Observations of magnetic reconnection in X-ray bright points

Dana Longcope

Description:

X-ray bright points are believed to arise from the reconnection of magnetic fields between two small features of opposite polarity. Recent theoretical work has begun to elucidate the geometry and kinematics of reconnection in three dimensions (Gorbochev and Somov 1988; Longcope 1996a). These new three-dimensional theories have been applied to the reconnection in X-ray bright points by Priest, Parnell and Golub (1995) and by Longcope (1999b). In particular, Longcope arrived at quantitative theoretical predictions for X-ray bright points from four magnetic parameters: bipolar separation, flux, orientation and the overlying (global) magnetic field strength. From these properties the model yields the X-ray luminosity, based on the rate of irreversible magnetic energy loss, and also yields an angle between the X-ray loop and the magnetic bipole axis (Kankelborg et al. 1996).

We propose to study the process of reconnection in X-ray bright points by using these theoretical predictions in conjunction with a combination of EIT spectroheliograms and MDI high-resolution magnetic field data. This study would require calibrated, daily images from EIT in all three EUV bands, taken in rapid succession, plus a consecutive pair of magnetograms from MDI's high-resolution FOV for each daily EUV set. We would also require information on the temperature response kernels of the telescopes in order to obtain temperature and pressure information.

Data which is presently archived for both instruments should be satisfactory for our purposes. Initially, we would hope to obtain a dataset large enough to identify about 50 XBPs within the MDI high- resolution field, resolved well enough to determine an orientation in EUV. We estimate that three weeks of daily EUV images would be ample. If our method of analysis shows promise based on this initial study, we would like to obtain a larger sampling of data in order to improve our statistics.

Gorbachev and Somov, 1988, Sol. Phys. 117, 77.

Kankelborg, C.C., Walker, A.B.C. Jr., Hoover, R.B. and Barbee, T.W., 1996, ApJ 466, 529.

Longcope, D.W., 1996a, "Topology and current ribbons: A model for current, reconnection and flaring in a complex evolving corona", Sol. Phys., to appear.

Longcope, D.W., 1996b, "Current sheets and reconnection in X-ray bright points", AGU fall 1996.

Parnell, C.E., Priest, E.R. and Golub, L., 1994, Sol. Phys. 151, 57.

No additional text was submitted for this proposal.