Source: TH
Context: Scientists from the Indian Institute of Astrophysics (IIA) observed a flareless coronal mass ejection (CME) using the Visible Emission Line Coronagraph (VELC) onboard Aditya-L1.
About Aditya-L1 Mission:
- Launched in: September 2, 2023.
- Developed by: ISRO, with contributions from Indian academic institutions.
- Mission Type: India’s first solar observation mission positioned at Lagrange Point 1 (L1).
- Distance from Earth:5 million km (1% of Earth-Sun distance).
- Primary Aim:
-
- Study the Sun’s corona, chromosphere, and solar emissions.
- Monitor solar wind, magnetic storms, and space weather impacts on Earth.
- Key Features:
-
- Constant Solar Observation: Uninterrupted view of the Sun due to L1 positioning.
- Indigenous Payloads: 7 payloads designed for spectroscopy, coronagraphy, and particle analysis.
- Minimized Fuel Usage: L1’s gravitational balance reduces orbital maintenance efforts.
- Early Warning System: Detects solar radiation and storms before they reach Earth.
About Flareless Coronal Mass Ejection:
- What is a Flareless Coronal Mass Ejection?
- A flareless CME is a massive ejection of plasma and magnetic field from the Sun’s corona that occurs without an associated solar flare.
- Unlike typical CMEs, it does not release intense electromagnetic radiation before the eruption.
- It challenges existing models of solar activity, requiring new insights into magnetic instabilities.
- How Flareless CMEs Form?
- Magnetic Reconnection: Occurs when magnetic field lines rearrange in the Sun’s atmosphere, leading to energy release.
- Gradual Magnetic Build-up: Magnetic stress accumulates over time, eventually releasing plasma without a sudden energy burst.
- Flux Rope Eruption: A pre-existing twisted magnetic structure in the corona slowly becomes unstable and erupts outward.
- No Preceding Flare: Unlike typical CMEs, no strong X-ray or UV burst precedes the plasma ejection.
- Sunspot Influence: Often linked to regions with weak or decaying magnetic fields, where flare energy is insufficient.
- Key Features of Flareless CMEs:
- Low Energy Signature: No significant X-ray or radio emissions, making early detection difficult.
- Slower Ejection Speeds: Travels at lower velocities (~400–1,000 km/s) than flare-associated CMEs.
- Magnetically Driven: Initiated by gradual destabilization of coronal magnetic fields rather than impulsive energy release.
- Space Weather Impact: Can still trigger geomagnetic storms on Earth, affecting satellites and communication systems.
- Rare Phenomenon: Less frequently observed compared to flare-associated CMEs, requiring continuous solar monitoring.
