MODELING THE LINE-OF-SIGHT INTEGRATED EMISSION IN THE CORONA: IMPLICATIONS FOR CORONAL HEATING

One of the outstanding problems in all of space science is uncovering how the solar corona is heated to temperatures greater than 1 MK. Though studied for decades, one of the major difficulties in solving this problem has been unraveling the line-of-sight (LOS) effects in the observations. The corona is optically thin, so a single pixel measures counts from an indeterminate number (perhaps tens of thousands) of independently heated flux tubes, all along that pixel's LOS. In this paper we model the emission in individual pixels imaging the active region corona in the extreme ultraviolet. If LOS effects are not properly taken into account, erroneous conclusions regarding both coronal heating and coronal dynamics may be reached. We model the corona as an LOS integration of many thousands of completely independently heated flux tubes. We demonstrate that despite the superposition of randomly heated flux tubes, nanoflares leave distinct signatures in light curves observed with multi-wavelength and high time cadence data, such as those data taken with the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. These signatures are readily detected with the time-lag analysis technique of Viall & Klimchuk in 2012. Steady coronal heating leaves a different and equally distinct signature that is also revealed by the technique.

[1]  J. Klimchuk,et al.  DIAGNOSING THE TIME DEPENDENCE OF ACTIVE REGION CORE HEATING FROM THE EMISSION MEASURE. II. NANOFLARE TRAINS , 2013, 1303.4466.

[2]  P. Cargill,et al.  ENTHALPY-BASED THERMAL EVOLUTION OF LOOPS. III. COMPARISON OF ZERO-DIMENSIONAL MODELS , 2012 .

[3]  J. Schmelz,et al.  THE COLD SHOULDER: EMISSION MEASURE DISTRIBUTIONS OF ACTIVE REGION CORES , 2012 .

[4]  J. Klimchuk,et al.  DIAGNOSING THE TIME-DEPENDENCE OF ACTIVE REGION CORE HEATING FROM THE EMISSION MEASURE. I. LOW-FREQUENCY NANOFLARES , 2012, 1209.0737.

[5]  J. Klimchuk.  The Role of Type II Spicules in the Upper Solar Atmosphere , 2012, 1207.7048.

[6]  H. Warren,et al.  A SYSTEMATIC SURVEY OF HIGH-TEMPERATURE EMISSION IN SOLAR ACTIVE REGIONS , 2012, 1204.3220.

[7]  NASA's Goddard Space Flight Center,et al.  EVIDENCE FOR WIDESPREAD COOLING IN AN ACTIVE REGION OBSERVED WITH THE SDO ATMOSPHERIC IMAGING ASSEMBLY , 2012, 1202.4001.

[8]  J. Klimchuk,et al.  PATTERNS OF NANOFLARE STORM HEATING EXHIBITED BY AN ACTIVE REGION OBSERVED WITH SOLAR DYNAMICS OBSERVATORY/ATMOSPHERIC IMAGING ASSEMBLY , 2011 .

[9]  H. Mason,et al.  EMISSION MEASURE DISTRIBUTION AND HEATING OF TWO ACTIVE REGION CORES , 2011, 1107.4480.

[10]  V. Kashyap,et al.  USING A DIFFERENTIAL EMISSION MEASURE AND DENSITY MEASUREMENTS IN AN ACTIVE REGION CORE TO TEST A STEADY HEATING MODEL , 2011, 1106.5057.

[11]  M. Aschwanden,et al.  DETERMINING THE STRUCTURE OF SOLAR CORONAL LOOPS USING THEIR EVOLUTION , 2011 .

[12]  D. J. Anderson,et al.  ISOTHERMAL AND MULTITHERMAL ANALYSIS OF CORONAL LOOPS OBSERVED WITH AIA , 2011 .

[13]  M. Aschwanden,et al.  SOLAR CORONA LOOP STUDIES WITH THE ATMOSPHERIC IMAGING ASSEMBLY. I. CROSS-SECTIONAL TEMPERATURE STRUCTURE , 2011, 1103.0228.

[14]  B. Pontieu,et al.  The Origins of Hot Plasma in the Solar Corona , 2011, Science.

[15]  H. Warren,et al.  CONSTRAINTS ON THE HEATING OF HIGH-TEMPERATURE ACTIVE REGION LOOPS: OBSERVATIONS FROM HINODE AND THE SOLAR DYNAMICS OBSERVATORY , 2010, 1009.5976.

[16]  P. Cargill,et al.  THE COOLING OF CORONAL PLASMAS. III. ENTHALPY TRANSFER AS A MECHANISM FOR ENERGY LOSS , 2010 .

[17]  A. Rest,et al.  ON THE INTERPRETATION OF SUPERNOVA LIGHT ECHO PROFILES AND SPECTRA , 2010, 1004.3783.

[18]  J. Klimchuk,et al.  A SIMPLE MODEL FOR THE EVOLUTION OF MULTI-STRANDED CORONAL LOOPS , 2010, 1004.2061.

[19]  K. Reeves,et al.  RELATING CORONAL MASS EJECTION KINEMATICS AND THERMAL ENERGY RELEASE TO FLARE EMISSIONS USING A MODEL OF SOLAR ERUPTIONS , 2010 .

[20]  S. Antiochos,et al.  CAN THERMAL NONEQUILIBRIUM EXPLAIN CORONAL LOOPS? , 2009, 0912.0953.

[21]  H. Warren,et al.  EVIDENCE FOR STEADY HEATING: OBSERVATIONS OF AN ACTIVE REGION CORE WITH HINODE AND TRACE , 2009, 0910.0458.

[22]  H. Warren,et al.  ACTIVE REGION TRANSITION REGION LOOP POPULATIONS AND THEIR RELATIONSHIP TO THE CORONA , 2009, 0901.1075.

[23]  P. Gallagher,et al.  Multi-wavelength observations and modelling of a canonical solar flare , 2008, 0812.0311.

[24]  H. Mason,et al.  ACTIVE REGION LOOPS: HINODE/EXTREME-ULTRAVIOLET IMAGING SPECTROMETER OBSERVATIONS , 2009 .

[25]  P. Young,et al.  On active region loops: Hinode/EIS observations , 2008, 0901.0095.

[26]  H. Warren,et al.  Observations of Active Region Loops with the EUV Imaging Spectrometer on Hinode , 2008, 0808.3227.

[27]  J. Klimchuk,et al.  Static and Impulsive Models of Solar Active Regions , 2008, 0808.2745.

[28]  J. Linker,et al.  The Formation of Coronal Loops by Thermal Instability in Three Dimensions , 2008 .

[29]  P. Cargill,et al.  Explosive heating of low-density coronal plasma , 2006 .

[30]  J. Klimchuk,et al.  Nonthermal Spectral Line Broadening and the Nanoflare Model , 2006 .

[31]  Harry P. Warren,et al.  An Investigation into the Variability of Heating in a Solar Active Region , 2006 .

[32]  P. Cargill,et al.  Highly Efficient Modeling of Dynamic Coronal Loops , 2005, 0710.0185.

[33]  H. Warren,et al.  Cooling Active Region Loops Observed with SXT and TRACE , 2005, astro-ph/0502270.

[34]  H. Warren,et al.  Evolving Active Region Loops Observed with the Transition Region and Coronal Explorer. I. Observations , 2003 .

[35]  Harry P. Warren,et al.  Evolving Active Region Loops Observed with the Transition Region and Coronal explorer. II. Time-dependent Hydrodynamic Simulations , 2003 .

[36]  H. Mason,et al.  Solar active regions: SOHO/CDS and TRACE observations of quiescent coronal loops , 2003 .

[37]  Harry P. Warren,et al.  Hydrodynamic Modeling of Active Region Loops , 2002 .

[38]  J. Cirtain,et al.  Observational Constraints on Coronal Heating Models Using Coronal Diagnostics Spectrometer and Soft X-Ray Telescope Data , 2001 .

[39]  P. Démoulin,et al.  Magnetic Field and Plasma Scaling Laws: Their Implications for Coronal Heating Models , 2000 .

[40]  James A. Klimchuk,et al.  A Nanoflare Explanation for the Heating of Coronal Loops Observed by Yohkoh , 1997 .

[41]  D. Kee,et al.  A computer-aided experimental setup for studying sorption kinetics , 1992 .