Chulhee Kim

Thorium-rich halo star HD 221170: Further evidence against the universality of the r-process ,

We report the abundance determination in the atmosphere of the bright halo star HD 221170. The spectra were taken with the Terskol Observatorys 2.0-m telescope with a resolution R = 45 000 and signal-to-noise ratio up to 250 in the wavelength region 3638-10 275 A. The adopted atmospheric parameters correspond to an effective temperature Teff = 4475 K, a surface gravity log g = 1.0, a microturbulent velocity vmicro = 1.7 km s −1 , and a macroturbulent velocity vmacro = 4k m s −1 . The abundances of 43 chemical elements were determined with the method of spectrum synthesis. The large overabundances (by 1 dex relative to iron) of elements with Z > 38 are shown to follow the same pattern as the solar r-abundances. The present HD 221170 analysis confirms the non-universality of the r-process, or more exactly the observation that the astrophysical sites hosting the r-process do not always lead to a unique relative abundance distribution for the bulk Ba to Hg elements, the Pb-peak elements, and the actinides.

TIME-SERIES ENSEMBLE PHOTOMETRY OF SX PHOENICIS STARS. I. BL CAMELOPARDALIS

We present an analysis of the multiperiodic SX Phoenicis star BL Camelopardalis (GD 428). Along with 24 times of maximum light from archival data, six previously unpublished times of maximum light from photomultiplier observations and 39 new CCD observations of maximum light are reported. The new CCD observations indicate that BL Cam is a double-mode variable with a primary period of 0.0391 day, a secondary period of 0.0306 day, and a π1/ π0 ratio of 0.783. The relation between metallicity and period ratio for large amplitude δ Scuti variables is examined in detail. Finally, evidence is presented that the fundamental period π0 has increased by 0.009 seconds in the last 20 years.

CHEMICAL ABUNDANCE PATTERNS FOR SHARP-LINED STARS

In order to increase the completeness of the investigations of stellar abundances, we can use spectrum synthesis method, new atomic data and observation of stellar spectra with resolution comparable to solar spectral atlases. We made a brief review of main problems of these three ways. We present new results of abundance determinations in the atmospheres of four stars. The first is the implementation of new atomic data to well known Przybylski`s star. We show that the number of spectral lines, which can be identificated in the spectrum of this star, can be significantly higher. The second example is the investigation of Cyg. We found the abundances of 51 elements in the atmosphere of this mild barium star. The third example is halo star HD221170. Our preliminary abundance pattern consists of 42 elements. The heaviest elements in this pattern are U and Th. The last star is the spectroscopic binary HD153720. The number of elements investigated in the spectra of components of this star is not large, but the results show that the components are Am-stars.

Photometric Studies of δ Scuti Stars. II. V1162 Orionis

ABSTRACT New photometric ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape

Differential Time‐Series CCD Photometry of BL Camelopardalis Revisited

uvby

VR c photometry of dwarf cepheids (II)

\end{document} β) observations of V1162 Orionis are reported. We derive a reddening value of \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \ren...

A METHOD FOR THE SIMULTANEOUS ESTIMATION OF ATMOSPHERIC PARAMETERS USING THE PHOTOMETRIC INDICES IN THE uvby COLOR SYSTEM

ABSTRACT New differential time‐series observations of BL Camelopardalis were secured using B and V filters. It was confirmed that BL Cam is an optical double star. Differential magnitudes were obtained through a photometric profile reduction procedure to eliminate the influence of a faint adjacent star. Variations in \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape

THE ATMOSPHERE PARAMETERS AND THE LINE PROFILE VARIATIONS OF ρ PUPPIS

O-C

Differential time-series photometry of a distant halo SX Phe variable BQ Pisces

\end{document} values for light maxima were investigated. We found that the parabolic period variation was recently reversed. The periods of BL Cam were investiga...

A Photometric and Spectrographic Study of BP PEGASI

In this paper, we present VRc photometric observations of four dwarf cepheids: YZ Boo (P = 0.d104, ΔV = 0.m5), AD CMi (P = 0.d123, ΔV = 0.m5), XX Cyg (P = 0.d135, ΔV = 0.m5), EH Lib (P = 0.d088, ΔV = 0.m7). The light curves were obtained at West Mountain Observatory, Provo, Utah on 14 nights from 1983 through 1986 and contain 589 data points in each of theV andR bands in the Cousin photometric system. A detailed study of these stars, based on the present light curves, will be published separately.