Search Publications
Multispacecraft Observations of a Widespread Solar Energetic Particle Event on 2022 February 15–16
Holmström, M.; Lario, D.; Palmerio, E. +37 more
On 2022 February 15–16, multiple spacecraft measured one of the most intense solar energetic particle (SEP) events observed so far in Solar Cycle 25. This study provides an overview of interesting observations made by multiple spacecraft during this event. Parker Solar Probe (PSP) and BepiColombo were close to each other at 0.34–0.37 au (a radial …
Enhanced Oxygen Ion Outflow at Earth and Mars due to the Concurrent Impact of a Stream Interaction Region
Thampi, Smitha V.; Bhaskar, Ankush; Venkataraman, V. +1 more
One of the major processes that solar wind drives is the outflow and escape of ions from the planetary atmospheres. The major ion species in the upper ionospheres of both Earth and Mars is O+, and hence it is more likely to dominate the escape process. On Earth, due to a strong intrinsic magnetic field, the major ion outflow pathways ar…
Galactic Cosmic Rays at Mars and Venus: Temporal Variations from Hours to Decades Measured as the Background Signal of Onboard Microchannel Plates
Barabash, Stas; Nilsson, Hans; Holmström, Mats +8 more
A microchannel plate (MCP) is a component widely used for counting particles in space. Using the background counts from MCPs on the Mars Express and Venus Express orbiters-operating over 17 yr and 8 yr, respectively-we investigated the galactic cosmic ray (GCR) characteristics of the inner solar system. The MCP background counts at Mars and Venus,…
Detecting the Oscillation and Propagation of the Nascent Dynamic Solar Wind Structure at 2.6 Solar Radii Using Very Long Baseline Interferometry Radio Telescopes
He, Jiansen; Venturi, Tiziana; Zhang, Peijin +30 more
Probing the solar corona is crucial to study the coronal heating and solar wind acceleration. However, the transient and inhomogeneous solar wind flows carry large-amplitude inherent Alfvén waves and turbulence, which make detection more difficult. We report the oscillation and propagation of the solar wind at 2.6 solar radii (Rs) by observation o…
Combined Multipoint Remote and in situ Observations of the Asymmetric Evolution of a Fast Solar Coronal Mass Ejection
Frahm, R. A.; Zhang, T. L.; Möstl, C. +8 more
We present an analysis of the fast coronal mass ejection (CME) of 2012 March 7, which was imaged by both STEREO spacecraft and observed in situ by MESSENGER, Venus Express, Wind, and Mars Express. Based on detected arrivals at four different positions in interplanetary space, it was possible to strongly constrain the kinematics and the shape of th…
Heliospheric Energetic Neutral Hydrogen Measured with ASPERA-3 and ASPERA-4
Barabash, S.; Grigoriev, A.; Wurz, P. +6 more
We re-analyze the signal of non-planetary energetic neutral atoms (ENAs) in the 0.4-5.0 keV range measured with the Neutral Particle Detector (NPD) of the ASPERA-3 and ASPERA-4 experiments on board the Mars and Venus Express satellites. Due to improved knowledge of sensor characteristics and exclusion of data sets affected by instrument effects, t…
Energetic Neutral Atoms from the Heliosheath
Barabash, S.; Grigoriev, A.; Wurz, P. +1 more
We present the measurement and analysis of hydrogen energetic neutral atoms (ENAs) recorded with the NPD sensor of the ASPERA-3 instrument on board Mars Express during the cruise phase and the Mars orbit phase. We conclude that the origin of these ENAs is the inner heliosheath. The ENA energy spectra are all very similar and can be fitted well by …
Lyα Absorption from Heliosheath Neutrals
Wood, Brian E.; Linsky, Jeffrey L.; Izmodenov, Vladislav V. +1 more
We assess the information that HST observations of stellar Lyα lines can provide on the heliosheath, the region of the heliosphere between the termination shock and heliopause. To search for evidence of heliosheath absorption, we conduct a systematic inspection of stellar Lyα lines reconstructed after correcting for ISM absorption (and heliospheri…
Direct Measurements of Energetic Neutral Hydrogen in the Interplanetary Medium
Fedorov, A.; Barabash, S.; Lundin, R. +16 more
We present an analysis of hydrogen energetic neutral atoms (ENAs) measured by the ASPERA-3 instrument on board Mars Express. We focus on ENAs that have no Martian origin. The energy spectra of these ENAs are all very similar and can be fitted well by a two-component power law. The fluxes, integrated from 0.2 to 10 keV, vary between 5×103