%R=BibCode
%A=Authors
%B=Abstract
%c=Copyright
%D=Date of publication
%E=Electronic file
%F=Original File
%I=Institute and/or Footnotes
%J-last page
%K=Keywords
%T=Title

%R 1998PASP..110..367B
%F ori/PASPv110n746
%J-373
%T The Discovery of a Low-Redshift, Red Quasar in the 2MASS Prototype Survey.
%A Beichman C.A.
%A Chester T.J.
%A Cutri R.
%A Lonsdale C.J.,
%A Kirkpatrick D.
%I Infrared Processing and Analysis Center, Jet Propulsion Laboratory, California
   Institute of Technology; (chas@ipac.caltech.edu)
%A Smith H.E.
%I University of California, San Diego, La Jolla, CA 92093
%A Skrutskie  M.
%I University of Massachusetts, Amherst, MA 01003
%B  A prototype camera designed to test the observing and data reduction
   techniques for the 2 Micron All Sky Survey (2MASS) has been used to search
   for extremely red objects. Selection criteria based on the combination of
   near-IR and visible light observations help separate the vast majority of
   ordinary stars from more exotic objects. Visible spectroscopic observations
   for objects selected using these criteria in an area of just a few tenths
   of a square degree has resulted in the discovery of a quasar with a redshift
   of 0.147. The number of quasars expected at {\em K}_{\em s}_ in the 2MASS
   survey based on typical quasar colors and on the surface density of optically
   selected samples is ~0.17 deg^-2^. The 2MASS survey will result in a sample
   of quasars relatively unbiased by the presence of dust and will allow a reliable
   determination of whether there is a significant population of quasars with
   internal dust absorption.
%K infrared: general
%K Galaxies: Quasars: General

%R 1998PASP..110..374H
%F ori/PASPv110n746
%J-379
%T Resolution of a {\em z} = 1 QSO with Adaptive Optics.
%A Hutchings J.B.,(1)
%A Crampton David ,(1)
%A Morris S.L.
%I Dominion Astrophysical Observatory, National Research Council of Canada,
   Victoria, B.C. V8X 4M6, Canadaand
%A Steinbring E.
%I Physics and Astronomy Department, University of Victoria, Victoria, Canada
%B  The Adaptive Optics Bonnette (AOB) of the Canada-France-Hawaii Telescope
   (CFHT) was used to obtain {\em H}-band and {\em I}-band images of the low-luminosity,
   optically selected quasar 1055.3+019 at z=1.06. The FWHMs of stars were 0".11
   in {\em H} and 0".3 in {\em I} during these observations, and the detectors
   used had 0".034 pixels in {\em H} and 0".12 pixels in {\em I}. Procedures
   for determining the point-spread function are described. The QSO is clearly
   resolved in both wave bands, with significant extended flux within 0".1 of
   the nucleus. Overall, it appears to be elongated in the direction of a knot
   and connecting feature extending about 1" northeast of the nucleus visible
   in the {\em H}-band image. There are no other evident close companions, but
   the host galaxy's hybrid luminosity profile and off-centered nucleus indicate
   recent tidal disturbance. The I-H colors of the host galaxy correspond to
   an unreddened stellar population that is currently star forming or is within
   a very short time of ending an initial starburst. The reddening must be small
   to match any models.
%K Galaxies: Nuclei
%K Galaxies: Quasars: General
%K quasars: individual (\objS{QSO 1055+019}{1055.3+019})
%I (1) Visiting Astronomers, Canada-France-Hawaii Telescope, operated by
   the National Research Council of Canada, the Centre de la Recherche Scientifique
   de France, and the University of Hawaii.

%R 1998PASP..110..380P
%F ori/PASPv110n746
%J-395
%T Two Galactic Supersoft X-Ray Binaries: V Sagittae and T Pyxidis.
%A Patterson Joseph ,(1,)(2)
%A Kemp Jonathan ,(1,)(2)
%A Shambrook Anouk ,(2,)(3)
%A Thorstensen John R.,(4)
%A Skillman David R.,(5)
%A Gunn Jerry ,(6)
%A Jensen Lasse ,(7)
%A Vanmunster Tonny  ,(8)
%A Shugarov Sergei ,(9)
%A Mattei Janet A.,(10)
%A Shahbaz Tariq ,(11)
%A Novak Rudolf (12)
%B  We discuss the nature of V Sagittae and T Pyxidis, two enigmatic blue
   variable stars commonly classed among the cataclysmic variables. These stars
   have bolometric luminosities in the range 1-50x10^36^ ergs.s^-1^, far exceeding
   that of any accretion-powered cataclysmic variable. They also show extremely
   blue colors (B-V=-0.3 and U-B=-1.3 after dereddening) and orbital light curves
   that are quite similar and yet are not seen in any normal cataclysmic variable.
   But in all these respects, as well as in the rich and highly excited emission-line
   spectrum, the stars provide a good match for the newly discovered class of
   ``supersoft'' X-ray binaries, probably powered by quasi-steady nuclear burning
   of accreted gas on a white dwarf. Both stars show photometric waves at the
   orbital period. V Sge also shows a deep minimum, a true eclipse of the accretion
   disk arising from fairly high binary inclination. T Pyx is nearly face-on
   (probably i~10{deg}-20{deg}), which results in narrow lines and a low amplitude
   for the orbital signal. T Pyx shows a very stable photometric wave at P=0.076227
   days, but interpretation of this is hampered by another transient signal
   at 0.1098 days. This might be construed as evidence for a magnetic white
   dwarf.
%I (1) Department of Astronomy, Columbia University, 550 West 120th Street,
   New York, NY 10027.
%I (2) Visiting Astronomer, National Optical Astronomy Observatories, which
   is operated by the Association of Universities for Research in Astronomy
   (AURA, Inc.) under contract with the National Science Foundation.
%I (3) Board of Studies in Astronomy and Astrophysics, University of California,
   Santa Cruz, Santa Cruz, CA 95064.
%I (4) Department of Physics and Astronomy, Dartmouth College, 6127 Wilder
   Laboratory, Hanover, NH 03755.
%I (5) Center for Backyard Astrophysics (East), 9517 Washington Avenue,
   Laurel, MD 20723.
%I (6) Center for Backyard Astrophysics (Illinois), 1269 North Skyview Drive,
   East Peoria, IL 61611.
%I (7) Center for Backyard Astrophysics (Denmark), Suhrs Alle 5, 3520 Farum,
   Denmark.
%I (8) Center for Backyard Astrophysics (Belgium), Walhostraat 1A, 3401
   Landen, Belgium.
%I (9) Sternberg Astronomical Institute, Moscow State University, Universitetsky
   Prospect 13, 119899 Moscow, Russia.
%I (10) American Association of Variable Star Observers, 25 Birch Street,
   Cambridge, MA 02138.
%I (11) Department of Astrophysics, Oxford University, Keble Road, Oxford,
   OX1 3RH, England, UK.
%I (12) Nicholas Copernicus Observatory, Kravi Hora 2, Brno 616 00, Czech
   Republic.

%R 1998PASP..110..396M
%F ori/PASPv110n746
%J-402
%T Polarimetry of the LMC X-Ray Binary A0538-66 during an ``On/Off'' Transition
   in 1991.
%A Misselt K.A.
%A Clayton Geoffrey C.
%I Department of Physics and Astronomy, Louisiana State University, Baton Rouge,
   LA 70803-4001; (misselt@rouge.phys.lsu.edu), (gclayton@fenway.phys.lsu.edu)
   and
%A Schulte-Ladbeck R.E.
%I Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh,
   PA 15620; (RSL@vms.cis.pitt.edu)
%B  We present polarimetric and spectroscopic observations of the X-ray
   binary A0538-66 obtained in 1991 near periastron passage during cycles 291,
   294, and 310. The system was in an active phase during cycle 291 ({phi}=0.98),
   with X-ray outbursts being observed in the previous two cycles. By cycle
   294 ({phi}=0.00-0.12) the system had entered a low-activity phase, and by
   cycle 310 ({phi}=0.06) the system appears to be fully ``off.'' We address the
   implications of these new observations and interpret them within the context
   of the model put forward by Clayton et al. in which the polarization arises
   from scattering of the B2 IIIe star's light from circumstellar disk material
   as well as additional material in the orbital plane. The rapid change in
   position angle near periastron passage, observed in the previous polarimetric
   studies and ascribed to additional scattering material in the Clayton et
   al. model, is not seen in our postoutburst observation. We suggest that the
   absence of additional scatterers may be associated with the transition from
   the ``on'' to the ``off'' state that took place in 1991.

%R 1998PASP..110..403P
%F ori/PASPv110n746
%J-414
%T Rapid Oscillations in Cataclysmic Variables. XIII. WZ Sagittae Revisited.
%A Patterson Joseph ,(1,)(2)
%A Richman Hayley ,(3)
%A Kemp Jonathan (1)
%I Department of Astronomy, Columbia University, 550 West 120th Street, New
   York, NY 10027; (jop@astro.columbia.edu), (jonathan@astro.columbia.edu)
%A Mukai Koji
%I Laboratory for High Energy Astrophysics, Goddard Space Flight Center, National
   Aeronautics and Space Administration,MS 660.2, Greenbelt, MD 20771; (mukai@lheavx.gsfc.nasa.gov)
%B  We report new observations of the dwarf nova WZ Sagittae, showing the
   return of the 27.87 s oscillation in 1995/1996 high-speed optical light curves.
   As was true in 1978, the main peak of the power spectrum generally occurred
   at 27.87 or 28.96 s, with the signals sometimes simultaneously present. Weak
   transient signals were also seen at 28.20 and 29.69 s. An {\em ASCA} X-ray
   observation showed a significant peak at 27.86+/-0.01 s in the 2-6 keV band,
   which appeared to establish the star's membership as a ``DQ Herculis star,''
   in which accretion onto the white dwarf is channeled by a strong magnetic
   field. The X-ray period is most likely the true white dwarf spin period.
   However, we certainly do not understand the distribution of power among these
   various signals of slightly different period. This puzzling multiperiodic
   structure remains an impediment to full acceptance of WZ Sge as a DQ Her
   star. The star's soft X-ray orbital light curve shows a strong but transient
   energy-dependent dip around orbital phase 0.7, which is probably due to absorption
   by an extended gas cloud in which the mass-transfer stream strikes the disk.
%I (1) Visiting Astronomer, Cerro Tololo Inter-American Observatory, National
   Optical Astronomy Observatories, which is operated by the Association of
   Universities for Research in Astronomy, Inc. (AURA), under cooperative agreement
   with the National Science Foundation.
%I (2) Visiting Astronomer, Kitt Peak National Observatory, National Optical
   Astronomy Observatories.
%I (3) Current address: 400 East 84th Street, 34B, New York, NY 10028; (hayley.richman@gs.com).

%R 1998PASP..110..415P
%F ori/PASPv110n746
%J-419
%T Rapid Oscillations in Cataclysmic Variables. XIV. Orbital and Spin Ephemerides
   of FO Aquarii.
%A Patterson Joseph ,(1,)(2,)(3)
%A Kemp Jonathan ,(1,)(2)
%A Richman Hayley R.,(1,)(2,)(4)
%A Skillman David R.,(5)
%A Vanmunster Tonny ,(6)
%A Jensen Lasse ,(7)
%A Buckley David A.H.,(8)
%A O'Donoghue Darragh ,(8)
%A Kramer Rachel (9)
%B  We report on 17 years of photometry of FO Aquarii, a cataclysmic variable
   with a rapidly rotating, magnetic white dwarf. We give ephemerides for its
   variations at the 4.8 hr binary period and the 21 minute spin period. The
   orbital period is constant at 0.2020596(1) day. The spin period decreases
   on a timescale of 10^6^ yr, but with additional wiggles on timescales of
   years to decades. The observed alternation between spin-down and spin-up
   suggests that the star is near its equilibrium spin period, an important
   prediction of the theory of magnetic cataclysmic variables.
%I (1) Department of Astronomy, Columbia University, 550 West 120th Street,
   New York, NY 10027; (jop@astro.columbia.edu), (jonathan@astro.columbia.edu).
%I (2) Visiting Astronomer, Cerro Tololo Inter-American Observatory, National
   Optical Astronomy Observatories, which is operated by the Association of
   Universities for Research in Astronomy, Inc. (AURA), under cooperative agreement
   with the National Science Foundation.
%I (3) Visiting Astronomer, Kitt Peak National Observatory, National Optical
   Astronomy Observatories.
%I (4) Current address: 400 East 84th Street, 34B, New York, NY 10028; (hayley.richman@gs.com).
%I (5) Center for Backyard Astrophysics (East), 9517 Washington Avenue,
   Laurel, MD 20723; (cbaceo@clark.net).
%I (6) Center for Backyard Astrophysics (Belgium), Walhostraat 1A, 3401
   Landen, Belgium; (tvanmuns@innet.be).
%I (7) Center for Backyard Astrophysics (Denmark), Suhrs Alle 5, 3520 Farum,
   Denmark; (ltj@tt.dk).
%I (8) South African Astronomical Observatory, P. O. Box 9, Observatory
   7935, Cape Town, South Africa; (dibnob@saao.ac.za), (dod@saao.ac.za).
%I (9) 191 Mather Mail Center, Harvard College, Cambridge, MA 02138; (rkramer@fas.harvard.edu).

%R 1998PASP..110..420H
%F ori/PASPv110n746
%J-424
%T The Phase 0.5 Absorption in SW Sextantis-Type Cataclysmic Variables.
%A Hellier Coel
%I Department of Physics, Keele University, Keele, Staffordshire, ST5 5BG, England,
   UK; (ch@astro.keele.ac.uk)
%B  The SW Sextantis stars are a group of cataclysmic variables with distinctive
   observational characteristics, including absorption features in the emission-line
   cores at phases 0.2-0.6. Hellier & Robinson have proposed that these features
   are caused by the accretion stream flowing over the accretion disk. However,
   in a simple model the absorption occurred at all orbital phases, which is
   contradicted by the data. I show that invoking a flared accretion disk resolves
   this problem.

%R 1998PASP..110..425C
%F ori/PASPv110n746
%J-432
%T Separate Spectra of the Components of the Low-Mass BinariesRoss 614A,B and
   L722-22A,B.
%A Chance  Don R.
%A Hershey John L.
%I Astronomy Programs, Computer Sciences Corporation, Space Telescope Science
   Institute, 3700 San Martin Drive, Baltimore, MD 21218; (chance@stsci.edu),
   (hershey@stsci.edu)
%B  The {\em Hubble Space Telescope} Faint Object Spectrograph has been
   used to acquire separate spectra of each of the component stars in the binaries
   Ross 614A,B (Gl 234A,B) and L722-22A,B (GJ 1005). Spectral types have been
   determined for each: M4.0 V, M5.5 V, M3.5 V, and M5.0 V, respectively, relative
   to a series of ground-based CCD spectra, in the 6500-8000 {AA} region. The four
   members of the two binaries form a narrow locus in the spectral type-mass
   plane, from 0.18 to 0.08 {\em M}_{sun}_ and reaching 0.08 {\em M}_{sun}_
   near spectral type M6.0. Both binaries are believed to be members of a relatively
   young disk population. Their masses and newly determined spectra imply that
   the apparently single M dwarf stars, of a similar population and with spectral
   types of M6, are likely to be near, or less massive than, 0.08 {\em M}_{sun}_.
   Presumably, dwarf M7, M8, and M9 stars of a similar age and population are
   in a declining mass sequence and thus should reach well below the theoretical
   main-sequence mass limit of 0.08 {\em M}_{sun}_ and by current theory are
   substellar or ``brown dwarf'' objects.
%K Stars: Binaries: General
%K Stars: Evolution
%K Stars: Low-Mass, Brown Dwarfs

%R 1998PASP..110..433W
%F ori/PASPv110n746
%J-450
%T Studies of Large-Amplitude {delta} Scuti Variables. III. DY Pegasi(1).
%A Wilson W.J.F.
%A Milone E.F.,(2)
%A Fry D.J.I.,(2)
%A Van Leeuwen J.
%I Rothney Astrophysical Observatory, Department of Physics and Astronomy, University
   of Calgary, 2500 University Drive, NW Calgary, AB T2N 1N4, Canada; (milone@acs.ucalgary.ca),
   (wjfwilso@acs.ucalgary.ca), (fry@acs.ucalgary.ca)
%B  This is the third in a series of papers on large-amplitude {delta} Scuti
   and related stars intended to determine Baade-Wesselink radii and luminosities
   with precision. The first two papers discussed our method of analysis and
   its application to the {delta} Scuti variables EH Librae and DY Herculis;
   in the present paper we discuss the observations and analysis of the SX Phoenicis
   variable DY Pegasi. Optical ({\em BVI}) and infrared ({\em JH}) photometry
   and cross-correlated radial velocity data have been obtained and analyzed.
   Fourier representations for the {\em BVIH} light curves and for the radial
   velocity curve were used to derive a value for the minimum radius for each
   of 22 combinations of flux and color index, from which we obtain a mean value
   for the minimum radius of R_min_=2.09+/-0.25 {\em R}_{sun}_. When combined
   with effective temperatures from Burki & Meylan, we find a mean bolometric
   luminosity of <L_bol_>=11.34 {\em L}_{sun}_ and a mean absolute magnitude
   of <M_bol_>=2.11. The radial excursion (R_max_-R_min_) is 0.073 {\em R}_{sun}_.
%I (1) {\em Publication of the Rothney Astrophysical Observatory}, Number
   71.
%I (2) Guest Investigator, Dominion Astrophysical Observatory.

%R 1998PASP..110..451J
%F ori/PASPv110n746
%J-457
%T Photometric Studies of {delta} Scuti Stars. I. IP Virginis.
%A Joner Michael D.(1,)(2)
%A Hintz Eric G.(1,)(3)
%I Department of Physics and Astronomy, Brigham Young University, N281 ESC,
   Provo, UT 84602-4604; (jonerm@astro.byu.edu), (doctor@tardis.byu.edu)
%A Collier Matthew W.(1)
%I US Geological Survey, Baton Rouge, LA 70803; (mwcoll@usgs.gov)
%B  We report 15 new times of maximum light for the {delta} Scuti star IP
   Virginis (formerly known as SA 106-1024). An analysis of all times of maximum
   light indicates that IP Vir has been decreasing in period at a constant rate
   of -7.4x10^-9^ days.day^-1^. Evidence is also presented that IP Vir is a
   double-mode variable with a period ratio of {pi}_1_M{pi}_0_=0.774. This period
   ratio predicts a [Fe/H] value of -0.3. From photometric ({\em uvby}{beta})
   observations, we find a foreground reddening of Eb-y=0.008 mag and a metallicity
   of [Fe/H] = +0.05. It is shown that [Fe/H] = -0.3 is most likely the correct
   value. Intrinsic b-y- and {\em c}_1_-values, plotted in a model atmosphere
   grid, indicate a mean effective temperature, <T_eff_>=7400 K, and a mean
   surface gravity, <{\rf log}g>=3.89. All of these physical parameters support
   Landolt's initial conclusion that IP Vir is an ordinary {delta} Sct star.
%I (1) Visiting Astronomer, Kitt Peak National Observatory, National Optical
   Astronomy Observatories, operated by the Association of Universities for
   Research in Astronomy, Inc., under cooperative agreement with the National
   Science Foundation. Observations made with the Burrell Schmidt Telescope
   of the Warner and Swasey Observatory, Case Western Reserve University.
%I (2) Visiting Astronomer, Cerro Tololo Inter-American Observatory, National
   Optical Astronomy Observatories, which are operated by the Association of
   Universities for Research in Astronomy, Inc., under contract with the National
   Science Foundation.
%I (3) Bear Lake Observatory Postdoctoral Fellow.

%R 1998PASP..110..458G
%F ori/PASPv110n746
%J-465
%T New Spectroscopic Observations of the Planetary Nebula PC 11.
%A Guti\'errez-Moreno A.
%A Moreno H.(1)
%I Departamento de Astronom\'ia, Universidad de Chile, Casilla 36-D, Santiago,
   Chile; (agutierr@das.uchile.cl), (hmoreno@das.uchile.cl)
%B  New observations of the planetary nebula PC 11, made in 1991, are presented
   and discussed. The object is a compact planetary nebula, small and dense,
   with a low mass of ionized gas. It is losing matter through one or more jets,
   formed mainly by O III. The central star is a binary, with a cool component
   of spectral type F0-F1 V. The hot component has an energy balance temperature
   of 105,000 K, a mass of 0.638 {\em M}_{sun}_, and very low luminosity, estimated
   as 11 {\em L}_{sun}_, with a radius of the order of 0.01 {\em R}_{sun}_.
   The position of PC 11 in the H-R diagram is peculiar, since it seems incompatible
   with its being a very young planetary nebula, as suggested by its small size
   and high density.
%I (1) Visiting Astronomer, Cerro Tololo Inter-American Observatory, National
   Optical Astronomy Observatories, operated by the Association of Universities
   for Research in Astronomy, Inc. (AURA), under cooperative agreement with
   the National Science Foundation.

%R 1998PASP..110..466H
%F ori/PASPv110n746
%J-479
%T The Optical Spectrum of the Planetary Nebula NGC 2440.
%A Hyung Siek
%I Bohyunsan Optical Astronomy Observatory, Jachun P. O. Box 1, Youngcheon,
   Kyungbuk 770-820, South Korea; (hyung@astro.ucla.edu), (hyung@hanul.issa.re.kr)
   and
%A Aller Lawrence H.
%I Physics and Astronomy Department, University of California, Los Angeles,
   CA 90095; (aller@bonnie.astro.ucla.edu)
%B  Wavelengths and identifications have been provided for approximately
   300 lines between 3660 and 10125 {AA} in the spectrum of the bipolar planetary
   nebula NGC 2440. These lines measured with the Hamilton echelle spectrograph
   at Lick Observatory and supplemented by published {\em IUE} results are used
   to construct diagnostic diagrams and derive ionic concentrations. The electron
   temperature indicated by [O III] is ~14,200 K; the electron density is ~5000
   cm^-1^. With the aid of a standard model and an ionization correction factor
   method, we obtain a set of abundances that are compared with the Sun and
   with results of previous studies. As with other Peimbert Type I's, He and
   N are enriched as compared with the Sun; C is likewise overabundant. NGC
   2440 evolved from a progenitor star that was more massive than the Sun. The
   central star temperature seems close to 180,000 K.
%K ISM: planetary nebulae, nebular abundances: nebula, individual: NGC 2440

%R 1998PASP..110..480B
%F ori/PASPv110n746
%J-489
%T Characteristics of the 2MASS Prototype Survey.
%A Beichman C.A.
%A Chester T.J.
%I Infrared Processing and Analysis Center, Jet Propulsion Laboratory, California
   Institute of Technology; (chas@ipac.caltech.edu)
%A Skrutskie M.
%I University of Massachusetts
%A Low F.J.
%I Steward Observatory, University of Arizona
%A Gillett F.
%I National Optical Astronomy Observatory
%B  The 2 Micron All Sky Survey (2MASS) will catalog over 100,000,000 individual
   objects, the vast majority of which will be stars of spectral type K and
   later. For many projects it will be important to develop techniques to identify
   interesting objects within this data set. The combination of near-IR and
   visible light observations will be a powerful tool for finding objects from
   brown dwarfs to dust-enshrouded quasars. This paper describes prototype hardware
   and software systems used as part of the preparation for the 2MASS survey.
   Three years of observations with prototype systems have produced a database
   of more than 1 million objects. A companion paper describes the comparison
   of these data with optical plate material and visible spectroscopic observations
   resulting in the discovery of a quasar with a redshift of 0.147.
%K Cosmology: Large-Scale Structure of Universe
%K Galaxies: General
%K galaxy: structure
%K Stars: Low-Mass, Brown Dwarfs
%K Stars: Luminosity Function, Mass Function
%K Infrared Radiation

%R 1998PASP..110..490L
%F ori/PASPv110n746
%J-492
%T Happy Islands: A Personal Remembrance of Gene Shoemaker.
%A Levy David H.
%I University of Arizona, Tucson, AZ 85721-0065