No description available.

Two dimensional photometry of NGC 1068 and NGC 1566 at visual and red wavelengths has been obtained. An H⍺ image of NGC 1068 has also been obtained. Decomposition of the luminosity profiles derived from the data shows that the inner region (r<18") of NGC 1566 consists of a nuclear point source component, a spheroidal bulge, and an exponential disk. Colors for each component are derived which show that the disk is redder at the outer edge than at the center The point source component is quite weak, contributing only 5% of the total light in an 8.5 aperture. A color map is also presented, showing an enhancement of red emission in the center and at the outer edges of the image. For NGC 1068, the profiles permit a bulge component to be determined for r<11". Subtraction of the seeing convolved bulge reveals a point source component in the red image. This feature is not observed in the visual image, due to obscuration by dust. The color map for NGC 1068 shows a strong color gradient in that the central region is much redder than the outer region, for r<18". There is also an enhancement in red light along the major axis that may describe a bar-like component. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

We examine the precise radial velocities and chromospheric emission and derive the fundamental parameters of eight K stars - 36 Ophiuchi A, B (K0 V, K1 V), 61 Cygni A, B (K5 V, K7 V), β Geminorum (K0 IIIb ), δ Sagittarii (K2.5 IIIa), α Tauri (K5 III), and ϵ Pegasi (K2 Ib) - through analyses of high quality (S/N > 1000) near-infrared (864-878 nm) spectra. The spectra were obtained as part of the hydrogen fluoride precise (≈ 15 — 30 m s-1) radial velocity (RV) program at the Canada-France-Hawaii 3.6-m telescope (1981- 1992) and the Dominion Astrophysical Observatory 1.22-m telescope (1991- 1995). We define the ∆EW 866.2 index used to quantify changes in the core flux of the Ca II 866.214 nm line and show the index is a sensitive measure of changes in chromospheric emission. We compare the “reference” spectrum for each star with synthetic spectra of the 864.7-867.7 nm region and derive the fundamental parameters: effective temperature [special characters omitted] surface gravity [special characters omitted], metallicity ([M/H]), and microturbulence (ξ). We describe an efficient, time-saving method which identifies and eliminates insignificant lines. Through our comparisons of the narrow spectral region for these “well-known” stars and through our development of a rapid synthesis method, we demonstrate a solid foundation for a broader, more comprehensive study of this region of the H-R diagram. The nearly identical stars 36 Oph A and B have dissimilar chromospheric activity. For these stars, we derived [special characters omitted] = 5125 K, log g = 4.67, [M/H] = -0.25, and ξ = 1.4 km s-1, in excellent agreement with relationships predicted by stellar interior models for [special characters omitted] ≈ 0.75 and [Fe/H] = -0.3. For 61 Cyg A, we detect a rotation period of 36.2 days in the ∆EW 866.2 index and of 37.8 days in the radial velocities, implying that active regions are spatially and temporally coherent over long time scales for this star. For 61 Cyg A, we derived [special characters omitted] = 4545 K, log g = 4.55, [M/H] = -0.40, and ξ = 1.5 km s-1; for 61 Cyg B, [special characters omitted] = 4150 K, log g = 4.55, [M/H] = -0.40, and ξ = 0.7 km s-1. These parameters are in excellent agreement with relationships predicted by stellar interior models for [Fe/H] = -0.4 and [special characters omitted] ≈ 0.65 for 61 Cyg A, and [special characters omitted] ≈ 0.55 for 61 Cyg B. Low-amplitude RV variability is a ubiquitous characteristic of the K giants. For β Gem, we find similar RV {K = 46.23 ± 3.9 m s-1, P = 584.65 ± 3.3 dy) and ∆EW 866.2 index (K = 0.583 ± 1.9 pm, P = 587.7 ± 12 dy) periods. If due to rotation modulation of some surface feature, this period is inconsistent with the most reliable ν sin i value for this star. We detect a long-term (> 12 yr) change in the ∆EW 866.2 index for this star, reminiscent of a solar-type magnetic cycle. For δ Sgr, we find significant long-term trends in the radial velocities and ∆EW 866.2 index, and significant, but aliased, RV periods at 1.98 days (K = 82.1 ± 9.1 m s-1) and 293 days {K = 68.8 ± 9.8 m s-1). α Tauri has a 647.93-dy period (K = 114.9±10.6 m s-1) in the radial velocities, but no corresponding period in the ∆EW 866.2 index. From 1.22- m telescope observations, we find a 1.8358-dy RV period (K = 32.0 ± 5.0 m s-1) consistent with theoretical granulation-driven acoustic modes or a fundamental overtone (n ≈ 4). The supergiant ϵ Peg resembles a semi-regular RV variable. We find multiple RV periods (not aliases) of 65.2 days (K = 415.8 ± 59.0 m s-1), 46.3 days (K = 559.1 ± 57.0 m s-1), perhaps both fundamental overtones, and 10.7 days (K = 410.3 ± 66.0 m s-1), perhaps related to solar-type spicules. The 10.7-dy period is present in the ∆EW866.2 index for this star. / Graduate

No description available.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (p. 183-190).

The goal of this study was to obtain photometry of three poorly studied close binary star systems. These observations were obtained at Lowell Observatory in Flagstaff, Arizona and the Ball State University Observatory. In both cases charged coupled device detectors were used. Light variations were detected in all three stars. For one of the binaries the temperatures of the component stars were found by fitting multi-color light curves with black body models. In addition, the temperature difference between the two hemispheres of the secondary star was found. This difference is believed to be the product of heating by the stellar companion. / Department of Physics and Astronomy

The unique advantages for astronomy on the Antarctic plateau are now well established. In particular, Dome C, Antarctica is potentially one of the best new sites for optical, infrared and sub-millimeter astronomy, presenting the opportunity to build unique astronomical instruments. Located high on the Antarctic plateau, Dome C offers low wind, clear skies, and negligible precipitation. This thesis addresses three additional properties of the site relevant to optical astronomy-sky brightness, atmospheric extinction and optical turbulence. The sky at an optical astronomy site must be dark, and the atmosphere very clean with minimal light extinction. At present little is known from an astronomer's perspective about the optical sky brightness and atmospheric extinction at most Antarctic sites. The high latitude of Dome C means that the Sun spends a relatively small amount of time far below the horizon, implying longer periods of astronomical twilight and less optical dark time than other sites, especially those close to the equator. We review the contributions to sky brightness at high-latitude sites, and calculate the amount of usable dark time at Dome C. We also explore the implications of the limited sky coverage of high-latitude sites, and review optical extinction data from the South Pole. A proposal to extend the amount of usable dark time through the use of polarising filters is examined, and we present the design and calibration of an instrument (called Nigel) to measure the brightness, spectrum and temporal characteristics of the twilight and night sky. The atmospheric turbulence profile above an astronomical site limits the achievable resolution and sensitivity of a telescope. The atmospheric conditions above high plateau Antarctic sites are different to temperate sites; the boundary layer of turbulence is confined very close to the surface, and the upper atmosphere turbulence very weak. We present the first winter-time turbulence profiles of the atmosphere above Dome C, and characterise the site in terms of the achievable precision for photometry and astrometry, and the isoplanatic angle and coherence time for the adaptive optics.

In the last few years, two major contributions to the asteroid database have been the eight-color and thermal radiometric surveys. The former consists of broad-band photometric measurements through eight filters spanning the 0.3 to 1.1 μm wavelength range. The latter consists of thermal flux measurements at 10 and/or 20 μm, and when combined with measures of the reflected light, can yield reliable estimates of their geometric albedos. Visual display of the eight-color survey data can be simplified by reducing the dimensionality of the problem. A principal components analysis was performed to accomplish this task. The analysis shows that 95 percent of the information contained in the seven independent color indices is contained in two principal components. This result is due to the fact that most asteroid spectra can be explained in terms of two absorption features, one at ultraviolet and the other at near-infrared wavelengths. The photometric and radiometric data sets were also used, along with cluster analysis techniques, to produce an improved asteroid taxonomic system. Seven major classes are now recognized and are designated A, C, D, E, M, P, and S. Three interesting minor classes are also identified: B, F, and G. Marginal evidence for an eighth major class, here called T, exists in the data, but the reality of this class awaits confirmation by further observations of potential members. Three asteroids do not fall into any of the above classes and are assigned unique designations: R (349 Dembowska), Q (1862 Apollo), and V (4 Vesta). Four E-class asteroids are now known to exist in the main belt, yet nearly twice this number exist in or near the Hungaria region. Twenty eight D-class asteroids have been identified in the outer belt, where they represent a significant fraction of the population. Five D asteroids exist in the main belt, which one lying near the inner edge of the belt, which is dominated by S-class asteroids. Two of the interesting minor classes are associated with particular dynamical families. The Nysa family, with the single exception of Nysa itself, consists entirely of class F asteroids, while the B asteroids are found almost exclusively in the Themis family. The earth-approaching population is represented by at least two objects similar to Vesta and Dembowska, which are as many as are in the entire main belt, while most of the earth-approachers are of class S.

No description available.

No description available.