Repository of works by Caltech published authors.
Group = Big Bear Solar Observatory
Mostrando recursos 1 - 10 de 10
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...
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
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.
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.
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...
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
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...
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.
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,...