Search Publications
Radio detections of the neutron star X-ray binaries 4U 1820 - 30 and Ser X-1 in soft X-ray states
Homan, J.; van der Klis, M.; Fender, R. P. +4 more
We present the analysis of simultaneous X-ray (RXTE) and radio (VLA) observations of two atoll-type neutron star X-ray binaries: 4U 1820 - 30 and Ser X-1. Both sources were steadily in the soft (`banana') X-ray state during the observations. We have detected the radio counterpart of 4U 1820 - 30 at 4.86 and 8.46 GHz at a flux density of ~0.1 mJy. …
Mass Segregation in the Globular Cluster Palomar 5 and its Tidal Tails
Grebel, Eva K.; Caldwell, John A. R.; Koch, Andreas +2 more
We present the stellar main-sequence luminosity function (LF) of the disrupted, low-mass, low-concentration globular cluster Palomar 5 and its well-defined tidal tails, which emanate from the cluster as a result of its tidal interaction with the Milky Way. The results of our deep (B~24.5) wide-field photometry unequivocally indicate that preferent…
The distance to the Pleiades from orbital solution of the double-lined eclipsing binary HD 23642
Munari, U.; Soubiran, C.; Siviero, A. +3 more
Combining precise B, V photometry and radial velocities, we have been able to derive a firm orbital solution and accurate physical parameters for the newly discovered eclipsing binary HD 23642 in the Pleiades open cluster. The resulting distance to the binary and therefore to the cluster is 132 ± 2 pc. This closely confirms the distance modulus ob…
An XMM-Newton observation of Ark 120: the X-ray spectrum of a `bare' Seyfert 1 nucleus
Piro, L.; Vaughan, S.; Fabian, A. C. +3 more
We report on a long (100 ks) XMM-Newton observation of the bright Seyfert 1 galaxy Arakelian 120. The source previously showed no signs of intrinsic reddening in its infrared-ultraviolet continuum and previous observations had shown no evidence for ionized absorption in either the ultraviolet or X-ray bands. The new XMM-Newton Reflection Grating S…
Chemical abundances of planetary nebulae from optical recombination lines - I. Observations and plasma diagnostics
Liu, Y.; Barlow, M. J.; Liu, X. -W. +1 more
We have obtained deep optical spectra of medium resolution for a sample of 12 Galactic planetary nebulae (PNe). Optical recombination lines (ORLs) from carbon, nitrogen and oxygen have been detected in 11 of them and neon ORLs in nine of them. All spectra were obtained by scanning a long slit across the nebular surface, yielding relative line inte…
Stellar and Gaseous Abundances in M82
Maiolino, R.; Ranalli, P.; Comastri, A. +1 more
The near-infrared (near-IR) absorption spectra of starburst galaxies show several atomic and molecular lines from red supergiants that can be used to infer reliable stellar abundances. The metals locked in stars give a picture of the galaxy metallicity prior to the last burst of star formation. The enrichment of the new generation of stars born in…
The high energy emission line spectrum of NGC 1068
Bianchi, S.; Guainazzi, M.; Molendi, S. +1 more
We present and discuss the high energy (E>4 keV) XMM-Newton spectrum of the Seyfert 2 galaxy, NGC 1068. Possible evidence for flux variability in both the neutral and ionized reflectors with respect to a BeppoSAX observation taken 3.5 years before is found. Several Fe and Ni emission lines, from both neutral and highly ionized material, are det…
Deep Luminosity Functions of Old and Intermediate-Age Globular Clusters in NGC 1316: Evidence for Dynamical Evolution of Second-Generation Globular Clusters
Gilmore, Diane; Whitmore, Bradley C.; Schweizer, François +1 more
The Advanced Camera for Surveys on board the Hubble Space Telescope has been used to obtain deep high-resolution images of the giant early-type galaxy NGC 1316, an obvious merger remnant. These observations supersede previous shallower imagery that revealed the presence of a population of metal-rich globular clusters of intermediate age (~3 Gyr). …
The Luminosity-Metallicity relation of distant luminous infrared galaxies
Elbaz, D.; Flores, H.; Cesarsky, C. J. +3 more
One hundred and five 15 \mum-selected objects in three ISO (Infrared Space Observatory) deep survey fields (CFRS 3h, UDSR and UDSF) are studied on the basis of their high-quality optical spectra with resolution R>1000 from VLT/FORS2. ∼92 objects (88%) have secure redshifts, ranging from 0 to 1.16 with a median value of z_med=0.587. <…
The Deuterium-to-Hydrogen Ratio in a Low-Metallicity Cloud Falling onto the Milky Way
Kruk, J. W.; Savage, B. D.; Wakker, B. P. +13 more
Using Far Ultraviolet Spectroscopic Explorer (FUSE) and Hubble Space Telescope observations of the QSO PG 1259+593, we detect D I Lyman series absorption in high-velocity cloud Complex C, a low-metallicity gas cloud falling onto the Milky Way. This is the first detection of atomic deuterium in the local universe in a location other than the nearby…