ID)94185688-823d-4f47-946f-10b2aa3187f9 (Local ID)94185688-823d-4f47-946f-10b2aa3187f9 (Archive number)94185688-823d-4f47-946f-10b2aa3187f9 (OAI)
Note
Validerad; 2013; 20130318 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Ramstad, R., Futaana, Y., Barabash, S., Nilsson, H., Martin del Campo B, S., Lundin, R. & Schwingenschuh, K. (2013). Phobos 2/ASPERA data revisited: Planetary ion escape rate from Mars near the 1989 solar maximum (ed.). Geophysical Research Letters, 40(3), 477-481
Open this publication in new window or tab >>Phobos 2/ASPERA data revisited: Planetary ion escape rate from Mars near the 1989 solar maximum
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2013 (English)In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 40, no 3, p. 477-481Article in journal (Refereed) Published
Abstract [en]

1] Insights about the near-Mars space environment from Mars Express observations have motivated a revisit of the Phobos 2/ASPERA ion data from 1989. We have expanded the analysis to now include all usable heavy ion (O+, O, CO) measurements from the circular orbits of Phobos 2. Phobos 2/ASPERA ion fluxes in the Martian tail are compared with previous results obtained by the instruments on Phobos 2. Further validation of the measurement results is obtained by comparing IMP-8 and Phobos 2/ASPERA solar wind ion fluxes, taking into account the time lag between Earth and Mars. Heavy ion flux measurements from 18 circular equatorial orbits around Mars are bin-averaged to a grid, using the MSE (electric field) frame of reference. The binned data are subsequently integrated to determine the total escape rate of planetary ions. From this we derive a total planetary heavy ion escape rate of (2–3) × 1025 s−1 from Mars for the 1989 solar maximum

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-10868 (URN)10.1002/grl.50149 (DOI)000317831000003 ()2-s2.0-84878168074 (Scopus ID)9bd8cf3a-a956-4c3f-9f41-836e190fe2f3 (Local ID)9bd8cf3a-a956-4c3f-9f41-836e190fe2f3 (Archive number)9bd8cf3a-a956-4c3f-9f41-836e190fe2f3 (OAI)
Note

Validerad; 2013; 20130215 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-09-04Bibliographically approved
Dhanaya, M., Bhardwaj, A., Futaana, Y., Fatemi, S., Holmström, M., Barabash, S., . . . Thampi, R. (2013). Proton entry into the near-lunar plasma wake for magnetic field aligned flow (ed.). Paper presented at . Geophysical Research Letters, 40(2), 2913-2917
Open this publication in new window or tab >>Proton entry into the near-lunar plasma wake for magnetic field aligned flow
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2013 (English)In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 40, no 2, p. 2913-2917Article in journal (Refereed) Published
Abstract [en]

We report the first observation of protons in the near-lunar (100–200 km from the surface) and deeper (near anti-subsolar point) plasma wake when the interplanetary magnetic field (IMF) and solar wind velocity (vsw) are parallel (aligned flow; angle between IMF and vsw≤10°). More than 98% of the observations during aligned flow condition showed the presence of protons in the wake. These observations are obtained by the Solar Wind Monitor sensor of the Sub-keV Atom Reflecting Analyser experiment on Chandrayaan-1. The observation cannot be explained by the conventional fluid models for aligned flow. Back tracing of the observed protons suggests that their source is the solar wind. The larger gyroradii of the wake protons compared to that of solar wind suggest that they were part of the tail of the solar wind velocity distribution function. Such protons could enter the wake due to their large gyroradii even when the flow is aligned to IMF. However, the wake boundary electric field may also play a role in the entry of the protons into the wake.

National Category
Aerospace Engineering
Research subject
Space Technology
Identifiers
urn:nbn:se:ltu:diva-12002 (URN)10.1002/grl.50617 (DOI)000321951300007 ()2-s2.0-84880556861 (Scopus ID)b0f78c4c-2759-40ce-a049-728aabb97cb7 (Local ID)b0f78c4c-2759-40ce-a049-728aabb97cb7 (Archive number)b0f78c4c-2759-40ce-a049-728aabb97cb7 (OAI)
Note
Validerad; 2013; 20130620 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Dieval, C., Stenberg, G., Nilsson, H., Edberg, N. & Barabash, S. (2013). Reduced proton and alpha particle precipitations at Mars during solar wind pressure pulses: Mars Express results (ed.). Paper presented at . Journal of Geophysical Research, 118(6), 3421-3429
Open this publication in new window or tab >>Reduced proton and alpha particle precipitations at Mars during solar wind pressure pulses: Mars Express results
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2013 (English)In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 118, no 6, p. 3421-3429Article in journal (Refereed) Published
Abstract [en]

1] We performed a statistical study of downward moving protons and alpha particles of ~keV energy (assumed to be of solar wind origin) inside the Martian induced magnetosphere from July 2006 to July 2010. Ion and electron data are from the Analyzer of Space Plasma and Energetic Atoms (ASPERA-3) package on board Mars Express. We investigated the solar wind ion entry into the ionosphere, excluding intervals of low-altitude magnetosheath encounters. The study compares periods of quiet solar wind conditions and periods of solar wind pressure pulses, including interplanetary coronal mass ejections and corotating interaction regions. The solar wind ion precipitation appears localized and/or intermittent, consistent with previous measurements. Precipitation events are less frequent, and the precipitating fluxes do not increase during pressure pulse encounters. During pressure pulses, the occurrence frequency of observed proton precipitation events is reduced by a factor of ~3, and for He2+ events the occurrence frequency is reduced by a factor of ~2. One explanation is that during pressure pulse periods, the mass loading of the solar wind plasma increases due to a deeper penetration of the interplanetary magnetic flux tubes into the ionosphere. The associated decrease of the solar wind speed thus increases the pileup of the interplanetary magnetic field on the dayside of the planet. The magnetic barrier becomes thicker in terms of solar wind ion gyroradii, causing the observed reduction of H+/He2+ precipitations.

National Category
Aerospace Engineering
Research subject
Space Technology
Identifiers
urn:nbn:se:ltu:diva-7478 (URN)10.1002/jgra.50375 (DOI)000325217100060 ()2-s2.0-84882740127 (Scopus ID)5dfb6c16-d185-44d4-83c7-fff153449552 (Local ID)5dfb6c16-d185-44d4-83c7-fff153449552 (Archive number)5dfb6c16-d185-44d4-83c7-fff153449552 (OAI)
Note
Validerad; 2013; 20130626 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Fatemi, S., Holmström, M., Futaana, Y., Barabash, S. & Lue, C. (2013). The lunar wake current systems (ed.). Paper presented at . Geophysical Research Letters, 40(1), 17-21
Open this publication in new window or tab >>The lunar wake current systems
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2013 (English)In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 40, no 1, p. 17-21Article in journal (Refereed) Published
Abstract [en]

We present the lunar wake current systems when the Moon is assumed to be a non-conductive body, absorbing the solar wind plasma. We show that in the transition regions between the plasma void, the expanding rarefaction region, and the interplanetary plasma, there are three main currents flowing around these regions in the lunar wake. The generated currents induce magnetic fields within these regions and perturb the field lines there. We use a three-dimensional, self-consistent hybrid model of plasma (particle ions and fluid electrons) to show the flow of these three currents. First, we identify the different plasma regions, separated by the currents, and then we show how the currents depend on the interplanetary magnetic field direction. Finally, we discuss the current closures in the lunar wake.

National Category
Aerospace Engineering
Research subject
Space Technology
Identifiers
urn:nbn:se:ltu:diva-15427 (URN)10.1029/2012GL054635 (DOI)000317826300004 ()2-s2.0-84874894590 (Scopus ID)eeef2afd-1d38-4484-9bd8-1fd12fb30356 (Local ID)eeef2afd-1d38-4484-9bd8-1fd12fb30356 (Archive number)eeef2afd-1d38-4484-9bd8-1fd12fb30356 (OAI)
Note
Validerad; 2013; 20130121 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Nordström, T., Stenberg, G., Nilsson, H., Barabash, S. & Zhang, T. (2013). Venus ion outflow estimates at solar minimum: Influence of reference frames and disturbed solar wind conditions (ed.). Paper presented at . Journal of Geophysical Research, 118(6), 3592-3601
Open this publication in new window or tab >>Venus ion outflow estimates at solar minimum: Influence of reference frames and disturbed solar wind conditions
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2013 (English)In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 118, no 6, p. 3592-3601Article in journal (Refereed) Published
Abstract [en]

Recent estimates of ion escape rates from Venus, based on ASPERA-4 data, differ by more than a factor of 4. Whereas the ASPERA-4 instrument provides state-of-the art observations, the limited field of view of the instrument and the strongly limited geographical coverage of the spacecraft orbit means that significant assumptions must be used in the interpretation of the data. We complement previous studies by using a method of average distribution functions to obtain as good statistics as possible while taking the limited field of view into account. We use more than 3 years of data, more than any of the previous studies, and investigate how the choice of a geographical reference frame or a solar wind electric field oriented reference frame affects the results. We find that the choice of reference frame cannot explain the difference between the previously published reports. Our results, based on a larger data set, fall in between the previous studies. Our conclusion is that the difference between previous studies is caused by the large variability of ion outflow at Venus. It matters significantly for the end result which data are selected and which time period is used. The average escape rates were found to be 5.2±1.0×1024 s−1for heavy ions (m/q ≥16) and 14±2.6×1024 s−1for protons. We also discuss the spatial distribution of the planetary ion outflow in the solar wind electric field reference frame.

National Category
Aerospace Engineering
Research subject
Space Technology
Identifiers
urn:nbn:se:ltu:diva-2658 (URN)10.1002/jgra.50305 (DOI)000325217100078 ()2-s2.0-84882785895 (Scopus ID)04f9f73a-75b0-4e98-82b8-244ff8bb42a9 (Local ID)04f9f73a-75b0-4e98-82b8-244ff8bb42a9 (Archive number)04f9f73a-75b0-4e98-82b8-244ff8bb42a9 (OAI)
Note
Validerad; 2013; 20130614 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Dieval, C., Kallio, E., Barabash, S., Stenberg, G., Nilsson, H., Futaana, Y., . . . Brain, D. (2012). A case study of proton precipitation at Mars: Mars Express observations and hybrid simulations (ed.). Paper presented at . Journal of Geophysical Research, 117
Open this publication in new window or tab >>A case study of proton precipitation at Mars: Mars Express observations and hybrid simulations
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2012 (English)In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 117Article in journal (Refereed) Published
Abstract [en]

Using the data from the Analyzer of Space Plasma and Energetic Atoms (ASPERA-3) experiment on board Mars Express and hybrid simulations, we have investigated the entry of protons into the Martian induced magnetosphere. We discuss one orbit on the dayside with observations of significant proton fluxes at altitudes down to 260 km on 27 February 2004. The protons observed below the induced magnetosphere boundary at an altitude of less than 700 km have energies of a few keV, travel downward, and precipitate onto the atmosphere. The measured energy flux and particle flux are 108–109 eV cm−2 s−1 and 105–106 H+ cm−2 s−1, respectively. The proton precipitation occurs because the Martian magnetosheath is small with respect to the heated proton gyroradius in the subsolar region. The data suggest that the precipitation is not permanent but may occur when there are transient increases in the magnetosheath proton temperature. The higher-energy protons penetrate deeper because of their larger gyroradii. The proton entry into the induced magnetosphere is simulated using a hybrid code. A simulation using a fast solar wind as input can reproduce the high energies of the observed precipitating protons. The model shows that the precipitating protons originate from both the solar wind and the planetary exosphere. The precipitation extends over a few thousand kilometers along the orbit of the spacecraft. The proton precipitation does not necessarily correlate with the crustal magnetic anomalies.

National Category
Aerospace Engineering
Research subject
Space Technology
Identifiers
urn:nbn:se:ltu:diva-7041 (URN)10.1029/2012JA017537 (DOI)000305385700001 ()55cfa245-2744-46a5-8fe1-6e5ccff22baa (Local ID)55cfa245-2744-46a5-8fe1-6e5ccff22baa (Archive number)55cfa245-2744-46a5-8fe1-6e5ccff22baa (OAI)
Note
Validerad; 2012; Bibliografisk uppgift: Article number A06222; 20120711 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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