Search Publications
Infrared Surface Brightness Fluctuations of the Coma Elliptical Galaxy NGC 4874 and the Value of the Hubble Constant
Graham, James R.; Liu, Michael C.
We have used the Keck I telescope to measure K-band surface brightness fluctuations (SBFs) of NGC 4874, the dominant elliptical galaxy in the Coma Cluster. We use deep Hubble Space Telescope (HST) WFPC2 optical imaging to account for the contamination due to faint globular clusters and improved analysis techniques to derive measurements of the SBF…
Circumstellar Carbonaceous Material Associated with Late-Type Dusty WC Wolf-Rayet Stars
Tielens, A. G. G. M.; Chiar, J. E.
We have studied the 5-8.5 µm infrared spectra of the late-type Wolf-Rayet stars WR 118, WR 112, and WR 104, the WN star WR 147, the B5 hypergiant Cygnus OB2 No. 12, and the Galactic center luminous blue variable Pistol Star using the Short Wavelength Spectrometer on the Infrared Space Observatory. We attribute an absorption feature at 6.2 &m…
A Far-Infrared Study of the CfA Seyfert Sample. I. The Data
Pérez García, A. M.; Rodríguez Espinosa, J. M.
We present mid- and far-IR Infrared Space Observatory data of the CfA Seyfert galaxy sample. These data allow a detailed study of the far-IR spectral energy distribution (SED) of these galaxies. A Bayesian inversion method has been used to invert the SED of these objects and to identify three characteristic temperature ranges of dust emission. The…
Two-dimensional Kinematical and Ionization Structure of the Warm Gas in the Nuclear Regions of Arp 220
Arribas, Santiago; Colina, Luis; Clements, David
Integral field optical spectroscopy using the INTEGRAL system has been used to characterize the kinematic and ionization properties of the warm gas within 2 kpc of the dust-enshrouded nucleus of Arp 220. Owing to the large internal extinction toward the nuclei, the brightest stellar and line-emitting regions observed at optical wavelengths do not …
Hydrodynamic Simulations of Proplyd Bow Shocks
Henney, W. J.; Arthur, S. J.; García-Arredondo, F.
We present two-dimensional hydrodynamic simulations of the interaction between an ionized photoevaporation flow from a proplyd and a stellar wind from a hot star. We consider both the case of a fully supersonic wind and the case of a wind that passes through a global shock to become subsonic before reaching the proplyd. We compare the results of o…
Hubble Space Telescope Observations of the CfA Seyfert 2 Galaxies: Near-Infrared Surface Photometry and Nuclear Bars
Ravindranath, Swara; Pogge, Richard W.; Martini, Paul +1 more
We present near-infrared J and H surface photometry of 24 of the nearby Seyfert 1.8, 1.9, and 2 galaxies from the CfA Seyfert sample. The excellent angular resolution of the Hubble Space Telescope probes spatial scales as small as tens of parsecs in most of these active galactic nuclei (AGNs) and is sensitive to the presence of nuclear bars and ot…
Horizontal-Branch Models and the Second-Parameter Effect. IV. The Case of M3 and Palomar 3
Catelan, M.; Ferraro, F. R.; Rood, R. T.
We present a detailed analysis of the ``second-parameter pair'' of globular clusters M3 (NGC 5272) and Palomar 3. Our main results can be summarized as follows: (1) The horizontal-branch (HB) morphology of M3 is significantly bluer in its inner regions (observed with the Hubble Space Telescope) than in the cluster outskirts (observed from the grou…
Far Ultraviolet Spectroscopic Explorer Observations of Capella
Young, P. R.; Moos, H. W.; Linsky, J. L. +4 more
Far Ultraviolet Spectroscopic Explorer observations of the binary system Capella reveal a rich emission-line spectrum containing neutral and ionic species, among them H I, O I, C III, O VI, S VI, Ne V, and Ne VI. In addition, Fe XVIII λ974.85, formed at temperatures of ~6×106 K, is detected. Whereas the strong transition region lines pr…
Multiwavelength Study of the Starburst Galaxy NGC 7714. II. The Balance between Young, Intermediate-Age, and Old Stars
Leitherer, Claus; Lançon, Ariane; González Delgado, Rosa M. +1 more
We combine existing multiwavelength data (including an HST/GHRS UV spectrum and a ground-based optical spectrum) with unpublished HST/WFPC2 images, near-IR photometry, and K-band spectroscopy. We use these data to constrain the young, the intermediate-age, and the old stellar populations in the central regions of the starburst galaxy NGC 7714. In …
Ultraviolet Spectropolarimetry of Narrow-Line Radio Galaxies
Dey, Arjun; Spinrad, Hyron; van Breugel, Wil +4 more
We present the results of UV spectropolarimetry (λrest~=2000-3000 Å) and far-UV spectroscopy (λrest~=1500-2000 Å) of two low-redshift narrow-line radio galaxies (NLRGs) taken with the Faint Object Spectrograph on board the Hubble Space Telescope (HST). Spectropolarimetry of several NLRGs has shown that, by the presence of bro…