JOP183 STUDY OF THE QUIET SUN FINE STRUCTURES ============================================= SHORT TITLE: JOP183 QUIET SUN FINE STRUCTURES REVISION HISTORY: 2005/09/19 Version 1 AUTHORS: G. Tsiropoula (POC, National Observatory of Athens, Greece) K. Tziotziou (National Observatory of Athens, Greece) P. Mein and N. Mein (Observatoire de Paris, France) P. Heinzel and P. Kotrc (Odrejov Observatory, Czech Republic) U. Schuehle (MPS, Katlenburg-Lindau, Germany ) P. Young (CCLRC Rutherford Appleton Laboratory, UK) B. Fleck (ESA) INSTRUMENTS: GBO: THEMIS, DOT, Ondrejov Multi-Channel Spectrograph SPACE: SOHO (SUMER, CDS, MDI), TRACE SCIENTIFIC OBJECTIVES The objectives of the proposed JOP are: (a) the study of the short-term dynamics of mottles and spicules observed on the solar disk and at the limb, respectively, (b) the determination of their physical parameters (3-D morphology, flows, temperature, density) and changes of these parameters during the lifetime of structures), (c) the connection of mottles/spicules with other small-scale dynamic phenomena and their relationship with the magnetic field, (d) the contribution of small-scale structures to the mass balance and energy budget of the solar chromosphere and corona. SCIENTIFIC JUSTIFICATION The highly inhomogeneous appearance of the quiet Sun is characterized by a rich diversity of fine-scale dynamic structures which have profound effects on the mass and energy flow to the outer solar atmosphere. The principal inhomogeneities are related to roughly cellular patterns that constitute the "network", which is best observed in chromospheric lines and persists throughout the chromosphere-corona transition region and the low corona. The most prominent features residing at the chromospheric network boundaries are mottles and spicules, which are short-lived dynamic events, originating at low heights, rising with an apparent speed of ~ 25 km/s, reaching a maximum height of about 10 Mm, and then either fading or descending to the photosphere (Beckers, 1972). Over the past decade, apart from the well-known spicules, many complicated and dynamic fine structures have been discovered in association with the network boundaries, like explosive events, blinkers, network flares, upflow events, Há-1A jets. However, their interpretation, inter-relationship and their relation to the underlying photospheric magnetic concentrations remain ambiguous, because the same feature has a different appearance when observed in different spectral lines. For most of the events mentioned above, magnetic reconnection has been suggested as the driving mechanism (Innes et al. 1997, Chae et al.1998, Wilhelm 2000) just like for spicules (Tziotziou et al. 2003). The majority of them appears within the network boundaries where many new bipolar elements that emerge in the network cells drift by the supergranular flow (Wang et al. 1996, Schrijver et al. 1997), and cancel there against magnetic elements of the opposite polarity. Magnetic reconnection, suggested as their driving mechanism, is probably the most suitable mechanism not only for releasing energy with important implications for the heating of the chromosphere and corona, but also for the transfer of cool gas from the chromosphere to the corona and the solar wind (Tsiropoula and Tziotziou, 2004). The aim of the proposed observations is the comprehension of the dynamical behaviour of mottles/spicules and other fine structures, their association with the magnetic field and their interrelationship, using multiwavelength observations both from the ground and space. These studies are crucial to understanding the dynamics of the solar atmosphere, as well as the role such structures play in the mass balance and heating of the overlying solar atmosphere. POINTING We will scan quiet Sun regions both on the disk and at the limb and take sequences of the same region for the study of the temporal evolution of the small-scale structures. Selection of the target will be made one day in advance. (a) Pointing 1: A quiet region near disk center to eliminate projection effects (b) Pointing 2: A quiet region between the disk center and the solar limb (c) Pointing 3: Regions at the limb The hours of the observation ïn Canaries will be approximately 8-17 UT. The best conditions are usually between 8-12 UT. INSTRUMENTS Ground-based telescopes (a) THEMIS (Tenerife): MSDP mode, two lines Há and NaD1 (or NaD2). (b) DOT (La Palma): G band, blue and red continua, Ca II H, Há and Ba II (if it is available by the time of observations) (c) Ondrejov Multi-Channel Spectrograph: Há and Hâ spectra together with slit jaw images Space telescopes (a) SOHO (i) MDI High resolution Mag/Doppler/Filt measurements in the limited FOV around the disk center at 1min cadence. Low resolution full disk measurements when the region of intrest is outside the Hi-Re field-of-view with a slower cadence. (ii) SUMER The SUMER observing sequence has one raster scan and a sit-and-stare period. The raster scan will have a FOV of 50" x 50". The study contains the lines Ne VIII = 770.420; Si II = 1533.43; C IV = 1548.21; C IV = 1550.77; Ne VIII = 780.34; N VI = 1530.30; We will also run an observating sequence with Lyman-á and Si III line. (iii) CDS Four studies have been designed and 2 line lists have been selected. Line list 1 contains most of the strong 'cool' lines seen by the NIS, while line list 2 has a reduced number of lines to improve the cadence for the large raster. The line lists are: Line list 1: O IV 554.5 Ca X 557.6 Ne VI 562.8 Ne V 572.3 He I 584.3 Ca VIII 595.7 O III 599.6 Mg IX 368.1 O IV 625.9 O V 629.7 Line list 2 (short list) O IV 554.5 Ca X 557.6 He I 584.3 O III 599.6 Mg IX 368.1 O V 629.7 The observing sequences are: THEMIS_1: 152x240 raster, 31mins, line list 1 THEMIS_2: 60x240 raster, 12mins, line list 1 THEMIS_3: sit-and-stare, 60 repeats, 48mins, line list 1 THEMIS_4: 240x240 raster, 28mins, line list 2 (b) TRACE 8.5' X 8.5' at 0.5". Similar FOV as MDI. Before the start of the sequence a white light image as well as dark images in the selected filters. We would like to have temporal series at the highest possible cadence of: 1550A,1600A,1700A, 171A and 195A obtained simultaneously. The first three images will be used to obtain "clear" CIV images (Handy et al., 1999) which are proxies for lower TR plasma, for co-alignment with SUMER OVI (or CIV or Si IV (TBD)) and for comparison with chromospheric lines and EUV images. The 171A and 195A images will be used for the determination of the hydrogen and helium column density of the plasma absorbing coronal lines according to Mein et al. (2001), Anzer and Heinzel (2005). REFERENCES Anzer U. and Heinzel P.: 2005, ApJ 622, 714 Beckers J.M.: 1972, Ann. Rev. Astr. Astrophys., 10, 73 Chae J. et al.: 1998, ApJ, 479, L109 Handy et al.: 1999, Sol. Phys. 187, 229 Innes D.E. et al.: 1997, Nature, 386, 811 Mein et al.: 2001, ApJ 556, 438 Schrijver C.J. et al.:, 1997, ApJ, 487, 424 Tsiropoula G. and Tziotziou K.:2004, A&A 424, 279 Tziotziou K., Tsiropoula G. and Mein P.:, 2003, A&A, 402, 361 Wang H. et al.:, 1996, Sol. Phys. 165, 223 Wilhelm K.:, 2000, A&A 360, 351