Title: 
==============
Diagnostic of coronal bright points

Lead Investigator:
=======
Bocchialini (Institut d'Astrophysique Spatiale)

Team Members:
==================
Vial (Institut d'Astrophysique Spatiale)
Einaudi (University of Pisa) 	
	     

Local Coordinator:
==================
Julia Saba

Lead Programmer:
=====


Technical Summary:
==================
 
Propagating waves are good candidates to provide energy and heat the
corona. But to ascertain the viability of a wave theory of coronal
heating, we still have to check if the energy is actually deposited by
the travelling waves in the time interval corresponding to the crossing
of the corona by the wave itself.  The dissipation properties of MHD
waves are governed by equations where the coefficients of dissipative
terms are very small. Therefore the rate of dissipation of MHD waves is
strongly related to the existence of small scales (Malara et al.,
1992). These small scales are not observable, but could have signatures
such as small and intermittent energetic bursts, like bright points.
These elementary small magnetic structures (size between 10" and 30")
can be observed in the network boundaries, in the quiet Sun or in
coronal holes, and evolve on timescale of several minutes.

The aim of the program is to derive a diagnostic (Temperature,
densities, etc) of the bright points using different lines formed a
different altitudes, and ratios of lines sensitive to the temperature
and density; the observing profiles will be compared with theoretical
ones computed from the thermodynamical parameters provided by the
numerical code developped at the University of Pisa.  We are now
performing a statistical study of bright points as a function of the
energy, as it has been discussed in Einaudi et al. (1996).

Proposal Text:  
======================= 

The program requires the cooperation of SUMER, EIT, MDI and CDS.
It is based on two sequences:

SUMER and CDS:  
A- The disk target of SUMER and CDS is selected using
EIT images in Fe XV, in several regions such as quiet Sun, coronal hole
(polar and equatorial). MDI provides map of the longitudinal magnetic
field.  A scan along a 120" field containing several bright points is
performed with the 120" slit.

B-i) One bright point is selected and 40 scans of 25"x25" are performed
around this structure, with the 1"x120" slit, in L (1025 E) and O VI
(1032 E), with a 1s exposure time. A sqrt compression is needed.

ii) A second mode can be used in which 6 lines are selected: L, O VI
1032 and 1037 E, Si II 1020 E, and Ne VI 1006 and 1010 E). The 4
moments are transmitted for each lines, formed at different heights,
which offers the possibility to scan a large part of the atmosphere
from 2 10 to 4 10 K

MDI:
       Longitudinal magnetic field maps or high res. in B, v, cont.
       Observed area: 11' x 11'

OBSERVATIONS CONCERNING THIS JOP HAVE BEEN PERFORMED AT THE FOLLOWING DATES:
* AUGUST 30 1996 BETWEEN  13 AND 17 UT 
* JANUARY 1997, OBSERVATIONS PERFORMED IN HIGH RES (MAG/VEL)
7 15-23 UT 
8 21-23 UT 
9 00-05 UT AND 16-23 UT
10 16-23 UT 
11 16-23 UT 
12 16-23 UT


See Also:  
========= 
Malara, Veltri, Chiuderi, Einaudi, 1992, ApJ, 396, 297
Einaudi, Velli, Politano, Pouquet, 1996, ApJ, 457, L-1113