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Scale size of comet...
Scale size of cometary bow shocks
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- Edberg, Niklas J. T. (author)
- Uppsala universitet,Institutet för rymdfysik, Uppsalaavdelningen,Swedish Institute of Space Physics (IRF), Uppsala, Sweden
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- Eriksson, Anders I. (author)
- Uppsala universitet,Institutet för rymdfysik, Uppsalaavdelningen,Swedish Institute of Space Physics (IRF), Uppsala, Sweden
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- Vigren, Erik (author)
- Uppsala universitet,Institutet för rymdfysik, Uppsalaavdelningen,Swedish Institute of Space Physics (IRF), Uppsala, Sweden
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- Nilsson, H. (author)
- Swedish Inst Space Phys IRF, Kiruna, Sweden.,Swedish Institute of Space Physics (IRF), Kiruna, Sweden
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- Gunell, Herbert (author)
- Umeå universitet,Institutionen för fysik,Umeå Univ, Dept Phys, Umeå, Sweden.
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- Götz, C. (author)
- Northumbria Univ, Dept Math Phys & Elect Engn, Newcastle Upon Tyne, England.,Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle-upon-Tyne, United Kingdom
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- Richter, I. (author)
- Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, Braunschweig, Germany.,Institut fur Geophysik und Extraterrestrische Physik, Technische Universität Braunschweig, Braunschweig, Germany
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- Henri, P. (author)
- CNRS, Lab Phys & Chim Environm & Espace, F-45071 Orleans, France.;Lab Lagrange, OCA, CNRS, UCA, F-06304 Nice, France.,Laboratoire de Physique et Chimie de l'Environnement et de l'Espace, Cnrs, Orléans, France; Laboratoire Lagrange, Oca, Cnrs, Uca, Nice, France
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- De Keyser, J. (author)
- Royal Belgian Inst Space Aeron, BIRA IASB, Brussels, Belgium.,Royal Belgian Institute for Space Aeronomy, BIRA-IASB, Brussels, Belgium
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(creator_code:org_t)
- EDP Sciences, 2024
- 2024
- English.
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 682
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Abstract
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- Context. In past decades, several spacecraft have visited comets to investigate their plasma environments. In the coming years, Comet Interceptor will make yet another attempt. This time, the target comet and its outgassing activity are unknown and may not be known before the spacecraft has been launched into its parking orbit, where it will await a possible interception. If the approximate outgassing rate can be estimated remotely when a target has been identified, it is desirable to also be able to estimate the scale size of the plasma environment, defined here as the region bound by the bow shock.Aims. This study aims to combine previous measurements and simulations of cometary bow shock locations to gain a better understanding of how the scale size of cometary plasma environments varies. We compare these data with models of the bow shock size, and we furthermore provide an outgassing rate-dependent shape model of the bow shock. We then use this to predict a range of times and cometocentric distances for the crossing of the bow shock by Comet Interceptor, together with expected plasma density measurements along the spacecraft track.Methods. We used data of the location of cometary bow shocks from previous spacecraft missions, together with simulation results from previously published studies. We compared these results with an existing model of the bow shock stand-off distance and expand on this to provide a shape model of cometary bow shocks. The model in particular includes the cometary outgassing rate, but also upstream solar wind conditions, ionisation rates, and the neutral flow velocity.Results. The agreement between the gas-dynamic model and the data and simulation results is good in terms of the stand-off distance of the bow shock as a function of the outgassing rate. For outgassing rates in the range of 1027–1031–s-1, the scale size of cometary bow shocks can vary by four orders of magnitude, from about 102 km to 106 km, for an ionisation rate, flow velocity, and upstream solar wind conditions typical of those at 1 AU. The proposed bow shock shape model shows that a comet plasma environment can range in scale size from the plasma environment of Mars to about half of that of Saturn.Conclusions. The model-data agreement allows for the planning of upcoming spacecraft comet encounters, such as that of Comet Interceptor, when a target has been identified and its outgassing rate is determined. We conclude that the time a spacecraft can spend within the plasma environment during a flyby can range from minutes to days, depending on the comet that is visited and on the flyby speed. However, to capture most of the comet plasma environment, including pick-up ions and upstream plasma waves, and to ensure the highest possible scientific return, measurements should still start well upstream of the expected bow shock location. From the plasma perspective, the selected target should preferably be an active comet with the lowest possible flyby velocity.
Subject headings
- NATURVETENSKAP -- Fysik -- Fusion, plasma och rymdfysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Fusion, Plasma and Space Physics (hsv//eng)
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Keyword
- comets: general
- plasmas
Publication and Content Type
- ref (subject category)
- art (subject category)
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