University of Oulu

Kocharov, L., Pesce-Rollins, M., Laitinen, T., Mishev, A., Kühl, P., Klassen, A., Jin, M., Omodei, N., Longo, F., Webb, D. F., Cane, H. V., Heber, B., Vainio, R., & Usoskin, I. (2020). Interplanetary Protons versus Interacting Protons in the 2017 September 10 Solar Eruptive Event. The Astrophysical Journal, 890(1), 13.

Interplanetary protons versus interacting protons in the 2017 September 10 solar eruptive event

Saved in:
Author: Kocharov, Leon1; Pesce-Rollins, Melissa2; Laitinen, Timo3;
Organizations: 1Sodankylä Geophysical Observatory, University of Oulu, P.O.B. 3000, Oulu FI-90014, Finland
2Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa, Italy
3Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK
4Space Climate Research Unit, University of Oulu, Oulu FI-90014, Finland
5Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, Kiel D-24118, Germany
6Lockheed Martin Solar and Astrophysics Lab, Palo Alto, CA 94304, USA
7SETI Institute, Mountain View, CA 94043, USA
8W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USA
9Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste, Italy
10Dipartimento di Fisica, Università di Trieste, I-34127 Trieste, Italy
11ISR, Boston College, Chestnut Hill, MA 02459, USA
12Department of Mathematics and Physics, University of Tasmania, Hobart, Tasmania, Australia
13Space Research Laboratory, Department of Physics and Astronomy, University of Turku, Turku FI-20014, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.4 MB)
Persistent link:
Language: English
Published: IOP Publishing, 2020
Publish Date: 2020-02-11


We analyze the relativistic proton emission from the Sun during the eruptive event on 2017 September 10, which caused a ground-level enhancement (GLE 72) registered by the worldwide network of neutron monitors. Using the neutron monitor data and interplanetary transport modeling both along and across interplanetary magnetic field (IMF) lines, we deduce parameters of the proton injection into the interplanetary medium. The inferred injection profile of the interplanetary protons is compared with the profile of the >100 MeV γ-ray emission observed by the Fermi Large Area Telescope, attributed to pion production from the interaction of >300 MeV protons at the Sun. GLE 72 started with a prompt component that arrived along the IMF lines. This was followed by a more prolonged enhancement caused by protons arriving at the Earth across the IMF lines from the southwest. The interplanetary proton event is modeled using two sources—one source at the root of the Earth-connected IMF line and another source situated near the solar western limb. The maximum phase of the second injection of interplanetary protons coincides with the maximum phase of the prolonged >100 MeV γ-ray emission that originated from a small area at the solar western limb, below the current sheet trailing the associated coronal mass ejection (CME). A possible common source of interacting protons and interplanetary protons is discussed in terms of proton acceleration at the CME bow shock versus coronal (re-)acceleration in the wake of the CME.

see all

Series: Astrophysical journal
ISSN: 0004-637X
ISSN-E: 1538-4357
ISSN-L: 0004-637X
Volume: 890
Issue: 1
Article number: 13
DOI: 10.3847/1538-4357/ab684e
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: This research is supported by the Academy of Finland at University of Oulu (projects 304435/CRIPA-X and 267186) and University of Turku (decision 312357). SoHO is a project of international cooperation between ESA and NASA.
Academy of Finland Grant Number: 304435
Detailed Information: 304435 (Academy of Finland Funding decision)
267186 (Academy of Finland Funding decision)
Copyright information: © 2020. The American Astronomical Society. All rights reserved. Published in this repository with the kind permission of the publisher.