Issue |
A&A
Volume 670, February 2023
Solar Orbiter First Results (Nominal Mission Phase)
|
|
---|---|---|
Article Number | A140 | |
Number of page(s) | 18 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202245165 | |
Published online | 20 February 2023 |
Modeling Solar Orbiter dust detection rates in the inner heliosphere as a Poisson process
1
Department of Physics and Technology, UiT The Arctic University of Norway,
9037
Tromsø, Norway
e-mail: samuel.kociscak@uit.no
2
Department of Mathematics and Statistics, UiT The Arctic University of Norway,
9037,
Tromsø, Norway
3
LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris,
Paris, France
Received:
7
October
2022
Accepted:
3
January
2023
Context. Solar Orbiter provides dust detection capability in the inner heliosphere, but estimating physical properties of detected dust from the collected data is far from straightforward.
Aims. First, a physical model for dust collection considering a Poisson process is formulated. Second, it is shown that dust on hyperbolic orbits is responsible for the majority of dust detections with Solar Orbiter’s Radio and Plasma Waves (RPW). Third, the model for dust counts is fitted to Solar Orbiter RPW data and parameters of the dust are inferred, namely radial velocity, hyperbolic meteoroids predominance, and the solar radiation pressure to gravity ratio as well as the uncertainties of these.
Methods. Nonparametric model fitting was used to get the difference between the inbound and outbound detection rate and dust radial velocity was thus estimated. A hierarchical Bayesian model was formulated and applied to available Solar Orbiter RPW data. The model uses the methodology of integrated nested Laplace approximation, estimating parameters of dust and their ncertainties.
Results. Solar Orbiter RPW dust observations can be modeled as a Poisson process in a Bayesian framework and observations up to this date are consistent with the hyperbolic dust model with an additional background component. Analysis suggests a radial velocity of the hyperbolic component around (63 ± 7) km s−1 with the predominance of hyperbolic dust being about (78 ± 4)%. The results are consistent with hyperbolic meteoroids originating between 0.02 AU and 0.1 AU and showing substantial deceleration, which implies effective solar radiation pressure to a gravity ratio ≳ 0.5. The flux of the hyperbolic component at 1 AU is found to be (1.1 ± 0.2) × 10−4 m−2s−1 and the flux of the background component at 1 AU is found to be (5.4 ± 1.5) × 10−5 m−2s−1.
Key words: zodiacal dust / methods: statistical
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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