Search Publications
X-ray imaging-spectroscopy of Abell 1835
Kaastra, J. S.; Arnaud, M.; Fabian, A. C. +6 more
We present detailed spatially-resolved spectroscopy results of the observation of Abell 1835 using the European Photon Imaging Cameras (EPIC) and the Reflection Grating Spectrometers (RGS) on the XMM-Newton observatory. Abell 1835 is a luminous (1046 ergs {s}-1), medium redshift (z=0.2523), X-ray emitting cluster of galaxies.…
Infrared Space Observatory's Discovery of C4H2, C6H2, and Benzene in CRL 618
Waters, L. B. F. M.; Cernicharo, José; Tielens, A. G. G. M. +4 more
We report on the detection with the Infrared Space Observatory (ISO), for the first time in the circumstellar medium, of the polyacetylenic chains C4H2 and C6H2 and of benzene (C6H6) in the direction of the proto-planetary nebula CRL 618. Surprisingly, the abundances of di- and tria…
Observational Constraints on the Formation and Evolution of Binary Stars
Ghez, A. M.; White, R. J.
We present a high spatial resolution multiwavelength survey of 44 young binary star systems in Taurus-Auriga with separations of 10-1000 AU. These observations, which were obtained using the Hubble Space Telescope and the NASA Infrared Telescope Facility, quadruple the number of close (less than 100 AU) binary stars with spatially resolved measure…
Late-type members of young stellar kinematic groups - I. Single stars
Montes, D.; López-Santiago, J.; Cornide, M. +3 more
This is the first paper of a series aimed at studying the properties of late-type members of young stellar kinematic groups. We concentrate our study on classical young moving groups such as the Local Association (Pleiades moving group, 20-150Myr), IC 2391 supercluster (35Myr), Ursa Major group (Sirius supercluster, 300Myr), and Hyades supercluste…
Radiation-driven winds of hot luminous stars. XIII. A description of NLTE line blocking and blanketing towards realistic models for expanding atmospheres
Pauldrach, A. W. A.; Hoffmann, T. L.; Lennon, M.
Spectral analysis of hot luminous stars requires adequate model atmospheres which take into account the effects of NLTE and radiation driven winds properly. Here we present significant improvements of our approach in constructing detailed atmospheric models and synthetic spectra for hot luminous stars. Moreover, as we regard our solution method in…
The Infrared Spectral Energy Distribution of Normal Star-forming Galaxies
Dale, Daniel A.; Helou, George; Silbermann, Nancy A. +2 more
We present a new phenomenological model for the spectral energy distribution of normal star-forming galaxies between 3 and 1100 µm. A sequence of realistic galaxy spectra are constructed from a family of dust emission curves assuming a power-law distribution of dust mass over a wide range of interstellar radiation fields. For each interstell…
The Galactic Disk Mass Budget. I. Stellar Mass Function and Density
Chabrier, Gilles
In this paper, we use the general theory worked out within the past few years for the structure and the evolution of low-mass stars to derive the stellar mass function in the Galactic disk down to the vicinity of the hydrogen-burning limit from the observed nearby luminosity functions. The accuracy of the mass-magnitude relationships derived from …
The Metamorphosis of SN 1998bw
Leibundgut, Bruno; Kouveliotou, Chryssa; Nomoto, Ken'ichi +23 more
We present and discuss the photometric and spectroscopic evolution of the peculiar SN 1998bw, associated with GRB 980425, through an analysis of optical and near-IR data collected at ESO-La Silla. The spectroscopic data, spanning the period from day -9 to day +376 (relative to B maximum), have shown that this supernova (SN) was unprecedented, alth…
Properties of Globular Cluster Systems in Nearby Early-Type Galaxies
Forbes, Duncan A.; Brodie, Jean P.; Huchra, John P. +2 more
We present a study of globular clusters (GCs) in 17 relatively nearby early-type galaxies, based on deep F555W and F814W images from the Wide Field Planetary Camera 2, on board the Hubble Space Telescope. A detailed analysis of color distributions, cluster sizes, and luminosity functions is performed and compared with GCs in the Milky Way. In near…
Dust in active nuclei. I. Evidence for ``anomalous'' properties
Maiolino, R.; Marconi, A.; Oliva, E. +5 more
We present observational evidences that dust in the circumnuclear region of AGNs has different properties than in the Galactic diffuse interstellar medium. By comparing the reddening of optical and infrared broad lines and the X-ray absorbing column density we find that the EB-V/N_H ratio is nearly always lower than Galactic by a factor…