Search Publications
Overall Pattern Comparison of the FK5 Proper-Motion System withHipparcos
Zhu, Zi; Yang, Tinaggao
We have performed an overall pattern comparison between the proper motions of the FK5 (Fifth Fundamental Catalogue) systems (FK5, Astrographic Catalog Reference Stars [ACRS], and PPM Catalogue) and those of Hipparcos. The global rotation (time dependent) between the two reference frames is found to be different for different stellar samples, depen…
Chemically Decoupled Nuclei in the Spiral Galaxies NGC 4216 and NGC 4501
Burenkov, A. N.; Sil'chenko, O. K.; Vlasyuk, V. V.
By using bidimensional spectral data obtained at the 6 m telescope for the Virgo spirals NGC 4216 and NGC 4501, we have found chemically distinct metal-rich nuclei in these galaxies. Under the assumption of equal ages for the nuclear and bulge stellar populations, the metallicity difference between the nuclei and their environments in the galaxies…
The Relationship between Ultraviolet Line Emission and Magnetic Field Strength in Magnetic Cataclysmic Variables
Howell, Steve B.; Cash, Jennifer; Mason, Keith O. +1 more
We present the first UV spectral observations of six magnetic cataclysmic variables discovered by the ROSAT Wide Field Camera (WFC). Using the^ International Ultraviolet Explorer (IUE), 1200-3400 Å spectra were obtained of the AM Herculis stars RE 0531-46, RE 1149+28, RE 1844-74, QS Tel (RE 1938-46), and HU Aqr (RE 2107-05) and the DQ Herculis sta…
Echelle Spectroscopy of Interstellar Absorption toward MU Columbae with the Goddard High Resolution Spectrograph
Savage, B. D.; Sembach, K. R.; Ebbets, D. C. +17 more
Goddard High Resolution Spectrograph echelle-mode observations of the interstellar absorption lines of Mg II, Si IV, C IV, and N V toward mu Columbae (HD 38666) are presented. The observations have a spectral resolution of 3.5 km s^-1 and signal-to-noise ratios (S/Ns) of 20-200. The mu Col sight line (l=237.3d, b=-27.1d, d=0.40 kpc, z=-0.18 kpc) e…
Serendipitous Discovery of a Cataclysmic Variable in the Globular Cluster NGC 6624
Anderson, Scott F.; Margon, Bruce; Deutsch, Eric W. +1 more
Despite indications that classical cataclysmic variable (CV) stars are rare in globular clusters in general, and in the cluster NGC 6624 in particular, we have serendipitously discovered such a star ~6" from the cluster center. A Hubble Space Telescope spectrum of the m~22 object shows strong, broad emission lines typical of numerous field CVs, an…
VLBI Observations of Symmetric Parsec-Scale Twin Jets in the Narrow-Angle-Tail Radio Galaxy NGC 1265 (3C 83.1B)
O'Dea, Christopher P.; Xu, Chun; Biretta, John A.
We present global VLBI observations of the nucleus of the narrow-angle-tail radio galaxy NGC 1265. We report the discovery of symmetric parsec-scale twin jets which are well aligned with the kiloparsec-scale jets. We also present an archival Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) image of the galaxy, showing an apparently alm…
A Morphological and Multicolor Survey for Faint QSOS in the Groth-Westphal Strip
Anderson, Scott F.; Beck-Winchatz, Bernhard
Quasars that are representative of the populous faint end of the luminosity function are frustratingly dim, with m~24 at intermediate redshift; moreover, ground-based surveys for such faint QSOs suffer substantial morphological contamination by compact galaxies with similar colors. In order to establish a more reliable ultrafaint QSO sample, we us…
HUBBLE SPACE TELESCOPE View of the Heart of Ursa Minor
Battinelli, Paolo; Demers, Serge
Hubble Space Telescope F606W observations to 26th magnitude are used to investigate the stellar distribution in the center of the Ursa Minor dwarf spheroidal galaxy. The central surface density is found to be low, less than 700 stars arcmin^-2, with no sign of a pronounced cusp. The maximum of the surface density is not found at our adopted center…
Hubble Space Telescope WFPC2 Imaging of Three Low Surface Brightness Dwarf Elliptical Galaxies in the Virgo Cluster
Impey, C. D.; Bothun, G. D.; O'Neil, Karen
Utilizing the F814W and F300W filters, Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) images were taken of three low surface brightness dwarf elliptical galaxies in the Virgo Cluster. The intent of the observations was to determine the small-scale structure in these enigmatic galaxies and to attempt to learn something about the natur…
Analyses of the Short-Period Cepheid SU Cassiopeiae
Volk, K.; Milone, E. F.; Wilson, W. J. F.
Baade-Wesselink analyses of this important Galactic classical Cepheid provide new values for the radius, luminosity, distance, and mass and show SU Cas likely to be pulsating in the first overtone. Application of a modified Baade-Wesselink technique and the maximum likelihood method, which we have previously applied to δ Scuti-type variables, yiel…