%R 1995PASP..107....1T
%J-21
%T Astrophysics in 1994
%A VIRGINIA TRIMBLE and PETER J. T. LEONARD
%B 1994 was the year in which we saw the first images from the repaired Hubble Space Telescope; the probable detection
of a diffuse intergalactic medium, a black hole in M87, and an enormous primordial deuterium abundance; the discovery of
the first (and second) superluminal objects within our own galaxy; not to mention the demise of the Jovian dinosaurs.
But, as always, most astronomers continued to work away on the projects that have interested them for years or decades,
and we attempt also to report some progress in broader areas, including cooling flows, extragalactic globular cluster
populations, disk instabilities, phases of the interstellar medium, and brown dwarfs among microlenses and other
populations. Several sections of short items range from the obvious to the remarkable to the unbelievable. As in
previous years, the ordering of the topics attempts to preserve the near-to-far custom of elementary astronomy
textbooks.

%R 1995PASP..107...22H
%J-26
%T On the Nature of the Companion to HD 114762
%A ALAN HALE
%B The results of a recent study of coplanarity tendencies between stellar equatorial and binary orbital planes are
applied to the low-metal F9V star HD 114762, for which a possible substellar companion was reported by Latham et al.
(1989). High-resolution spectroscopy is performed on HD 114762 in order to extract its projected rotational velocity (v
sin i). This is then combined with an expected rotational velocity determined via age-scaling, providing an estimate of
the star's equatorial inclination, which when combined with the results of the coplanarity study provides an approximate
indication of the companion's orbital inclination. Although the former uncertainties in this process preclude an
accurate estimate of the companion's inclination, the results suggest that the inclination is low, possibly low enough
to force the companion's mass above the limit for hydrogen fusion. It is thus possible the companion may be nothing more
exotic than a low-mass M star, as opposed to a brown dwarf. These results add support to a similar conclusion recently
obtained by Cochran et al. (1991).

%R 1995PASP..107...27J
%J-31
%T The Gronbech-Olsen Photometry: Transformations to a Hyades-Coma System
%A MICHAEL D. JONER, BENJAMIN J. TAYLOR, and JOHN M. POWELL
%B In this paper, we consider the zero points of six sets of Stromgren-beta photometry. The color-index system to which
our results are referred is a "Hyades-Coma" system composed of photometry by Crawford and Perry (1966AJ.....71..206C) and
Barnes (1969AJ.....74..407C). For V magnitudes, we use measurements by Taylor and Joner (1992PASP..104..911T). Our
results are as follows: (1) The zero points of photometry by Gronbech and Olsen (1976A&AS...25..213G; 1977A&AS...27..443G)
are offset from those of the Hyades-Coma system. The offsets can amount to several mmag; they appear for V and all
color indices except beta, and depend on right ascension and (usually) declination. (2) These offsets can be applied to
photometry by Stetson (1991AJ....102..589S), who reduced his results to the Gronbech-Olsen system. After correction,
Stetson's results for a set of "transfer stars" differ from comparable data published by Crawford and Barnes (1970AJ.....75..978C).
(3) A direct comparison of the transfer stars to the Hyades yields consistency between the Hyades-Coma and
Crawford-Barnes zero points (for the transfer stars specifically). This result supports a conclusion drawn by Taylor and
Joner, and suggests that there is some problem with the zero points of Stetson's transfer-star data. (4) From Stetson's
corrected data, one finds that the Crawford-Perry zero points for the Hyades are consistent with the Crawford-Barnes
zero points for Coma. This result agrees with a conclusion drawn by Taylor and Joner from their own data, and suggests
that the problem postulated for Stetson's transfer-star data does not extend to his results for the Hyades and Coma.

%R 1995PASP..107...32A
%J-48
%T CN and Ca Abundance Variations among the Giants in M22
%A BARBARA J. ANTHONY-TWAROG, BRUCE A. TWAROG, and JASON CRAIG
%B We have obtained uvbyCa data for over 300 giants and horizontal branch stars in three fields of M22. The spread in
(b-y) for the giant and horizontal branches is consistent with a spread in foreground reddening Delta-E (B-V) ~0.08.
Reanalysis of the data of Norris and Freeman (1983) indicates not only positive correlations between CH, CN and a
unimodal distribution for Ca. Our photometric indices, m_1, and hk, demonstrate a range in metallicity that persists to
two magnitudes below the horizontal branch, and confirm the correlation between calcium abundance and CN/CH. We infer
from comparisons to spectroscopic data that m_1 is dominated by the CN and CH abundance and find no independent evidence
of a range in [Fe/H]. The excessive ranges in m_1 and hk also suggest the influence of a continuous opacity source,
reminiscent of the Bond-Neff effect, that is correlated with CNO abundance. The relative contributions of internal
mixing and primordial variations for M22's giants are discussed.

%R 1995PASP..107...49R
%J-57
%T An Infrared Embedded Source in the L1251 Molecular Cloud
%A J. M. ROSVICK and T. J. DAVIDGE
%B Using the Dominion Astrophysical Observatory's 1.8 m telescope and infrared array detector, we have detected a
near-infrared extended source embedded in the dark molecular cloud L1251. We measure the mean surface brightnesses in J,
H and K to be 16.5, 14.1, and 14.1 magnitudes per square arcsecond, respectively. The central object is associated with
the IRAS point source 22343+7501, and is composed of more than one source. Millimetre observations using the James Clerk
Maxwell telescope yield integrated fluxes ranging from 0.23 (at 1.3 mm) to 0.71 (at 0.8 mm) Jy. Deep J and K' images
taken with the Redeye detector on the Canada-France-Hawaii telescope show the source near the extended nebulosity to be
multiple. The nebulosity contains a great deal of chaotic structure, and extends more than 30 arcseconds in J and over
20 arcseconds in K'. \par The line-of-sight absorption to IRAS 22343+7501 is estimated to be 32+- 5 magnitudes, which is
comparable to values found for similar objects. \par The spectral energy distribution is characteristic of an embedded
source, and the range of fluxes at the different wavelengths imply that a single temperature for the cloud is not valid.
\par The near-IR, far-IR and mm observations are consistent with the objects in this cloud being just past the protostar
stage of evolution.

%R 1995PASP..107...58W
%J-61
%T New Interesting Objects Discovered in Optical Sky Surveys
%A R. WEINBERGER
%B From a compliation of objects discovered during our long-term systematic searches on optical sky surveys, six
particularly interesting objects have been selected. These hitherto unknown objects were investigated as to their
optical appearance and seem to represent the following types of objects: a nearby dwarf irregular galaxy, a supernova
remnant, a distant star cluster or nearby dwarf spheroidal galaxy, a galaxy clustering containing a bright "arc," a
planetary nebula, and an extragalactic H II region. All the objects deserve detailed follow-up examination.

%R 1995PASP..107...62L
%J-67
%T A Fiber-Fed Echelle Spectrograph for the Hale 5-m Telescope
%A K. G. LIBBRECHT and M. L. PERI
%B We describe a new fiber-fed echelle spectrograph which is now in operation on the Hale 5-meter telescope at Palomar
Observatory. The instrument is optimized for high spectral stability, necessary for asteroseismology measurements of
small periodic variations in stellar radial velocities. It features a 7-element all-spherical 610-mm focal length f/3.0
lens system and prism cross-disperser in a compact double-pass quasi-Littrow configuration. Light enters the system at
prime focus, and is channeled to the spectrograph by a fiber optic cable. The instrument rests on a fixed-orientation
optical bench inside the telescope's East Arm. It can be operated in a low-resolution mode, with resolution R=20,000 and
overal efficiency (including atmospheric seeing) e~5 percent at 550 nm, or a high-resolution mode, with R=40,000 and
e~1.5 percent at 550 nm; both modes have R_pixel=100,000. With large-format CCD detector (2048X2048 with 27-micron
pixels), the entire visible spectrum from 400-1000 nm can be recorded in two exposures, with no gaps. We have also
incorporated a novel imaging system to produce a circularly symmetric guide image of the input fiber tip. Using a
fiber-optic double scrambler, the instrument produces radial-velocity measurements which are stable at the ~1 m/sec
level over short (<~ 30 minute) time periods.

%R 1995PASP..107...68G
%J-76
%T Measuring Stellar Kinematics in Galaxies with the Near-Infrared (2-0) 12CO
   Absorption Bandhead
%A NIALL I. GAFFNEY, DAN F. LESTER, and GREG DOPPMANN
%B The shape and strength of the near infrared (2-0) 12CO absorption bandhead provides astronomers with a unique tool
for measuring stellar kinematics in galaxies with strong dust obscuration. However, the asymmetric shape of the bandhead
introduces complexities when extracting the kinematics from an observed spectrum. This paper discusses the benefits,
drawbacks, and observational constraints associated with using this bandhead to measure kinematics in galaxies, focusing
on applications in high spectral resolution data. Additionally, we discuss techniques found useful for extracting the
kinematics from the absorption feature, and outline our success with two different mothods.

%R 1995PASP..107...77A
%J-84
%T Bispectral Stellar Image Reconstruction: Image Truncation, Dynamic
   Range, and Object Complexity
%A G. J. M. AITKEN, R. JOHNSON, and J. MENG
%B Truncation of the speckle cloud by the edges of an image detector causes significant artifacts and distortions in
images reconstructed from their 2nd and 3rd-order spectra such as the Knox-Thompson (KT) and triple correlation (TC)
bispectra. At high signal levels the near-axis, TC transfer function has a lower phase variance than the KT transfer
function. This gives TC a higher dynamic range, an important property when observing detail. In both cases, the amount
of improvement in image quality obtained by using additional bispectral planes increases with object complexity.
Examples illustrate these properties.

%R 1995PASP..107...85F
%J-89
%T An Image-Restoration Technique for the Removal of Cosmic Ray Hits from
   Dithered Images
%A WOLFRAM FREUDLING
%B A method is proposed to find and remove cosmic rays from stacks of images which are not registered. Such dithered
images obtained with undersampling cameras, such as the Widefield and Planetary Camera 2 (WFPC2) on board the Hubble
Space Telescope, can be used to recover some of the resolution lost by a large pixel size. The proposed method
simultaneously cleans the images of cosmic rays and deconvolves them. Cosmic ray hits are dynamically identified at each
iteration. The output is a combined and restored image and a list of cosmic ray hits for each of the input images. The
final lists of cosmic ray hits are useful even if a restoration of the images is not desired. A simulated application of
the method to WFPC2 images is presented.

%R 1995PASP..107...90M
%J-90
%T Observations of Photoevaporating Interstellar Clouds
%A PETER RANKIN MCCULLOUGH
%B In the first part of this thesis, we present a tabulation of parameters for 50 globules, most of which are
bright-rimmed clouds, observed in transitions of 12CO, 13CO, CS, and HCO+ with a 1 arcminute diameter beam. H-alpha
images for many bright-rimmed clouds and long-slit H-alpha spectra of two such clouds are presented. The observations
are interpreted in terms of the rocket effect and D-critical ionization fronts. The elongated clouds (the so called
elephant trunk globules and cometary clouds) tend to point toward their source of ionization, although a possible
counter-example is presented. They often have velocity gradients along their lengths; a few examples are newly presented
along with others collected from the literature. Mechanisms for forming elongated clouds are discussed. Also, means of
determining the three-dimensional geometry of an H II region are discussed. The hypothesis that bright rims implode
clouds and induce star formation is reviewed and found to be controversial. \par In the second part, we present images
of the Orion Trapezium made with a unique adaptive optics system that uses either starlight or Rayleigh-backscattered
laser light to correct for atmospheric wavefront distortion. The H-alpha and I band images reveal the region around the
bright Trapezium stars, which has been studied extensively at radio wavelengths. Approximately one half of the stars in
this region are positionally associated with knots of ionized gas, known as pigs, which are interpreted as
photoevaporating envelopes of low mass stars. Disks are not observed directly but are inferred from the relatively low
extinction to the stars inside the pigs. The comet-like morphology of the pigs is the result of an equilibrium between
photoionization, recombination, and shadowing; interaction with the wind from theta-1C ~Ori is not required. The sizes
of the ionized component of the envelopes increase with distance from the source of ionization, theta-1C Ori. The
size-distance relationship suggests that the mass loss rates from the pigs are all approximately the same. The actual
value of the mass loss rate is model dependent, but is ~1.2 x 10^-7 M_\odot yr^-1. \par In the third and last part, we
extend the laser beacon concept to a polychromatic beacon in order to infer the wavefront tilt by measuring the
differential tilt caused by dispersion. The general concept of a polychromatic beacon is to make the atmosphere produce
a second beacon of a different color at altitude. Two mechanisms capable of producing the color conversion are Raman
scattering in the troposphere, and resonant florescence in the mesosphere. Because the differential tilt is quite small,
high precision is required and thus also high photon return rates. Our analysis indicates that existing lasers may
satisfy the theoretical requirements; however, the installation and operation of such lasers may be prohibitively
expensive using current technology.

%R 1995PASP..107...91M
%J-91
%T Near-Infrared Properties of Quasar and Seyfert Host Galaxies
%A KIM KATRIS MCLEOD
%B We present near-infrared images of nearly 100 host galaxies of Active Galactic Nuclei (AGN). Our quasar sample is
comprised of the 50 quasars from the Palomar Green Bright Quasar Survey with redshifts z<=0.3. We have restricted the
redshift range to ensure adequate spatial resolution, galaxy detectability, and minimal distance-dependent effects,
while still giving a large sample of objects. For lower-luminosity AGN we have chosen to image the CfA Seyfert sample.
This sample is composed of 48 Seyferts, roughly equally divided among types 1, 1.5-1.9, and 2. This sample was
spectroscopically selected, and, therefore, is not biased towards Seyferts with significant star formation. Taken
together, these samples allow a statistical look at the continuity of host-galaxy properties over a factor of 10,000 in
nuclear luminosity. \par We find the near-infrared light to be a good tracer of luminous mass in these galaxies. The
Seyferts are found in galaxies of type S0 to Sc. The radio quiet quasars live in similar kinds of galaxies spanning the
same range of mass centered around L*. However, for the most luminous quasars, there is a correlation between the
minimum host-galaxy mass and the luminosity of the active nucleus. Radio-loud quasars are generally found in hosts more
massive than an L* galaxy. We also detect a population of low-mass host galaxies with very low-luminosity Seyfert
nuclei. \par The low luminosity quasars and the Seyferts both tend to lie in host galaxies seen preferentially face-on,
which suggests there is a substantial amount of obscuration coplanar with the galaxian disk. The obscuration must be
geometrically thick (thickness-to-radius ~1) and must cover a significant fraction of the narrow line region (r>100 pc).
\par We have examined our images for signs of perturbations that could drive fuel toward the galaxy nucleus, but there
are none we can identify at a significant level. The critical element for fueling is evidently not reflected clearly in
the large scale distribution of luminous mass in the galaxy. \par We also present an infrared image of the jet of 3C 273
and compare it to visible and radio images from the literature.

%R 1995PASP..107...92M
%J-92
%T The Hot Stars in Symbiotic Systems
%A URS MUERSET
%B Symbiotic stars are interacting binaries, consisting of a late giant and a very hot companion, whose radiation
ionizes the wind from the cool star. They strike the observers by their complex spectra and variability. A small
subgroup, the symbiotic novae, undergo outbursts with an amplitude of several magnitudes and a duration of several
decades. \par The ionizing binary component is usually too hot to be observed in the optical light. It emits mainly EUV
photons, and in spectral regions better accessible to observers, nebula and cool star are much brighter than the hot
star. Direct observations of hot components have therefore been restricted to special cases. Consequently, our knowledge
about the hot components was poor. This thesis presents indirect methods allowing to extract crucial information on the
ionizing star from the spectrum of the ionized nebula. Fundamental characteristics such as temperature, radius, and
outburst energy are determined. They characterize the nature of the hot star, its outbursts, and the evolutionary status
of the system. \par The IUE archive proved best suited as observational base. It contains thousands of far UV spectra of
symbiotic stars. The UV continuum and the He II lambda-1640 recombination line turned out to be particularly sensitive
to the hot star's parameters. For one object ROSAT observations of photospheric X-ray emission exist. They confirm the
results obtained from IUE spectra. Unfortunately, only a subset of the symbiotics are bright enough to be observable in
the UV, and moreover, the outburst of most symbiotic novae started long before the advent of space observatories.
Possibilities to use optical spectroscopy are explored for these cases. T* can be derived from the observed ionization
stages, and L* can be estimated from UBV magnitudes. \par The main result is displayed in Figure 1. Typically, the hot
component of a symbiotic system has a radius ~0.1~R\odot, a surface temperature ~100,000~K, and a luminosity
~1000~L\odot. They occupy the same portion of the HR diagram as nova remnants and central stars of planetary nebulae.
Like these, they seem to be basically white dwarfs with a hot atmosphere. They have not yet cooled or have been
re-heated due to accretion of matter from the red giant. In particular, the results for the outbursts of symbiotic novae
confirm the commonly adopted scenario of a thermo-nuclear event in an accreted layer on the surface of a white dwarf,
largely analogous to a classical nova outburst. Unlike in classical novae, the cool component remains outside the
outburst event, and the accreted matter slowly burns out over decades. While classical novae are hard to investigate
when fading, the evolution of symbiotic novae can be tracked with the help of the subsisting nebular emission from the
ionized part of the red giant's wind. The evolutionary paths roughly follow the theoretical models for novae. During the
outburst of a symbiotic nova an energy around ~10^47~erg is released, i.e. ~10^-5 M\odot of hydrogen is burnt. Besides
supernovae, the outburst of symbiotic novae are the most energetic stellar events. \par The thesis is written in German.