Coronal Heating Mechanisms and Solar Irradiance Variability

1. C9: Coronal Heating and Irradiance Chairs: Warren/Martens Status: Draft, 1/6/05 HMI/AIA science teams meeting; Monterey; Feb. 2006

2. II: Science questions and tasks • Primary scientific question • What is the physical mechanism that determines the magnitude and variability of the solar irradiance at UV, EUV, and SXR wavelengths? • SDO/AIA science tasks: • Characterize the thermal properties of coronal structures • Develop physical models of loop atmospheres • Construct physical models of the solar UV, EUV, and SXR irradiance with predictive capability HMI/AIA science teams meeting; Monterey; Feb. 2006

3. III: Science context • Near-Term Developments • Significant results on coronal heating are expected from Solar-B, which will launch in 2006. Solar B will provide • EUV Spectra • Soft X-ray imaging • High resolution magnetograms • Vector magnetic field measurements • Chromospheric imaging • Continued development of CHIANTI and other atomic physics databases. • Continued analysis of SOHO, Yohkoh, and TRACE data; comparisons with TIMED SEE irradiance data HMI/AIA science teams meeting; Monterey; Feb. 2006

4. III: Science context • Unique contributions from SDO • Full Sun: SDO will allow us to take the insights gained from the high spatial resolution Solar-B observations and apply them to the global corona. • Solar-B/FPP  SDO/HMI • Solar-B/XRT/EIS  SDO/AIA • Spectral Irradiance: SDO/EVE irradiance observations will provide for absolute benchmarks over a much broader range of wavelengths. • AIA provides thermal resolution that is unsurpassed for previous imagers. • Extended Mission: The extended length of the SDO mission will allow for measurements over a significant fraction of a solar cycle. HMI/AIA science teams meeting; Monterey; Feb. 2006

5. Magnetic Field Field Lines Heating Rate ε(s,t) Hydro Model n(s), T(s) Predicted Intensities Observations Simulating Active Region Emission: An Overview Extrapolation of the surface magnetic fields is not unique. The relationship between the heating rate and the properties of the magnetic field should be motivated by theory. Calculating the plasma response to heating is time consuming. Solutions are approximate. radiative losses Atomic Physics Dynamical processes, such as non-equilibrium ionization, are difficult to include in the calculated intensities. plasma emissivity Instrumental effects (e.g., scattered light, calibration) can complicate comparisons with observations. HMI/AIA science teams meeting; Monterey; Feb. 2006

6. IV: Science investigation • Hurdles, bottlenecks, uncertainties: • Magnetic field extrapolations: uniqueness, efficiency of calculation • Loop geometry: do loops really have constant cross sections? • Heating rates: what do theories really predict • Hydro simulations: need faster codes • Atomic databases: completeness, non-equilibrium effects • Comparisons with observations: calibration, instrumental effects • DEM inversion techniques: uniqueness, efficiency of calculation HMI/AIA science teams meeting; Monterey; Feb. 2006

7. V: Implementation: general • What do we need to make progress on the science questions in general? • Small workshop(s) focused on these tasks • Codes and Resources • atomic physics databases • magnetic field extrapolation techniques • hydro codes HMI/AIA science teams meeting; Monterey; Feb. 2006

8. VI: Implementation: AIA+HMI • What do we need from and for SDO to make progress on our major science? • The standard AIA and HMI observations will be sufficient to address these tasks. HMI/AIA science teams meeting; Monterey; Feb. 2006

9. VII: AIA (+HMI+EVE) data products • Data products • SDO data: • HMI magnetogram, vector magnetic field (critical) • HMI “instantaneous” Carrington maps (desirable) • AIA image data in all passbands (critical) • EVE irradiance observations (critical) • Supporting data from other observatories: • Solar B EIS spectra (desirable) • Solar B XRT images (desirable) HMI/AIA science teams meeting; Monterey; Feb. 2006

10. VIII: AIA (+HMI+EVE) data production • Assessment of required resources/codes/etc: • Reliable, well documented, and frequently recalibrated AIA_prep software. • Fast, reliable, fully automated, well documented, and cross- calibrated DEM inversion codes, preferably several to choose from. • Fast, reliable, well documented hydrocodes, preferably open to use by the community. Supporting but independent s/w to produce simulated AIA data and DEM’s. • Need at least some codes for every step (prep, DEM, hydro, simdata) that run easily on current standard PC’s and laptops (e.g. current iMac G5 with 1 GB RAM, 250 GB HD, 2 GHz processor). • Need clearing house type website for codes, results, calibrations, benchmark requirements, preprints. Plus email newsletter (e.g. RHESSI). HMI/AIA science teams meeting; Monterey; Feb. 2006

11. IX: Business plan: Resources • [What data and codes must we have to make SDO a success (at pipeline, supporting, and research levels)? Who will provide the required codes?] -- First question answered in VIII. Schedule and responsibilites perhaps something to start discussing at the team meeting? It is unrealistic to expect a complete plan before the meeting, I think. • … HMI/AIA science teams meeting; Monterey; Feb. 2006

12. X: Business plan: Implementation • Define key milestones, test procedures, and target dates, … • … • Communication: define or list meetings, topical sessions, etc., where progress can be presented, discussed, evaluated, … • … HMI/AIA science teams meeting; Monterey; Feb. 2006