Recursos de colección

Caltech Authors (147.820 recursos)

Repository of works by Caltech published authors.

Group = Big Bear Solar Observatory

Mostrando recursos 1 - 10 de 10

  1. Development of Activity in McMath 128 and the 24 January 1971 Flare

    Zirin, Harold
    The development of McMath 11128 is a fascinating example of the role of magnetic field reconnection and solar activity. When this active region came over the limb on January 14, it was an ordinary active region. The sunspots in the leading part, consisting of two p spots (p1 and p2) and one f spot (f1) remained almost identical for the entire period. However on January 19 a new sunspot group developed in the following part of the region and rapidly spread to overtake the f spot of the first group. In the subsequent reconnection of fields, a considerable amount of activity took place, finally leading up to the great flare of...

  2. The Thermal X-Ray Plasma in Solar Flares

    Moore, R. L.
    The observational knowledge of the thermal x-ray plasma in solar flares and its physical interpretation are reviewed, including results from Skylab prior to the Skylab Solar Workshop on Solar Flares. The review covers the main results and ideas in the published literature through 1977.

  3. Thick Target Models of Impulsive Chromospheric Flares

    LaBonte, Barry J.
    The most impulsive flares show large amplitude intensity variations in times of order 10 s. An attempt is made to reproduce the properties of these events with a model in which the heating of a static chromosphere by a nonthermal electron beam is balanced by thermal radiation cooling. The computed results suggest that the assumed static equilibrium may be achieved in some parts of the flares, and indicate improvements necessary for more accurate models of this type of flare.

  4. The Solar Cycle Field Reversal

    Adams, W. M.
    A non-mathematical model of the solar cycle field reversal is presented. The basic process producing the reversal in this model is surface reconnection of higher latitude p-flux with lower latitude f-flux. This picture differs substantially from the reversal aspect of the solar cycle field geometry presented by Babcock (1961), but the discussion is carried out entirely within the context of the flux ropes he originally considered.

  5. The Caltech Videomagnetograph: A Report on its Design and Operation

    Mosher, James
    The present report describes the installation of the Caltech videomagnetograph at Big Bear Solar Observatory, and its initial operation during 1971-1972. When fed by a 10" refracting aperture and 1/8 Å λ5324 birefringent filter, the instrument produced an approximately 4x6 arc-minute field of view, within which high resolution (2-3 arc-second) cancellations could be electronically generated and displayed in real time on a video monitor. These cancellations reveal the structure of the photospheric velocities and magnetic fields in time lapse movies. The amount of data which can be created in this manner is impressive. Daily operation between January-September, 1972 produced some 3500' of magnetic movies...

  6. Solar XUV Spectral Irradiance Monitor

    Moore, R. L.
    Scientific uses for an XUV (A < 3000 A) spectral flux monitor on the Solar Physics Spacelab and the performance requirements for these uses are defined for the disciplines of solar physics and aeronomy. The study emphasizes solar physics uses with particular emphasis on solar flares. It is concluded that: 1. An XUV monitor which meets the needs of solar physics will also be very useful for aeronomy. 2. The observation of solar flares is the scientific use of greatest potential. 3. The measurement of the XUV flux of a significant number of flares during a Spacelab mission requires a sensitivity of 0.1%. Some basic design questions posed by the results of the study...

  7. Slow X-Ray Bursts and Chromospheric Flares with Filament Disruption

    Roy, J.-René; Tang, Frances
    The data from OGO-5 and OSO-7 X-ray experiments have been analyzed to study six chromospheric flares with filament disruption associated with slow thermal x-ray bursts. Filament activation accompanied by a slight x-ray enhancement precedes the first evidence of Hα flare by a few minutes. Rapid increase of the soft X-ray flux is accompanied by a sudden brightening of the filament when viewed on-band Hα. Thereafter the bright chromospheric strands reach their maximum brightness with maximum X-ray flux. Any plateau or slow decay phase in the x-ray flux is accompanied by a quieting in filament activity and even by filament re-appearance. The height of the disrupted prominence is proportional to the soft X-ray...

  8. Solar Flares

    Zirin, Harold
    When we look at a solar flare we observe at relatively close hand a sample of the most energetic phenomena in the universe. These dynamic eruptions can only truly be appreciated from time-lapse movies or spectra. They fill the interplanetary medium with cosmic rays and shock waves, and produce plasmas with temperatures of 50 million degrees. They are rewarding both from the astrophysical and aesthetic points of view.

  9. The Relation Between Chromospheric Structure, Magnetic Field and Filaments

    Foukal, Peter

  10. The Helium Chromosphere, Coronal Holes, and Stellar X-Rays

    Zirin, H.
    The solar chromosphere at the limb seen in D3 is an irregular bright band 1000 km thick with a dark band 1000 km thick beneath. The D3 chromosphere disappears in coronal holes. We demonstrate how the D3 emission, as well as the other He I and He II lines, can be explained quantitatively by photoionization by coronal back-radiation. A Chapman layer with N(He) = 5X10^17 is formed near τ = 1 in the He I and He II continua. The chromospheric He emission or absorption is weak in coronal holes because there is no coronal back-radiation. Based on this model,...

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