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Exoplanet Predictions Based on Harmonic Orbit Resonances  

Markus J Aschwanden   Submitted: 2017-05-19 12:52

The current exoplanet database includes 5454 confirmed planets and candidate planets observed with the KEPLER mission. We find 932 planet pairs from which we extract distance and orbital period ratios. While earlier studies used the Titius-Bode law or a generalized version with logarithmic spacing, which both lack a physical model, we employ here the theory of harmonic orbit resonances, which contains quantized ratios instead, to explain the observed planet distance ratios and to predict undetected exoplanets. We find that the most prevailing harmonic ratios are (2:1), (3:2), and (5:3), in 73% of the cases, while alternative harmonic ratios of (5:4), (4:3), (5:2), (3:1) occur in 27% of the other cases. Our orbital predictions includes 171 exoplanets, 2 Jupiter moons, one Saturn moon, 3 Uranus moons, and 4 Neptune moons. The accuracy of the predicted planet distances amounts to a few percent, which fits the data significantly better than the Titius-Bode law or a logarithmic spacing. This information may be useful for targeted exoplanet searches with Kepler data and to estimate the number of live-carrying planets in habitable zones.

Authors: Markus J. Aschwanden and Felix Scholkmann
Projects:

Publication Status: 2017, Galaxies 5(4), 56
Last Modified: 2017-09-25 09:07
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Modeling of Coronal EUV Loops Observed with TRACE : I. Hydrostatic Steady-State Solutions with Nonuniform Heating  

Markus J Aschwanden   Submitted: 2000-08-18 13:05

Recent observations of coronal loops in EUV wavelengths with the {sl Transition Region and Coronal Explorer (TRACE)} and the {sl Extreme-ultraviolet Imaging Telescope (EIT)} on the {sl Solar and Heliospheric Observatory (SoHO)} demonstrated three new results that cannot be explained with most of the existing loop models: (1) EUV loops are near-isothermal along their coronal segments, (2) they show an overpressure or overdensity compared with the requirements of steady-state loops with uniform heating, and (3) the brightest EUV loops exhibit extended scale heights up to four times the hydrostatic scale height. These observations cannot be reconciled with the classical RTV (Rosner, Tucker, & Vaiana) model, they do not support models with uniform heating, and partially even violate the requirements of hydrostatic equilibrium. - In this study we conduct numeric calculations of steady-state solutions of the hydrodyn- hydrodynamic equations of mass conservation, momentum balance, and energy balance. We calculate some 500 solutions that cover a large parameter space of loop lengths (L approx 4-300 Mm), of nonuniform heating functions (with heating scale heights in the range of {lambda}_H approx 1-300 Mm), as well as the limit of uniform heating ({lambda}_H gg L). The parameter space can be subdivided into 3 regimes, which contain (1) solutions for stable loops, (2) solutions for unstable loops, and (3) no solutions. Short heating scale heights ({lambda}H, Mm lapprox sqrt{LMm}) lead to unstable loops. Fitting the hydrostatic solutions to 41 EUV loops observed with {sl TRACE} we find that 60% are dynamically unstable, 30% are near a steady-state equilibrium, and 10% are cooling off. Those loops near steady-state are all found to be heated near the footpoints, with a heating scale height of {lambda}_H=12 pm 5 Mm, covering a fraction {lambda}_H/L=0.2pm0.1 of the loop length. None of the observed loops is consistent with a uniform heating function in steady-state. Because the observed heating scale heights are all found less than a factor of 2 within the instability limit, most of the coronal heating episodes seem to operate with relatively short heating scale heights, producing mostly dynamical- dynamically unstable loops and transient brightenings.

Authors: Markus J. Aschwanden, Carolus J. Schrijver, and David Alexander
Projects:

Publication Status: ApJ, subm. (2000 Aug 7)
Last Modified: 2000-08-18 13:05
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Evidence for Nonuniform Heating of Coronal Loops Inferred from Multi-Thread Modeling of TRACE Data  

Markus J Aschwanden   Submitted: 2000-05-26 13:04

The temperature Te(s) and density structure n_e(s) of active region loops in EUV observed with {sl TRACE} is modeled with a multi-thread model, synthesized from the summed emission of many loop threads that have a distribution of maximum temperatures and that satisfy the steady-state Rosner-T- Rosner-Tucker-Vaiana (RTV) scaling law, modified by Serio et al. for gravitatio- gravitational stratification (called RTVS_p in the following). In a recent Letter, Reale & Peres demonstrated that this method can explain the almost isothermal appearance of TRACE loops (observed by Lenz et al.) as derived from the filter-ratio method. From model-fitting of the 171 and 195 ang fluxes of 41 loops, which have loop half lengths in the range of L=4-320 Mm, we find: (1) The EUV loops consist of near-isothermal loop threads with substantially smaller temperature gradients than predicted by the RTVS_p model, (2) the loop base pressure, p_0 approx 0.3pm 0.1 dyne cm-2, is independent of the loop length L, it agrees with the RTVS_p model for the shortest loops, but exceeds the RTVS_p model up to a factor of 35 for the largest loops, and (3) the pressure scale height is consistent with hydrostatic equilibrium for the shortest loops, but exceeds the temperature scale height up to a factor of approx 3 for the largest loops. The data indicate that cool EUV loops in the temperature range of Teapprox 0.8-1.6 MK cannot be explained with the static steady-state RTVS_p model in terms of uniform heating, but are fully consistent with Serio's model in the case of nonuniform heating (RTVSph), with heating scale heights in the range of s_H=17 pm 6 Mm. This heating function provides almost uniform heating for small loops (L lapprox 20 Mm), but restricts heating to the footpoints of large loops (Lapprox 50-300 Mm). Chromospheric upflows appear to be the most likely heating source of EUV loops.

Authors: Markus J. Aschwanden, Richard W. Nightingale, and David Alexander
Projects:

Publication Status: ApJ 541:1059-1077 (2000 October 1)
Last Modified: 2000-10-06 08:35
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Tomography of the Soft X-Ray Corona: Measurements of Electron Densities, Temperatures, and Differential Emission Measure Distributions above the Limb  

Markus J Aschwanden   Submitted: 2000-05-04 16:02

We analyze long-exposure and off-pointing {sl Yohkoh/SXT} data of the solar corona observed on 1992 Aug 26. We develop a new tomographic method which is based on a forward-fitting method of a 4-parameter model to the observed soft X-ray fluxes F_1(h) and F_2(h) of two {sl SXT} wavelength filters as function of height h. The model is defined in terms of a {sl differential emission measure (DEM)} distribution dEM(h, T)/dT, which includes also a temperature dependence of density scale heights {lambda}_n(T) =qlambda {lambda}_T and allows to quantify deviations (qlambda eq 1) from hydrostatic equilibrium, i.e. {lambda}_n(T)={lambda}_T. This parametrization faciliates a proper line-of-sight integration and relates the widely-used filter-ratio temperature TFR to the peak of the DEM distribution. A direct consequence of the multi-scale-height atmosphere is that the filter ratio temperature TFR(h) is predicted to increase with height, even if all magnetic field lines are isothermal. Our model-fitting reveals that coronal holes and Quiet Sun regions are in perfect hydrostatic equilibrium, but that coronal streamers have a scale height that exceeds the hydrostatic scale height by a factor of up to qlambdalapprox 2.3, which underscores the dynamic nature of coronal streamers. Our density measurements in coronal holes are slightly lower than most of the white-light polarized brightness inversions, and seem to come closer to the requirements of solar wind models. Our DEM model provides also a physical framework for the semi-empirical {sl Baumbach-Allen formula}, and quantifies the temperature ranges and degree of hydrostaticity of the {sl K-, L-, } and {sl F-corona}.

Authors: Markus J. Aschwanden and Loren W. Acton
Projects:

Publication Status: ApJ 550, 475-492
Last Modified: 2001-04-09 07:52
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The Effect of Hydrostatic Weighting on the Vertical Temperature Structure of the Solar Corona  

Markus J Aschwanden   Submitted: 2000-04-07 13:05

We investigate the effect of hydrostatic scale heights {lambda}(T) in coronal loops on the determination of the vertical temperature structure T(h) of the solar corona. Every method that determines an average temperature at a particular line-of-sight from optically thin emission (e.g. in EUV or soft X-ray wavelengths) of a mutli-temperature plasma, is subject to the emission measure- measure-weighted contributions dEM(T)/dT from different temperatures. Because most of the coronal structures (along open or closed field lines) are close to hydrostatic equilibrium, the hydrostatic temperature scale height introduces a height-dependent weighting function that causes a systematic bias in the determination of the temperature structure T(h) as function of altitude h. The net effect is that the averaged temperature seems to increase with altitude, dT(h)/dh > 0, even if every coronal loop is isothermal (at different temperatures). We simulate this effect with differential emission measure distributions observed by {sl SERTS} for an instrument with a broadband temperature filter such as {sl Yohkoh/SXT} and find that the apparent temperature increase due to hydrostatic weighting is of order Delta T approx T (h/rsun). We suggest that this effect largely explains the systematic temperature increase in the upper corona reported in recent studies (e.g. by Sturrock et al., Wheatland et al., or Priest et al.), rather than being an intrinsic signature of a coronal heating mechanism.

Authors: Aschwanden,M.J. and Nitta,N.
Projects:

Publication Status: 2000, ApJ 535, L59-L62
Last Modified: 2000-08-31 08:01
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Quadrupolar Magnetic Reconnection in Solar Flares: I. 3D Geometry inferred from Yohkoh Observations  

Markus J Aschwanden   Submitted: 2000-01-25 14:02

We analyze the 3-dimensional (3D) geometry of solar flares that show so-called {sl interacting flare loops} in soft X-ray, hard X-ray, and radio emission, as previously identified by Hanaoka and Nishio. The two flare loops that appear brightest after the flare are assumed to represent the outcome of a quadrupolar magnetic reconnection process, during which the connectivity of magnetic polarities is exchanged between the four loop footpoints. We parametrize the 3D geometry of the 4 involved magnetic field lines with circular segments, additionally constrained by the geometric condition that the two pre-reconnecti- pre-reconnection field lines have to intersect each other at the onset of the reconnection process, leading to a 10-parameter model. We fit this 10-parameter model to Yohkoh SXT and HXT data of 10 solar flares and determine this way the loop sizes and relative orientation of interacting field lines before and after reconnection. We apply a flare model of Melrose to calculate the magnetic flux transfer and energy released when two current-carrying field lines reconnect to form a new current-carrying system in a quadrupolar geometry. The findings and conclusions are: (1) The pre-reconnection field lines always show a strong asymmetry in size, consistent with the scenario of new-emerging small-scale loops that reconnect with pre-existing large-scale loops. (2) The relative angle between reconnecting field lines is near-collinear in half of the cases, and near-perpendicular in the other half, contrary to the anti-parallel configurati- configuration that is considered to be most efficient for magnetic reconnection. (3) The angle between interacting field lines reduces by approx 10^circ-50^- 10^circ-50^circ after quadrupolar reconnection. (4) The small-scale flare loop experiences a shrinkage by a factor of 1.31pm0.44, which is consistent with the scaling law found from previous electron time-of-flight measurements, suggesting that electron acceleration occurs near the cusp of quadrupolar configurations. (5) The large-scale loop is found to dominate the total induction between current-carrying loops, providing a simple estimate of the maximum magnetic energy available for flare energy release due to current transfer, which scales as Delta E^I approx 1029.63 (r_2/109 { m cm}) (I_2/1011 A)^2, (with r2 the curvature radius and I2 the current of the large-scale loop) and is found to correlate with observed flare energies deduced from soft X-ray and hard X-ray fluxes. Most of the energy is transferred to small-scale loops that have half of the large-scale current (I_1=I_2/2). (6) The quadrupolar reconnection geometry provides also a solution of {sl Canfield's dilemma} of the offset between the maximum of vertical currents and the HXR flare loop footpoints. (7) The quadrupolar geometry provides not only a framework for interacting double-loop flares, but can also be considered as a generalized version of (cusp-shaped) single-loop flares.

Authors: Aschwanden,M.J., Kosugi,T., Hanaoka,Y., Nishio,M., and Melrose,D.B.
Projects:

Publication Status: Astrophys.J. 1999, Vol. 526, p. 1026-1045.
Last Modified: 2000-01-25 14:02
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3D-Stereoscopic Analysis of Solar Active Region Loops:  

Markus J Aschwanden   Submitted: 2000-01-25 14:02

In this paper we study the three-dimensional (3D) structure of hot (Teapprox 1.5-2.5 MK) loops in solar active region NOAA 7986, observed on 1996 August 30 with the {sl Extreme-ultraviolet Imaging Telescope (EIT)} onboard the {sl Solar and Heliospheric Observatory (SoHO)}. This complements a first study (Paper I) on cooler (Teapprox 1.0-1.5 MK) loops of the same active region, using the same method of {sl Dynamic Stereoscopy} to reconstruct the 3D geometry. We reconstruct the 3D-coordinates x(s), y(s), z(s), the density n_e(s), and temperature profile Te(s) of 35 individual loop segments (as a function of the loop coordinate s) using EIT 195 ang and 284 ang images. The major findings are: (1) All loops are found to be in hydrostatic equilibrium, in the entire temperature regime of Te=1.0-2.5 MK; (2) The analyzed loops have a height of 2-3 scale heights, and thus only segments extending over about one vertical scale height have sufficient emission measure contrast for detection; (3) The temperature gradient over the lowest scale height is of order dT/dsapprox 1-10 K/km; (4) The radiative loss rate is found to exceed the conductive loss rate by about two orders or magnitude in the coronal loop segments, implying that the loops cannot be in quasistatic equilibrium, since standard steady-state loop models show that radiative and conductive losses are comparable; (5) A steady-state could only be maintained if the heating rate EH matches exactly the radiative loss rate in hydrostatic equilibrium, requiring a heat deposition length {lambda}_H of the half density scale height lambda. (6) We find a correlation of p propto L-1 between loop base pressure and loop length, which is not consistent with the scaling law predicted from steady-state models of large-scale loops. - All observational findings indicate consistently that the energy balance of the observed EUV loops cannot be described by steady-state models.

Authors: Aschwanden,M.J., Alexander,D., Hurlburt,N., Newmark,J.S.,Neupert,W.M., Klimchuk,J.A., and G.A.Gary
Projects:

Publication Status: 1999, ApJ 515, 842-867
Last Modified: 2000-08-31 08:27
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Hard X-Ray Timing Experiments with HESSI  

Markus J Aschwanden   Submitted: 1999-11-04 18:01

We design three high-precision timing experiments that can be pursued with HESSI: (1) relative timing of magnetically conjugate footpoint hard X-ray sources (similar to previous studies by Sakao), (2) relative timing between footpoint and looptop or above-the-loop-top sour-ces (in the case of Masuda-ty- Masuda-type flares), and (3) relative timing between electrons (in hard X-rays) and protons (in gamma-rays). Re-analyzing Sakao's simultaneity measurements between conjugate footpoints in 14 flares we confirm his results and find an average uncertainty of {sigma} auapprox pm 250 ms for HXT (with a signal-to-noise ratio of 10: 1), which can be improved down to {sigma} au- {sigma} auapprox pm 22 ms for HESSI (for a signal-to-noise ratio of 100: 1). These timing experiments are expected to convey new information on the particle kinematics in solar flares.

Authors: Markus J. Aschwanden
Projects:

Publication Status: ASP Conf.Ser., High Energy Solar Physics: Anticipating HESSI, (R.Ramaty and N.Mandzhavidze eds.), subm. 1999 Nov 4.
Last Modified: 1999-11-04 18:01
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Particle Acceleration and Kinematics in Solar Flares and the Solar Corona'' (Invited Review)  

Markus J Aschwanden   Submitted: 1999-10-06 21:04

          and the Solar Corona'' (Invited Review)We review theoretical models of particle acceleration applied to solar flares (DC electric fields, wave-turbulence stochastic acceleration, shock acceleration acceleration) and confront these models with new observational findings from the {sl Compton Gamma Ray Observatory (CGRO), Solar Maximum Mission (SMM), Yohkoh}, and radio observations. Remote sensing of energetic particles via hard X-ray bremsstrahlung, gyrosynchrotron emission, and beam-driven plasma emission requi- requires a self-consistent modeling of the particle kinematics in the solar flare plasma, including acceleration, injection, propagation, trapping, and energy loss of the particles. New insights in these kinematic processes have been obtained, besides modeling of energetic particle spectra, increasingly from sub-second timing studies, e.g. in the context of Masuda's discovery of above-the-loop-top hard X-ray sources, from electron time-of-flight delay measurements, from the relative timing of propagation to magnetically conjugate footpoints, from the relative timing of particle signatures in interacting flare loops with quadrupolar geometry, and from the relative timing of gyrosynchrotron emission and hard X-ray signatures in magnetic traps. We anticipate significant progress to be made with the {sl High Energy Solar Spectroscopic Imager (HESSI)}, to be launched in 2000.           ``Magnetic Fields and Solar Processes'', Florence, Italy,          12-18 Sept 1999, ESA SP-448, Dec 1999, in press.

Authors: Aschwanden,M.J.
Projects:

Publication Status: in Proc. of the Ninth European Meeting on Solar Physics,
Last Modified: 1999-10-06 21:04
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Radio and Hard X-Ray Observations of Flares and their Physical Interpretation'', (Invited Review)  

Markus J Aschwanden   Submitted: 1999-10-06 21:04

        Interpretation'', (Invited Review)We review a selection of observations in radio, hard X-rays (HXR) and soft X-rays (SXR) that constrain geometrical and physical requirements for solar flare models. Guided by observations of interacting flare loops we discuss a flare model based on shear-driven quadrupolar reconnection, which explains single-loop and double-loop flares in a unified picture. We interpret various observational findings in the light of this unified flare model: {- topology and geometry of interacting flare loops, } {- localization of particle acceleration region, } {- scale invariance of electron time-of-flight path and flare loop geometry, } {- density and magnetic field diagnostic in accelerati- acceleration region, } {- bi-directionality of injected electron beams, } {- electron beam trajectories and correlated HXR pulses, } {- bifurcation of directly-precipitating and trap-precipitating electrons, } {- density and magnetic field diagnostic of trap region, } {- elementary time scales and dynamics in acceleration region. }         on

Authors: Aschwanden,M.J.
Projects:

Publication Status: in Proc. Nobeyama Symposium
Last Modified: 1999-10-06 21:04
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Do EUV Nanoflares Account for Coronal Heating?  

Markus J Aschwanden   Submitted: 1999-10-06 21:04

Recent observations with EUV imaging instruments such as SoHO/EIT and TRACE have shown evidence for flare-like processes at the bottom end of the energy scale, in the range of Ethapprox 1024-1027 erg. Here we compare these EUV nanoflares with soft X-ray microflares and hard X-ray flares across the entire energy range. From the observations we establish empirical scaling laws for the flare loop length, L(T) propto T, the electron density, n_e(T) propto T^2, from which we derive scaling laws for the loop pressure, p(T) propto T^3, and the thermal energy, Eth propto T^6. Extrapolating these scaling laws into the {sl picoflare regime} we find that the pressure conditions in the chromosphere constrain a height level for flare loop footpoints, which scales with heq(T) propto T-0.5. Based on this chromospheric pressure limit we predict a lower cutoff of flare loop sizes at Lminlapprox 5 Mm and flare energies Eminlapprox 1024 erg. We show evidence for such a rollover in the flare energy size distribution from recent TRACE EUV data. Based on this energy cutoff imposed by the chromospheric boundary condition we find that the energy content of the heated plasma observed in EUV, SXR, and HXR flares is insufficient (by 2-3 orders of magnitude) to account for coronal heating.         and Transition Region'', Monterey, California, 24-27 August 1999),        Solar Physics, Dec issue, in press.

Authors: Aschwanden,M.J.
Projects:

Publication Status: (Contribution to the TRACE workshop ``Physics of the Solar Corona
Last Modified: 1999-10-06 21:04
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Solar Flares: Energetic Particles  

Markus J Aschwanden   Submitted: 1999-10-06 21:04

Solar Flares: Nonthermal electrons         Institute of Physics and Macmillan Publishing,         in press.

Authors: Aschwanden,M.J.
Projects:

Publication Status: in Encyclopedia of Astronomy, (ed. E.Priest),
Last Modified: 2002-04-03 04:52
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Time Variability of the Quiet Sun Observed with TRACE. I. Instrumental Effects, Event Detection, and Discrimination of EUV Nanoflares  

Markus J Aschwanden   Submitted: 1999-10-06 21:02

The {sl Transition and Coronal Explorer (TRACE)} observed a ``Quiet Sun'' region on 1999 Feb 17 from 01: 30 UT to 10: 00 UT with full resolution (0.5'' pixel size), high cadence (125 s), and deep exposures (65 s and 46 s) in the 171 ang and 195 ang wavelengths. We start our investigation of the time variability of ``Quiet Sun'' images with a detailed analysis of instrumental and nonsolar effects, such as orbital temperature variations, filtering of particle radiation spikes, spacecraft pointing jitter, and solar rotation tracking. We quantify the magnitude of various noise components (photon Poisson statistics, data digitization, data compression, readout noise) and establish an upper limit for the data noise level, above which temporal variability can safely be attributed to solar origin. We develop a pattern recognition code which extracts spatio-temporal events with significant variability, yielding a total of 3131 events in 171 ang and 904 events in 195 ang . We classify all 904 events detected in 195 ang according to flare-like characteristics and establish a numerical flare criterion based on temporal, spatial, and dynamic cross-correla- cross-correlation coefficients between the two observed temperatures (0.9 MK and 1.4 MK). This numerical criterion matches the visual flare classification in 83% and can be used for automated flare search. Using this flare discrimination criterion we find that only 35% (and 25%) of the events detected in 171 (and 195) ang represent flare-like events. The discrimination of flare events leads to a frequency distribution of peak fluxes, N(Delta F) propto Delta F-1.83pm0.07 at 195 ang, that is significantly flatter than the distribut- distribution of all events. A sensitive discrimination criterion of flare events is therefore important for microflare statistics and for conclusions on their occurrence rate and efficiency for coronal heating.

Authors: Aschwanden,M.J., Nightingale,R., Tarbell,T. S., and Wolfson,C.J.
Projects:

Publication Status: ApJ 535, 1027-1046, (2000)
Last Modified: 2000-08-31 07:47
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Time Variability of the Quiet Sun Observed with TRACE. II. Physical Parameters, Temperature Evolution, and Energetics of EUV Nanoflares  

Markus J Aschwanden   Submitted: 1999-10-06 21:02

We present a detailed analysis of the geometric and physical parameters of 281 EUV nanoflares, simultaneously detected with the {sl TRACE} telescope in the 171 and 195 ang wavelengths. The detection and discrimination of these flare-like events is detailed in Paper I. We determine the loop length l, loop width w, emission measure EM, the evolution of the electron density n_e(t) and temperature Te(t), the flare decay time { au}decay, and calculate the radiative loss time { au}loss, the conductive loss time { au}cond { au}cond, and the thermal energy Eth. The findings are: (1) EUV nanoflares in the energy range of 1024-1026 erg represent miniature versions of larger flares observed in soft X-rays and hard X-rays, scaled to lower temperatures (Te lapprox 2 MK), lower densities (n_e lapprox 109 cm-3), and somewhat smaller spatial scales (lapprox 2-20 Mm); (2) The cooling time { au}decay is compatible with the radiative cooling time { au}rad, but the conductive cooling time scale { au}cond is about an order of magnitude shorter, suggesting repetitive heating cycles in time intervals of a few minutes; (3) The frequency distribution of thermal energies of EUV nanoflares, N(E)approx 10-46(E/1024)-1.8 [s-1 cm-2 erg-1] matches that of SXR microflares in the energy range of 1026-10^- 1026-1029, and exceeds that of nonthermal energies of larger flares observed in HXR by a factor of 3-10 (in the energy range of 1029-1032 erg. Discrepancies of the power-law slope with other studies, which report higher values in the range of aschwanden@lmsal.com: =2.3-2.6 (Krucker & Benz, or Parnell & Jupp), are attributed to methodical differences in the detection and discrimination of EUV microflares, as well as to different model assumptions in the calculation of the electron density. Besides the insufficient power of nanoflares to heat the corona, we find also other physical limits for nanoflares at energies lapprox 1024 erg, such as the area coverage limit, the heating temperature limit, the lower coronal density limit, and the chromospheric loop height limit. Based on these quantitative physical limitations, it appears that coronal heating requires other energy carriers that are not luminous in EUV, SXR, and HXR.

Authors: Aschwanden,M.J., Tarbell,T.D., Nightingale,R.W., Schrijver,C.J., Title,A.,
Projects:

Publication Status: 2000, ApJ 535, 1047-1065
Last Modified: 2000-08-31 07:59
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Abstracts by Author
Exoplanet Predictions Based on Harmonic Orbit Resonances
Modeling of Coronal EUV Loops Observed with TRACE : I. Hydrostatic Steady-State Solutions with Nonuniform Heating
Evidence for Nonuniform Heating of Coronal Loops Inferred from Multi-Thread Modeling of TRACE Data
Tomography of the Soft X-Ray Corona: Measurements of Electron Densities, Temperatures, and Differential Emission Measure Distributions above the Limb
The Effect of Hydrostatic Weighting on the Vertical Temperature Structure of the Solar Corona
Quadrupolar Magnetic Reconnection in Solar Flares: I. 3D Geometry inferred from Yohkoh Observations
3D-Stereoscopic Analysis of Solar Active Region Loops:
Hard X-Ray Timing Experiments with HESSI
Particle Acceleration and Kinematics in Solar Flares and the Solar Corona'' (Invited Review)
Radio and Hard X-Ray Observations of Flares and their Physical Interpretation'', (Invited Review)
Do EUV Nanoflares Account for Coronal Heating?
Solar Flares: Energetic Particles
Time Variability of the Quiet Sun Observed with TRACE. I. Instrumental Effects, Event Detection, and Discrimination of EUV Nanoflares
Time Variability of the Quiet Sun Observed with TRACE. II. Physical Parameters, Temperature Evolution, and Energetics of EUV Nanoflares

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