Evidence from IRIS that Sunspot Large Penumbral Jets...
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Evidence from IRIS that Sunspot Large Penumbral Jets Spin Sanjiv K. Tiwari 1*,2 , Ronald L. Moore 3,4 , Bart De Pontieu 1 , Theodore D. Tarbell 1 , Navdeep K. Panesar 3 , Amy R. Winebarger 3 , Alphonse C. Sterling 3 1 Lockheed Martin Solar And Astrophysics Laboratory, 3251 Hanover Street Bldg 252, Palo Alto, CA 94304 2 Bay Area Environmental Research Institute, 625 2 nd St. Ste 209 Pealuma, CA 94952 3 NASA Marshall Space Flight Center, ZP 13, Huntsville, AL 35812 4 Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35805 Abstract Recent observations from Hinode (SOT/FG) revealed the presence of large penumbral jets (widths ≥ 500 km, larger than normal penumbral microjets, which have widths < 400 km) repeatedly occurring at the same locations in a sunspot penumbra, at the tail of a filament or where the tails of several penumbral filaments apparently converge (Tiwari et al. 2016, ApJ). These locations were observed to have mixed-polarity flux in Stokes-V images from SOT/FG. Large penumbral jets displayed direct signatures in AIA 1600, 304, 171, and 193 channels; thus they were heated to at least transition region temperatures. Because large jets could not be detected in AIA 94 Å, whether they had any coronal-temperature plasma remains unclear. In the present work, for another sunspot, we use IRIS Mg II k 2796 Å slit jaw images and spectra and magnetograms from Hinode SOT/FG and SOT/SP to examine: whether penumbral jets spin, similar to spicules and coronal jets in the quiet Sun and coronal holes; whether they stem from mixed-polarity flux; and whether they produce discernible coronal emission, especially in AIA 94 Å images. The few large penumbral jets for which we have IRIS spectra show evidence of spin. If these have mixed-polarity at their base, then they might be driven the same way as coronal jets and CMEs. Summary and Outlook: The slit should be placed across a jet during its peak time to see if it is twisting. We find at least four such examples in our 4h data. In each case we find blue and red shifts across the slit position of the jet, suggesting that large penumbral jets spin, similar to other coronal jets and CMEs. This, together with the fact that they have mixed polarity field at their base, indicates that large penumbral jets could form the same way as the coronal jets and CMEs. A more extensive study is underway. Sunspot Large Penumbral Jets Fig. 3. An example large penumbral jet during its peak time, when the IRIS slit was placed across the middle of the jet. In the right panel a dopplergram is shown, clearly displaying a blue and red shifted region across the jet. Note that part of the jet is obscured by the slit. Of the 8-slit raster the fourth slit caught this event. This work is supported by NASA contract NNG09FA40C (IRIS). NKP is supported by appointments to the NASA Postdoctoral Program at the NASA MSFC, administered by USRA through a contract with NASA. RLM and ARW are supported by funding from the LWS TRT Program of the Heliophysics Division of NASA’s SMD. Fig. 1. A large penumbral jet, numbered “2” from Tiwari et al. 2016, ApJ. Stokes-V image shows a mixed polarity field at the base of the jet, where tails of several penumbral filaments appear to converge. The bottom panels show direct signature of this jet in AIA 1600, 171, and 193 Å images. Neither this one nor any other jet showed any signature in 94 Å (not shown here). Twisting of Large Penumbral Jets Fig. 2. Magnetic reconnection between spine field and tail field probably leads to the formation of large penumbral jets, as shown. Other smaller jets form by reconnection of the spine field with the opposite polarity field at the sides of penumbral filaments. All jets propagate along the spine field. *[email protected] redshift blueshift Mg II k 2796 line profiles for the example jet Mg II k-line 2796 Å SJ image Dopplergram Schematic diagram depicting the formation mechanism of penumbral jets https://ntrs.nasa.gov/search.jsp?R=20170007973 2019-06-15T23:01:03+00:00Z
Transcript of Evidence from IRIS that Sunspot Large Penumbral Jets...
Evidence from IRIS that Sunspot Large Penumbral Jets SpinSanjiv K. Tiwari1*,2, Ronald L. Moore3,4, Bart De Pontieu1, Theodore D. Tarbell1,
Navdeep K. Panesar3, Amy R. Winebarger3, Alphonse C. Sterling31Lockheed Martin Solar And Astrophysics Laboratory, 3251 Hanover Street Bldg 252, Palo Alto, CA 94304
2Bay Area Environmental Research Institute, 625 2nd St. Ste 209 Pealuma, CA 949523NASA Marshall Space Flight Center, ZP 13, Huntsville, AL 35812
4Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35805
Abstract Recent observations from Hinode (SOT/FG) revealed the presence of large penumbral jets (widths ≥ 500 km, larger than normal penumbral microjets, which have widths < 400 km) repeatedlyoccurring at the same locations in a sunspot penumbra, at the tail of a filament or where the tails of several penumbral filaments apparently converge (Tiwari et al. 2016, ApJ). These locationswere observed to have mixed-polarity flux in Stokes-V images from SOT/FG. Large penumbral jets displayed direct signatures in AIA 1600, 304, 171, and 193 channels; thus they were heatedto at least transition region temperatures. Because large jets could not be detected in AIA 94 Å, whether they had any coronal-temperature plasma remains unclear. In the present work, foranother sunspot, we use IRIS Mg II k 2796 Å slit jaw images and spectra and magnetograms from Hinode SOT/FG and SOT/SP to examine: whether penumbral jets spin, similar to spiculesand coronal jets in the quiet Sun and coronal holes; whether they stem from mixed-polarity flux; and whether they produce discernible coronal emission, especially in AIA 94 Å images. Thefew large penumbral jets for which we have IRIS spectra show evidence of spin. If these have mixed-polarity at their base, then they might be driven the same way as coronal jets and CMEs.
Summary and Outlook: The slit should be placed across a jet during its peak time to see if it is twisting. We find at least four such examples in our 4h data. In each case we find blue and redshifts across the slit position of the jet, suggesting that large penumbral jets spin, similar to other coronal jets and CMEs. This, together with the fact that they have mixed polarity field at theirbase, indicates that large penumbral jets could form the same way as the coronal jets and CMEs. A more extensive study is underway.
Sunspot Large Penumbral Jets
Fig. 3. An examplelarge penumbral jetduring its peak time,when the IRIS slitwas placed across themiddle of the jet. Inthe right panel adopplergram isshown, clearlydisplaying a blue andred shifted regionacross the jet. Notethat part of the jet isobscured by the slit.Of the 8-slit rasterthe fourth slit caughtthis event.
This work is supported by NASA contract NNG09FA40C (IRIS). NKP is supported by appointments to the NASA Postdoctoral Program at the NASA MSFC, administered by USRA through a contract with NASA. RLM and ARW are supported by funding from the LWS TRT Program of the Heliophysics Division of NASA’s SMD.
Fig. 1. A large penumbral jet, numbered “2” from Tiwari et al. 2016, ApJ. Stokes-V image showsa mixed polarity field at the base of the jet, where tails of several penumbral filaments appear toconverge. The bottom panels show direct signature of this jet in AIA 1600, 171, and 193 Åimages. Neither this one nor any other jet showed any signature in 94 Å (not shown here).
Twisting of Large Penumbral Jets
Fig. 2. Magneticreconnection betweenspine field and tail fieldprobably leads to theformation of largepenumbral jets, as shown.Other smaller jets form byreconnection of the spinefield with the oppositepolarity field at the sidesof penumbral filaments.All jets propagate alongthe spine field.
redshiftblueshiftMg II k 2796 line profiles for the example jet
Mg II k-line 2796 Å SJ image Dopplergram
Schematic diagram depicting the formation mechanism of penumbral jets
https://ntrs.nasa.gov/search.jsp?R=20170007973 2019-06-15T23:01:03+00:00Z
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