Palermo October 10, Flare observations in the recent solar maximum H.S. Hudson Space Sciences Lab, UC Berkeley

Palermo October 10, Organization of talk Background Major new observational results on flares Modern analysis trends Personal advertisements

Palermo October 10, PERSONAL ADVERTISEMENTS Shared topics: hard X-rays; models Research topic #1: white-light flares Research topic #2: the solar radius Other topics: two lines of “science nuggets” and the Solar Flare Cartoon Archive

Palermo October 10, Solar physics is no longer the only branch of astrophysics in which movies can be considered to be data…

Palermo October 10, Schema (inspired by R. Genzel) Object: Galactic Center Astronomer’s view: Black hole! Astrophysicist’s view: We can learn about relativity, gravity, etc in a new environment! Object: Solar Flare Astronomer’s view: Magnetic reconnection! Astrophysicist’s view: We can learn about plasma behavior in a new environment!

Palermo October 10, What is the solar corona? Low-beta plasma in a concentric cavity Slowly-varying lower boundary condition imposing vertical currents Body currents (and current sheets) in an electrically isopotential volume Massive solar wind forming a lumpy upper boundary Flaring (flares and CMEs)

Palermo October 10, What is the solar corona? Low-beta plasma in a concentric cavity Slowly-varying lower boundary condition imposing vertical currents Body currents (and current sheets) in an electrically isopotential volume Massive solar wind forming a lumpy upper boundary Flaring (flares and CMEs)

Palermo October 10, G. A. Gary, Solar Phys. 203, 71 (2001) (v A ~ 200  -1/2 km/s at coronal temperatures) CH Distribution of coronal plasma 

Palermo October 10, Yohkoh, RHESSI, TRACE and ground-based data: 5 recent wonders and marvels

Palermo October 10, Movie of dimming (Aug 28, 1992) (1) Coronal Dimming

Palermo October 10, TRACE 1600A TRACE 171A Shrinkage, dimming, destruction, oscillation Helix, ribbons (separatrices?)

Palermo October 10, (2) RHESSI  -ray imaging

Palermo October 10, x10 20 Mx -1.02x10 20 Mx +1.91x10 20 Mx +0.19x10 20 Mx +0.63x10 20 Mx -0.27x10 20 Mx I II III IV V VI Courtesy Y.H. Yang; cf H.M. Wang et al., ApJ 576, 497 (2002) (3) MAGNETIC FIELD CHANGES X-ray Flare

Palermo October 10, Field changes are now observed with essentially every X-class flare, and they match the flare ribbon locations Survey of 15 flares by Sudol & Harvey (2004)

Palermo October 10, Note that the B field changes correspond with the impulsive phase, GOES rise to maximum

Palermo October 10, (4) BOLOMETRIC DETECTION OF SOLAR FLARES (Kopp et al. 2004)

Palermo October 10, Dennis et al., 2005

Palermo October 10, If these SEPs are accelerated by CME-driven shocks, they use a significant fraction of the shock kinetic energy (~3% to 20%) (Mewaldt et al., 2005; see also Emslie et al. 2005).

Palermo October 10, (5) Microflares and jets

Palermo October 10, One month of RHESSI microflare observations (2003) Map of ~2000 flare locations of tiny flares seen by RHESSI (microflares) RHESSI microflares take place in active regions Rauscher et al. 2004

Palermo October 10, Six months of RHESSI microflare observations (2004) Map of ~3500 flare locations of tiny flares seen by RHESSI (microflares) RHESSI microflares take place in active regions even towards solar minimum Christe & Hannah, 2005

Palermo October 10, Imaging the bremsstrahlung from type III burst electrons?

Palermo October 10, Two analysis directions: 1. Timewise development of magnetic reconnection

Palermo October 10,

Palermo October 10, Bogachev et al., ApJ 630, 561 (2005) Study of HX footpoint motions I II I. Motion away from NL: 13% II. Shear motion: 26% III. Parallel motion: 35%

Palermo October 10, Bogachev et al., ApJ 630, 561 (2005) Study of HX footpoint motions I II I. Motion away from NL: 13% II. Shear motion: 26% III. Parallel motion: 35% Unpredicted!

Palermo October 10, Why is the footpoint motion so important? The HXR footpoints show the photospheric anchors of the coronal field. They thus map to the energy source of the flare The motion of the footpoints measures the rate and direction of magnetic reconnection, hence maybe identifying the mechanism

Palermo October 10, Evidence for a large-scale coronal current sheet? Sui & Holman, 2004 Anzer & Pneuman, 1982

Palermo October 10, First “modern” flare cartoon (Hirayama, 1974)

Palermo October 10, MDI magnetic artifacts

Palermo October 10, “Opacity minimum” flare IR (1.56  ) (Xu et al., 2004)

Palermo October 10, Apparent source motion correlates with energy release (Krucker et al., 2003)

Palermo October 10, Deposited Energy vs Footpoint Separation Mar 18, 2003 From Magnetogram: B fp  500 G Assume: B corona  B fp /5 A r = L h ·L v  360 arcsec 2 Perpendicular motion From HXR image: L h  5-10 arcsec  L v  arcsec (lower limit !!)

Palermo October 10, Reconnection electric field Given a large-scale reconnection geometry, one can calculate E = v x B and find it to be of order v/cm (eg, Kopp & Poletto 1984) This field, if it exists, is unidirectional and does not explain double footpoints It is necessary to understand the microscopic plasma physics during reconnection

Palermo October 10, Good news: We can estimate the V x B electric field, and it is very large (> v/cm). Bad news: A V x B electric field electric field won’t accelerate particles, since it is perpendicular to B and the particles don’t gain energy directly. cf. Litvinenko, Solar Phys. 212, 379 (2003) and references cited there

Palermo October 10, The “collapsing trap”

Palermo October 10, Shrinking magnetic field? Sui & Holman 2004 Veronig et al. (2005) now have ~5 RHESSI events

Palermo October 10, “Isomagnetobars” Before After Hudson cartoon from Archive

Palermo October 10, “Collapsing trap” - Karlicky & Kosugi, 2004

Palermo October 10, “Collapsing trap” - Aschwanden, 2004

Palermo October 10, LATE PHASE ACCELERATION X17 flare of 2005 Sept. 7 17:17 UT (courtesy S. Krucker) cf. Qiu et al. 2004

Palermo October 10, A “Collapsing Trap” analysis may help to understand both for the thermal plasma (the flare loops) and also for the non-thermal particles.

Palermo October 10, Coronal magnetic field Quantitative before/after magnetic models Aly conjecture Use of images (“data assimilation”) Problems - focusing the energy, accelerating particles, launching shock What is the eigenmode structure of an active region?

Palermo October 10, SUMMARY There have been many new solar flare results in the past (current?) maximum New analysis directions are beginning, with some surprises Another new wave of solar spacecraft is coming: Solar-B, STEREO, SDO. Alas, no HXR; double alas, no X-ray spectroscopy

Palermo October 10, PERSONAL ADVERTISEMENTS Shared topics: hard X-rays; models Research topic #1: white-light flares Research topic #2: the solar radius Other topics: two lines of “science nuggets” and the Solar Flare Cartoon Archive

Palermo October 10, WHITE-LIGHT FLARES TRACE observations, 2004 July 22 n.b. TRACE “white-light” response includes the UV, hence most of the flare luminosity “White light”Difference (reversed) UV 1700A

Palermo October 10, SOLAR RADIUS

Palermo October 10, CARTOONS

Palermo October 10, NUGGETS

Palermo October 10, End