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Author name code: babcock
ADS astronomy entries on 2022-09-14
author:"Babcock, Horace W."
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Title: Zeeman effect in stellar spectra (Astrophysical Journal 1947)
Authors: Babcock, H. W.
1993inas.book..358B Altcode:
No abstract at ADS
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Title: The solar magnetograph (Astrophysical Journal 1953)
Authors: Babcock, H. W.
1993inas.book..373B Altcode:
No abstract at ADS
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Title: Adaptive Optics in Perspective
Authors: Babcock, H. W.
1992AAS...180.5701B Altcode: 1992BAAS...24..821B
No abstract at ADS
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Title: Optical Gyroscopes Applied to Telescopes
Authors: Babcock, H. W.
1991PASP..103..468B Altcode:
Optical gyroscopes mounted directly on a telescope can provide its
precise angular coordinates referred to the fundamental inertial
system. Tracking of a star can be accomplished by computing
continually in real time its changing apparent place and by applying
computer-generated corrections to the telescope to maintain coincidence
between the output of the gyros and the apparent place of the star. This
system circumvents mechanical imperfections of the mounting and drives
of the telescope, thereby promising significant cost reduction as well
as improved performance.
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Title: Optical Gyroscopes Applied to Telescopes
Authors: Babcock, H. W.
1991BAAS...23R.977B Altcode:
No abstract at ADS
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Title: Adaptive Optics Revisited
Authors: Babcock, Horace W.
1990Sci...249..253B Altcode:
From the earliest days and nights of telescopic astronomy, atmospheric
turbulence has been a serious detriment to optical performance. The new
technology of adaptive optics can overcome this problem by compensating
for the wavefront distortion that results from turbulence. The result
will be large gains in resolving power and limiting magnitude, closely
approaching the theoretical limit. In other words, telescopic images
will be very significantly sharpened. Rapid and accelerating progress
is being made today by several groups. Adaptive optics, together
with the closely related technology of active optics, seems certain
to be utilized in large astronomical telescopes of the future. This
may entail significant changes in telescope design.
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Title: Erratum: "Test for a magnetic field in the white dwarf 40
Eridani B" [Publ. Astron. Soc. Pac., Vol. 100, No. 633, p. 1299 -
1301 (1988)].
Authors: Babcock, H. W.
1989PASP..101..135B Altcode:
No abstract at ADS
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Title: Test for a Magnetic Field in the White Dwarf 40 Eridani B
Authors: Babcock, Horace W.
1988PASP..100.1299B Altcode:
This paper is reproduced from Publ. Astron. Soc. Pac., Vol. 60, p. 368 -
370 (1948) to celebrate the centenary of the Publications. See also
126.086.
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Title: Preliminary Design of an 8-Meter Pneumatic Telescope
Authors: Babcock, H. W.
1988ESOC...30...99B Altcode: 1988vltt.conf...99B; 1988vlti....1...99B
No abstract at ADS
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Title: Carnegie Institution of Washington Southern Observatory site
survey, 1963 - 68.
Authors: Babcock, H. W.; Irwin, J. B.
1987iopo.conf...99B Altcode:
The CARSO site-testing team investigated ten coastal mountains in
Chile between 27°S and 31°S; extended quantitative measurements
of the seeing were made on four of them. Data from 900 nights are
presented. High-level seeing between 29°S and 30,5°S was uniformly
good, averaging 0.8 arcsec. Excellent seeing (<0.55 arcsec) occurred
19% of the time. The selection of the 5-km-long Las Campanas ridge
with its four summits was based not only on the quality of the seeing
but on topography, logistics, and remoteness from artificial lights.
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Title: Diffraction gratings at the Mount Wilson Observatory
Authors: Babcock, Horace W.
1986PhT....39g..34B Altcode:
No abstract at ADS
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Title: Diffraction gratings at the Mount Wilson Observatory
Authors: Babcock, Horace W.
1986VA.....29..153B Altcode:
No abstract at ADS
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Title: Air-support concept for a large telescope
Authors: Babcock, H. W.
1985ApOpt..24.1248B Altcode:
The advantages that accrue to a large telescope mounting concept
in which air pressure is used to support over 250 metric tons, in
the case of a 7.5-m diameter primary mirror, are discussed. This air
support concept obviates the conventional external dome and accomodates
such comparatively long focal ratios as those in the f/3-4 range,
thereby yielding a less limited field and superior optical figuring and
collimation. The telescope is housed within a sphere, and manipulated
from below in either an altazimuth or equatorial mode. The cost of
a telescope of this design will compare favorably with other designs
recently proposed in the literature.
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Title: Instrumentation - the Du-Pont Telescope - Anta-Barbara
Computing Facility - Direct Image Tube Camera for Las-Campanas -
Infrared Photometer for the Swope Telescope - Infrared Fabry-Perot
Spectrometer - Prime-Focus Universal Extragalactic Instrument -
Authors: Babcock, H.; Brucato, R.; Kennicutt, R.; Persson, S.; Mould,
J.; Geballe, T.; Gunn, J.; Westphal, J.
1979haob.rept..777B Altcode:
No abstract at ADS
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Title: Requirements for ground-based telescopes.
Authors: Babcock, H. W.
1978otf..conf...37B Altcode:
Performance criteria for ground-based telescopes are enumerated. They
include: (1) the power to differentiate between the image of a faint
star and the image of a quasar, (2) resolution of fine structural
details within galaxies, and (3) in wide-field photography, the
capability of producing aberration-free star images of uniformly good
quality over the whole of the large plate. Since seeing is such an
important factor, one cannot overemphasize the importance of site
selection.
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Title: First Tests of the Irenee du Pont Telescope
Authors: Babcock, Horace W.
1977S&T....54...90B Altcode:
No abstract at ADS
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Title: Guest Investigators at the Hale Observatories
Authors: Babcock, Horace W.
1975PASP...87..639B Altcode:
No abstract at ADS
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Title: Guest Investigators at Hale Observatories
Authors: Babcock, H. W.
1974PASP...86..340B Altcode:
H. W. BABCOCK Hale Observatories
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Title: Guest Investigators at the Hale Observatories
Authors: Babcock, H. W.
1973PASP...85..476B Altcode:
H. W. BABCOCK Hale Observatories
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Title: Guest Investigators at the Hale Observatories
Authors: Babcock, H. W.
1972PASP...84..596B Altcode:
H. W. BABCOCK Hale Observatories
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Title: General Magnetic Field of the Sun
Authors: Sugiura, M.; Heppner, J. P.; Boldt, E.; Babcock, H. W.;
Howard, R. F.
1972AIPH....5..304S Altcode:
No abstract at ADS
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Title: Guest Investigators at the Hale Observatories
Authors: Babcock, H. W.
1971PASP...83..375B Altcode:
No abstract at ADS
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Title: Notice: Guest Investigators at the Hale Observatories
Authors: Babcock, H. W.
1971BAAS....3..413B Altcode:
No abstract at ADS
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Title: The Las Campanas Observatory
Authors: Babcock, H. W.
1971cltd.conf...37B Altcode:
No abstract at ADS
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Title: Guest Investigators at the Hale Observatories
Authors: Babcock, H. W.
1970PASP...82..927B Altcode:
No abstract at ADS
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Title: NOTICE Guest Investigators at the Hale Observatories
Authors: Babcock, H. W.
1970BAAS....2..280B Altcode:
No abstract at ADS
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Title: Guest Investigators at the Mount Wilson and Palomar
Observatories
Authors: Babcock, H. W.
1969PASP...81..447B Altcode:
No abstract at ADS
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Title: Guest Investigators at the Mount Wilson and Palomar
Observatories
Authors: Babcock, H. W.
1968PASP...80..235B Altcode:
No abstract at ADS
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Title: Guest Investigators at the Mount Wilson and Palomar
Observatories
Authors: Babcock, H. W.
1968AJS....73..159B Altcode:
Yellow and blue photoelectric light curves have been obtained for
the eclipsing system BR Cygni. A new value of the period has been
determined. Orbital elements are derived and a computed light curve is
found to compare very well with the yellow observations. A peculiar
difference is noted between the yellow and blue light curves at
primary minimum.
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Title: Optical Astronomy in Perspective
Authors: Babcock, Horace W.
1967ASPL...10...89B Altcode: 1967ASPL..462.....B
No abstract at ADS
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Title: Optical Astronomy in Perspective
Authors: Babcock, Horace W.
1967Sci...156.1317B Altcode:
No abstract at ADS
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Title: Guest Investigators at the Mount Wilson and Palomar
Observatories
Authors: Babcock, Horace W.
1967PASP...79..262B Altcode:
No abstract at ADS
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Title: Concentration of Elements Over the Surface of a Magnetic Star
Authors: Babcock, Horace W.
1967mrs..conf...97B Altcode:
No abstract at ADS
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Title: The Zeeman effect in astrophysics
Authors: Babcock, Horace W.
1967Phy....33..102B Altcode:
George E. Hale discovered the Zeeman effect in sunspot spectra in 1908,
and derived the laws of sunspot polarity. Recent observations of the
much weaker (1 to 50 gauss) magnetic fields of the solar photosphere,
made with the solar magnetograph, are described. The bearing of these
results on circulation in the sun and their consequences for the
topology of the sun's magnetic field are mentioned, with reference to
the solar cycle and to reversal of the sun's polar field. The problem
of measuring the magnetic field of stars is outlined, with reference
to instrumental requirements. Spectrographs and crystals are described,
together with techniques of measurement of magnetic fields in sharp-line
stellar spectra. Results of a systematic program of observations with
the 100-inch and 200-inch telescopes are reviewed. All stellar magnetic
fields are variable; some are periodic. The strongest yet measured is
34 000 gauss. The magnetic variations are usually related to variations
in light, color, line width, and line intensity. Chemical abundance
anomalies are common in magnetic stars, and this has led to much work
on nuclear reactions in stellar atmospheres, but the phenomena have
not been satisfactorily explained. The possible importance of element
concentration through paramagnetic migration in strong magnetic field
gradients, enhanced by optical pumping, is pointed out.
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Title: The Solar Magnetic Cycle
Authors: Babcock, H. W.
1965ASSL....3....7B Altcode: 1965pss..conf....7B
No abstract at ADS
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Title: Stellar Magnetic Fields
Authors: Babcock, H. W.
1964PrCmg...3..393B Altcode:
No abstract at ADS
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Title: Measurement of Stellar Magnetic Fields
Authors: Babcock, H. W.
1964aste.book..107B Altcode: 1964S&SS....2..107B
No abstract at ADS
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Title: Instrumental Recording of Astronomical Seeing
Authors: Babcock, Horace W.
1963PASP...75....1B Altcode:
No abstract at ADS
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Title: Concentration Elements Over the Surface of a Magnetic Star.
Authors: Babcock, H. W.
1963ApJ...137..690B Altcode:
No abstract at ADS
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Title: Magnetic and Light Variations of 53 Camelopardalis
Authors: Babcock, Horace W.
1963PASP...75...74B Altcode:
No abstract at ADS
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Title: The Sun's Magnetic Field
Authors: Babcock, H. W.
1963ARA&A...1...41B Altcode:
No abstract at ADS
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Title: Photoelectric Recording of Astronomical Seeing.
Authors: Babcock, H. W.
1963AJ.....68Q.272B Altcode:
An instrument has been built and tested for objectively and continuously
monitoring the quality of astronomical seeing. A reticle in the
form of a fine grid or lattice is placed at the focus of a small
telescope, which is pointed at Polaris. Image tremor (imperfect seeing)
causes fluctuations of the light passing the reticle and entering a
photomultiplier, thus producing a Fourier frequency spectrum. (The
component due to scintillation can be distinguished by occasional
defocusing; it is generally of secondary importance.) The signal is
analyzed with the aid of an ac amplifier, bandpass filter, rectifier,
and recorder. Tests at Mount Wilson have shown that the instrument
discriminates well among various grades of seeing, and that it can be
calibrated by comparison with large telescopes.
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Title: The Solar Magnetic Cycle
Authors: Babcock, H. W.
1962IAUTB..11..419B Altcode:
No abstract at ADS
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Title: The Topology of the Sun's Magnetic Field and the 22-YEAR Cycle.
Authors: Babcock, H. W.
1961ApJ...133..572B Altcode:
Shallow submerged lines of force of an initial axisymmetric dipolar
field of 8 X 1021 maxwells are drawn out in longitude by the
differential rotation (after the suggestion of Cowling) to produce
a spiral wrapping of five turns in the north and south hemispheres
after 3 years. The amplification factor approaches 45, with a marked
dependence on latitude. Twisting of the irregular flux strands by
the faster shallow layers in low latitudes forms "ropes" with local
concentrations that are brought to the surface by magnetic buoyancy
to produce bipolar magnetic regions (BMR's) with associated sunspots
and related activity. The field intensity required for producing BMR's
is reached at progressively lower latitudes according to the derived
formula sin = + 1.5/(n + 3), where n is the number of years since the
beginning of the sunspot cycle. This accounts satisfactorily for 's law
and the Maunder "butterfly diagram." Sufficient flux rope for more than
102 BMR's is produced. "Preceding" parts of BMR's expand toward the
equator as they age, to be neutralized by merging; "following" parts
expand or migrate poleward so that their lines of force neutralize and
then replace the initial dipolar field. This process, which involves
severing and reconnection of lines of force in the corona, as well as
expulsion of flux loops, need be only 1 per cent efficient. The result,
after sunspot maximum, is a main dipolar field of reversed polarity. The
process repeats itself, so that the initial conditions are reproduced
after a complete 22-year magnetic cycle. This model accounts for Hale's
laws of sunspot polarity and provides a qualitative explanation of the
proponderance of "preceding" spots, of the forward tilt of the axes
of older spots, of the recurrence of activity in preferred longitudes,
and of Hale's chromospheric "whirls."
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Title: The 34-KILOGAUSS Magnetic Field of HD 215441.
Authors: Babcock, Horace W.
1960ApJ...132..521B Altcode:
The AOp star HD 215441 has a magnetic field sufficiently strong
and uniform to show distinct resolution of many spectrum lines
into the ir and components of their Zeeman patterns. The mean field
intensity derived from four plates is +34400+ 266 gauss. The field
fluctuates irregularly, but 20 plates all show the same polarity. Random
variations in radial velocity in the range +3.0 to -8.9 km/sec have been
observed. The degree of spectral peculiarity is not extreme, although
lines of Si ii, Ti ii, and Cr ii are strong, and the anomalous presence
of lines of Fe iii has been noted. Sharp lines of Ca ii, showing a
relatively weak Zeeman effect, are judged to arise in a circumstellar
cloud having an effective height of 1.2 stellar radii above the surface
and showing a mean outward velocity of S km/sec. The magneticenergy
density at the surface is 4.6 X 10 ergs/cm3, and the magnetic pressure
is sufficient to dominate over the gas pressure in the outer layers
of the star. If a 34-kilogauss field prevails throughout the interior,
the total internal magnetic energy is about 1041 ergs.
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Title: Magnetic Fields Associated with the Solar Flare of July
16, 1959.
Authors: Howard, Robert; Babcock, Horace W.
1960ApJ...132..218H Altcode:
Fourteen "fine-scan" magnetograms at intervals of 15 minutes were
obtained during the progress of a large solar flare on July 16,
1959. The pattern of magnetic fields associated with the flare
showed no changes other than minor effects attributable to seeing and
imperfections in scanning.
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Title: Test for Polarization in the Integrated Light of Sunspots
Authors: Babcock, Horace W.
1960PASP...72..204B Altcode:
No abstract at ADS
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Title: Need for Photoelectric Observations of Magnetic Stars
Authors: Babcock, Horace W.
1960PASP...72...53B Altcode:
No abstract at ADS
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Title: Stellar Magnetic Fields
Authors: Babcock, H. W.
1960stat.book..282B Altcode: 1960stat.conf..282B; 1960S&SS....6..282B
No abstract at ADS
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Title: Magnetic Field Associated with a Great Solar Flare
Authors: Howard, Robert; Cragg, Thomas; Babcock, Horace W.
1959Natur.184..351H Altcode:
AN unusually large solar flare, of intensity 3+, was observed at
Mount Wilson on July 16, 1959. The flare was in an active region
centered on the spot group at approximately 18° N., 29° W. It
showed a predominantly S-shaped or double spiral configuration, with
marked variations of relative intensity in its various parts. Visual
observations of the spectrum showed that the flare commenced abruptly
between 21.19 and 21.24 U.T.; maximum was between 22.01 and 22.13
U.T. Lines of Ca II, Na, He and H were observed to be in emission
for more than 1 hr.; the width of the Hα emission was greater than
6 A. Emission persisted in the lines of Ca II and of H until after
observations were terminated at 01.00 U.T. on July 17.
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Title: Magnetic Fields of the A-Type Stars.
Authors: Babcock, Horace W.
1958ApJ...128..228B Altcode:
A discussion of rotational line broadening in the spectra of A-type
stars tends to confirm the view that strong coherent magnetic fields
are a property of all rapid rotators having convective zones but
that fields are observable only in the small proportion of such
stars that happen to be observed nearly pole-on. The A stars with
observable fields are classed as a-variables (showing periodic magnetic
variations); p-variables (irregular magnetic variations with reversal
of polarity); -variables (irregular magnetic fluctuations without
reversal of polarity); and variables (erratic spectrum variables with
irregular magnetic variations). All groups have "peculiar" spectra
(abundance anomalies), undoubtedly arising from magnetic activity. The
magnetic fluctuations must occur through intrinsic magnetohydrodynamic
motions of the stellar material that carries the magnetic lines of
force. Irregular atmospheric mixing in the p- and roups results in
peculiar spectra but relatively invariant line intensities; a higher
degree of organization in the magnetically periodic a-variables results
in peculiar spectra with synchronous variations in line intensity A
basic physical process must underlie the extraordinary properties of
the typical a-variables: they show large-amplitude, nearly symmetric
magnetic reversals in periods ranging from 4 to 9 days; they display
selective variations in line intensity, as well as the crossover effect
and variations in luminosity The proposal is made that this process
is a vastly amplified and accelerated magnetohydrodynamic oscillation
analogous to the 22-year solar magnetic cycle An alternative model,
the oblique rotator, is also discussed
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Title: Stellar Magnetic Fields
Authors: Babcock, H. W.
1958IAUS....6..161B Altcode:
No abstract at ADS
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Title: Photospheric Magnetic Fields
Authors: Babcock, H. W.; Babcock, H. D.
1958IAUS....6..239B Altcode:
No abstract at ADS
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Title: A Catalog of Magnetic Stars.
Authors: Babcock, Horace W.
1958ApJS....3..141B Altcode: 1957ApJS....3..141B
This is a catalog of magnetic stars with a compilation of numerous
observations. The analysis and discussion of the results will be taken
up in a later paper. The observations have been made over a period of
11 years with the 100-inch and 200-inch telescopes, using an analyzer
for the Zeeman effect. Table 1 lists repeated observations of 89
sharp-line stars. Ma etic polarity, field strength, and velocity
are tabulated. Notes on spectral peculiarities and line widts are
given. Table 2 lists 66 stars that probably, but not definitely, show
the Zeeman effect. Table 3 consists of 61 sharp-line stars not showing
evidence of a coherent magnetic field. Table 4 is a collection of 122
stars with lines too broad to permit measurement. Of the magnetic
stars in Table 1, one is a cluster-type variable, 1 is a subdwarf,
2 are of type S, 3 are M giants, 7 are "metallic4ine" objects, and
70 are A-type stars with sharp or ultra-sharp lines. Stellar magnetic
fields are therefore probably ubiquitous. All stellar magnetic fields
appear to be variable. Of the A-type stars sufficiently observed, S
are regnlar magnetic variables having periods near 1 week, very large
and nearly uniform magnetic amplitude, and nearly symmetrical reversal
of polarity; about 22 are irregnlar variables showing reversal of
polarity; and about 15 are irregnlar variables showing always the same
polarity. The irregnlar variations prove that large-scale intrinsic
hydromagnetic fluctuations occur in the photospheric layers.
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Title: Identification of Solar "m" Regions with Unipolar Magnetic
Regions.
Authors: Babcock, H. W.
1957ApJ...126..224B Altcode:
No abstract at ADS
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Title: The Magnetic Variable HD 71866.
Authors: Babcock, Horace W.
1956ApJ...124..489B Altcode:
Sixty-one spectrograms made with the differential analyzer for
the Zeeman effect have been measured in a study of the magnetic
variations of this peculiar A-type star. The strong magnetic field (H
= 2 kilogauss; Hp = 6 kilogauss) shows nearly symmetrical reversals
of polarity in a period of about 6.8 days that is probably slightly
irregular; irregularities in amplitude also occur. The lines of Eu ii
under- go moderate variations in intensity in phase with the magnetic
variations, but the spectrum variability is of much lower degree than
that of HD 125248 Velocity measurements yield only random fluctuations
within a range of several kilometers per second, without definite
evidence for harmonic variations. The star may be classed along with
a2 CVn, HD 153882, and HD 125248 as one of a small group of regularly
reversing magnetic variables of large and nearly equal amplitude,
all of which have periods of about 1 week. The crossover effect on
the line profiles in polarized light is unusually prominent for Fe I
but is much less so for lines of ionized elements. On the reasonable
assumption that the visibility of the effect is near maximum owing to
a matching of the Zeeman displacements by Doppler displacements for two
hypothetical areas of opposite magnetic polarity, the matching velocity
is derived from several lines of Fe I; it is about S km/sec. On the
"rotator niodel" this leads to a V (axial rotation) of 3.5 km/sec,
whereas an AO star with a period of axial rotation of 6.8 days should
have V = 16 km/sec. Furthermore, the line widths in HD 71866, by direct
measurement, are appreciably narrower than would be indicated by the
rotator model
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Title: An Improved Automatic Guider
Authors: Babcock, H. W.; Rule, B. H.; Fassero, J. S.
1956PASP...68..256B Altcode:
No abstract at ADS
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Title: Magnetic Field of RR Lyrae
Authors: Babcock, Horace W.
1956PASP...68...70B Altcode:
No abstract at ADS
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Title: Association of a "Unipolar" Magnetic Region on the Sun with
Changes of Primary Cosmic-Ray Intensity
Authors: Simpson, J. A.; Babcock, H. W.; Babcock, H. D.
1955PhRv...98.1402S Altcode:
A new instrument for observing weak magnetic fields on the photosphere
of the sun has recently revealed the presence of an unusual area on the
solar surface which may be called a "unipolar" magnetic (UM) region
because the field is of one sign and no magnetic flux has been found
returning to the sun. A region of this type was observed at central
solar meridian on seven consecutive solar rotations in 1953. In the
present paper it is shown that there is a striking association of this
UM region with (1) times of maximum primary cosmic ray intensity as
measured by neutron detectors and an ionization chamber, and with (2)
the recurring geomagnetic storms-the geomagnetic disturbances being
most pronounced ~3-4 days after both the central meridian passage of
the UM region and the time of maximum cosmic-ray intensity.
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Title: The Sun's Magnetic Field, 1952-1954.
Authors: Babcock, Horace W.; Babcock, Harold D.
1955ApJ...121..349B Altcode:
More than 450 magnetograms, showing the distribution, intensity,
and polarity of weak magnetic fields (> 0.3 gauss) on the sun have
been obtained with the solar magnetograph over a two-year period. This
interval includes the recent minimum of solar magnetic activity. The
records show a pattern with a fluctuating fine structure and certain
large-scale regularities. General magnetic fietd.-Consistent evidence
is found for a general field, predominantly dipolar, with polarity
opposite to that of the earth. The mean intensity is of the order of 1
gauss. The general field is usually limited to heliographic latitudes
greater than about t 550; it has a varying fine structure and shows
remarkable random fluctuations in effective intensity and extent. There
seems to be no prevailing obliquity between the magnetic and rotational
axes. The total flux is estimated to be nearly 10 maxwells. Bipolar
magnetic (BM) regions.-In the lower latitndes the stronger magnetic
effects appear as contiguous areas of opposite magnetic polarity,
as if loops of a submerged toroidal field were occasionally brought
to the surface by rising material. The BM regions obey Hale's laws
of sunspot polarity, but spots are comparatively rare, occurring,
when at all, within the BM regions while they are young. Ca ii
plages are observed where the field intensity is greater than about
2 gauss. Hydrogen filaments occur around the borders of BM regions
or, alternatively, seem to divide the region into parts of opposite
polarity. As the regions age, they generally expand, showing a decrease
in field intensity, and disintegrate until lost in the background of
irregular weak fields. There is much diversity in total magnetic flux,
duration, area, and course of development. Unipolar magnetic (UM)
regions.-Occasional extended magnetic areas of only one outstanding
polarity were recognized. The most prominent UM region of 1953 had an
intensity 3 gauss and a duration of many months; it may well have been
related to a prominent sequence of 27-day-recurrent terrestrial magnetic
storms. UM regions may be remnants of disintegrating BM regions. We
suggest that UM regions may be identified as the heretofore hypothetical
"M" regions of Bartels. Repeated tracings of the same area of the sun
at intervals of a few minutes show changes of the order of 1 gauss
in the fine structure of the magnetic pattern within a half-hour. The
observations provide objective evidence for the heretofore inferential
hypothesis that magnetic fields are fundamental to sunspots, plages,
prominences, chromospheric fine structure, bright coronal emissions,
and, probably, regions of strong radio emission. Several solar
phenomena can be synthesized on the proposition that neutral but
ionized corpuscular streams are continually being ejected from all
turbulent regions of the surface characterized by coherent magnetic
fields of average intensity gauss or more. A hydromagnetic model,
based on chromospheric spicules, is proposed for such ejection.
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Title: Book Reviews: Astronomical Photoelectric Photometry
Authors: Babcock, Horace W.
1954SciMo..79...61W Altcode:
No abstract at ADS
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Title: The Magnetic Variable HD 188041.
Authors: Babcock, Horace W.
1954ApJ...120...66B Altcode:
Fifty-seven observations of the magnetic field of HD 188041 have been
made at intervals during the last seven years. The field is always
of positive polarity but varies between the extreme limits 600 and
4800 gauss, with some irregnlarities in amplitude, in a period of 226
days The star is also a spectrum variable in which lines of Eu rr,
Gd ii, and Sr ii are stronger when the field is strong; the phase of
the intensity-curve for Gd ii is earlier than the magnetic curve by
about 0.1 of the period. When the field is increasing most rapidly, Gd
ii shows a stronger magnetic-field intensity than do other elements,
and Fe II shows a stronger field than Fe I. The velocity shows small
random fluctuations.
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Title: The Polarity of the Sun's Magnetic Field and the
Richardson-Schwarzschild Oscillation.
Authors: Babcock, Horace W.
1954ApJ...119..687B Altcode:
No abstract at ADS
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Title: Stellar Wave Lengths of EU II as Affected by Hyperfine
Structure.
Authors: Babcock, Horace W.
1954ApJ...119..463B Altcode:
No abstract at ADS
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Title: The flash spectrum without eclipse
Authors: Babcock, H. W.
1953Obs....73..241B Altcode:
No abstract at ADS
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Title: The Solar Magnetograph.
Authors: Babcock, Horace W.
1953ApJ...118..387B Altcode:
A new instrument for measuring and recording weak magnetic fields
on the surface of the sun has been developed for use with the
150-foot solar telescope and 75-foot spectrograph of the Hale Solar
Laboratory. Principal features include: a superior grating of high
resolving power for use in the fifth-order spectrum; an electro-o tic
analyzer for polarization; a double-slit detector for the longitudinal
Zeeman effect; and a self-sync ronous system by which the disk of
the sun is scanned in a raster of parallel traces, the results as
to magnetic intensity and polarity being presented conformally on
the screen of a cathode-ray tube and recorded by a camera. The noise
level (about 0.1 gauss) is such that fields of the order of 1 gauss
can be recorded readily. The method of calibration is described,
and the possibility is pointed out of using the instrument, with a
slight optical modification, for studying small Doppler shifts in the
sun's atmosphere.
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Title: The Possibility of Compensating Astronomical Seeing
Authors: Babcock, H. W.
1953PASP...65..229B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic Observations of HD 188041 and HD 133029
Authors: Babcock, Horace W.
1953PASP...65..194B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Mapping the Magnetic Fields of the Sun
Authors: Babcock, Horace W.; Babcock, Harold D.
1953sun..book..704B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Magnetically Variable Star HD 153882.
Authors: Gjellestad, Guro; Babcock, Horace W.
1953ApJ...117...12G Altcode:
The reversing magnetic field of the peculiar A-type star HD 153882 has
been investigated on twenty spectrograms made with the double analyzer
for circularly polarized light. The effective magnetic field intensity
at the pole, H , as determined from measures of the Zeeman effect on
about thirty jines on each plate, varies periodically between the limits
t4SOO gauss and - 4000 gauss. The derived period is 6.005 days. Measures
of Hp and of radial velocity have been tabulated for elements at various
phases. The mean velocity-curve is anharmonic, with a range of 5.3
Irm/sec. Systematic velocity differences between elements are small;
this is probably related to the fact that the spectrum shows little or
no variability in relative line intensities. The spectrum is peculiar
in that Cr I, Cr Ir, and Mn I are strong, and the K line is sharp,
but the star is not a typical spectrum variable. A cross-over effect
in the polarized line profiles, rather similar to that previously
found in lID 125248 and in a2 CVn, was observed at phases when the
effective magnetic field is near zero.
---------------------------------------------------------
Title: General magnetic fields in the Sun and stars (Report on
progress of astronomy)
Authors: Babcock, H. W.; Cowling, T. G.
1953MNRAS.113..357B Altcode:
Since the early work of G. E. Hale (x, 2) a number of attempts have
been made to detect and measure the general magnetic field of the
Sun. Also magnetic fields on a large scale have been observed in a
variety of stars. The first part of this report (by H.W.B.) will give
a brief survey of the observational work on such fields. Theories of
the fields will be briefly discussed in the second part (by T.G.C.).
---------------------------------------------------------
Title: Mapping the Magnetic Fields of the Sun
Authors: Babcock, Horace W.; Babcock, H. D.
1952PASP...64..282B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Magnetically Variable Star HD 153882
Authors: Gjellestad, Guro; Babcock, Horace W.
1952PASP...64..226G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Variable Magnetic Field of α^{2} Canum Venaticorum.
Authors: Babcock, Horace W.; Burd, Sylvia
1952ApJ...116....8B Altcode:
This well-known peculiar star is found to have a strong magnetic
field, the polarity of which is reversed in step with the periodic
changes in line intensity. The Zeeman effect has been investigated on
twenty-one spectrograms made with the double polarizing analyzer. Polar
magnetic-field strength and radial velocity for various elements have
been tabulated as a function of phase in the period of 5.5 days. The
extremes of Hp are approximately -4000 gauss when the Eu ii lines are
at maximum intensity and +5000 gauss a half-period later, when Cr ii
is at maximum.
---------------------------------------------------------
Title: Magneto-hydrodynamic oscillations of a star
Authors: Gjellestad, G.; Babcock, H. W.
1952AnAp...15..276G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Stellar magnetism.
Authors: Babcock, H. W.
1951AJ.....56..116B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Magnetically Variable Star HD 125248.
Authors: Babcock, Horace W.
1951ApJ...114....1B Altcode:
The reversing magnetic field of the peculiar A-type star HD 125248 =
BD - has been investigated on twenty-seven high-dispersion spectrograms
made with the double analyzer for circularly polarized light. The
magnetic-field intensity at the pole, Hp, as determined from the Zeeman
effect on numerous Fraunhofer lines, has been tabulated for several
elements at different phases in the 9.295-day period found by Deutsch
for the variations in line intensity. The lines of Fe I, Fe ii, and Ti
ii, which vary only slightly in intensity, indicate a field represented
by Hp = 2000 + 6600 cos 0-1600 cos 20 gauss. The positive extreme (+7000
gauss) is reached near zero phase, when the lines of the rare earths are
at maximum intensity and lines of Cr I and Cr ii are at minimum. The
negative extreme (-6200 gauss) is reached at mid-period when Eu ii is
weak and Cr is at maximum intensity. Hp determined from the Cr lines is
"more negative" than that indicated by Fe-Ti, while, especially at the
"cross-over" phases (0.35 and 0.7, when Hp = 0), Eu ii gives a stronger
positive field. If results from all elements are averaged, the extremes
are close to +7600 and - 7600 gauss. Velocities in the line of sight
are also tabulated for elements at various phases. Again, systematic
differences are found between the Fe-Ti group, the rare-earth group,
and Cr. Rather sudden decelerations occur just as 11p reaches maximum. A
"cross-over effect" on the profiles of Fraunhofer lines was discovered
on plates made near phases 0.35 and 0.7. This is interpreted as a
combination of differential velocity and temporary opposite magnetic
polarity on two zones of the star; apparently, the magnetic field
reverses in a rapid, progressive manner over the surface. The rare
earths and Cr seem to be concentrated in separate atmospheric zones,
which vary in effective size or location; Fe and Ti are supposed to be
rather uniformly distributed and to represent best the general magnetic
field. Two fundamentally different physical models are considered:
the magnetic oscillator and the oblique rotator. The latter does
not satisfactorily represent the observations. Consequently, it is
concluded that HD 125248 is observed pole-on and that it is oscillating,
perhaps in a manner suggested by Schwarzschild, for only by large-scale
motions of the material of the star can rapid changes of the magnetic
field be explained. In his solution (odd mode), specialized pulsations
of the star are coupled with an oscillating dipole component of the
field. The constant component (+2000 gauss) indicated by Fe-Ti can
perhaps be interpreted most plausibly according to the Elsasser-Bullard
theory, although the observations yield no data as to rate of axial
rotation (or as to differential rotation). For lack of these data the
electromotive forces in the atmosphere cannot be specified completely;
however, the oscillating component of the electric field induced by
the changing magnetic field is specified in Schwarzschild's solution
(for a nonconducting atmosphere). This has an an plltude at the equator
of 36 volts/cm. To account for the varying equivalent widths of lines,
it is assumed that the effective atmospheric Eu and Cr have become
concentrated in zones, Eu near the poles, Cr in an equatorial belt,
and that the extent of these zones varies as the star oscillates. As a
tentative approach to this separation of elements, a mass-spectrograph
effect is considered, depending upon the transient differential drift
velocities of ions, as a function of charge/mass, in crossed electric
and magnetic fields.
---------------------------------------------------------
Title: The ruling of diffraction gratings at the Mount Wilson
Observatory.
Authors: Babcock, Harold D.; Babcock, Horace W.
1951AJ.....56Q.120B Altcode:
The newer ruling engine of the Mount Wilson Observatory is now producing
sizeable diffraction gratings of high quality in all respects. Several
recent gratings are 7~41 inches wide with grooves 543 inches long,
and one is 8 by 5~' inches. Curved-edge ruling diamonds, developed
here, have been used in blazing these gratings to specifications for
astronomical use. High luminous efficiency is combined with practically
complete absence of scattered light, either general or local in
the spectrum. Resolving power of 500,000 is achieved. Rowland ghost
intensity is held to about 0.00004 in the first order of 15,000 line
per inch rulings and is negligible. Most ruling to date has been at
300, 400, 600, or 900 grooves per millimeter, but other spacings are
available. The rather considerable modifications of the Rowland-type
engine are described, with particular reference to the monorail
diamond carriage, the coupling of the nut to the grating carriage, the
end-thrust bearing of the screw, the use of Xitralloy steel ways, and
the spacing mechanism. That the principles of this entirely mechanical,
single-screw machine are thoroughly sound is attested by the quality
of its products. Blazed plane gratings have almost entirely supplanted
prisms in fast stellar spectrographs of both short and long focus. Our
methods of testing gratings are outline~ and a formula is proposed for
the evaluation of gratings. Mount Wilson and Palomar Observatories,
Pasadena, Ca 1sf.
---------------------------------------------------------
Title: The Strong Magnetic Field of HD 133029
Authors: Babcock, Horace W.; Burd, Sylvia
1951PASP...63...81B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic Field of a Late-Type Star, HD 4174
Authors: Babcock, Horace W.
1950PASP...62..277B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Stellar Magnetic Fields
Authors: Babcock, H. W.
1950Natur.166..249B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Contour Photometer
Authors: Babcock, H. W.
1950PASP...62...18B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Three Magnetic Variable Stars Showing Reversal of Polarity
Authors: Babcock, H. W.
1949PASP...61..226B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Stellar magnetic fields and rotation
Authors: Babcock, H. W.
1949Obs....69..191B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic Intensification of Stellar Absorption Lines.
Authors: Babcock, Horace W.
1949ApJ...110..126B Altcode:
The total intensity of a saturated absorption line may be increased
several fold in a magnetic field of a few kilogauss because the Zeeman
pattern may be considerably wider than the thermal Doppler profile. The
effect should be particularly marked for lines having wide, anomalous
Zeeman patterns of many components; it is enhanced for elements of
high atomic weight at reduced temperatures and in the ab- sence of
turbulence. An upper limit to the intensification factor is half the
number of components in the Zeeman pattern of the line. A method is
developed for computing the magnetic intensification, W~/W0, for a
saturated line of given pattern in integrated light of a star viewed
from the direction of the pole (i = 00) or viewed from the plane of
the star's equator (~ = 90°). For the line Fe i X 4260, having a
triplet pattern (Z = 1.60), W~/Wo = 1.25 for a field of 8 kilogauss
and a temperature of 10,000°. The intensification factor appears to be
essentially independent of i; it may approach 7 for an exceptional line
like Eu ii X 4205, which has 21 widespread components. If equivalent
widths can be measured, it should be possible in principle to estimate
stellar magnetic field strengths by detailed comparisons of lines
se]ectively intensified by Zeeman splitting, even if pronounced
rotational broadening is present. In a number of the peculiar stars
of type A, magnetic fields ranging up to several kilogauss have been
measured with the polarizing analyzer; the conclusion is practically
inescapable that magnetic intensifica- tion must contribute to the
abnormal line intensities in the spectra of some of these stars. For
about fifty lines in the spectrum of a2 CVn, for which intensity
estimates at three phases of the spectral variation have been published
by Struve and Swings, the degree of observed intensity variation is
compared with the magnetic intensification factor predicted from the
Zeeman patterns; a satisfactory correspondence is found. I. INTRODUCTIO
---------------------------------------------------------
Title: Test for a Magnetic Field in the White Dwarf 40 Eridani B
Authors: Babcock, Horace W.
1948PASP...60..368B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Magnetic Field of γ Equulei.
Authors: Babcock, Horace W.
1948ApJ...108..191B Altcode:
The present status of the observational work on stellar magnetic
fields determined through analysis of the Zeeman effect is briefly
summarized. The strongest fields have been found in the peculiar stars
of types A and early F, particularly in the spectrum variables. Some
of the magnetic fields are variable. In y Equulei, however, there is
no conclusive evidence that the field varies; measures of forty-seven
lines on each of four or five plates of dispersion 2.9 A/mm give H~ =
1900 ± 250 (p.e.) gauss. The magnetic polarity observed is positive
in y Equ, negative in 78 Virginis. Magnetic moment and rotation in
`y Equ are probably antiparallel, as in the earth. Lines of medium and
strong intensity yield a somewhat smaller H~ than do weak lines. This
result is interpreted as the effect of the curve of growth on the Zeeman
components of the stronger lines. * The proportionality between magnetic
moment and angu'ar momentum is briefly discussed, with consideration
of variable fields. INTRODUCTIO
---------------------------------------------------------
Title: Magnetic Intensification of Absorption Lines
Authors: Babcock, Horace W.
1948PASP...60..245B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic Variable Stars as Sources of Cosmic Rays
Authors: Babcock, Horace W.
1948PhRv...74..489B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Photoelectric Guider for Astronomical Telescopes.
Authors: Babcock, Horace W.
1948ApJ...107...73B Altcode:
A new and simple method of optical scanning with a rotating knife-edge,
in combination with the modern electron multiplier phototube, makes
practicable for the first time an automatic device for guid- ing
astronomical telescopes. A comparatively simple guider, working in both
right ascension and declina- tion and employing a single phototube,
is performing satisfactorily in guiding the 100-inch reflector for
high-dispersion spectrographic work. T1~e instrument compensates for
fluctuations in the apparent posi- lion of the star due to "seeing"
and for residual errors in the driving mechanism of the telescope
---------------------------------------------------------
Title: No. 739. A photoelectric guider for astronomical telescopes.
Authors: Babcock, Horace W.
1948CMWCI.739....1B Altcode: 1948QB4.M93n739....
No abstract at ADS
---------------------------------------------------------
Title: An Automatic Guider for Astronomical Telescopes
Authors: Babcock, Horace W.
1947RScI...18..854B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Reversing Magnetic Field of BD-18°3789
Authors: Babcock, Horace W.
1947PASP...59..260B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic Fields of Astronomical Bodies
Authors: Babcock, Horace W.
1947PhRv...72...83B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Remarks on Stellar Magnetism
Authors: Babcock, Horace W.
1947PASP...59..112B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Zeeman Effect in Stellar Spectra.
Authors: Babcock, H. W.
1947ApJ...105..105B Altcode:
Some stars of early spectral type which exhibit sharp metallic lines
may be in rapid rotation, with their axes directed nearly toward the
observer. On the possibility that strong magnetic fields are corre-
lated with rapid rotation in such objects, the Zeeman effect for a
normal triplet line, as observed through a circular analyzer, has
been integrated over the visible hemisphere of the star. Reasonable
assumptions are made regarding field distribution and limb darkening. It
is found that the integrated Zeeman effect for a normal triplet should
give a displacement of about 3 X 106 A/gauss at A 4600. Observations of
the star 78 Vir (type A2p), made with a differential circular analyzer
in front of the slit of the coudé spectrograph of the 100-inch
telescope, show displacements of the metallic absorption lines that
are interpreted as a Zeeman effect resulting from a general magnetic
field having a strength of 1500 gauss at the pole. The control star ~
Peg (type KO) shows no effect
---------------------------------------------------------
Title: No. 727. Zeeman Effect in stellar spectra.
Authors: Babcock, H. W.
1947CMWCI.727....1B Altcode: 1947QB4.M93n727....
No abstract at ADS
---------------------------------------------------------
Title: The Spectrum of Zcamelopardalis and of Other U Geminorum-Type
Variables
Authors: Elvey, C. T.; Babcock, H. W.
1946PAAS...10...51E Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Spectra of U Geminorum Type Variable Stars.
Authors: Elvey, C. T.; Babcock, H. W.
1943ApJ....97..412E Altcode:
Spectrograms of several U Geminorum variable stars and of a few related
objects have been obtained with the Cassegrain spectrographs on the
82-inch telescope. The linear dispersions varied from 75 A/mm to 340
A/mm at Hy. Descriptions of the spectra of the following objects are
given for one or more phases in their light-curves: UTJ Aqi, SS Aur,
SS Cyg, U Gem, X Leo, AY Lyr, RU Peg, STJ TJMa, TW Vir, RX And, Z Cam,
All Her, CN On, TZ Per, EY Cyg, CY Lyr, CO On, UX On, CL Sco, T Pyx, and
V Sge. A brief summary is given of the characteristics of the spectra
of the U Geminorum type of variable stars at minimum and maximum light
---------------------------------------------------------
Title: Development of the Coronaviser.
Authors: Babcock, H. W.
1942ApJ....96..242B Altcode:
The principles of the coronaviser are discussed, and an equation
is developed by means of which the performance of the instrument
can be predicted in terms of several disposable parameters. The
equation indicates that some degree of useful performance should be
attainable under favorable conditions. The original coronaviser of
Skellett was tested at the McDonald Observatory, but without positive
results. Following this, a new scanning mechanism, in combination
with an optical system of the Lyot type, was constructed. Tests of
this instrument have not been completed, but a report of progress is
given now, as the work must be laid aside for some time
---------------------------------------------------------
Title: Note: Remarks on the Spectra of Comets 1941c Paraskevopoulos-De
Kock) and 1941d (van Gent).
Authors: Elvey, C. T.; Swings, P.; Babcock, H. W.
1942ApJ....95..218E Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Spectrophotometric Study of the Light of the Night Sky
Authors: Babcock, H. W.; Johnson, J. J.
1941ApJ....94..271B Altcode:
A spectrophotometric comparison of the night sky and M ~ i shows
that the night sky is relatively much stronger than the nebula in
ultraviolet light and suggests that for nebular photography improved
contrast may be obtained by the use of a filter to remove ultraviolet
light. An extensive series of intensity measurements of night-sky
radiations shows that no marked varia- tions may be expected within a
single night, in the absence of polar auroras, but that on occasional
nights the sky is extraordinarily bright, thus greatly reducing the
efficiency of direct photography. If periods of unusual activity are
excepted, X 5577 and the red pair of lines at X 6300 and X 6364 seem
to vary lila com- plementary fashion throughout a given night, but
over longer intervals all radiations tend to vary similarly and together
---------------------------------------------------------
Title: The Spectrum of Comet Cunningham, 1940C.
Authors: Swings, P.; Elvey, C. T.; Babcock, H. W.
1941ApJ....94..320S Altcode:
Slit spectrograms of Comet Cunningham secured at the McDonald
Observatory reveal well-resolved ultraviolet bands due to OH and NH;
oniy the lines of low rotational quantum number are observed, as in
the case of CH. The abundances of OH and NH molecules seem to be of the
same order as that of CN. Each branch of the violet bands of CN has two
maxima, one corresponding to a rotational distribution for T - 400° K
and one corresponding to T 500 K. The tail bands of CN are absent. The
authors dis- cuss the variation with heliocentric distance of the
relative intensities of the vibrational transitions. The rotational
intensity distribution and the extension of the different bands in the
head have been investi- gated. The cometary bands of CH belonging to
the two electronic transitions, A2L~ -~ x211 (near X 4300) and B2»=~
-~ x211 (near X 3900), are described. The bands observed between X
4000 and X 4130 are dis- cussed but remain unidentified
---------------------------------------------------------
Title: La rotation de la Nébuleuse d'Andromède (Lick. Bull. 498,
oct. 1939)
Authors: Babcock, H. W.
1941C&T....57...91B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Interstellar Absorption Near the North Pole of Rotation.
Authors: Keenan, Philip C.; Babcock, Horace W.
1941ApJ....93...64K Altcode:
Revised spectral classes for B8-A~ stars north of +800 declination
confirm essentially the variation of interstellar absorption with
distance found by Stebbins, Huffer, and Whitford for these stars. The
total visual absorption, which is inappreciable for distances less
than 200 parsecs, increases to 0.3 mag. at 400 parsecs
---------------------------------------------------------
Title: Radiations of the Night Sky Photographed with a Grating
Authors: Babcock, Horace W.
1939PASP...51...47B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The rotation of the Andromeda Nebula
Authors: Babcock, Horace W.
1939LicOB..19...41B Altcode: 1939LicOB.498...41B
No abstract at ADS
---------------------------------------------------------
Title: Spectrographic Observations of the Rotation of the Andromeda
Nebula
Authors: Babcock, Horace W.
1938PASP...50..174B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the Rotation of the Andromenda Nebula.
Authors: Babcock, Horace W.
1938PhDT.........1B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Recent Observations of Solar Chromospheric and Disk Spectra
in the Infra-Red
Authors: Babcock, H. W.
1935PASP...47..321B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Some New Features of the Solar Spectrum
Authors: Babcock, H. D.; Babcock, H. W.
1934PASP...46..132B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Paschen Series of Hydrogen Lines in the Spectrum of the
Solar Chromosphere
Authors: Babcock, H. W.
1932PASP...44..323B Altcode:
No abstract at ADS
