Novel Method to Determine Instantaneous Expansion Speed and Radial Size of Coronal Mass Ejections
The novel method was tested using a CME that erupted from the Sun on April 3, 2010, with data from NASA & ESA’s SOHO, STEREO, and Wind spacecraft.
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- Country:
- India
In a breakthrough study, astronomers at the Indian Institute of Astrophysics (IIA) have devised a novel method to determine the instantaneous expansion speed and radial size of Coronal Mass Ejections (CMEs) using single-point spacecraft observations in the interplanetary medium. This innovation is expected to enhance space weather predictions and improve understanding of CMEs' impact on Earth's communication systems.
Why Understanding CME Expansion Matters?
CMEs are magnetized plasma bubbles ejected from the Sun, traveling through space at high speeds. They are the primary cause of geomagnetic storms, which can lead to:
Disruptions in satellite communications
Power grid failures
Deorbiting of satellites
GPS signal disturbances
One of the key parameters influencing the duration of geomagnetic storms is the radial dimension of a CME, which is governed by its expansion in the interplanetary medium. The expansion occurs due to pressure differences between the CME and the surrounding solar wind. However, measuring this expansion using single-point spacecraft observations has been a challenge—until now.
A New Approach to Measuring CME Expansion
Traditional methods struggle to accurately estimate CME expansion speeds using data from single spacecraft. The new technique, developed at IIA (an autonomous institute under the Department of Science and Technology, DST), enables the estimation of instantaneous expansion speed using data from a single-point in situ spacecraft—an approach that is particularly useful for sub-L1 space weather monitors.
The researchers:
- Inferred the acceleration of different CME substructures (leading edge, center, and trailing edge) using in situ observations.
- Used propagation speeds of at least two substructures at the same time to calculate the instantaneous expansion speed.
- Computed the radial size and distance traveled by the CME at various instances.
“Our non-conventional approach utilizes the propagation speed of any two CME substructures at the same instance to determine the instantaneous expansion speed,” said Wageesh Mishra, faculty at IIA and co-author of the study.
Key Findings and Future Applications
1️⃣ CME Expansion Varies Over Time: The study suggests that the aspect ratio of CMEs (radial size vs. distance from the Sun) changes dynamically. Initially, it increases, remains constant at a certain height, and then systematically decreases in the interplanetary medium.
2️⃣ Space Weather Predictions: The accurate measurement of CME expansion speed will allow better predictions of arrival times at Earth, particularly for substructures like the center and trailing edge, which are crucial for understanding space weather.
3️⃣ Application in Future Space Missions: The team aims to implement their method using Aditya Solar Wind Particle Experiment (ASPEX) onboard India’s first solar observatory, Aditya-L1.
“We are looking forward to utilizing single-point in situ observations from Aditya-L1 to further understand CME expansion using our approach,” Mishra added.
Case Study and Validation
The novel method was tested using a CME that erupted from the Sun on April 3, 2010, with data from NASA & ESA’s SOHO, STEREO, and Wind spacecraft. The results showed that CME substructures evolve differently due to varying forces acting on them in space.
Significance of This Research
- Enhances CME tracking and forecasting, improving early warnings for space weather events.
- Contributes to scientific advancements in heliophysics and solar-terrestrial interactions.
- Supports upcoming solar missions like Aditya-L1 for real-time space weather monitoring.
With this pioneering approach, India's space research community is making significant strides in space weather forecasting, ensuring better protection for satellites, power grids, and communication networks from solar storms.
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- Coronal Mass Ejections