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LWS-spectroscopy of Herbig Haro objects and molecular outflows in the Cha II dark cloud.
Ade, P. A. R.; Liseau, R.; White, G. J. +34 more
We present the first far infrared spectra of the Herbig Haro objects HH 52-53-54 and of IRAS 12496-7650, all located in the nearby star forming region known as Chamaleon II dark cloud, obtained with the Long Wavelength Spectrometer (LWS) onboard the Infrared Space Observatory (ISO). The richest spectrum is found in HH 54, showing molecular transit…
The Disappearing Broad Absorption Lines and Variable Emission Lines in NGC 3516
Robinson, Andrew; Horne, Keith; Goad, Michael R. +17 more
The Seyfert 1 galaxy NGC 3516 was monitored during 1993 February 16- May 13 by IUE every 4 days for the first month, and then every 2 days for 2 months giving a total of 40 observations. This paper gives the initial results from this campaign. (1) The broad C IV λ1549 emission line variations are delayed relative to those of the ionizing continuum…
The boron isotope ratio in the interstellar medium
Federman, S. R.; Lambert, David L.; Cardelli, Jason A. +1 more
OBSERVATIONS of the abundances of elements provide insight into their production and distribution. The production of light elements (in particular, lithium, beryllium and boron) is dominated by spallation reactions1, in which cosmic rays break apart more massive nuclei. Models2,3 suggest that the 11B/10B…
The Ultraviolet Spectra of the Jovian Aurora
Dalgarno, A.; Liu, Weihong
The ultraviolet spectra of molecular hydrogen H2 due to electron impact excitation are calculated and compared with the high-resolution (0.56 Å) spectra of the Jovian aurora obtained with the Hubble Space Telescope Goddard High-Resolution Spectrograph. All the observed features are reproduced by electron impact excitation emissions of H…
HST and groundbased observations of the `Hubble-Sandage' variables in M 31 and M 33.
Stahl, O.; Davidson, K.; Humphreys, R. M. +4 more
The small group of peculiar stars known as the Hubble-Sandage variables in M 31 and M 33 belong to the class of stars we now call the Luminous Blue Variables - highly unstable, evolved massive stars found in many spiral and irregular galaxies. We have used the Hubble Space Telescope to obtain UV imaging and spectroscopy of several of the LBVs in M…
Photoionization resonances of SiII in stellar spectra.
Lanz, T.; Artru, M. -C.; Hubeny, I. +1 more
We have studied the influence of the Si^+^ photoionization on stellar atmospheres. Recent calculations using the R-matrix code provide detailed cross-sections with autoionization resonances for the first 50 energy levels of Si^+^. These photoionization cross-sections are included in the calculation of the far ultraviolet synthetic spectrum of A an…
New X-ray sources detected among mild barium and S stars.
Schmitt, J. H. M. M.; Jorissen, A.; Ginestet, N. +2 more
We report on the detection by ROSAT of X-rays from the mild barium star HD 165141 (K0III/IIBa1) and from the S stars HD 35155 (S4,1) and HR 363 (S3/2). For the S stars, the X-ray flux is attributed to the accretion of the red-giant wind by the white dwarf companion. The strong variability observed in the X- and UV fluxes on time scales of both hou…
An HST Study of OB Associations and Star Clusters in M101
Stetson, Peter B.; Bresolin, Fabio; Kennicutt, Robert C., Jr.
The massive stellar content, the OB associations and the star clusters in an HST field in M101 = NGC 5457 are investigated. A clustering algorithm yields 79 putative associations. Their size distribution is similar to that found in the Magellanic Clouds, M31, and M33, with an average size around 90 pc. The V luminosity function for the stars conta…
Globular Clusters in the Inner Regions of NGC 5128 (Centaurus A)
Minniti, Dante; Jablonka, Pascale; Goudfrooij, Paul +2 more
We have identified 26 new globular cluster candidates in the inner 3 kpc of NGC 5128 (Centaurus A), the nearest known large galaxy that is the probable product of a merger. The clusters are selected on the basis of their structural parameters (observed core diameters and ellipticities), as measured from archival Wide Field Planetary Camera (WFPC) …
LWS observations of the colliding galaxies NGC 4038/39.
Malkan, M. A.; Ade, P. A. R.; Miles, J. W. +31 more
Infrared Space Observatory (ISO) Long Wavelength Spectrometer (LWS) and ground-based Fabry-Perot imaging spectroscopic observations are used to penetrate the extinction to the powerful burst of star formation that has occurred in the extranuclear molecular cloud complex in the galaxy overlap region of the galaxies NGC 4038/39 ("The Antennae"). Par…