Search Publications
Blue Stragglers, Young White Dwarfs, and UV-Excess Stars in the Core of 47 Tucanae
Ferraro, Francesco R.; Paltrinieri, Barbara; Possenti, Andrea +2 more
We used a set of archived Hubble Space Telescope/WFPC2 images to probe the stellar population in the core of the nearby galactic globular cluster (GGC) 47 Tuc. From the ultraviolet (UV) color magnitude diagrams (CMDs) obtained for ~4000 stars detected within the Planetary Camera (PC) field of view we have pinpointed a number of interesting objects…
A Chandra Study of the Circinus Galaxy Point-Source Population
Bauer, F. E.; Brandt, W. N.; Netzer, H. +4 more
We have used the Chandra X-Ray Observatory to resolve spatially and spectrally the X-ray emission from the Circinus galaxy. We report here on the nature of the X-ray emission from the off-nuclear point sources associated with the disk of Circinus, which make up ~34% of the total 0.5-10 keV emission. We find that many of the serendipitous X-ray sou…
The White Dwarf Distance to the Globular Cluster 47 Tucanae and its Age
Zoccali, M.; Bragaglia, A.; Rich, R. M. +9 more
We present a new determination of the distance (and age) of the Galactic globular cluster 47 Tucanae (NGC 104) based on the fit of its white dwarf (WD) cooling sequence with the empirical fiducial sequence of local WD with known trigonometric parallax, following the method described by Renzini and collaborators. Both the cluster and the local WDs …
New Insights from Hubble Space Telescope Studies of Globular Cluster Systems. II. Analysis of 29 S0 Systems
Kundu, Arunav; Whitmore, Bradley C.
We examine the globular cluster systems (GCSs) of a sample of 34 S0 galaxies from a WFPC2 snapshot survey in the V and I bands. Of these 34 galaxies, 29 have measurable globular cluster systems. The mean color of the GCSs of individual galaxies vary from V-I=0.85 mag to V-I=1.17 mag. The average color of GCSs in all 29 S0 galaxies, V-I=1.00+/-0.07…
The XMM-Newton view of stellar coronae: High-resolution X-ray spectroscopy of Capella
Bromage, G. E.; Raassen, A. J. J.; Mewe, R. +5 more
We present the high-resolution RGS X-ray spectrum of the stellar binary Capella observed by the XMM-Newton satellite. A multi-thermal approach has first been applied to fit the data and derive elemental abundances. Using the latter, the emission measure distribution has been reconstructed using a Chebychev polynomial fit. Its shape is found to dis…
Time-resolved spectral analysis of the pulsating helium star V652 Her
Jeffery, C. S.; Woolf, V. M.; Pollacco, D. L.
A series of 59 moderate-resolution high signal-to-noise spectra of the pulsating helium star
The properties of field elliptical galaxies at intermediate redshift - III. The Fundamental Plane and the evolution of stellar populations from z~0.4 to z=0
Treu, T.; Stiavelli, M.; Møller, P. +2 more
We report on the study of a sample of 25 field early-type galaxies, in the redshift range z~0.1-0.5, selected on the basis of colours and morphology from the Medium Deep Survey (MDS) of the Hubble Space Telescope (HST). Surface photometry in two colours (F606W and F814W) and redshifts have been derived for all the galaxies in the sample, while vel…
Proper Motions of the HH 111 Jet Observed with the Hubble Space Telescope
Hartigan, Patrick; Bally, John; Reipurth, Bo +2 more
New Hα and [S II] images of the HH 111 jet taken with the Hubble Space Telescope reveal marked proper motions and morphological changes when compared with similar images obtained 4 years earlier. Knots in the jet, which are dominated by emission from nested bow shocks, generally move ballistically, with no evidence for turbulent motions even in re…
Young Clusters in the Nuclear Starburst of M83
Conselice, Christopher J.; Calzetti, Daniela; Gallagher, John S., III +2 more
We present a photometric catalog of 45 massive star clusters in the nuclear starburst of M83 (NGC 5236), observed with the Hubble Space Telescope Wide Field Planetary Camera 2, in both broadband (F300W, F547M, and F814W) and narrowband (F656N and F487N) filters. By comparing the photometry with theoretical population synthesis models, we estimate …
Modulation of Jovian and galactic electrons in the heliosphere: 1. Latitudinal transport of a few MeV electrons
Fichtner, H.; Ferreira, S. E. S.; Potgieter, M. S. +2 more
The heliospheric modulation of galactic and Jovian electrons is studied using a fully three-dimensional, steady state model based on Parker's transport equation including the Jovian source. The modulation of low-energy electrons is a handy tool to establish and to construct a suitable diffusion tensor to assure compatibility between model computat…