Search Publications
Missions
Journals
Publication Years
The Star Clusters in the Irregular Galaxy NGC 4449
Gallagher, J. S.; Hunter, Deidre A.; Gelatt, Andrea E.
We examine the star clusters in the luminous irregular galaxy NGC 4449. We use a near-infrared spectrum and broadband images taken with the Hubble Space Telescope to place a limit of 8-15 Myr on the age of the bright central object in NGC 4449. Its luminosity and size suggest that it is comparable to young super star clusters. However, there is a …
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…
Low-excitation atomic gas around evolved stars. II. ISO observations of O-rich nebulae
Barlow, M. J.; Bujarrabal, V.; Tielens, A. G. G. M. +4 more
We have observed atomic fine-structure lines in the far-infrared (FIR) from 12 oxygen-rich evolved stars. The sample is composed of mostly proto-planetary nebulae (PPNe) and some planetary nebulae (PNe) and asymptotic giant branch (AGB) stars. ISO LWS and SWS observations of [O I], [C II], [N II], [Si I], [Si II], [S I], [Fe I], and [Fe II] lines …
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…
The PAH 7.7 mu m/850 mu m ratio as new diagnostics for high extinction in ULIRGs - increasing evidence for a hidden quasar in Arp 220
Klaas, U.; Haas, M.; Chini, R. +2 more
A new method is presented to reveal high mid-infrared (MIR) extinction in ultraluminous infrared galaxies (ULIRGs): the ratio between the PAH 7.7 mu m feature and the sub-mm continuum at 850 mu m. While the sub-mm radiation is optically thin and serves for normalization, any high MIR extinction reduces the observed PAH 7.7 mu m strength. Since the…
The discovery of the ``21'' mu m and ``30'' mu m emission features in Planetary Nebulae with Wolf-Rayet central stars
Waters, L. B. F. M.; Hony, S.; Tielens, A. G. G. M.
We report the discovery of the ``21'' mu m and ``30'' mu m features in the planetary nebulae around the hydrogen-deficient stars HD 826 and HD 158269. The carriers of these features are known to be produced in outflows around carbon-rich stars. This discovery demonstrates that the bulk of the dust in these nebulae has been produced during a carbon…
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…