Flare Dynamics in the Lower Solar Atmosphere H. S. Hudson Space Sciences Laboratory, University of California, Berkeley, USA Astronomy & Astrophysics Group, Glasgow St. Andrews Feb. 9, 2011

Outline St. Andrews Feb. 9, )Some background on the lower atmosphere 2) Some background on flares 3)My current passion: EVE and spectroscopy - three small discoveries

Motivation: the chromosphere St. Andrews Feb. 9, 2011 Wedemeyer-Bohm (ex cartoon archive)

Extrapolation of photospheric field St. Andrews Feb. 9, 2011 De Rosa et al. 2009

Modeling the chromosphere St. Andrews Feb. 9, 2011 Semi-empirical 1D models (VAL-C type) 1D radiation hydro models (e.g. Fisher, McClymont) of flares 3D (MHD) models (Asplund triumph; Abbett) Plasma physics; see pages at how/plasma/webpage/plasma.html VAL-C

Motivation: the flares St. Andrews Feb. 9, 2011 Cartoon archive home page how/cartoons.html (cartoon archive random samples)

Motivation: the flares St. Andrews Feb. 9, 2011 Fletcher-Hudson 2008F

Motivation: the flares St. Andrews Feb. 9, 2011 Fletcher-Hudson 2008F What is the tensor conductivity? How is momentum conserved? How are the particles accelerated?

Part III: studying the flare EUV St. Andrews Feb. 9, 2011 Motivation for studying the EUV The EVE spectrographs on SDO Three discoveries

Motivation: flare global spectrum St. Andrews Feb. 9, 2011 Hudson et al THz WLF EUV f = f Quiet Sun Flare Excesses

Motivation: flare global spectrum St. Andrews Feb. 9, 2011 Hudson et al THz WLF EUV f = f Quiet Sun Flare Excesses

More motivation - motions St. Andrews Feb. 9, 2011 Milligan & Dennis 2009

Still more motivation – lines St. Andrews Feb. 9, 2011 Kowalski et al. 2010

…and yet more motivation St. Andrews Feb. 9, 2011 Peter et al.1990 Charge-exchange continuum from  - particles MeV

Introductory conclusions The chromosphere is complicated but has rich physics (e.g. coupling to interior) Flares provide excellent test cases for the dynamics: we can use energy and momentum conservation There has been a paucity of useful data, but that is changing now St. Andrews Feb. 9, 2011

Sun-as-a-star EUV tools SOHO/SEM: broad EUV band at nm SDO/EVE MEGS-A: far-UV, 1 A resolution, 10 s cadence (data available) SDO/EVE MEGS-B: near-UV, 1 A resolution, 10 s cadence (some problems?) SDO/EVE ESP (broad EUV bands, 0.25 s cadence) St. Andrews Feb. 9, 2011

Vicinity of He II “Ly-  ” at 30.4 nm St. Andrews Feb. 9, 2011

EVE 304A for SOL St. Andrews Feb. 9, 2011 RHESSI 100 keV EVE 30.4 nm

EVE 304A for SOL St. Andrews Feb. 9, 2011

Line detail, total and subtracted St. Andrews Feb. 9, 2011 Flare vs preflare Impulsive vs gradual

Doppler shift? St. Andrews Feb. 9, 2011

EVE 304A for SOL St. Andrews Feb. 9, 2011

EVE 304A for SOL St. Andrews Feb. 9, 2011 Fits via gaussfit in IDL Note the high precision (six sig. figures) Uncertainty comparable with the best solar work Can almost begin to search for unknown solar planets

EUV compared with White Light St. Andrews Feb. 9, 2011 WLF EUV flare QS Woods et al Flare bolometric signature

EVE 304A for SOL St. Andrews Feb. 9, 2011

…and yet more motivation St. Andrews Feb. 9, 2011 Peter et al.1990 Charge-exchange continuum from alpha particles MeV

EVE 304A for SOL St. Andrews Feb. 9, 2011 ??

Evaporation flow St. Andrews Feb. 9, 2011 Milligan & Dennis 2009

Sun-as-a-star EUV irradiance St. Andrews Feb. 9, 2011

Three discoveries The EUV does not have the bulk of the flare energy; only the UV is left as a viable candidate EVE is good enough to measure Doppler shifts useful for flare dynamics in the lower atmosphere In the first example, EVE spectra do not show the charge-exchange signature expected from “solar cosmic rays” St. Andrews Feb. 9, 2011

Comments on EVE There are lots of lines to work with He II spectrum in the impulsive phase (Ly-  excellent; can see Ly-  and a hint of Ly-  in SOL ) Need bigger flares Looking forward to near UV (MEGS-B) as a part of WLF characterization St. Andrews Feb. 9, 2011

Conclusions The SDO data for the Sun “as a star” are rather fine There are many applications of these data - Global flare spectra - Doppler shifts / flare dynamics - Charge-exchange components - Seismology (classical) - Seismology (coronal) St. Andrews Feb. 9, 2011

Other slides St. Andrews Feb. 9, 2011

304 time series, one day St. Andrews Feb. 9, 2011

Flux and Doppler, one day St. Andrews Feb. 9, 2011

ESP 304A for SOL St. Andrews Feb. 9, 2011

EVE ESP and SOL St. Andrews Feb. 9, 2011

EVE 304 narrow vs SEM St. Andrews Feb. 9, 2011

EVE 304 narrow vs SEM St. Andrews Feb. 9, 2011

EVE 304, SEM, EVE broad St. Andrews Feb. 9, 2011

EVE 304 vs SEM, broad St. Andrews Feb. 9, 2011

Flare SOL T00:57 St. Andrews Feb. 9, 2011 Martinez-Oliveros et al. 2011

Flare SOL T00:57 St. Andrews Feb. 9, 2011 Martinez-Oliveros et al Eve 304A