Search Publications
A New Infrared Band in Interstellar and Circumstellar Clouds: C4 or C4H?
Cernicharo, José; Goicoechea, Javier R.; Benilan, Yves
We report on the detection with the Infrared Space Observatory of a molecular band at 57.5 µm (174 cm-1) in carbon-rich evolved stars and in Sgr B2. Taking into account the chemistry of these objects, the most likelihood carrier is a carbon chain. We tentatively assign the band to the ν5 bending mode of C4 fo…
Complex X-Ray Spectral Variability in Markarian 421 Observed with XMM-Newton
Edelson, R.; Turner, M. J. L.; Markowitz, A. +2 more
The bright blazar Mrk 421 has been observed four times for uninterrupted durations of ~9-13 hr during the performance verification and calibration phases of the XMM-Newton mission. The source was strongly variable in all epochs, with variability amplitudes that generally increased to higher energy bands. Although the detailed relationship between …
Elemental Abundances and Ionization States within the Local Interstellar Cloud Derived from Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer Observations of the Capella Line of Sight
Redfield, Seth; Wood, Brian E.; Linsky, Jeffrey L. +1 more
We use ultraviolet spectra of Capella from the Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer satellites to study interstellar absorption lines from the Local Interstellar Cloud (LIC). Measurements of these lines are used to empirically determine the ionization states of carbon, nitrogen, and silicon in the LIC, for comparison w…
A New Abundance Analysis of the ONeMg Nova QU Vulpeculae
Schwarz, Greg J.
This paper presents a new determination of the ejecta elemental abundances of the moderately fast ONeMg nova QU Vul 1984 using published ultraviolet, optical, infrared, and radio observations. The technique uses an optimization code in combination with CLOUDY photoionization models to fit the emission-line spectra obtained at multiple epochs durin…
The Extended Emission-Line Region of 4C 37.43
MacKenty, John W.; Stockton, Alan; Hu, Esther M. +1 more
We have explored the nature of the extended emission-line region around the z=0.37 quasar 4C 37.43, using extensive ground-based and Hubble Space Telescope (HST) imaging and spectroscopy. The velocity field of the ionized gas shows gradual gradients within components but large jumps between components, with no obvious global organization. The HST …
A Comparison between Coronal Emission Lines from an Isothermal Spectrum Observed with the Coronal Diagnostic Spectrometer and CHIANTI Emissivities
Dere, K. P.; Landi, E.; Feldman, U.
The present paper compares off-disk spectral observations of the solar corona in the ranges 307-379 and 513-633 Å with theoretical emissivities calculated using the CHIANTI database. The observed spectra were recorded by the Coronal Diagnostic Spectrometer instrument on board the Solar and Heliospheric Observatory using the normal-incidence portio…
XMM-Newton Observations of the Spiral Galaxy M74 (NGC 628)
Soria, Roberto; Kong, Albert K. H.
The face-on spiral galaxy M74 (NGC 628) was observed by XMM-Newton on 2002 February 2. In total, 21 sources are found in the inner 5' from the nucleus (after rejection of a few sources associated to foreground stars). Hardness ratios suggest that about half of them belong to the galaxy. The higher luminosity end of the luminosity function is fitte…
Intermediate- and High-Velocity Ionized Gas toward ζ Orionis
Jenkins, Edward B.; York, Donald G.; Raymond, John C. +2 more
We combine near-UV spectra obtained with the Hubble Space Telescope GHRS echelle with far-UV spectra obtained with the Interstellar Medium Absorption Profile Spectrograph and Copernicus to study the abundances and physical conditions in the predominantly ionized gas seen at high velocity (-105 km s-1<~vsolar<~-65 km s
The Star Formation History of the Blue Compact Dwarf Galaxy UGCA 290
Greggio, Laura; Hopp, Ulrich; Schulte-Ladbeck, Regina E. +1 more
We present the star formation history of UGCA 290, a galaxy with properties intermediate between blue compact dwarfs (BCDs) and dwarf irregulars. This galaxy is particularly interesting because its young stellar population is extremely similar to that of the well-studied type iE blue compact dwarf VII Zw 403, despite its different spatial morpholo…
A Probable Optical Counterpart to the Isolated Neutron Star RX J1308.6+2127
Kulkarni, S. R.; van Kerkwijk, M. H.; Kaplan, D. L.
Using a very deep observation from the Hubble Space Telescope Space Telescope Imaging Spectrometer, we have searched for an optical counterpart to the nearby radio-quiet isolated neutron star RX J1308.6+2127 (RBS 1223). We have identified a single object in the 90% Chandra error circle that we believe to be the optical counterpart. This object has…