EDP Sciences
Free access
Issue
A&A
Volume 393, Number 3, October III 2002
Page(s) L73 - L76
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20021252


A&A 393, L73-L76 (2002)
DOI: 10.1051/0004-6361:20021252

Letter

What is the real nature of blinkers?

D. Marik and R. Erdélyi

Space & Atmosphere Research Center, Dept. of Applied Mathematics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH, England, UK
    e-mail: Robertus@sheffield.ac.uk

(Received 14 May 2002 / Accepted 23 August 2002)

Abstract
In the present paper a simple physical model of blinkers based on the process of magnetic reconnection is developed. Blinkers were first found in transition region lines (e.g. He I, O III, O IV, O V and Mg IX) by SOHO CDS. Their typical lifetime is approximately 16 min, the intensity enhancement ratios are around 1.8, and they appear at 1-20 s -1 on the solar disk. According to observations, blinker events seem to be increases in density and/or filling factor rather than increases in temperature. Most blinkers have a repetitive nature and a high percentage of these events occur above unipolar magnetic fields. Magnetic reconnection in the lower transition region of the solar atmosphere is numerically simulated by solving the fully nonlinear, time-dependent, dissipative, radiative 2D MHD equations. Setting the initial parameters describing transition region explosive events as in Roussev et al. ([CITE],b,c), we computed the evolution of the reconnection jets. Taking into account the limit of the spatial and temporal resolution of the CDS camera and converting the high-resolution numerical results into "CDS-resolution", the propagating reconnection jets are found to have similar properties as those described by CDS blinker observations. These results suggest SOHO CDS may actually observe reconnection driven explosive events as blinkers.


Key words: Sun: atmosphere -- transition region -- evolution -- magnetic fields -- magnetohydrodynamics -- numerical

Offprint request: D. Marik, D.Marik@sheffield.ac.uk



© ESO 2002