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  • 1
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    Flare Physics in Solar Activity Maximum 22 : Proceedings of the International SOLAR-A Science Meeting Held at Tokyo, Japan, 23–26 October 1990 (1991)
    Berlin ; Heidelberg : Springer
    Details
    ISBN: 9783540543831
    URL: http://www.springerlink.com/openurl.asp?genre=book&isbn=978-3-540-54383-1
    Language: English
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  • 2
    Electronic Resource
    Electronic Resource
    Fluctuations of brightness and vertical velocity at various heights in the photosphere (1973)
    Springer
    Solar physics 33 (1973), S. 33-48 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In a spectrogram of exceptionally high spatial resolution, brightness and velocity fluctuations in seven weak to medium-strong Fe i lines have been measured and analyzed. Heights of formation of these lines have been computed using the Harvard-Smithsonian Reference Atmosphere (Gingerich et al., 1972), taking into account departures from LTE. The results show that granular velocity fluctuations decrease with increasing height up to the vicinity of the temperature minimum. If extrapolated downward to the height of formation of the continuum, the rms velocity fluctuation is 0.8 km s-1 with an estimated error of ± 0.2 km s-1. The correlation of continuum brightness fluctuations with velocity fluctuations decreases rapidly with height, and even becomes slightly negative at h 〉 160 km. This finding is consistent with the picture of the granulation consisting of convective elements overshooting into a stable atmosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00152375
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  • 3
    Electronic Resource
    Electronic Resource
    Theoretical chromospheric flare spectra (1974)
    Springer
    Solar physics 34 (1974), S. 193-206 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We simultaneously solve the equations of radiative transfer and statistical equilibrium for a model hydrogen atom including Lyman-α, Lyman-β, Balmer-α and the Lyman, Balmer and Paschen continua. The model atmospheres we use are the results of Nakagawa et al. (1973) for a kinematic model of the chromospheric solar flare. We find that the models adequately predict the total intensity of Bα, its wing broadening, the presence of a red-shifted wing, the maximum electron density, the total line-of-sight second-level population and the narrowness in height of the Bα emitting region. The profile of Bα is strongly self-reversed, however, and agrees with observations only in the presence of 40–70 km s−1 macroturbulent motion. We find that Nakagawa et al. (1973) seriously overestimate the radiative loss function, which will have a large effect on their models. Proper radiative loss calculations must be included in any physically realistic model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149612
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  • 4
    Electronic Resource
    Electronic Resource
    Observed Lα profiles for two solar flares: 14∶12 UT 15 June, 1973 and 23∶16 UT 21 January, 1974 (1980)
    Springer
    Solar physics 67 (1980), S. 339-350 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Photographic observations of the time development of the profile of the Lα line of hydrogen during flares were obtained with the NRL spectrograph on ATM. The profiles for the 15 June, 1973 and 21 January, 1974 flares reported here cover both core and wings of the line. The time sequences begin before flare maximum, and continue well into the decay phase. Careful attention has been given to photometry and absolute calibration. In the case of the 15 June, 1973 flare, data are presented both first-order corrected and uncorrected for incomplete filling of the spectrograph slit by flaring material. Correction of the 21 January, 1974 flare was not possible. We discuss core symmetry and shift, and show that our observations imply integrated flare Lα/Hα intensity ratios within a factor of two of unity for these two flares.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149811
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  • 5
    Electronic Resource
    Electronic Resource
    Hα profiles from electron-heated solar flares (1978)
    Springer
    Solar physics 57 (1978), S. 399-408 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We briefly review the status of models of optical flare heating by electron bombardment. We recompute Brown's (1973a) flare model atmospheres using considerably revised radiative loss rates, based on Canfield's (1974b) method applied to α, Lα, and H−. Profiles of α are computed and compared with observation. The computed profiles agree satisfactorily with those observed during the large 1972 August 7 flare, if spatial and velocity inhomogeneities are assumed. The electron injection rate inferred from α is one order of magnitude less than that inferred from hard X-rays, for this event. This may be due to either (1) the neglect of a mechanism that reduces the thick-target electron injection rate or (2) failure to incorporate important radiative loss terms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00160112
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  • 6
    Electronic Resource
    Electronic Resource
    Spatial structure in lines in the 3398–3526 å region at the extreme limb: Observation, identification and interpretation (1978)
    Springer
    Solar physics 58 (1978), S. 263-277 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have obtained spectrograms of high spatial and spectral resolution of the extreme solar limb, using the vacuum tower telescope of Sacramento Peak Observatory. We have identified emission lines in the range 3398–3526 Å, and classified them according to intensity, spatial structure (intensity variation), and profile. Some lines show spatial intensity variation; others do not. We show that this effect is related to the abundance of the element responsible for the line and the mean lower-level excitation potential of interlocked lines. We explain the effect in terms of radiative interlocking with other lines, as well as the characteristic size of the volume contributing to the mean intensity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00157271
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  • 7
    Electronic Resource
    Electronic Resource
    The height variation of granular and oscillatory velocities (1976)
    Springer
    Solar physics 50 (1976), S. 239-254 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Previous observations of spatially-resolved vertical velocity variations in ten lines of Fe i spanning the height range 0 ≲ h ≲ 1000 km are re-analyzed using velocity weighting functions. The amplitudes and scale heights of granular and oscillatory velocities are determined, as well as those of the remaining unresolved velocities. I find that the optimal representation of the amplitude of the outward-decreasing granular velocities is an exponentially decreasing function of height, with a scale height of 150 km and a velocity at zero height of 1.27 km s−1. The optimal representation of the same quantities for oscillatory velocities is an exponential increase with height, with a scale height of 1100 km and a velocity at zero height of 0.35 km s−1. The remaining unresolved velocities decrease with height, with a scale height of 380 km and a velocity at zero height of 2.3 km s−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00155287
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  • 8
    Electronic Resource
    Electronic Resource
    A novel observational test of momentum balance in a solar flare (1987)
    [s.l.] : Nature Publishing Group
    Nature 326 (1987), S. 165-166 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Impulsive hard X-rays from the small C2 flare were detected by the Solar Maximum Mission (SMM) hard X-ray burst spectrometer from 23:43:42 to 23:44:33 on 30 April 1985. Before this burst the region showed enhanced counts in the O vm and Mg XI channels of the SMM flat crystal spectrometer (PCS). ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/326165a0
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  • 9
    Electronic Resource
    Electronic Resource
    A measurement of the non-thermal velocity in the low chromosphere (1971)
    Springer
    Solar physics 20 (1971), S. 275-281 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract I have determined horizontally averaged non-thermal velocities from Jensen and Orrall's (1963) observations of Doppler widths of weak rare-earth emission lines in the wings of H and K. Combining these results with previous rare-earth line results, I conclude that this velocity in the low chromosphere (300–600 km) is 2.0 ± 0.2 km/s, and changes little with height.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00159755
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  • 10
    Electronic Resource
    Electronic Resource
    Theoretical chromospheric flare spectra (1974)
    Springer
    Solar physics 34 (1974), S. 339-348 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We obtain simultaneous solutions of the equations of radiative transfer and statistical equilibrium for hydrogen excitation and ionization. The model atom includes Lα, Lβ, Balmer-α and the Lyman, Balmer and Paschen continua. The model atmospheres are these of Brown (1973) representating the effects of heating by non-thermal electrons on the Harvard-Smithsonian Reference Atmosphere. The spectral and atmospheric properties of Brown's (1973) models characterize a flare of strength markedly less than a typical large flare, but within the range observed. The Balmer-α profiles are self-reversed, but to a much lesser extent than those of Paper I. However, Brown (1973) uses a radiative-loss estimate that is more than an order of magnitude too large in the region of Balmer-α formation. Until this problem is remedied one cannot meaningfully compare the computed profiles to observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00153672
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