explanation blue bibcodes open ADS page with paths to full text
Author name code: roberts-walter-orr
ADS astronomy entries on 2022-09-14
=author:"Roberts, W.O." OR =author:"Roberts, Walter Orr"
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Title: Space Phoenix
Authors: Ware, Randolph H.; Rogers, Thomas F.; Padua, David J.;
Roberts, Walter Orr
1988SpPol...4..143W Altcode:
The US federal government is collaborating with a non-profit university
consortium and its commercial project managers to develop the Space
Shuttle fleet's expended external fuel tanks for scientific and
commercial uses in space. Nearly a half dozen years in evolution, the
Space Phoenix Program is a private-sector civil space programme with
the long-term goal of opening the Earth's space to as many people,
organizations and activities as possible, as soon as possible, and
at the lowest cost to them as possible. In time it is expected to
be a major focus for private-sector activities in space. This report
describes how it will work.
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Title: On the Apparent Modulation of Thunderstorms by Solar Plages
Authors: Olson, R. H.; Roberts, W. O.
1983wcrs.proc..469O Altcode:
No abstract at ADS
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Title: Panel Discussion: The Reality of the Association Between
Solar Activity (Such as Flares) and Atmospheric Electrical Effects
(Including Thunderstorms)
Authors: Roberts, W. O.
1983wcrs.proc..495R Altcode:
No abstract at ADS
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Title: A Suggested Approach to Research on the Sun / Weather Problems
Authors: Roberts, W. O.; Olson, R. H.
1982coas.conf..161R Altcode: 1982cia..conf..161R
No abstract at ADS
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Title: Interplanetary Magnetic Field Polarity and the Size of
Low-Pressure Troughs Near 180 degrees W Longitude
Authors: Wilcox, J. M.; Duffy, P. B.; Schatten, K. H.; Svalgaard,
L.; Scherrer, P. H.; Roberts, W. O.; Olson, R. H.
1979Sci...204...60W Altcode:
When the interplanetary magnetic field is directed away from the sun,
the area of wintertime low-pressure (300-millibar) troughs near 180
degrees W longitude is significantly larger than when the field is
toward the sun. This relation persists during most of the winters of
1951 to 1973.
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Title: Introductory Review of Solar-Terrestrial Weather and Climate
Relationships
Authors: Roberts, W. O.
1979stiw.conf...29R Altcode:
No abstract at ADS
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Title: Solar plages and the vorticity of the earth's atmosphere
Authors: Olson, R. H.; Roberts, W. O.; Prince, H. D.; Hedeman, E. R.
1978Natur.274..140O Altcode:
Three superimposed epoch analyses of the vorticity area index (VAI)
at 500 mbar are described. The analyses used the following definitions
of the zero days: (1) the central meridian passage (CMP) of very active
solar plages; (2) the occurrence of peak values of the 10.7 cm solar
radio flux; and (3) the CMP of active solar plages also accompanied at
CMP by sharp rises in 10.7 cm solar radio noise. All three superimposed
epoch analyses show a sustained rise in VAI several days before the
zero day; the rise continues through the zero day and is followed by a
sustained minimum in VAI several days after the zero day. The results
suggest that the location of the very active plages play an important
role in determining their meteorological influence. It is possible that
the initial rise in VAI is caused by enhanced electromagnetic radiation
associated with the solar activity, and that the decrease some days
later is the result of the geomagnetic storm particle emission that
generally follows the zero date.
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Title: Analysis of a possible Sun-weather correlation
Authors: Gerety, Edward J.; Olson, Roger H.; Roberts, Walter Orr
1978Natur.272..231G Altcode:
XANTHAKIS<SUP>1</SUP> has reported a striking, if complex, relationship
between solar activity and Northern Hemisphere precipitation. This
resulted in a strong negative correlation between rainfall and solar
activity found in the latitude belt of 60° to 70°N. Other belts
showed pronounced positive correlations, or a change from negative
to positive correlation. We decided that these correlations needed
a totally independent confirmation<SUP>2</SUP>, and so we repeated
the analysis, using a more extensive data base. Xanthakis has since
published a more extensive survey of global precipitation and solar
activity<SUP>3</SUP>. This also contains detailed information on his
methods of analysis, and extends the study to the Southern Hemisphere,
where further verification of the association is claimed. Our studies
reported here also encompassed both hemispheres and our results show
only a general similarity with those of Xanthakis.
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Title: The Influence of Solar Proton Flares on the Circulation of
the Earth's Troposphere (Abstract)
Authors: Olson, R. H.; Roberts, W. O.; Shea, M. A.; Smart, D. F.
1977ICRC....5..245O Altcode: 1977ICRC...15e.245O
No abstract at ADS
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Title: Short term relationships between solar flares, geomagnetic
storms, and tropospheric vorticity patterns
Authors: Olson, R. H.; Roberts, W. O.; Zerefos, C. S.
1975Natur.257..113O Altcode:
No abstract at ADS
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Title: Relationships Between Solar Activity and Climate Change
Authors: Roberts, Walter Orr
1975NASSP.366...13R Altcode: 1975prbs.conf...13R
No abstract at ADS
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Title: Influence of Solar Magnetic Sector Structure on Terrestrial
Atmospheric Vorticity.
Authors: Wilcox, John M.; Scherrer, Philip H.; Svalgaard, Leif;
Roberts, Walter Orr; Olson, Roger H.; Jenne, Roy L.
1974JAtS...31..581W Altcode:
The solar magnetic sector structure has a sizable and reproducible
influence on tropospheric and lower stratospheric vorticity. The
average vorticity during winter in the Northern Hemisphere north of
2ON latitude reaches a minimum approximately one day after the passing
of a sector boundary, and then increases during the following two or
three days. The effect is found at all heights within the troposphere,
but is not prominent in the stratosphere, except at the lower levels. No
single longitudinal interval appears to dominate the effect.
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Title: C. G. Abbot, 1872 May 31 - 1973 December 17
Authors: Roberts, W. O.
1974PhT....27e..65R Altcode:
No abstract at ADS
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Title: Solar Magnetic Sector Structure: Relation to Circulation of
the Earth's Atmosphere
Authors: Wilcox, John M.; Scherrer, Philip H.; Svalgaard, Leif;
Roberts, Walter Orr; Olson, Roger H.
1973Sci...180..185W Altcode:
The solar magnetic sector structure appears to be related to the
average area of high positive vorticity centers (low-pressure troughs)
observed during winter in the Northern Hemisphere at the 300-millibar
level. The average area of high vorticity decreases (low-pressure
troughs become less intense) during a few days near the times at which
sector boundaries are carried past the earth by the solar wind. The
amplitude of the effect is about 10 percent.
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Title: New evidence for effects of variable solar corpuscular emission
on the weather.
Authors: Roberts, W. O.; Olson, R. H.
1973RvGSP..11..731R Altcode: 1973RvGeo..11..731R
No abstract at ADS
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Title: Sydney Chapman, 1888-1970
Authors: Roberts, Walter Orr
1970Icar...13..354R Altcode:
No abstract at ADS
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Title: After the Moon, the Earth!
Authors: Roberts, Walter Orr
1970Sci...167...11R Altcode:
No abstract at ADS
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Title: Book Reviews
Authors: Goodman, J. W.; Roberts, W. O.
1967StAst..20...92G Altcode:
Two items are reviewed: Intelligent Life in the Universe, by
I. s. Shklovskii and Carl Sagan; and Neighbors of the Earth, edited
and annotated by Thornton Page and Lou Williams Page.
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Title: Book Reviews
Authors: Cruikshank, D. P.; Bartlett, J. C.; Gordon, R. W.; Roberts,
W. O.
1967StAst..20...58C Altcode:
The following are reviewed: Solar Radio Astronomy by Mikul R. Kundu;
Names of the Plough by Antonio Paluzíe-Borrell; The Names of Orion and
its Stars by Antonio Paluzíe-Borrel; The Names of the Minor Planets
and their Meanings by Antonio Paluzíe-Borrel; Mariner IV to Mars,
by Willy Ley; and The Moon, A Fundamental Survey, by Ralph B. Baldwin
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Title: Book Reviews
Authors: Roberts, W. O.; Smith, J. R.
1967StAst..20...28R Altcode:
Two items are reviewed: The American Ephemeris and Nautical Almanac
For the Year 1967, issued by the Nautical Almanac Office, U. S. Naval
Observatory; and 1967 Celestial Calendar and Handbook, authored and
published by Chas. F. Johnson, Jr.
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Title: Book Reviews
Authors: Roberts, W. O.
1966StAst..19..164R Altcode: 1966JALPO..19..164R
The following were reviewed: Galaxies, Nuclei, and Quasars, by Fred
Hoyle; Atlas Eclipicalis; Atlas Borealis; Atlas Australis; Photographic
Star Atlas I/II; and Photographic Star Atlas III.
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Title: Book Reviews
Authors: Hodgson, R. G.; Roberts, W. O.; Gordon, R. W.
1966StAst..19...86H Altcode: 1966JALPO..19...86H
Three books are reviewed: Satellites of the Solar System, by Werner
Sander; Kepler's Dream, by John Lear; and Lunar and Planetary Surface
Conditions, by Nicholas Weil.
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Title: Atmospheric Sciences for the Space Age
Authors: Roberts, Walter Orr
1966NASSP..82...40R Altcode:
No abstract at ADS
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Title: Book Review
Authors: Roberts, W. O.
1965StAst..19...25R Altcode: 1965JALPO..19...25R
One book is reviewed: Wanderers in the Sky, edited with commentary by
Thornton Page and Lou Williams Page.
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Title: Book Reviews
Authors: Roberts, W. O.
1965StAst..18..199R Altcode: 1965JALPO..18..199R
Two books were reviewed: Telescopes, edited by Gerard P. Kuiper and
Barbara Middlehurst; The Dawn of Astronony, by J. Norman Lockyer.
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Title: The origin of M-region geomagnetic storms
Authors: Billings, Donald E.; Roberts, Walter Orr
1964ApNr....9..147B Altcode:
No abstract at ADS
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Title: Representation and representatives
Authors: Waldmeier, M.; Ellison, M. A.; Roberts, W. O.
1962IAUTB..11...52W Altcode:
No abstract at ADS
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Title: Corrigenda
Authors: Roberts, W. O.; Zirin, H.
1961JGR....66..340R Altcode:
No abstract at ADS
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Title: Recent Progress in Solar Physics
Authors: Roberts, Walter Orr; Zirin, Harold
1960JGR....65.1645R Altcode:
A number of significant recent advances in solar physics are
reviewed. New kinds of observations made during the present sunspot
cycle, which began in 1954, have emphasized still further the
apparent complexity of solar phenomena and the need of nonequilibrium
theoretical treatments. Among the new developments discussed are
solar cosmic rays and high-energy particles, flares and prominences,
coronal condensations, solar magnetic fields, and solar radio noise
emission. Theoretical analyses of the conditions of the solar atmosphere
as a hot plasma, and as a gaseous ensemble exhibiting gross departures
from thermodynamic equilibrium, are discussed. New work on atomic
collisional parameters is also reviewed. The article concludes with
a synopsis of certain major unsolved problems of the solar atmosphere.
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Title: Further Evidence of a Solar Corpuscular Influence on
Large-Scale Circulation at 300 Mb
Authors: MacDonald, Norman J.; Roberts, Walter Orr
1960JGR....65..529M Altcode:
Statistical evidence from three successive winter half-years strongly
indicates that, when the earth is bombarded by unusually intense solar
corpuscular emission, certain troughs in the 300-mb circulation are
subsequently amplified. The troughs so affected enter or are formed
in the Gulf of Alaska-Aleutian Islands area on the second, third, or
fourth day after the start of the corpuscular increases. The trough
amplifications maximize a variable number of days later, which may
explain why the result was not apparent to earlier workers. The result
has been found independently, at about the same level of significance,
in the data each of the three winters treated separately. For the data
of three half-years grouped together the probability of such a strong
chance association is less than 10<SUP>-6</SUP>.
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Title: Evidence of a Solar Corpuscular Influence on Large-Scale
Weather Phenomena.
Authors: McDonald, N. J.; Roberts, W. O.
1960AJ.....65Q..54M Altcode:
Statistical evidence from three successive winter half-years strongly
indicates that when the earth is bombarded by unusually intense solar
corpuscular emission, certain low-pressure troughs in the 300-mb
circulation are subsequently amplified. The troughs so affected enter
or are formed in the Gulf of Alaska-Aleutian Islands area on the second,
third, or fourth days after the start of the corpuscular increases. The
trough amplifications maximize a variable number of days later, and in
different locations, which may explain why the result was not apparent
to earlier workers. The same result has been found independently, at
about the same level of significance, in each of the three winters
treated separately. For the three halfyears grouped together the
probability of so strong a chance association is less than 10-6.
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Title: Atmospheric Magnetic Filelds above Active Solar Region of
April 13, 1950.
Authors: Correll, Malcolm; Roberts, Walter Orr
1958ApJ...127..726C Altcode:
We have analyzed a period of well-observed prominence activity over a
clear-cut active at central meiidian passage (CMP) on April 13,1950, at
N. 13 heliographic latitude. Good-quality Climax west-limb prominence
films in Ha revealed that the region had an associated homogeneous
field of motions that extended from the region to more than 7 X l0
km We found that the trajectories could be well described by assuming
that they lay along the lines of force of a magnetic dipole buried 0
03 solar radii below the solar surface, with its axis tilted +50 from
the plane of projection The projection of the axis was approximately
radial There is evidence that a solar radio-noise storm at meter wave
length was associated with the region and was emitted parallel to the
dipole axis rather than in a radial direction from the active region
There was also a geomagnetic disturbance so timed that it may well have
resulted from solar corpuscles also emitted parallel to the dipole axis,
at the same large angle from the solar radius.
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Title: Sun-Earth Relationships
Authors: Roberts, Walter Orr
1958eas..conf....5R Altcode:
No abstract at ADS
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Title: Department of Astro-Geophysics at the University of Colorado
Authors: Roberts, Walter Orr
1957PASP...69..268R Altcode:
No abstract at ADS
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Title: Optical evidences of radiational and corpuscular emission
from active solar regions
Authors: Roberts, W. O.
1957IAUS....4..336R Altcode:
No abstract at ADS
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Title: Solar-Terrestrial Relationships: Weather and Communications
Authors: Roberts, Walter Orr
1956SCoA....1...99R Altcode:
No abstract at ADS
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Title: Some coronagraph spectra of chromosphere
Authors: Roberts, Walter Orr
1956AJ.....61Q.189R Altcode:
No abstract at ADS
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Title: Solar Corpuscles Responsible for Geomagnetic Disturbances
Authors: Pecker, Jean-Claude; Roberts, Walter Orr
1955JGR....60...33P Altcode:
A qualitative hypothesis is given that attributes recurrent "M-region"
geomagnetic disturbances to the arrival at the earth of solar
corpuscles that have been gathered into beams by the deflecting action
of coronal-region fields, presumably magnetic, associated with centers
of heightened solar activity. The hypothesis identifies the source of
solar corpuscles that produces M-region magnetic disturbances with
"quiet areas" of the solar surface. A related hypothesis associates
non-recurrent magnetic storms, the greatest ones, with a different
solar corpuscular source, found in the active region itself.
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Title: The Prominence of July 25, 1951.
Authors: Rothschild, Kurt; Pecker, Jean-Claude; Roberts, Walter Orr
1955ApJ...121..224R Altcode:
The motions of 49 knots in the large prominence of July 25, 1951, have
been measured. For 17 of them, a definite variation of acceleration
vectors has been found. The dynamics of the motion still remains
obscure. It seems difficult to represent them by a coherent field of
forces. Moreover, gravity seems to play no role in this prominence.
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Title: Coronal Line Intensities at the Khartoum Eclipse.
Authors: Athay, R. G.; Roberts, W. O.
1955ApJ...121..231A Altcode:
Coronal line and continuum intensities were measured at several
position angles on the limb and as a function of height above the limb
on the slitless spectrograms obtained at Khartoum by the High Altitude
Observatory. The lines XX 5303, 6374, and 7892 and the continuum were
measured at fifteen points around the limb. The relative line and
continuum intensities around the limb showed large variations. In one
active region where the emission in some lines was intense, the yellow
coronal line X 5694 was observed. In this same region the lines X 6702
and X 7060 were intense enough to measure, and it was found that lines
of high ionization potential were at maxima in intensities, whereas
lines of low ionization potential were at minima. The yellow line
was at maximum in this region, confirming that it is a high4oniza-
tion-potentia] line. The correlation between line and continuum
intensities was found to increase markedly as the ionization
potential increased for the three lines studied. The correlation
between line intensities was found to increase as the difference in
ionization potential decreased. Intensities of X 5303, X 7892, and the
continuum were measured as a function of height above the limb in four
regions. Two of these regions were active centers, one of which showed
the yellow line, and two were more nearly average regions. The change
of X 7892 intensities with height in the latter two regions showed
that the maximum intensity occurred below 10,000 km. Changes in the
relative intensities of the two lines with height showed that in the
yellow-line region the temperature decreased with height, but in the
other regions the temperature increased with height. A comparison of
the changes in line intensities to the changes in continuum intensities
showed that the average temperature in the active regions was above the
value at which the line X 5303 had a maximum intensity, but in the two
more normal regions the temperature was between the limits where the
lines X 5303 and X 7892 have maxima. The active regions were found to
be regions of high density.
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Title: Identification of the Yellow Coronal Line.
Authors: Pecker, Charlotte; Billings, Donald E.; Roberts, Walter Orr
1954ApJ...120..509P Altcode:
Confirmation of Edinn's tentative identification of Ca xv as the atom
responsible for the yellow coronal emission line X 5694 is given. From
line-profile analysis, the atomic weight of the responsible atom is
shown to be close to 40. The existence of an additional emission line
at about X , demanded by theory and previously reported by Waldmeier,
is verified. The ratio of the intensities X 5694/X 5446 is found to
be in agreement with theoretical values for Ca xv emission.
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Title: Study of profiles of coronal emission lines.
Authors: Billings, D. E.; Pecker, C.; Roberts, W. O.
1954AJ.....59..316B Altcode:
Coronal lines occasionally show a marked broadening in those very active
regions of the sun's atmosphere that are characterized by flares and
yellow line emission.1 We have selected a number of spectrograms in
which such broadening is apparent, and have subjected them to analysis,
both by microphotometer and visually with a travelling microscope. Most
of the work was on the red coronal line although in some cases the
green and yellow line profiles were also analyzed. In one of the
spectra, the distorted red line was clearly split into two parts
separated by 3 A, indicating that one fragment of coronal material
was moving away from the observer at approximately 150 km/sec. Such
evidence of large-scale motion was very exceptional, however. Most
of the broadened lines were surprisingly symmetrical. Half-widths,
corrected for i nstru - mental profile on the assumption of Gaussian
profiles, corresponded to temperatures ranging as high as sixteen
million degrees, with the greater number studied corresponding to six
or seven million degrees. Profiles of the red line in less disturbed
regions consistently corresponded to a temperature about 2.3 X 106
degrees. The broadened profiles generally differed appreciably from
Gaussian form in the direction of triangular profiles. We consider
two interpretations for the line broadening, high temperatures and
randomly distributed macroscopic velocities. According to the latter,
and assuming a temperature of 2.3 X 106 degrees, we compute root mean
square macroscopic velocities as high as 63 km/sec. The symmetry of the
line profiles, however, suggests the high temperature hypothesis. One
set of profiles of special interest is that of the yellow, red, and
green coronal lines observed on February 2, 1950. When the abscissas
of these profiles are corrected to the same wave length and atomic
weight, using 40 for the atomic weight of the yellow-line emitting
ion, the profiles coincide well within the limits of experimental
error. This coincidence holds even though the shape of the profiles
departs considerably from Gaussian. If, as Menzel has suggested to us,
we interpret the shape of the profiles as a superposition of various
temperatures along the line of sight, we need assume only that Edlen's
original identification of the yell6w line as Ca xv is correct, and that
the sources of coronal emission are distributed in the same proportion
in the various temperature regions along the line of sight. If we
adhere to the macroscopic velocity concept, we must postulate a very
special distribution of velocities for the yellow-line emitting atoms,
an improbable situation. We are confronted with the dilemma of the
coexistence of atoms radiating Ha, and the coronal lines XX5303,
6374 and 5694 implying a wide range of ionization temperatures. A
theoretical explanation of how this can occur has, however, been
given by Goldberg and Meuzel.2 We find in active centers, moreover,
a definite correlation between line broadening in Ha and in the red
coronal line, suggesting independently the coexistence of these atomic
species at comparable kinetic temperatures. This work was supported
by the Office of Naval Research. I.Dolder, F. D., W. 0. Roberts,
and D. E. Billings, Ap. J. 119, 120, 1954. 2.Centennial Symposia,
pp. 279-297, Harv. Obs. Monogr. No. 7, 1948. High A ltitude Observatory,
Boulder, Colo.
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Title: Solar corpuscles responsible for geomagnetic disturbances.
Authors: Pecker, Jean-Claude; Roberts, Walter Orr
1954AJ.....59..330P Altcode:
Some years ago C. W. Allen presented all extensive analysis of
geomagnetic storms, and offered suggestions for their explanation
in terms of streams of corpuscles originating in the sun.' We offer
a qualitative hypothesis, that incorporates Allen's suggestions and
identifies the solar source of corpuscular emission responsible both for
recurrent and non-recurrent geomagnetic disturbances. We postulate two
different types of solar sources of such particles as follows: (a) Small
jets of corpuscles, distributed in a fine network all over the surface
of the sun, and presumably associated with chromospheric spicules
or photospheric granules. These jets, in the absence of deflecting
solar magnetic fields, would send radial streams of corpuscles in all
directions; the streams would be present at all times, regardless of
the state of solar activity. In the presence of deflecting magnetic
fields from active centers, and the general magnetic field of the sun,
the corpuscles are deflected to form the streams responsible for the
recurrent "M-region" geomagnetic disturbances. (b) Irregular streams
of ions associated with active regions, and probably most intense at
the time of solar flares. Not all active centers have such streams
present at all times, and there is probably also a large dispersion of
particle velocities and stream energies for this type of corpuscular
stream. We present evidence from a study of geomagnetic disturbances
in 1952-53 to support the hypothesis of the formation of recurrent
magnetic storms by particle streams of the first type. In particular
we find evidence that above certain active regions there is a "cone of
avoidance" with low particle density. The center of the cone reaches
earth three days later. We also show that there is some evidence that
at the edges of the cone-of-avoidance the deficiency of corpuscles is
compensated by regions with an excess particle density. The hypothesis
is in accord with the explanation we gave earlier for the formation
of the K component of the white light corona,' here associated with
the solar-terrestrial corpuscular beams. The hypothesis suggests that
daily coronagraphic observation of the white light corona may prove of
great value for prediction of the times of occurrence of geomagnetic
storms and associated phenomena. This work was supported by the Air
Force Cambridge Research Center, Geophysical Research Directorate, Air
Research and Development Command. 5.M. N. 104, 53, 5944. 2.Roberts,
W. 0., R. Grenchik, and D. E. Billings, A. f. 58, 225, 5953. High
Altitude Observatory, Boulder, Colo.
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Title: Active Region Prominences and the Yellow Coronal Line.
Authors: Dolder, F. P.; Roberts, W. O.; Billings, D. E.
1954ApJ...120..112D Altcode:
Regions of the sun characterized by emission of the rarely observed
yellow coronal line X 5694 were found to be positively associated
with the following characteristic behavior of prominences at the same
location: (a) large numbers of associated surge-type prominences; (b)
predominance of scattered knots; (c) formation of continuous streamers;
(d) downward motion of knots and streamers toward an active center;
and (e) sharp curvatures and focusing effects in trajectories. On the
other hand, the principal observed characteristics of quiescent solar
prominences were found to be negatively associated with the regions
of yellow coronal-line emission.
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Title: The active region on the west solar limb during the eclipse
of 25 February 1952.
Authors: Athay, R. G.; Evans, J. W.; Roberts, W. O.
1954AJ.....59..182A Altcode:
At the Khartoum eclipse there was an active region at io0S latitude
on the west limb. This region was first observed as a small sunspot
group and plage area near the east limb on 12 February. One flare was
reported in this region on 13 February, one on i6 February, two on 24
February and two on 25 February."2 The west limb spectrograms of the
chromospheric flash obtained by the High Altitude Observatory showed
a small region of enhanced emission and immediately adjacent to it
a small region of greatly reduced emission. Moon profile pictures
taken at Khartoum showed that the observed effects could not be
attributed to irregularities in the moon's profile. A few degrees
away from these regions there was a bright prominence that appeared
to be of a surge type. The region of reduced emission showed mainly
in the chromospheric lines. There was also an apparent decrease in
the coronal line intensities in the lowest levels of the corona, but
there was no marked decrease in the continuum intensity. The decrease
in the line intensities apparently resulted from either a cloud of
absorbing matter or an actual decrease in chromospheric emission. The
region of enhanced emission showed a maximum in the continuum and all
chromospheric and coronal line intensities. The greatest increase in
chromospheric lines was in He+, X4686. The yellow coronal line, X5694,
showed in this region on our spectrograms. It did not show at any
other positions, and to our knowledge has not been observed at previous
eclipses. Lyot and Doilfus have also reported this coronal line and four
new coronal lines from observations at Khartoum.3 All of these lines
were found in this region of enhanced emission. The intensities of all
of the chromospheric lines decreased much more slowly with height in
this region than in an east limb region previously analyzed,4 which
seemed to represent the undisturbed chromosphere. It was suggested
that the region of enhanced emission was caused by a limb flare. A
preliminary interpretation of the data from this region showed that
both the electron density and kinetic temperature were greater than in
the east limb region, and that the temperature increased less rapidly
with height. A more detailed analysis of this region will be published
elsewhere. This work was supported by the Office of Naval Research
and carried out in cooperation with the Naval Research Laboratory.
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Title: Recent Studies of Chromospheric Spicules
Authors: Rush, J. H.; Roberts, W. O.
1954AuJPh...7..230R Altcode:
No abstract at ADS
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Title: Astronomy and Mathematics. (Book Reviews: Dialogue on
the Great World Systems; Dialogue concerning the Two Chief World
Systems--Ptolemaic & Copernican)
Authors: Kuhn, Thomas S.; Nelson, E. C.; Kron, Gerald E.; Athay,
R. Grant; Roberts, Walter Orr; Miller, Frederic H.
1954Sci...119..546K Altcode: 1954Sci...119..546G
No abstract at ADS
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Title: Solar Flares and the Yellow Coronal Line.
Authors: Dolder, Frederick P.; Roberts, Walter Orr; Billings, Donald E.
1954ApJ...119..120D Altcode:
Emission of the unidentified yellow coronal line visible at Climax
from 1946 through 1950 is shown to be highly correlated with flares at
the sun's limb at the same position, indicating a close relationship
between the two phenomena. The probability of a chance correlation as
close as the observed is less than 2 X 10- .
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Title: The active region on the west solar limb during the eclipse
of 1952 25 February
Authors: Athay, R. G.; Evans, J. W.; Roberts, W. O.
1953Obs....73..244A Altcode:
No abstract at ADS
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Title: Isophotal Photometry of a Solar Flare.
Authors: Billings, Donald E.; Roberts, Walter Orr
1953ApJ...118..429B Altcode:
The paper presents isophotal contour maps of the solar flare of April
12,1950, at various stages of development, and a plot of integrated
intensity of the flare as a function of time. Our measurements indicate
that at flare maximum the earth received a radiation of solar Ha
energy/sec which exceeded "quiet' `-sun Ha radiation by nearly 2 X
1(V8 ergs/sec. The estimated total energy in Ha reaching the earth
from the sun between the recognized start of the flare and its end
exceeded that from the quiet sun for a corresponding time interval by
approximately 9 X 1021 ergs.
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Title: Eruptive Prominence Associated with Limb Flare of may 8, 1951.
Authors: Bartlett, Thomas J.; Witte, Bruno; Roberts, Walter Orr
1953ApJ...117..292B Altcode:
A solar prominence of violently eruptive character accompanied the
limb flare of May 8, 1951. Measures of several knots in the prominence
show that forces large compared with solar gravitation were present,
but no simple laws of motion emerge from the data.
---------------------------------------------------------
Title: Preliminary intensities of Balmer lines from the flash spectrum
of the 1952 solar eclipse.
Authors: Athay, R. G.; Billings, D. E.; Evans, J. W.; Roberts, W. O.
1953AJ.....58R..33A Altcode:
Spectrographic observations of the flash spectrum at the February 25,
1952 solar eclipse at Khartoum, Sudan, were made by the High Altitude
Observatory of Harvard University and University of Colorado. A primary
purpose of the expedition was to obtain information about the hydrogen
Balmer and Paschen series. This information, in turn, will be used to
determine the electron temperature and electron density as a function
of height in the chromosphere. The observations employed three slitless
spectrographs covering the spectral range X88oo to X340o. *Of papers
presented at the Eighty-eighth Meeting of the American Astronomical
Society, Amherst, Mass., Dec. 28-31, 1952. We obtained 29 pairs of
visible and 17 pairs of ultraviolet spectrograms from X6400 to X3400,
which are of satisfactory quality. The 16 infrared spectrograms X88oo
to X6100 are underexposed. Imaged on the film during each exposure
were two simultaneous spectra, the pair having an intensity ratio
approximately 30:1. Each exposure also contained a data panel. The data
panel included clocks for determining the beginning and end of each
exposure and a photographic step-wedge for checking the characteristic
curve. Standard exposures from a tungsten ribbon-filament lamp taken
on the same roll of film as the eclipse spectrograms, but separately
processed, provide data for a first approximation to the characteristic
curve at any desired wave length. Corrections carried out by comparing
densities in the corresponding light and dark spectral images will then
give us reliable characteristic curves. The distribution of densities
in the coronal continuum gives further information for improving
the accuracy of the characteristic curve. More direct determination
of the characteristic curves is not possible because a part of the
standardizing program failed at the time of the eclipse. Using the
approximate characteristic curve obtained from the standard exposures,
we made preliminary measures of the intensities of the Balmer lines
near the series limit on 12 spectrograms at second contact. For this
we worked from positive prints of the original spectra. The heights at
which measurements were made extend from 700 km to 1930 km above the
base of the chromosphere, with observations every 108 km. We found
that the intensity of H31 is measurable to a height of 2150 km and
the intensity of H23 is measurable to 2700 km. In some spectrograms
a tentative identification shows H34, H35, and H36 to be resolved. We
are now initiating a more complete and more accurate reduction of the
data, working from the original films. The eclipse program of the High
Altitude Observatory is supported by the Naval Research Laboratory,
Office of Naval Research, and has been conducted in close collaboration
with the Laboratory. Three of the four authors are connected with the
High Altitude Observatory, J. W. Evans with the Upper Air Research
Observatory. High A ititude Observatory, Boulder, Cob., and Upper Air
Research Observatory, Sacramento Peak, Clouderoft, N. Mex.
---------------------------------------------------------
Title: Isophotal contour photometry of a solar flare.
Authors: Billings, Donald E.; Roberts, Walter Orr
1953AJ.....58R..35B Altcode:
The High Altitude Observatory recently constructed an electronic contour
densitometer, following suggestions of Oliphant,1 and Babcock,2 which
automatically plots isophotal contours from a photographic plate.3
Using the instrument we have plotted nine isophotal contour maps of
a brilliant solar flare that began at 18:44 UT on 12 April 1950. By
determining the brightness corresponding to the various contours
of the maps, and measuring the areas within the contours, we have
arrived at integrated intensities for the flare at nine stages in its
development. By making certain assumptions concerning the average Ha
line-width and the scattering in the 0.5 A birefringent filter that we
used for photographing the flare, we have concluded that the total Ha
energy per unit time in the solid angle subtended by the earth (i.e.,
the power that reached the earth from the flare) reached at maximum
nearly 5 >C 1015 ergs!sec or approximately 2 per cent of that
radiated to earth from the full solar disk in a I A band of the solar
continuum adjacent to Ha. The estimated total energy in Ha reaching the
earth from the flare between its recognized start at 18:44 UT and its
end at 23:00 UT was approximately 2 X 1022 ergs. I.The Observatory 69,
228 (1949). 2.Pub. A. S. P. 62, i8 (1950). 3.F. E. Fowler, D. S. Johnson
and D. E. Billings, J. Opt. Soc. Amer. (in press). High A ltitude
Observatory, Boulder, Colo. A LIST OF 16 Ha EMISSION REGIONS BET~
Object b 3008 +i?~ Small faint nt NGC6193 304.5 -2.6 Over2~diam IC 4628
312.6 +0.4 Involved witi nehulosity. NGC 6281 315.5 +o.8 McD 70. Exc:
NGC6302 316.3 -1.0 Appears like NGC6334 318.8 -o.8 5small,very NGC
6357 320.9 +0.3 Contains Wol NGC6383 323.3 -1.3 Large faint 323.4 -0.5
Small faint 334 -3 Large field of NGC 6559. IC 1284 339.3 -3.3 Includes
NG( complex 341 -3 Small Sagitta 342.5 +1.9 Small, faint r M17 342.8
-2.2 Very intense Mi6 344.7 -o.6 Very strong ii NGC6Oo4 346.1 -0.2
Large,faintn the Boyden Station of Harvard Observatory. The principal
instrument used in the southern survey is a camera with a ~-inch Zeiss
Sonnar lens (f/I.5), on loan from Mr. Richard S. Perkin, fitted with
a Corning 2403 red filter and a Baird Ha interference filter. In the
present paper we report on the distribution of Ha emission regions
between galactic longitudes 2650 and 3550 Dr. Dorrit Hoffleit is
reporting elsewhere on the remarkable concentration of Ha emission
regions between galactic longitudes 2500 and 2650. The photography
for the section between 1800 and 2500 is still in progress. We list
in the accompanying table, the 16 regions of Ha emission that seem to
be well established. We are still checking on an additional group of
ten uncertain regions and some further doubtful patches. A list of
associated 0 and B stars has been prepared and these are now on the
Boyden Station spectral and photo-electric programs for further study
to determine their distances. The most noteworthy result of our study
is probably the absence of any but the very weakest Ha emission between
galactic longitudes 2650 and 3000. There is obviously a gap or break in
---------------------------------------------------------
Title: Evolution of coronal regions.
Authors: Billings, D. E.; Liebenberg, D. H.; Roberts, W. O.
1953AJ.....58S.211B Altcode:
The authors have examined the behavior of regions in the solar corona
near sunspot groups, which show intense coronal line emission. The
results led them to formulate the following working hypothesis of
the origin of the emission line corona. I. Yellow, red and green
line emission at XX 5694, 6374 and 5303 in a coronal region becomes
pronounced with infusion into the corona of gas of density considerably
higher than that of the corona prior to the infusion. 2. The infusion
takes place most strongly from active sunspot centers during their
periods of flare activity. 3. The gas spreads out through the corona
along magnetic lines of force at about I km/sec, at a sufficient rate to
replace the entire emission corona in the order of a few weeks. 4. As
the gas spreads out, its temperature rises slowly. 5. Resulting
temperature and density conditions are such that yellow line emission
persists for several hours, red line emission for a few days, green
line emission for about a week or two. 6. The coronal region drops
below a recognizable level of brightness as the gas expands to a
low density, but before the return to normal in its temperature. This
concept, arrived at from a study of coronagraphic data, agrees with that
suggested by Piddington and Davies from solar radio noise observations.1
The principal observational data which led to the concept are: A. The
close association of coronal emission and flare activity. B. The
spreading out of isophotal contours of coronal emission at a rate of
about 2' km/ sec during the growth of the coronal region and sometimes
after the sunspot and flare activity at the center has subsided. This
slow spread is perhaps related to the behavior of the "disparitions
brusques" reported by Bruzek following solar flares.2 C. Many cases
of a unidirectional change of the ratio of red line to green line
emission, usually downward, during a rise and fall of brightness of
coronal regions. We see no way to explain this last observation by
the hypothesis that coronal regions differ from the remainder of the
corona only in that they are of higher temperature. We can, however,
explain it by the spreading gas hypothesis. This work was carried out
with the support of the Office of Naval Research. I.Nature 171, 692,
1953. 2.Zs. Astroph. 31, 99, 1952. High Altitude Observatory, Boulder,
Cob., and University of Wisconsin, * Madison, Wis.
---------------------------------------------------------
Title: Origin of white-light coronal streamers.
Authors: Roberts, W. O.; Grenchik, R.; Billings, D. E.
1953AJ.....58S.225R Altcode:
Two hypotheses were adyanced for the explanation of the shape of
individual rays or streamers of the electron corona seen in white light
during eclipse, and sometimes found extending to distances of several
solar diameters. In the first, the shape was ~onsidered to be simply
the shape of the net magnetic field resulting from the combination high
in the corona of the individual magnetic fields above two active solar
regions separated by angles of the order of 600 or more of the solar
surface. In this hypothesis, the fields were taken as being similar
to isolated magnetic poles, with the field smoothly dropping off with
increasing distances from the region, and recognizable to distances of
the order of 200,000 km. The fields responsible for a ray or streamer
must, on this hypothesis, be of same sign. The ray then results from
illumination of electrons constrained by the field to move parallel to
it. The electrons, in this picture, are swept up from chromospheric
jets or spicules over the entire quiet surface between the focussing
field centers. The hypothesis, though it gave suitable streamer shapes,
ran into serious troubles in explaining other aspects of the electron
corona. However, a new hypothesis, closely related to the first, seems
to explain the principal observed features of the electron corona in
qualitative fashion, at least. In this, the isolated poles responsible
for the focussing are of opposite polarity, and the steady-state
streamer shape results from the distorting effect of the particle
energies which, in this view, carry the magnetic field lines far out
into the solar atmosphere. The hypothesis explains general coronal
shape variations, with sunspot activity, the quiet sun coronal form,
and the relationship of coronal rays to M-region magnetic storms
described by Allen in 1944.1 Some support for the concept is provided
by solar radio noise observations by Payne- Scott and Little.2
The qualitative success of the hypothesis suggests the importance
of a concerted theoretical attack on the problem. I.AL N. 104, 13,
1944. `2. AI~st. J. Sci. Res. ~A, 32, 1952. High Altitude Observatory,
Boulder, Colo., and University of Indiana,* Bloomington, Ind.
---------------------------------------------------------
Title: Solar limb flares and the yellow coronal line.
Authors: Dolder, Frederick P.; Roberts, Walter Orr
1953AJ.....58R..37D Altcode:
A list of all solar flares published in the I. A. U. Quarterly Bulletin
of Solar A clivity for 1946 through 1950, when treated by simple
statistical procedures, reveals an unmistakable degree of association
between flares that occurred within ~O of the solar limb and the 43
instances of occurrence in this period of the yellow coronal line
observed at Climax and Sacramento Peak. The probability for a number
of chance coincidences equal to or greater than the observed number
is less than 2 X I0-~. Additional evidences of association between the
yellow coronal line and solar prominences exist. Prominences associated
with this line showed, for example, decidedly more marked tendencies
towards downward motion and towards apparent inflow of material from
"space" than did prominences in general. The yellow line prominences
showed more tendency towards breaking up into scattered knots, and less
tendency towards formation of large stable masses than did prominences
chosen at random. The results combine to suggest that there is a strong
relationship between solar prominences of the character associated
with the yellow coronal line and areas of the sun exhibiting intense
coronal line emission in X5303 and X6374 of Fexiv and Fex. The work
reported here was supported by the Office of Naval Research. High
Altitude Observatory, Boulder, Colo.
---------------------------------------------------------
Title: Continuous Solar Survey, Cinematography, and Electronic
Sun-Follower
Authors: Roberts, Walter Orr
1953sun..book..653R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Recent studies of chromospheric spicules.
Authors: Rush, J. H.; Roberts, W. O.
1953AJ.....58R.226R Altcode:
Two film sequences of spicules at the south polar zone of the sun,
taken in 1949 with the Climax coronagraph in Ha, were analyzed. These
films were run at 6 frames/min. for a combined duration of 92 min. Both
films agreed on an upper limit of 22,000 spicules having lifetimes
of 0.3 min. or greater on the entire sun at a given time, assuming
uniform distribution. The lifetimes of 400 spicules were determined,
but could not be corrected for the effects of spatial distribution in
the line of sight. The number of spicules having a given lifetime was
inversely proportional to the lifetime. The mean lifetime was about 4
min., confirming an earlier result.1 Nearly all spicules were radial
to the sun. Upward speeds of 64 spicules ranged widely about a mean
of 32 km/sec. Apparent downward displacements were observed in many
cases, at speeds loosely correlated with upward speeds. Whether
apparent descent represented return of material or progressive
fading of intensity is not known. The coefficient of correlation
between maximum heights and upward speeds was 0.7. Neither heights
nor upward speeds were significantly correlated with lifetimes. The
spicules occurred randomly in time. The data suggested correlation
of some characteristics with latitude; but any such relations were so
intermingled with observational and other selection factors that they
could not be verified. The film reductions for this study were carried
out by a group under the direction of Dr. Z. Kopal at the Massachusetts
Institute of Technology. The research was supported in part by the
Office of Naval Research;the National Bureau of Standards, Research
Corporation, and the Radio Corporation of America. I.W. 0. Roberts,
Ap. J. 101, 136, 1945. High Altitttde Observatory, Boulder, Colo.
---------------------------------------------------------
Title: Sunspot Prominences and the Yellow Coronal Line.
Authors: Roberts, Walter Orr
1952ApJ...115..488R Altcode:
A study of twenty-five cases of bright emission of the yellow coronal
line X 5694, from 1946 through 1951 revealed close association between
this emission and fast-moving prominences of the "sunspot" type. It
also showed that unusually sharp discontinuities and intensifications
of the red coronal line X 6374 occurred at the regions where the yellow
coronal line was seen. In a few cases small Doppler effects in X 6374
also appeared at the solar-limb position of the X 5694 emission. The
observations lead to the preliminary speculation that the source of
the emission corona lies in a few, relatively small, active regions
scattered over the solar disk.
---------------------------------------------------------
Title: Sunspot prominences and the yellow coronal line.
Authors: Roberts, Walter Orr
1951AJ.....56Q.138R Altcode:
The results are given for part of a research program now in
progress. Twenty-five cases of the occurrence of bright emission of
the yellow coronal line 5694 A have been studied thus far. Of these,
a preponderance shows the coronal line to be closely associated with
sunspot prominences exhibiting unusually high activity and large
velocities. Some speculations are given regarding the possible
relationship of the yellow coronal line emission to the outbreak
of solar flares. High Altitude Observatory, Harvard University, and
University of Colorado, Climax, Colo,
---------------------------------------------------------
Title: Solar activity at the time of the eclipse of September 12,
1950.
Authors: Roberts, Walter Orr; Trotter, Dorothy; Witte, Bruno
1951AJ.....56R..47R Altcode:
Solar coronal observations were carried out at the Climax and Sacramento
Peak coronagraph stations on the days preceding and following the
total solar eclipse visible at Attu Island, Alaska, on September 12,
1950. We combined these observations to get isophotal contour maps
of the sun's green line coronal emission for September I 1, 1950,
treating the data from each station independently. We also obtained
detailed prominence observations from both stations at times as
close to the eclipse date as possible. The coronal contour maps
show that there were intense green-line coronal emission zones near
the east limb in both hemispheres, and near the central meridian in
the northern hemisphere. The coronal intensities near the west limb
were relatively low. On the other hand, the total area of all limb
prominences of the west limb greatly exceeded the total area of all
east-limb prominences. Except for one region of the maps, the two
stations gave results that were reasonably concordant. In one area,
about three days west of the central meridian and about 250 north,
there were substantial disagreements of an unexplained origin. Some
evidence exists that this region was also one of unusually changeable
coronal emlssion. Solar flare observations could not be made at Boulder
on September II or 12 because of cloudy weather. However, September
was a month of generally lower solar activity than prevailed during
the earlier portions of the year. This Research was supported in part
by the Central Radio Propagation Laboratory of the National Bureau
of Standards and the Air Force Cambridge Research Laboratory. High A
ltitude Observatory, Boulder, Coto.
---------------------------------------------------------
Title: New observations of solar spicules.
Authors: Roberts, Walter Orr; Brenton, Virginia K.; Shapley, Martha
B.; Kopal, Zdenek
1950AJ.....55R..80R Altcode:
We have analyzed three coronagraph films taken to show the small
hydrogen prominences we have called spicules. The films were made with
a 4 A pass birefringent filter at Climax, Colorado. Two were taken in
December 1943; one in February 1946. The frequency distribution of
lifetimes shows that the spicules have very short mean lifetimes of
the order of two minutes for all the films. Mean ascent velocities
for the spicules on the 1946 film substantially exceed those
for the two 1943 films which have mean velocities which are close
together. Strong observational selection, however, affects all measures
of velocity. Moreover, we cannot be sure that the velocities typical of
the larger spicules represent the velocities of the far more frequent
smaller spicules which it is difficult to measure. However, the results
suggest a time-variation of the mean ascent velocity; this variation
may be in phase with general solar activity variations. High Altitude
Observatory, Boulder, Colo. andDepartment of Electrical Engineer~ng,
Massachusetts Institute of Technology, Cambridge, Mass.
---------------------------------------------------------
Title: Observation of Chromospheric Opacity
Authors: Roberts, Walter Orr
1950PASP...62..219R Altcode: 1950HarRe.341....1R
No abstract at ADS
---------------------------------------------------------
Title: Further Measures of Chromospheric Spicules
Authors: Roberts, Walter Orr; Brenton, Virginia K.; Shapley, Martha
B.; Kopal, Zdenek
1949PASP...61..160R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Association of Corona with Prominence.
Authors: Roberts, Walter Orr
1948ApJ...108..523R Altcode: 1948HarRe.317....1R
A coronal spectrogram, taken on June 14, 1947, shows a striking
association between X 6374 of the corona and X 6563 of an active
prominence; at the same position the rarely observed unidentified
coronal line X 5694 shows clearly. The positions of sharp maxima of the
prominence spectrum and of the coronal spectrum coincide precisely for
the two brightest parts of the prominence. Some likelihood appears to
exist that the occurrence of A 5694 is generally associated with the
occurrence at the same place on the sun of rapidly moving prominences
of the "sun-spot" type
---------------------------------------------------------
Title: Association of solar corona and prominence.
Authors: Roberts, Walter Orr
1948AJ.....54...48R Altcode:
A coronal spectrogram taken 011 14 J une 1947 showed a striking
association between ~6374 of the corona and X6563 of an active
prominence. At the same position, the rarely-observed unidentified
coronal line ~5694 showed clearly. The positions of sharp maxima of the
prominence spectrum and of the coronal spectrum coincided precisely for
the two brightest parts of the prominence. There is some likelihood that
the occurrence of X5694 is generally associated with the occurrence
at the same place on the sun of rapidly moving prominences of the
"sun-spot" type. On at least one occasion, significant line-ofsight
velocities have been observed in the coronal line ~6374, associated
with such "sun-spot type" prom in ences. High A ltitude Observatory
of Harvard University and University of Colorado, Climax, Colorado
---------------------------------------------------------
Title: Solar Activity
Authors: Roberts, Walter Orr
1948HarMo...7..299R Altcode: 1948cent.symp..299R
No abstract at ADS
---------------------------------------------------------
Title: The Correlation of Magnetic Disturbances with Intense Emission
Regions of the Solar Corona.
Authors: Shapley, A. H.; Roberts, W. O.
1946ApJ...103..257S Altcode:
Correlation analyses of coronal and magnetic data, during the
period August, 1942-July, 1944, show that, on the average, magnetic
disturbance occun~ed when intense emission regions of the solar corona
were situated in the eastern hemisphere of the visible solar disk. Some
specific comparisons are cited with regard to the correspondence of
coronal-emission regions and M-regions. Although there are some valid
criticisms of the methods of correlation used thus far, the results
demonstrate that a correla- tion does exist and that more refined and
complete analysis is indicated to realize fully the value of coronal
observations as applied to short-term forecasts of disturbance. The
observing procedure used at, the Coronagraph Station of the Harvard
College Observatory at Climax, Colorado, and the uncertainties of
observation are detailed in the appendix
---------------------------------------------------------
Title: A Preliminary Report on Chromospheric Spicules of Extremely
Short Lifetime.
Authors: Roberts, Walter Orr
1945ApJ...101..136R Altcode: 1945HarRe.271....1R
Small spikes of chromospheric material, observed in Ha with the
coronagraph and quartz-polaroid monochromator, are described. These
spicules, seen in polar regions of the sun, have very brief lifetimes,
amounting on the average to 4 or 5 minutes. The typical spicule is low
in brightness and has a height at maximum of less than 15 seconds of
arc. At least in polar regions, they appear to be present in greater or
smaller numbers at all times. The spicules are apparently distributed at
random in the polar regions stud- ied. The behavior of the spikes, while
well typed, exhibits considerable variation. Possible association with
polar coronal "plumes" and with "rice grains" of the disk is discussed
---------------------------------------------------------
Title: Preliminary Studies of the Solar Corona and Prominences with
the Harvard Coronagraph.
Authors: Roberts, Walter Orr
1943PhDT.........1R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On Possible Changes in the Solar “Constant”
Authors: Sterne, Theodore Eugene; Guthe, Karl Frederick; Roberts,
Walter Orr
1940PNAS...26..399S Altcode: 1940HarRe.203....1S
No abstract at ADS
