Search Publications
Multivariate analysis of globular cluster horizontal branch morphology: searching for the second parameter
Djorgovski, S. G.; Recio-Blanco, A.; Piotto, G. +2 more
Aims.The interpretation of globular cluster horizontal branch (HB) morphology is a classical problem that can significantly blur our understanding of stellar populations.
Methods: .We present a new multivariate analysis connecting the effective temperature extent of the HB with other cluster parameters. The work is based on Hubble Space Telesc…
Spatial mapping of ices in the Ophiuchus-F core. A direct measurement of CO depletion and the formation of CO_2
Pontoppidan, K. M.
Aims.Ices in dense star-forming cores contain the bulk of volatile molecules apart from H2 and thus represent a large fraction of dark cloud chemistry budget. Mm observations of gas provide indirect evidence for significant freeze-out of CO in the densest cores. To directly constrain the freeze-out profile of CO, the formation route of CO2 and the…
Confirmation of the planet hypothesis for the long-period radial velocity variations of β Geminorum
Guenther, E. W.; Hatzes, A. P.; Cochran, W. D. +8 more
Aims.Our aim is to confirm the nature of the long period radial velocity measurements for β Gem first found by Hatzes & Cochran (1993).
Methods: .We present precise stellar radial velocity measurements for the K giant star β Gem spanning over 25 years. An examination of the Ca II K emission, spectral line shapes from high resolution data …
Spitzer/IRAC and ISOCAM/CVF insights on the origin of the near to mid-IR Galactic diffuse emission
Boulanger, F.; Reach, W. T.; Flagey, N. +3 more
Spitzer/IRAC images of extended emission provide a new insight on the nature of small dust particles in the Galactic diffuse interstellar medium. We measure IRAC colors of extended emission in several fields covering a range of Galactic latitudes and longitudes outside of star forming regions. We determine the nature of the Galactic diffuse emissi…
Abundance studies of sdB stars using UV echelle HST/STIS spectroscopy
Heber, U.; O'Toole, S. J.
Aims.We test the hypothesis that the pulsations in sdB stars are correlated with the surface abundances of iron-group elements. Any correlation might explain why, when given two spectroscopically similar stars, one will pulsate while the other will not.
Methods: .We have obtained high-resolution ultraviolet spectra two pulsating and three non-…
Newly discovered active binaries in the RasTyc sample of stellar X-ray sources. I. Orbital and physical parameters of six new binaries
Freire Ferrero, R.; Guillout, P.; Frasca, A. +3 more
We present the first results from follow-up optical observations, both photometric and spectroscopic, of stellar X-ray sources, selected from the RasTyc sample, resulting from the cross-correlation of ROSAT All-Sky Survey (RASS) and TYCHO catalogues. In particular, we report on the discovery of six late-type binaries, for which we obtained good ra…
XMM-Newton and Chandra measurements of the AGN intrinsic absorption: dependence on luminosity and redshift
Georgakakis, A.; Hatziminaoglou, E.; Georgantopoulos, I. +2 more
We combine bright XMM-Newton data with the Chandra Deep Field South observations to explore the behavior of the intrinsic AGN absorption, as a function of redshift and luminosity. Our sample consists of 359 sources selected in the hard 2-8 keV band, spanning the flux range 6 × 10-16-3 × 10-13 erg~cm-2~s-1
Recovering the star formation rate in the solar neighborhood
Prada Moroni, P. G.; Degl'Innocenti, S.; Cignoni, M. +1 more
Aims.This paper develops a method for obtaining the star formation histories of a mixed, resolved population through the use of color-magnitude diagrams (CMDs). The method provides insight into the local star formation rate, analyzing the observations of the Hipparcos satellite through a comparison with synthetic CMDs computed for different histor…
Observational evidence for a truncation of the star cluster initial mass function at the high mass end
Bastian, N.; Larsen, S. S.; Gieles, M. +3 more
We present the luminosity function (LF) of star clusters in M 51 based on HST/ACS observations taken as part of the Hubble Heritage project. The clusters are selected based on their size and with the resulting 5990 clusters we present one of the largest cluster samples of a single galaxy. We find that the LF can be approximated with a double power…
Multi-wavelength study of coronal waves associated with the CME-flare event of 3 November 2003
Magdalenić, J.; Temmer, M.; Vršnak, B. +4 more
The large flare/CME event that occurred close to the west solar limb on 3 November 2003 launched a large-amplitude large-scale coronal wave that was observed in Hα and Fe xii 195 Å spectral lines, as well as in the soft X-ray and radio wavelength ranges. The wave also excited a complex decimeter-to-hectometer type II radio burst, revealing the for…