JOP185 Spectroscopy and Imaging Tomography of the Solar Fibrils: 
Photospheric Drivers and Coronal Consequences

Short title: Solar Fibrils: Spectroscopy and Tomography

Principal Investigator: J. Rybk (1), choc at astro.sk

JOP leader deputy at GSFC: Bernhard Fleck (2)

Co-Investigators:  A. Kucera (1), J. Koza (3,1), P. Gmry (1)

Affiliation(s): 	
        (1) Astronomical Institute, Slovak Academy of Sciences,
  	     SK-05960 Tatransk Lomnica, Slovakia
  	(2) ESA, ESA Space Science Department,
  	      NASA Goddard Space Flight Center Code 682.3 Greenbelt, MD 20771, USA
  	(3) Sterrekundig Instituut, Utrecht University,
  	     NL-3508 TA Utrecht, The Netherlands

Dates: April 11-26 2006

Targets:

plages near active regions, internetwork and network of the quiet solar 
atmosphere; both near the disk center.

Cooperating instruments:

Swedish 1-meter Solar Telescope (SST)
Dutch Open Telescope (DOT), 
TRACE
SOHO CDS
SOHO MDI
SOHO EIT

Scientific objective:

Drivers of the solar fibrils are planned to be investigated using the high spatial 
resolution spectra of the Doppler and Zeeman photospheric lines taken with the SST
together with the DOT tomography of the chromospheric layers. Exploitation of the 
currently achieved high spatial resolutions of these instruments should provide not 
only further insight into the dynamics of the solar fibrils in the chromosphere but 
also the links between the photospheric velocity and magnetic fields and the fibrils. 
According to the spatial dimensions of the solar fibrils our observations require the 
highest possible spatial resolution. (Optionally the MDI/SOHO magnetograms are proposed 
to be used for further evolution of the magnetic fields in the vicinity of the selected 
target.) Utilization of the TRACE filtergrams and the SOHO/CDS spectra is planned to be 
performed to cover consequences of the fibrils in the transition region and low corona.
The already tested SOHO/CDS procedure of the SOHO JOP 171 observing program1 will be 
used for this purpose.

We expect that merging of the high cadence 2-D spectra from the SST with the time series 
of the speckle-reconstructed DOT filtergrams will provide significant added value for 
studying dynamics and reasons of the solar fibrils. Especially information derived from 
inversion of the spectral profiles of the photospheric lines should allow to extend results
of the recent research on solar spicules (DePontieu, Erdlyi & James, Nature 430, 536 (2004)). 
These information will contain dependence of the basic physical parameters like temperature, 
density, line-of-sight velocity and information on magnetic field strength on height in the 
photosphere. The consequences of the specific height stratification of the parameters could 
be followed by TRACE filtergrams and the SOHO/CDS spectra bringing some output on heating of 
the chromosphere and the transition region.

Hereafter the main details of our planned approach are explained: (1) Simultaneous inversion 
of spectral lines using the SIR code enables to determine time evolution of the physical 
parameters through the whole photosphere. Comparison of profiles of the Doppler and the 
Zeeman lines allows also to estimate the magnetic field strength using the SIR code. Therefore 
the Zeeman FeII line 6149 line with no linear polarization and the 'classical' pair of 
6301/6302  lines have been selected together with the Doppler 5576 line. These lines will 
be inverted in order to provide data on temporal and spatial development of granules and 
intergranular lanes beneath the observed fibrils. The main argument to try to acquire new 
data at the SST and the DOT together is to pool together the spectroscopic data from the 
SST with the DOT filtergrams derived from the tuned H$\alpha$ filter, Ca II H line core 
filter, and from the G-band filter. Other argument is to get the time coverage of measurements 
up to 60 minutes at least keeping the spatial resolution at the required very high level.

(2) Besides these main goal described above we have in mind to investigate consequences of 
the solar fibrils in the transition region and low corona. The latest TRACE results show that 
the TRACE satellite can acquire data needed for tracing dynamics of the coronal loops. 
Additionally the transition region emission can be traced using the CIV emission adequately 
by TRACE. Co-spatial and co-temporal measurements of the SST, DOT and TRACE should help to 
understand what sorts of the magnetic and/or dynamic phenomena in the photosphere are the 
solar fibrils and the oscillations of the coronal loops connected to. Additionally is there 
a coupling between the solar fibrils and longitudinal oscillations of the coronal loops and/or 
enhanced transition region emission respectively? The CDS spectroscopy, although of the low 
spectral resolution, provides a perfect temperature coverage of the line emission from 
chromosphere up to the corona. Therefore questions on the photospheric sources of the 
chromospheric and coronal heating and dynamics in the quiet solar atmosphere could be 
addressed

Observing procedures and requirements:

SST:

- telescope: AO and correlation tracker

- spectrograph: standard grating and 2-3 prefilters for the selected spectral ranges

- SJ system: simultaneous imaging of the slit-jaw FOV in the continua nearby the selected 
  spectral ranges and in Ca II H line (using a dichroic mirror placed in front of the spectrograph)

- Detectors: 4 Megaplus 1.6(i) cameras (2 for spectra, 2 for SJ continua), 1 Megaplus II 
  camera (spectrum at port C), 1 Megaplus 6.3 camera (Ca II H slit-jaw), in case that the 
  Magaplus II cameras will not work properly in year 2006 we can rely just on two 1.6i cameras
  placed at the ports A and B.

- Observing procedures: sequential scanning of a very narrow 2-D area ($\sim$2-3"wide) 
  for at least 60 minutes with a cadence of $\sim$1min per one raster of the area; 'save-all' 
  mode for all scientific cameras triggered by one selected SJ camera

- Selected spectral lines:

  Spectral range 	Spectral lines
  port A - 6301 	Fe I 6301.508, Fe I 6302.764, Fe I 6303.467 ,Ti I 6303.7619
  port B - 5576 	Fe I 5576.100 (g=0), Fe I 5577.028, Ni I 5578.729
  port C - 6149 	Fe II 6149.249 (no linear polarization), Fe I 6151.623

DOT:

As the main goal we plan to acquire five-wavelength profile sampling for H$\alpha$ line 
providing Dopplergrams for the chromospheric layers using tunable filter available at the 
DOT for this line. We expect to use also fixed filters for the blue and red continuum 
channels as well as G-band and CaII H channels. The resulting speckle-restored image 
sequences for the FOV of 90'' x 70'' with cadence of 30 seconds completely satisfy our 
demands on spatial and temporal resolution. Compensation for the solar rotation is needed
during the DOT observing runs. Final co-alignment with the SST (and TRACE data) will be 
performed using the white light images.

Application for the DOT support is submitted in parallel to the SST proposal. We apply for 
the external usage of the DOT in a service mode in which the DOT team operates the telescope.

TRACE:

In particular we are interested in the high resolution images (0.5'') taken in the white 
light (WL), UV 1600 continuum, CIV 1550, Lyman$\alpha$ and FeIX 171  channels. Expected 
exposure times are 4, 2, 2, 0.2, and 45sec respectively and cadence of 1 set of these exposures 
per 1 minute can be reached. The white light images will be used for the post-facto co-alignment 
with the SST slit-jaw images and the DOT images.

SOHO:

SOHO/CDS: 1-D measurements in center of previously taken 2-D raster are planned using the 
spectral lines forming over an extended temperature range: He I 584.33 (2$\times$10$^{4}$K), 
O III 599.59 (8$\times$10$^{4}$K), O V 629.74 (2.5$\times$10$^{5}$K), 
Ne VI 562.80 (8$\times$10$^{5}$K), Mg IX 386.04 (1$\times$ 10$^{6}$K), and 
Si XII 520.67 (2$\times$10$^{6}$K). Exposure cadence of only 10s is sufficient to trace 
possible variations of emission and dynamics of the outer solar atmosphere 
(e.g., Gmry et al. 2006).2

SOHO/MDI: high-resolution longitudinal magnetograms (0.6'') of the 1-min cadence will be 
acquired with some intensitygrams. These data will be used for tracing evolution of the 
photospheric magnetic flux within the FOV of the SST and the DOT. The WL intensitygrams 
will be used for post-facto coalignment of the MDI, TRACE and images from the SST and the DOT. 

SOHO/EIT: CME watch in 195 A channel (or 171 channel).

Additional information:

ESMN: This application for the SST+DOT observing time is partly prepared also as training 
of young students in the frame of the ESMN program. Reduction and interpretation of all 
data obtained from the involved instruments will be a part of training of PhD students in 
frame of the ESMN program.

MULTIDOT: This application is closely related to the EU MC fellowship named MULTIDOT with 
which one of proposers - J. Koza - has been granted for the period of 2 years starting last 
summer. The topic of the project is 'Solar fibrils and spicules at high resolution' and it 
is hosted by the Sterrekundig Instituut in Utrecht (The Netherlands).

TRACE and SOHO/(CDS+MDI) support: The TRACE, CDS and MDI parts of the SOHO JOP 171 led by 
Peter Gmry is proposed to be optionally operated during the SST+DOT observations in order 
to track evolution of the context photospheric magnetic fields, transition region and low 
corona. This TRACE, CDS and MDI program has been already run but only very limited DOT 
support (just few minutes) was acquired in the year 2005.

Team experience with the SST - October 2004: This proposal is in fact a re-application of 
the previous one which was granted by the SST+DOT observing time for October 2005. 
Unfortunately, weather and seeing conditions were so bad that no high quality data were 
acquired. Only some good individual snapshots were taken on Oct 19 and 22, but such 
material is not satisfactory for our specific scientific goal. More detailed notes on our 
SST campaign, held in October 2005, are available at 
http://www.astro.sk/$\widetilde{ }$choc/05$\underline{~}$campaign/05$\underline{~}$campaign.html.

Nevertheless our team has got very good experience with the SST operation including its 
CT, AO and the spectral science cameras. Additionally, the proposal is adapted according 
to our knowledge we have learned directly at the SST. In particular it was recognized that 
the scanned area width has to be limited to less than 3'' width, the 'save-all' mode was 
identified as the most appropriate mode for data acquisition, selection and position of 
the science cameras was made.