Stealth Coronal Mass Ejection (CME)

Context: Astronomers have linked an intense geomagnetic storm that struck Earth in March 2023 to a Stealth Coronal Mass Ejection (CME)—a faint solar eruption with no obvious warning signals.

About Stealth Coronal Mass Ejection (CME):

What are Stealth CMEs?

• Stealth Coronal Mass Ejections (CMEs) are solar eruptions that lack clear low-coronal signatures, such as solar flares, X-ray bursts, or strong radio emissions.
• Unlike typical CMEs, they appear optically weak or invisible in standard solar observations, yet can still travel to Earth and trigger severe geomagnetic storms.

Origin of Stealth CMEs:

Stealth CMEs generally originate from:

• Active regions on the Sun with weak or slowly evolving magnetic fields
• Areas close to coronal holes—regions where the Sun’s magnetic field is open

Unlike explosive eruptions, stealth CMEs emerge from gradual magnetic restructuring, making them difficult to detect in real time.

How do Stealth CMEs form?

The formation of stealth CMEs involves a subtle sequence of processes:

1. Magnetic flux rope buildup: A twisted magnetic structure forms in the Sun’s corona without producing flares.
2. Low-energy magnetic reconnection: Weak reconnection releases plasma slowly, leaving minimal electromagnetic signatures.
3. Acceleration via coronal holes: Nearby coronal holes emit high-speed solar wind, which can accelerate the CME and guide it toward Earth.
4. Interplanetary evolution: As the CME travels through space, it may expand, rotate its magnetic field, and align in a way that strongly interacts with Earth’s magnetosphere—especially if the magnetic field turns southward.

Why are Stealth CMEs geoeffective?

Despite being slow and faint, stealth CMEs can cause intense geomagnetic storms because:

• They may travel behind high-speed solar wind streams, increasing impact energy
• Their magnetic clouds can expand significantly en route to Earth
• A southward-oriented magnetic field enhances magnetic reconnection with Earth’s magnetosphere.

Implications of Stealth CMEs:

·        Space weather forecasting challenge: Current early-warning systems rely on visible solar flares and radio bursts, which stealth CMEs often lack.

·        Risks to modern infrastructure:

• They can disrupt:
  • Satellites and GPS systems
  • Radio communications
  • Power grids and aviation routes

·        Need for multi-point observation: The study used data from NASA Solar Dynamics Observatory, Solar Orbiter, STEREO-A, and WIND, showing that multi-spacecraft monitoring is essential.

·        Strategic importance for India: As India expands space assets, navigation systems, and digital infrastructure, accurate space weather prediction becomes a national resilience issue.