CMEchaser, Detecting Line-of-Sight Occultations Due to Coronal Mass Ejections
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CMEchaser, Detecting Line-of-Sight Occultations Due to Coronal Mass Ejections Golam Shaifullah 1 Pietro Zucca1
· Caterina Tiburzi 1
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Received: 16 March 2020 / Accepted: 9 September 2020 © Springer Nature B.V. 2020
Abstract We present a python-based tool to detect the occultation of back-ground sources by foreground solar coronal mass ejections. The tool takes as input standard celestial coordinates of the source and translates those to the helioprojective plane, and is thus well suited for use with a wide variety of background astronomical sources. This tool provides an easy means to search through a large archival dataset for such crossings and relies on the well-tested AstroPy and SunPy modules. Keywords Coronal mass ejections, initiation and propagation · Coronal mass ejections, interplanetary
1. Introduction Magnetic activity of the Sun is responsible for the generation of solar eruptions such as coronal mass ejections (CMEs) and solar flares (see, e.g., Vršnak, 2016). Solar flares result in broadband electromagnetic emission, while CMEs are a significant release of plasma with an embedded magnetic field (Kahler, 1992). CMEs directed towards the Earth may interact with the Earth’s magnetosphere, leading to a number of well identified phenomena such as aurorae, magnetic reconnections on both the day and the night sides of the Earth’s magnetosphere and potentially adverse space weather conditions. Key parameters to forecast the impact of CMEs on the Earth’s magnetosphere are their magnetic field direction and strength (see, e.g., Vourlidas et al., 2000). Estimating the magnetic fields of CMEs is a challenging task as coronal densities are not suitable for direct estimation of the magnetic field by Zeeman effect, as is commonly done for the solar photosphere (Howard, 1962). The only means to probe a CME magnetic field is by studying the Faraday rotation that it induces on the linearly-polarized radio emission of background sources, such as pulsars or quasars, during an occultation or via satellite borne
B G. Shaifullah
[email protected]
1
ASTRON, The Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, Dwingeloo 7991PD, The Netherlands
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probes, if those are fortunately located. In order to properly select the relative background sources, the location of the erupting CME needs to be well known in advance and this to date remains challenging. For this reason, it is important to identify any astronomical background source with a significant linear polarisation along the trajectory of the erupting CME. In this article we present CME CHASER, a software package able to calculate whether, during an observation, a certain astronomical object has been occulted by a CME. In Section 2 we thoroughly describe the software and its outputs. In Section 3 we demonstrate the effectiveness of the algorithm, while in Section 4 we show its possible applications. The conclusions are presented in Section 5.
2. A Python-Based Searching Algorithm for CME Occultations CM
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