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Title: Plasma physical parameters along coronal-mass-ejection-driven shocks. I. Ultraviolet and white-light observations

In this work, UV and white-light (WL) coronagraphic data are combined to derive the full set of plasma physical parameters along the front of a shock driven by a coronal mass ejection. Pre-shock plasma density, shock compression ratio, speed, and inclination angle are estimated from WL data, while pre-shock plasma temperature and outflow velocity are derived from UV data. The Rankine-Hugoniot (RH) equations for the general case of an oblique shock are then applied at three points along the front located between 2.2 and 2.6 R {sub ☉} at the shock nose and at the two flanks. Stronger field deflection (by ∼46°), plasma compression (factor ∼2.7), and heating (factor ∼12) occur at the nose, while heating at the flanks is more moderate (factor 1.5-3.0). Starting from a pre-shock corona where protons and electrons have about the same temperature (T{sub p} ∼ T{sub e} ∼ 1.5 × 10{sup 6} K), temperature increases derived with RH equations could better represent the proton heating (by dissipation across the shock), while the temperature increase implied by adiabatic compression (factor ∼2 at the nose, ∼1.2-1.5 at the flanks) could be more representative of electron heating: the transit of the shock causes a decoupling between electronmore » and proton temperatures. Derived magnetic field vector rotations imply a draping of field lines around the expanding flux rope. The shock turns out to be super-critical (sub-critical) at the nose (at the flanks), where derived post-shock plasma parameters can be very well approximated with those derived by assuming a parallel (perpendicular) shock.« less
Authors:
;  [1] ;  [2]
  1. Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Torino, Strada Osservatorio 20, I-10025 Pino Torinese, Torino (Italy)
  2. Center for Plasma Astrophysics (CPA), KU Leuven, Celestijnenlaan 200B, B-3001 Leuven (Belgium)
Publication Date:
OSTI Identifier:
22357279
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 784; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; COMPRESSION; COMPRESSION RATIO; ELECTRON TEMPERATURE; ELECTRONS; EQUATIONS; INCLINATION; ION TEMPERATURE; MAGNETIC FIELDS; MASS; PLASMA DENSITY; PROTON TEMPERATURE; PROTONS; ROTATION; SHOCK WAVES; SUN; ULTRAVIOLET RADIATION; VELOCITY; VISIBLE RADIATION