Hot explosions in the cool solar atmosphere Hardi Peter Max Planck Institute for Solar System Research Göttingen H. Tian, W. Curdt, D. Schmit, D. Innes, B. De Pontieu, & IRIS team
14
Embed
Hot explosions in the cool solar atmosphere Hardi Peter Max Planck Institute for Solar System Research Göttingen H. Tian, W. Curdt, D. Schmit, D. Innes,
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Slide 1
Hot explosions in the cool solar atmosphere Hardi Peter Max
Planck Institute for Solar System Research Gttingen H. Tian, W.
Curdt, D. Schmit, D. Innes, B. De Pontieu, & IRIS team
Slide 2
Emerging AR (24. Sep. 2013) : IRIS & SDO three bright
features with lifetimes of > 5 min Si IV spectroheliogram IRIS
1400 AIA 171 AIA 304 AIA 1600 HMI B los 70 x 35 these events happen
at places of flux cancellation
Slide 3
Normal spectrum: average plage
Slide 4
Strange spectra: in a bomb absorption lines ! ~5 km/s blueshift
absorption lines ! ~5 km/s blueshift missing O IV lines optically
thin bi-directional flow same profile envelope in Mg II, C II, Si
IV !! same profile envelope in Mg II, C II, Si IV !!
Slide 5
Density diagnostics Doppler shift relative to target line rest
wavelength [km/s]spectral radiance [DN / pixel] O IV 1399.77 O IV
1401.16 O IV 1400 O IV 1401 0.26 n e 4 x 10 10 cm -3 traditional
density diagnostics: ratio of forbidden lines with IRIS: O IV lines
around 1400 Si IV 1403.77 O IV 1400 O IV 1401 from C HIANTI
Slide 6
Density diagnostics in bombs: lower limit Doppler shift
relative to target line rest wavelength [km/s]spectral radiance [DN
/ pixel] O IV 1399.77 O IV 1401.16 Si IV 1403.77 Si IV 1394 O IV
1401 10 no O IV lines upper limit: Si IV 1394 O IV 1401 > 700 O
IV 1401.16 Si IV 1403.77
Slide 7
Density diagnostics in bombs: lower limit Doppler shift
relative to target line rest wavelength [km/s] spectral radiance
[DN / pixel] O IV 1401.16 Si IV 1403.77 Si IV 1394 O IV 1401 >
700 no O IV lines upper limit: density @ Si IV origin: >5 x 10
13 cm -3 @ Mg II origin: >3 x 10 14 cm -3 comparable to density
at T mimimum density @ Si IV origin: >5 x 10 13 cm -3 @ Mg II
origin: >3 x 10 14 cm -3 comparable to density at T mimimum
Slide 8
Summary of observations absorption lines (!) in EUV these line
of neutral or singly ionized species have blueshifts of ~5 km/s
cool layer above energy deposition event still optically thin in Si
IV bi-modal profile of Si IV (and C II, Mg II) strong
bi-directional flow (supersonic, ~ Alfven-speed) similar envelope
of line profile in Mg II, C II, Si IV multi-thermal flow hosting
plasma over a wide T range flux cancellation below brightenings
reconnection (consistent with flow speeds) no O IV forbidden line
emission with other evidence: source region in high-density plasma
(probably not effect of non-Maxwellian e distribution; Dudik et al.
2014, ApJ 780, L12) weak ( / no) signature in 171 and 304 bands
overlying cool layer absorbs in He I and He II Lyman continua
Slide 9
Scenario for the bombs similar to EB scenario 1 in Georgoulis
et al (2002) ApJ 575, 506
Slide 10
Relation to Ellerman bombs ? Ellerman bomb H- unclear from
observations, so far no H- Ellerman bombs found at locations of
these strange Si IV profiles (ongoing work, Vissers, G., Rouppe van
der Voort et al, poster 4.21) some of the Si IV bombs show also
coronal counterpart peaks of EB spectral profiles in H-a at
different Doppler shifts than Si IV and Mg II in Si IV bombs so far
no enhancement in TR emission reported for EBs energy estimations:
Ellerman bombs: ~ 10 28 ergs (Georgoulis et al. 2002; ApJ 575, 506)
Si IV bombs: ~ 10 29 ergs ~10 x EB Yang et al. (2013) Sol. Phys.
288, 39 Si IV bomb Si IV QS EB
Slide 11
Conclusions Hot explosions in the cool solar atmosphere
highlights importance of high spectral resolution (otherwise the
absorption lines would not be visible) energy release deep in the
atmosphere (near/below T minimum) overlying chromosphere is pushed
upwards huge amount of energy required to power flows and heat
plasma how is the chromospheric plasma heated to 100.000 K or even
more? 3D MHD models predict only modest T increase (e.g. Archontis
& Hood, 2009; A&A 508, 1469)
Slide 12
thanks
Slide 13
Line list
Slide 14
O IV lines and kappa-distributions Dudk et al (2014, ApJ 780,
L12)