TESS 2015

A large sunspot observed on Sept 2, 2013 showing umbral flashes and spikes. The radialy extending thin dark filaments seen against the light orange background are inflows of plasma into the sunspot. The small streaks of various length visible inside the sunspot against the dark orange background are the umbral spikes, which are oscilalting jets driven by sunspot oscillations.

Selected Figures

Fig. 1. The main spot of NOAA AR 11768 as seen in the chromospheric Halpha line (top and lower right panels) as well as the photospheric TiO 705 nm line (lower left). The top row shows off-band images of the sunspot taken at -0.02 nm (left, blue) and +0.02 nm (right, red) off the line center. The D.C. arrow in the lower left image points toward the disk center. The two line segments indicate the location of xt cuts. The mid size circles indicate several bright photospheric umbral dots with fine structures inside them. The small circles mark the base of several spikes (see text for more details). The long tick marks separate 1 Mm intervals.
Click the following lnks to play Halpha-0.02nm mp4 or wmv movie.
Fig. 2. Examples of spectral evolution as measured for 2 different umbral spikes (panels a-b). Panel c and d show spectral evolution immediately next to a spike and in UFs, correspondingly. Panel e represents spectral evolution in a super-penumbral filament outside the sunspot. 50 line profiles acquired within a 20 min time span were used to produce these plots. Click the following lnks to play a movie of an Halpha scan. (mp4 or wmv movie)
Fig. 3. Top panel: Time-distance plots showing chromospheric dynamics as it is seen at the Halpha-0.02 nm along the longer slit in Figure 1. The width of the slit was chosen to be 0.32 Mm. The white curve in both panels has a 3 min period and is plotted for illustration only. The white box outlines an area enlarged in Fig. 7. The bottom panel shows similar dynamics, however, observed at the Halpha-0.06 nm along the shorter slit.

Fig. 4. Locations of bright lanes of umbral flashes (UFs, green line segments) plotted over an off-band H-alpha image. The red dotted contours indicate the HMI line-of-sight magnetic field strength at -1000, -1400, -1600, and -1800 G. L1, L2, L3, R1, and R2 mark various UFs lanes discussed in the study.
Fig. 5. Dynamics of UFs as seen in NST Halpha+0.4A (top) and Halpha-0.4A (bottom) images. L1 and R1 mark locations of two bright UF lanes. The short line segments mark the edge of an expanding UF lane, while the arrow shows the direction of its expansion. The large tick marks in the leftmost top panel indicate 1 Mm intervals.
Fig. 6. NST Halpha 0.4A Doppler map (left) and IRIS Mg II k slit-jaw image. The black contour outlines the Mg II k sunspot and is drawn at an arbitrary level. The white arrow points to a blue shifted feature in the Halpha Doppler map that corresponds to the R1 UF lane. The two broken line segments mark two low contrast Mg II k UF fronts that are co-spatial with the two red-shifted features in the H® Doppler map.

Send Comments to: Vasyl Yurchyshyn at vayur at bbso njit edu
© BBSO/NJIT - Last modified: April 23, 2015.