FIRST COMPLETE DETERMINATION OF PLASMA PHYSICAL PARAMETERS ACROSS A CORONAL MASS EJECTION-DRIVEN SHOCK

Journal Article · Wed Sep 01 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/720/1/130· OSTI ID:21460143

Bemporad, A; Mancuso, S ^[1]

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1. Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Torino, Strada Osservatorio 20, 10025 Pino Torinese, Torino (Italy)

We report on the study of a fast coronal mass ejection (CME)-driven shock associated with the solar eruption of 2002 March 22. This event was observed in the intermediate corona both in white light and the extreme ultraviolet (EUV) by the LASCO and UVCS instruments on board the Solar and Heliospheric Observatory, as well as in metric and decametric wavelengths through space- and ground-based radio observatories. Clear signatures of shock transit are (1) strong type II emission lanes observed after the CME initiation, (2) strong O VI {lambda}{lambda}1032, 1037 line profile broadenings (up to {approx}2 x 10{sup 7} K) associated with the shock transit across the UVCS slit field of view, and (3) a density enhancement located in LASCO images above the CME front. Since the UVCS slit was centered at 4.1 R{sub sun}, in correspondence with the flank of the expanding CME, this observation represents the highest UV detection of a shock obtained so far with the UVCS instrument. White-light and EUV data have been combined in order to estimate not only the shock compression ratio and the plasma temperature, but also the strength of the involved coronal magnetic fields, by applying the Rankine-Hugoniot equations for the general case of oblique shocks. Results show that, for a compression ratio X = 2.06 as derived from LASCO data, the coronal plasma is heated across the shock from an initial temperature of 2.3 x 10{sup 5} K up to 1.9 x 10{sup 6} K, while at the same time the magnetic field undergoes a compression from a pre-shock value of {approx}0.02 G up to a post-shock field of {approx}0.04 G. Magnetic and kinetic energy density increases at the shock are comparable (in agreement with the idea of equipartition of energy), and both are more than two times larger than the thermal energy density increase. This is the first time that a complete characterization of pre- and post-shock plasma physical parameters has been derived in the solar corona.

• OSTI ID: 21460143
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 720; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTROPHYSICS
ATMOSPHERES
COMPRESSION RATIO
DIMENSIONLESS NUMBERS
ELECTROMAGNETIC RADIATION
ELECTRON TEMPERATURE
ENERGY
ENERGY DENSITY
EQUATIONS
ERUPTION
EXTREME ULTRAVIOLET RADIATION
ION TEMPERATURE
KINETIC ENERGY
MAGNETIC FIELDS
MAIN SEQUENCE STARS
METRICS
PHYSICS
PLASMA
RADIATIONS
RANKINE-HUGONIOT EQUATIONS
SHOCK WAVES
SOLAR ATMOSPHERE
SOLAR CORONA
STARS
STELLAR ATMOSPHERES
STELLAR CORONAE
SUN
ULTRAVIOLET RADIATION