The solar wind is a stream of charged particles (plasma) which flows supersonically away from the Sun. A magnetized planet carves out a “cavity” in the solar wind, known as a magnetosphere. Plasma can accumulate within magnetospheres in a number of ways, but the physics underpinning the stability of these systems dictates that this material cannot accumulate forever – the plasma created within or entering a magnetosphere must eventually be transported throughout the system, and ultimately lost from it.
Our group study magnetospheres including at Mercury, Earth, Jupiter and Saturn, comparing and contrasting the difference that solar wind influence, planetary rotation rate, planetary magnetic field strength, and internal plasma sources can make to magnetospheric dynamics. We have a special interest in the process of magnetic reconnection and in diagnosing how plasma is transported and lost in magnetospheres.
Planetary Space Weather:
Space Weather describes environmental conditions in space that can have an impact on Earth and other planets. In Earth’s magnetic environment, regular Space Weather-driven disturbances can dump huge amounts of energy into the upper atmosphere and impact everything from satellite communications to electricity power grids. Space is a variable and highly dynamic environment with direct implications for life on Earth, and understanding the intermittency and variable size of Space Weather disturbances is the first key to mitigating their effects. Space Weather in our solar system can be measured in a multitude of ways, including: (i) space-based satellite observation to sample magnetic field and plasma conditions in the solar wind and planetary magnetospheres, (ii) ground-based or space-based instrumentation including auroral cameras, radio telescopes, X-ray telescopes and ground magnetometer chains. We have data stretching back for decades and the quality, resolution and scope of data is increasing every year. This provides both an unprecedented opportunity for a system-level view of Space Weather, but also an enormous challenge to data assimilation and interpretation.
Our group use the latest data analytics techniques including machine learning to analyse huge volumes of data from spacecraft including Cassini (Saturn), Galileo, Voyager and Juno (Jupiter), MESSENGER and BepiColombo (Mercury), Cluster and Wind (Earth).
Auroral Emissions:
The visible auroral emissions at Earth are commonly referred to as the northern and southern lights. Many other planets in our solar system also display beautiful and dynamic auroral emissions and these provide a window on energetic plasma processes at work in those magnetospheres. Jupiter has the most powerful auroral emissions in our solar system, including at ultraviolet, infrared, X-ray, and radio wavelengths. We study the currents which produce these emissions and how they are driven.
Our group use data from X-ray telescopes like Chandra, XMM-Newton, and NuSTAR, as well as Ultraviolet images of planetary aurorae from the Hubble Space Telescope. Furthermore, we are using the I-LOFAR radio telescope in Birr Co. Offaly to study Jupiter’s radio emissions and to compare with other ground-based observatories such as Nancay and Nenufar and with the NASA Juno spacecraft in orbit at Jupiter.
Auroral Kilometric Radiation (AKR) is a cyclotron maser instability generated radio emission at Earth that is produced from source regions along high latitude magnetic field lines in the auroral zone (See Figure 1 above). AKR coincides with injection of suprathermal electrons and so also with intense auroral dynamics in the ionosphere during substorms and disturbances to the magnetosphere in general [e.g. Waters et al., 2022]. We have curated a list of AKR bursts from the Wind spacecraft Waves instrument which can be used alongside other metrics of magnetospheric disturbance to study the global system of solar wind-magnetosphere-ionosphere coupling. Below we detail some caveats for the use of the list.
The Wind spacecraft was launched in 1994 and houses the Waves instrument, of which the RAD1 receiver observes radio emissions between 20 – 1040 kHz. Our processing pipeline selects AKR emission, calibrates the observations, and then furthers this by refining the selection and creating a list of AKR bursts (further details in Waters et al. (2021) and Fogg et al. (2022)). Figure 2 above shows five panels that illustrate the burst selection process. The list contains the start and stop time of the AKR burst, as well as 3 minute resolution arrays of the lower and upper frequency bounds of the burst and Wind’s GSE coordinates. As well as the start and stop times, the median local time (LT) of Wind during the burst is given. Due to the beaming pattern of AKR sources and their spatial distribution in the inner magnetosphere, Wind’s position must be accounted for when interpreting the observations. Figure 3 below shows the projection of Wind’s orbital trajectory to the GSE XY plane between Jul 2001 and Sep 2004, illustrating the wide range of LTs covered by Wind during the early years of its orbit. For this reason, we include a Boolean quality flag for each burst, based on the median LT. While Wind may observe AKR emission from a source within ~4 hours of LT, we apply a conservative estimate for assurance that the observations best capture the AKR dynamics. Bursts observed by Wind between 2100-0100 LT (inclusive) are given a quality flag value of 1, while those outside have a value of 0.
The SPectrogram Analysis and Cataloguing Environment (SPACE) tool is an interactive python tool designed to label radio emission features of interest in a temporal-spectral map (called “dynamic spectrum”). The Software uses Matplotlib’s Polygon Selector widget to allow a user to select and edit an undefined number of vertices on top of the dynamic spectrum before closing the shape (polygon). Multiple polygons may be drawn on any spectrum, and the feature name along with the coordinates for each polygon vertex are saved into a “.json” file as per the “Time-Frequency Catalogue” (TFCat) format along with other data such as the feature id, observer name, and data units.
SPACE is part of the MASER (Measuring Analyzing & Simulating Emissions in Radio frequencies) project.
The SPACE labelling tool is available through GitHub, or pip install. Readthedocs documentation is accessible here.
The figure above from Louis et al., 2022 shows examples of plots from the SPACE labelling Tool. Panel (A) displays Cassini/RPWS (Radio and Plasma Waves Science, Gurnett et al., 2004) data (Lamy et al., 2008, 2009). The two panels show Intensity and Polarization data, respectively. At the top right of the top panel one can see a polygon that has just been drawn, with the window for naming the feature appearing at the top left of the graphics window. Other features have already been labelled, and appear in both intensity and polarisation views, with their names overlaid. The data displays in panel (B) are the estimated flux density (Louis et al., 2021a, c) from Juno/Waves measurements (Kurth et al., 2017), with the Louis et al. (2021b) catalogue overlaid. Panel (C) displays observations of Polar/PWI instrument (Gurnett et al., 1995) with the Smith et al. (2022) catalogue overlaid. The horizontal dashed-white line shows an example of the use of the -g [FREQUENCY GUIDE [FREQUENCY GUIDE …]] option. The variable dashed-white line show that the tool is also able to read a 1D table from the CDF file (provided that this has been specified in the configuration file).
I am always happy to consider hosting promising applicants for individual postdoctoral fellowships. These include Irish Research Council (IRC) Postdoctoral and Enterprise Partnership fellowships (2 years), EU Marie Sklodowska-Curie Fellowships (2 years), SFI-IRC Pathways fellowships (4 years) and Royal Society-SFI University Research fellowships (5 years).
PhD studentships:
I am happy to consider promising applications for the IRC postgraduate scholarship programme and I also occasionally advertise funded PhD positions here and through DIAS social media and findaphd.com.
Internships:
DIAS regularly run a summer intern programme for ~2-3 months with a call for applications in Spring time. Occasionally opportunities for internship placements at other times of year arise.
Applications are now open for two Summer Studentship with the Planetary Magnetospheres Group. More information available at dias.ie/vacancies, applications close on 15 March 2024!
Please contact Prof. Caitriona Jackman directly if you would like to discuss any of these possibilities in more detail.
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Planetary Magnetospheres
Research Group
Group Leader: Prof Caitriona Jackman
Research Fellows: Dr. Charles Bowers, Dr. Alexandra Fogg, Dr. Mika Holmberg, Dr Hans Huybrighs, Dr Matthew Rutala, Dr Affelia Wibisono.
Research Students: Seán McEntee
Visiting Research Students: Yang Wang
Publications: from the SAO/NASA Astrophysics Data System
Former Group Members:
Dr Corentin Louis, Postdoctoral Researcher, 2021 – 2023
→ Postdoctoral Researcher, Observatoire de Paris
Elizabeth O’Dwyer, PhD Student, 2021 – 2023
Dr. James Waters, PhD Student, visiting from Uni. Southampton, 2018-2022
→ Postdoctoral Researcher, Laboratoire d’Astrophysique de Marseille
Dr. Dale Weigt, PhD Student, visiting from Uni. Southampton, 2018-2022
→ Postdoctoral Researcher in Astroinformatics, Aalto University
Kevin Smith, Research Intern, 2021-2022
→ PhD Student, Trinity College Dublin
Dr. Tadhg Garton, Postdoctoral Researcher, visiting from Uni. Southampton and IRC fellowship, 2019-2021
→ Data Scientist
Collaborators
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Science
Planetary Magnetospheres:
The solar wind is a stream of charged particles (plasma) which flows supersonically away from the Sun. A magnetized planet carves out a “cavity” in the solar wind, known as a magnetosphere. Plasma can accumulate within magnetospheres in a number of ways, but the physics underpinning the stability of these systems dictates that this material cannot accumulate forever – the plasma created within or entering a magnetosphere must eventually be transported throughout the system, and ultimately lost from it.
Our group study magnetospheres including at Mercury, Earth, Jupiter and Saturn, comparing and contrasting the difference that solar wind influence, planetary rotation rate, planetary magnetic field strength, and internal plasma sources can make to magnetospheric dynamics. We have a special interest in the process of magnetic reconnection and in diagnosing how plasma is transported and lost in magnetospheres.
Planetary Space Weather:
Space Weather describes environmental conditions in space that can have an impact on Earth and other planets. In Earth’s magnetic environment, regular Space Weather-driven disturbances can dump huge amounts of energy into the upper atmosphere and impact everything from satellite communications to electricity power grids. Space is a variable and highly dynamic environment with direct implications for life on Earth, and understanding the intermittency and variable size of Space Weather disturbances is the first key to mitigating their effects. Space Weather in our solar system can be measured in a multitude of ways, including: (i) space-based satellite observation to sample magnetic field and plasma conditions in the solar wind and planetary magnetospheres, (ii) ground-based or space-based instrumentation including auroral cameras, radio telescopes, X-ray telescopes and ground magnetometer chains. We have data stretching back for decades and the quality, resolution and scope of data is increasing every year. This provides both an unprecedented opportunity for a system-level view of Space Weather, but also an enormous challenge to data assimilation and interpretation.
Our group use the latest data analytics techniques including machine learning to analyse huge volumes of data from spacecraft including Cassini (Saturn), Galileo, Voyager and Juno (Jupiter), MESSENGER and BepiColombo (Mercury), Cluster and Wind (Earth).
Auroral Emissions:
The visible auroral emissions at Earth are commonly referred to as the northern and southern lights. Many other planets in our solar system also display beautiful and dynamic auroral emissions and these provide a window on energetic plasma processes at work in those magnetospheres. Jupiter has the most powerful auroral emissions in our solar system, including at ultraviolet, infrared, X-ray, and radio wavelengths. We study the currents which produce these emissions and how they are driven.
Our group use data from X-ray telescopes like Chandra, XMM-Newton, and NuSTAR, as well as Ultraviolet images of planetary aurorae from the Hubble Space Telescope. Furthermore, we are using the I-LOFAR radio telescope in Birr Co. Offaly to study Jupiter’s radio emissions and to compare with other ground-based observatories such as Nancay and Nenufar and with the NASA Juno spacecraft in orbit at Jupiter.
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Tools and community software
Please visit github.com/diasplanetary to view open-access software developed by the group!
AKR burst list
Auroral Kilometric Radiation (AKR) is a cyclotron maser instability generated radio emission at Earth that is produced from source regions along high latitude magnetic field lines in the auroral zone (See Figure 1 above). AKR coincides with injection of suprathermal electrons and so also with intense auroral dynamics in the ionosphere during substorms and disturbances to the magnetosphere in general [e.g. Waters et al., 2022]. We have curated a list of AKR bursts from the Wind spacecraft Waves instrument which can be used alongside other metrics of magnetospheric disturbance to study the global system of solar wind-magnetosphere-ionosphere coupling. Below we detail some caveats for the use of the list.
The Wind spacecraft was launched in 1994 and houses the Waves instrument, of which the RAD1 receiver observes radio emissions between 20 – 1040 kHz. Our processing pipeline selects AKR emission, calibrates the observations, and then furthers this by refining the selection and creating a list of AKR bursts (further details in Waters et al. (2021) and Fogg et al. (2022)). Figure 2 above shows five panels that illustrate the burst selection process. The list contains the start and stop time of the AKR burst, as well as 3 minute resolution arrays of the lower and upper frequency bounds of the burst and Wind’s GSE coordinates. As well as the start and stop times, the median local time (LT) of Wind during the burst is given. Due to the beaming pattern of AKR sources and their spatial distribution in the inner magnetosphere, Wind’s position must be accounted for when interpreting the observations. Figure 3 below shows the projection of Wind’s orbital trajectory to the GSE XY plane between Jul 2001 and Sep 2004, illustrating the wide range of LTs covered by Wind during the early years of its orbit. For this reason, we include a Boolean quality flag for each burst, based on the median LT. While Wind may observe AKR emission from a source within ~4 hours of LT, we apply a conservative estimate for assurance that the observations best capture the AKR dynamics. Bursts observed by Wind between 2100-0100 LT (inclusive) are given a quality flag value of 1, while those outside have a value of 0.
1995-2004 AKR burst event list is available with documentation from: https://doi.org/10.25935/ayzp-1833
SPACE Labelling Tool
The SPectrogram Analysis and Cataloguing Environment (SPACE) tool is an interactive python tool designed to label radio emission features of interest in a temporal-spectral map (called “dynamic spectrum”). The Software uses Matplotlib’s Polygon Selector widget to allow a user to select and edit an undefined number of vertices on top of the dynamic spectrum before closing the shape (polygon). Multiple polygons may be drawn on any spectrum, and the feature name along with the coordinates for each polygon vertex are saved into a “.json” file as per the “Time-Frequency Catalogue” (TFCat) format along with other data such as the feature id, observer name, and data units.
SPACE is part of the MASER (Measuring Analyzing & Simulating Emissions in Radio frequencies) project.
The SPACE labelling tool is available through GitHub, or pip install. Readthedocs documentation is accessible here.
The figure above from Louis et al., 2022 shows examples of plots from the SPACE labelling Tool. Panel (A) displays Cassini/RPWS (Radio and Plasma Waves Science, Gurnett et al., 2004) data (Lamy et al., 2008, 2009). The two panels show Intensity and Polarization data, respectively. At the top right of the top panel one can see a polygon that has just been drawn, with the window for naming the feature appearing at the top left of the graphics window. Other features have already been labelled, and appear in both intensity and polarisation views, with their names overlaid. The data displays in panel (B) are the estimated flux density (Louis et al., 2021a, c) from Juno/Waves measurements (Kurth et al., 2017), with the Louis et al. (2021b) catalogue overlaid. Panel (C) displays observations of Polar/PWI instrument (Gurnett et al., 1995) with the Smith et al. (2022) catalogue overlaid. The horizontal dashed-white line shows an example of the use of the -g [FREQUENCY GUIDE [FREQUENCY GUIDE …]] option. The variable dashed-white line show that the tool is also able to read a 1D table from the CDF file (provided that this has been specified in the configuration file).
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Jobs, PhD positions and internships
Postdoctoral Positions:
I am always happy to consider hosting promising applicants for individual postdoctoral fellowships. These include Irish Research Council (IRC) Postdoctoral and Enterprise Partnership fellowships (2 years), EU Marie Sklodowska-Curie Fellowships (2 years), SFI-IRC Pathways fellowships (4 years) and Royal Society-SFI University Research fellowships (5 years).
PhD studentships:
I am happy to consider promising applications for the IRC postgraduate scholarship programme and I also occasionally advertise funded PhD positions here and through DIAS social media and findaphd.com.
Internships:
DIAS regularly run a summer intern programme for ~2-3 months with a call for applications in Spring time. Occasionally opportunities for internship placements at other times of year arise.
Applications are now open for two Summer Studentship with the Planetary Magnetospheres Group. More information available at dias.ie/vacancies, applications close on 15 March 2024!
Please contact Prof. Caitriona Jackman directly if you would like to discuss any of these possibilities in more detail.
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Funding
Our group’s work is supported by funding from Science Foundation Ireland, the Irish Research Council, and the European Space Agency.
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Astronomy and Astrophysics
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