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Nolte, J. T.

Publications and source records attributed to Nolte, J. T..

28 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Coronal holes as sources of solar wind

We investigate the association of high-speed solar wind with coronal holes during the Skylab mission by: (1) direct comparison of solar wind and coronal X-ray data; (2) comparison of near-equatorial coronal hole area with maximum solar wind velocity in the associated streams; and (3) examination of the correlation between solar and interplanetary magnetic polarities. We find that all large near-equatorial coronal holes seen during the Skylab period were associated with high-velocity solar wind streams observed at 1 AU.

Nolte, J. T.↗
NASA NTRS1975

Relation of large-scale coronal X-ray structure and cosmic rays. I - Sources of solar wind streams as defined by X-ray emission and H-alpha absorption features

The large-scale structure of the corona and the interplanetary medium during Carrington rotations 1601-1607 is discussed relative to recurrent high-speed solar wind streams and their coronal sources. Only streams A, C, D, and F recur on more than one rotation. Streams A and D are associated with coronal holes, while C and F originate in the high corona (20-50 solar radii) over faint X-ray emissions. The association of the streams with holes is confirmed by earlier findings that there are no large equatorial holes without an associated high-speed stream and that the area of the equatorial region of coronal holes is highly correlated with the maximum velocity observed in the associated stream near 1 AU.

Krieger, A. S.↗
NASA NTRS1975

Relation of large-scale coronal X-ray structure and cosmic rays. II - Coronal control of interplanetary injection of 300 keV protons

We report the striking coronal control of low-energy solar particles from the solar flare of September 7, 1973. The flare was at S18, W46 (Carrington longitude 188 deg) in McMath Plage Region 12307. We find strong intensity gradients in heliolongitude (about 10% per deg) that are nearly identical in protons, helium, and medium nuclei at energies about 0.5 MeV/nuc, as well as relativistic electrons and 3 MeV protons. This pervasive gradient occurs at longitudes over bright X-ray emission structures east of the flare site which interconnect large-scale chromospheric polarity regions identifiable in H-alpha filtergrams.

Roelof, E. C.↗
NASA NTRS1975

Mathematical formulation of scatter-free propagation of solar cosmic rays

The observations of strong persistent velocity anisotropies in solar flare events demand a mathematical theory closer to the extreme of scatter-free (deterministic) propagation rather than diffusive (stochastic) transport, since the latter breaks down as inferred mean-free-paths exceed 0.1 AU. Equations are derived for the time-dependent phase-space density, and Laplace transform techniques are used to obtain solutions under rather general conditions. The case of an Archimedean spiral field has been solved numerically, and the results compared with observations from Mariner and Explorer spacecraft of nearly 0.4 MeV proton intensity and anisotropy histories. These can both be replicated if the inner boundary of the modulation region is placed beyond 2 AU.

Nolte, J. T.↗
NASA NTRS1973

Large-scale structure of the interplanetary medium. II - Evolving magnetic configurations deduced from multi-spacecraft observations

Description of a method for constructing large-scale (about 0.25 AU) interplanetary magnetic field lines using only solar wind velocity from well-separated appropriately located spacecraft. The technique is based on 'labeling' the field lines at each spacecraft with their coronal connection longitudes calculated in the EQRH (extrapolated quasi-radial hypervelocity) approximation. Even though the EQRH approximation is most applicable to quasi-steady solar wind, it is proposed that it should also be satisfactorily accurate for moderately evolving conditions. For strongly evolving conditions (e.g., flare-associated plasma) a straightforward correction based on the inferred coronal longitudinal velocity profile is proposed. To illustrate the multispacecraft EQRH technique, a calculation is performed in which the interplanetary field lines in a model evolving solar wind disturbance are deduced from model observations at separated spacecraft. Since the expected agreement is found, data from Pioneers 8 and 9 and Vela are used to construct field lines for an unusually quiet period (Apr. 26-30, 1969) and for a flare-associated disturbance accompanied by a Forbush decrease (Mar. 23-25, 1969).

Nolte, J. T.↗