coronal mass ejection

coronal mass ejection
Name	Coronal mass ejection
Type	Solar phenomenon
Discovered	1971
Discovered by	Parker Solar Probe; Helios mission contributors
First observed	Skylab-era coronagraphs; Solwind

coronal mass ejection

A coronal mass ejection is a large-scale eruption of plasma and magnetic field from the solar corona that can drive geomagnetic disturbances in the heliosphere. Observations from Skylab, SOHO, STEREO, Parker Solar Probe, and Hinode have characterized their morphology, kinematics, and role in space weather. Research by institutions such as NASA, ESA, JAXA, CNSA, and ISRO integrates data from missions including ACE, Wind, Ulysses, Voyager 1, and Voyager 2.

Overview

CMEs are expulsions of magnetized plasma that propagate through interplanetary space and interact with planetary magnetospheres such as Earth, Mars, Jupiter, and Saturn. They are studied by observatories like Solar Dynamics Observatory, Mauna Loa Observatory, Big Bear Solar Observatory, and projects including International Space Weather Initiative and Living With a Star. Key scientific programs include collaborations among National Oceanic and Atmospheric Administration, European Space Agency, and the Indian Space Research Organisation.

Causes and Mechanisms

Eruption onset involves magnetic reconnection and magnetic flux rope destabilization tied to active regions, filaments, and prominences observed in data from Hinode, IRIS, and SDO/AIA. Theoretical frameworks derive from work by Eugene Parker, models like the CSHKP model and magnetohydrodynamic simulations used by centers such as NASA Goddard Space Flight Center and Jet Propulsion Laboratory. Mechanisms are compared with flare processes cataloged by observatories including GOES (satellite), RHESSI, and Nobeyama Radioheliograph.

Properties and Classification

CMEs are classified by speed, angular width, and magnetic structure; examples include halo CMEs, partial-halo CMEs, and stealth CMEs identified via SOHO/LASCO coronagraphs and catalogs maintained by CDAW Data Center and the Coordinated Data Analysis Workshops. Parameters such as velocity, mass, and magnetic helicity are measured by instruments on ACE, Wind, and the OMNIWeb dataset curated by NASA/GSFC. Classification schemes reference work from Richardson and Gosling.

Observations and Detection

Remote sensing uses coronagraphs and extreme ultraviolet imagers on missions like SOHO, STEREO, SDO, and ground facilities including Kanzelhöhe Observatory and Learmonth Solar Observatory. In situ detection relies on magnetometers and plasma instruments aboard ACE, Wind, DSCOVR, and Ulysses to record interplanetary CMEs (ICMEs). Data archives and models are supported by organizations such as CERN in cross-disciplinary collaborations and by data centers including CCMC and SPDF.

Effects on Space Weather and Earth

Strong CMEs can trigger geomagnetic storms, aurorae, and magnetospheric currents impacting technologies monitored by NOAA Space Weather Prediction Center, US Air Force, and commercial operators like Intelsat and SES. Historical technological impacts involved disruptions to TELSTAR, Austrian railway system, and incidents analogous to concerns for North American power grid operators and companies like PJM Interconnection. CMEs influence planetary atmospheres studied by missions such as MAVEN, Cassini–Huygens, and Juno and affect spacecraft charging observed on International Space Station and satellites managed by Iridium and Eutelsat.

Prediction and Modeling

Forecasting uses magnetohydrodynamic models like ENLIL, EUHFORIA, and empirical relations developed at NASA Ames Research Center, NOAA, Met Office, and research groups at Stanford University, University of Colorado Boulder, and University of Cambridge. Data assimilation combines helioseismology from GONG and magnetograms from SOLIS with coronagraph imagery from SOHO and STEREO to produce arrival-time predictions used by operators such as NASA, ESA, and Roscosmos. Machine learning efforts involve collaborations with Google and academic groups at MIT and Caltech.

Historical Events and Notable CMEs

Notable events include the 1859 Carrington Event observed by Richard Carrington and Richard Hodgson which affected telegraph networks and auroral reports compiled in archives at British Library and Smithsonian Institution; the 1989 Quebec blackout linked to a CME studied by Hydro-Québec and researchers at NRCan; the 2003 Halloween storms analyzed by teams at NOAA and NASA with impacts on SOHO and ACE data; and extreme events assessed in paleomagnetic records and ice core studies housed at Lamont–Doherty Earth Observatory and NCAR. Recent high-resolution studies draw on observations from Parker Solar Probe and Solar Orbiter with analyses by groups at Max Planck Institute for Solar System Research, Lockheed Martin Solar and Astrophysics Laboratory, and University of California, Berkeley.

Category:Solar phenomena