Search Publications
X-ray nature of the LINER nuclear sources
Guerrero, M. A.; González-Martín, O.; Márquez, I. +2 more
We report the results from a homogeneous analysis of the X-ray (Chandra ACIS) data available for a sample of 51 LINER galaxies selected from the catalogue by Carrillo et al. (1999, Rev. Mex. Astron. Astrofis., 35, 187) and representative of the population of bright LINER sources. The nuclear X-ray morphology has been classified by their nuclear co…
On the AU Microscopii debris disk. Density profiles, grain properties, and dust dynamics
Augereau, J. -C.; Beust, H.
Context: .
Dynamical mass estimates for two luminous star clusters in galactic merger remnants
Saglia, R. P.; Bastian, N.; Zoccali, M. +4 more
We present high-dispersion spectra of two extremely massive star clusters in galactic merger remnants, obtained using the UVES spectrograph mounted on the ESO Very Large Telescope. One cluster, W30, is located in the ~500 Myr old merger remnant NGC 7252 and has a velocity dispersion and effective radius of σ=27.5±2.5 km s-1 and Ref…
Reconstruction of solar irradiance variations in cycles 21-23 based on surface magnetic fields
Solanki, S. K.; Krivova, N. A.; Fröhlich, C. +1 more
Aims.We present a reconstruction of total solar irradiance (TSI) back to 1974, i.e. from the minimum of cycle 21 to the declining phase of cycle 23. We also present a cross-calibration between the magnetograms obtained by the 512 channel magnetograph and the spectromagnetograph at Kitt Peak.
Methods: .The TSI reconstruction is carried out usin…
Detection of Wolf-Rayet stars in host galaxies of gamma-ray bursts (GRBs): are GRBs produced by runaway massive stars ejected from high stellar density regions?
Le Floc'h, E.; Schaerer, D.; Dessauges-Zavadsky, M. +3 more
We have obtained deep spectroscopic observations of several nearby gamma-ray burst (GRB) host galaxies revealing for the first time the presence of Wolf-Rayet (WR) stars and numerous O stars located in rich and compact clusters or star forming regions. Surprisingly, high spatial resolution imaging shows that the GRBs and the associated supernovae …
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-…