UV Emitting Spicules

1980 ◽  
Vol 91 ◽  
pp. 199-201
Author(s):  
Giannina Poletto
Keyword(s):  
Coronal Hole ◽  
Extreme Ultraviolet ◽  
Emission Measure ◽  
Harvard College ◽  
Chromospheric Network ◽  
Harvard College Observatory ◽  
Ultraviolet Observations ◽  
Lower Limits

Extreme ultraviolet observations of the chromospheric network in a coronal hole obtained in 1973 by the Harvard College Observatory experiment aboard Skylab are analyzed. Upper and lower limits to the actual emission measure in UV spicules have been obtained, and the consistency of the derived values with the hypothesis that UV spicules are Hα spicules falling back after being heated is discussed.

scholarly journals Dynamical Effects in the EUV Chromospheric Network

1977 ◽  
Vol 43 ◽  
pp. 10-10
Author(s):  
F.G. Chiuderi-Drago ◽  
G. Poletto
Keyword(s):  
Extreme Ultraviolet ◽  
Network Models ◽  
Average Intensity ◽  
The Sun ◽  
Harvard College ◽  
Spatial Intensity Distribution ◽  
Euv Emission ◽  
Chromospheric Network ◽  
Harvard College Observatory ◽  
Ultraviolet Observations

Extreme ultraviolet observations of the chromospheric network obtained by the Harvard College Observatory experiment aboard Skylab on May 31st, 1973, are analyzed.The data, which have a spatial resolution of 5“ x 5“, cover an area of 5‘ x 5‘ near the center of the sun, where a large coronal hole was present, and are recorded in several lines formed in a range of temperatures from 104 to 106 °K.By studying the EUV spatial intensity distribution, the average intensity in cell and network, the contrast, and the emission measures have been derived.The network distribution, highly asymmetrical and skewed to higher intensity, suggests an inhomogeneous network structure, probably associated with the presence of spicules, not resolved by the instrument.A dynamical model of the transition zone is therefore developed, and the resulting EUV emission in spicules is computed and compared with available observations, and with previous network models.

scholarly journals Non-Equilibrium Excitation and Ionization of Be-Sequence Ions

1977 ◽  
Vol 43 ◽  
pp. 14-14
Author(s):  
J .C . Raymond ◽  
A.K. Dupree
Keyword(s):  
Solar Flares ◽  
Resonance Line ◽  
Coronal Holes ◽  
Detailed Comparison ◽  
Temporal Variations ◽  
Ionization State ◽  
Harvard College ◽  
Harvard College Observatory ◽  
Ultraviolet Observations ◽  
Non Equilibrium

Intensities of resonance and subordinate lines in C III and O V are calculated for several non-equilibrium states expected to occur in the solar atmosphere. In particular, cooling (recombination) phases of solar flares, and regions of mass flow such as coronal holes and the network offer conditions where non-equilibrium phenomena can be significant. In such situations, the ionization state may not be in equilibrium with the electron temperature. Detailed comparison is made with the ultraviolet observations from the Harvard College Observatory experiment on Skylab which show temporal variations as well as clear non-equilibrium enhancement of the ratio of the 2s2p 3P - 2p23P transition 2 1 1 to the resonance line 2s21S - 2s2p 1P in both C III and O V.

EUV Observations of the Active Sun from the Harvard Experiment on ATM

1975 ◽  
Vol 68 ◽  
pp. 3-17 ◽  
Author(s):  
R. W. Noyes ◽  
P. V. Foukal ◽  
M. C. E. Huber ◽  
E. M. Reeves ◽  
E. J. Schmahl ◽  
...  
Keyword(s):  
Solar Activity ◽  
Extreme Ultraviolet ◽  
Coronal Holes ◽  
Active Regions ◽  
Harvard College ◽  
Preliminary Results ◽  
Harvard College Observatory

In this paper we review some preliminary results from the Harvard College Observatory Extreme Ultraviolet Spectroheliometer on ATM that pertain to solar activity. The results reviewed here are described in more detail in other papers referred to in the text. In the following paragraphs we first describe the instrument and its capabilities, and then turn to results on active regions, sunspots, flares, EUV bright points, coronal holes, and prominences.

Some comments about observations and image processing of comet 29P/Schwassmann-Wachmann 1

1999 ◽  
Vol 173 ◽  
pp. 243-248
Author(s):  
D. Kubáček ◽  
A. Galád ◽  
A. Pravda
Keyword(s):  
Image Processing ◽  
Large Scale ◽  
Harvard College ◽  
Oak Ridge ◽  
Large Scale Structures ◽  
Short Period Comet ◽  
Short Period ◽  
Scale Structures ◽  
Harvard College Observatory ◽  
Period Comet

AbstractUnusual short-period comet 29P/Schwassmann-Wachmann 1 inspired many observers to explain its unpredictable outbursts. In this paper large scale structures and features from the inner part of the coma in time periods around outbursts are studied. CCD images were taken at Whipple Observatory, Mt. Hopkins, in 1989 and at Astronomical Observatory, Modra, from 1995 to 1998. Photographic plates of the comet were taken at Harvard College Observatory, Oak Ridge, from 1974 to 1982. The latter were digitized at first to apply the same techniques of image processing for optimizing the visibility of features in the coma during outbursts. Outbursts and coma structures show various shapes.

scholarly journals Harvard college observatory circular no. 27

1898 ◽  
Vol 146 (9) ◽  
pp. 139-142
Author(s):  
Edward C. Pickering
Keyword(s):  
Harvard College ◽  
Harvard College Observatory
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