Search Publications
High-z massive galaxies in the Hubble Deep Field South
Fontana, A.; Vanzella, E.; Cristiani, S. +6 more
A census of massive galaxies at redshift increasingly higher than z∼1 may provide strong constraints for the history of mass assembly and star formation. Here we report the analysis of three galaxies selected in the Hubble Deep Field South at K s≤22 on the basis of their unusually red near-IR color J-K≥3. We have used population synthesis models t…
XMM-Newton EPIC observation of the galaxy cluster A 3667
Finoguenov, A.; Briel, U. G.; Henry, J. P.
The Abell cluster of galaxies A 3667 was observed with XMM-Newton in 6 partially overlapping pointings. We present here the resulting X-ray surface brightness, temperature, entropy and pressure maps and discuss the structure of this cluster on scales from 0.1 to 30 arcmin. Based on these observations we refine the origin of the A 3667 cold front t…
A study of the expanding envelope of Nova V1974 Cyg 1992 based on IUE high resolution spectroscopy
Altamore, A.; Rossi, C.; González-Riestra, R. +2 more
We have carried out a detailed analysis of the IUE archival high resolution spectra of the classical nova V1974 Cyg 1992. The main UV resonance lines show P Cygni profiles in the first days, which change into symmetric pure emission lines, and then slowly become fainter and narrower. Lines of higher ionization species reach their peak luminosity l…
The 3-D ionization structure and evolution of NGC 7009 (Saturn Nebula)
Sabbadin, F.; Turatto, M.; Cappellaro, E. +2 more
Tomographic and 3-D analyses for extended, emission-line objects are applied to long-slit ESO NTT + EMMI high-resolution spectra of the intriguing planetary nebula NGC 7009, covered at twelve position angles. We derive the gas expansion law, the diagnostics and ionic radial profiles, the distance and the central star parameters, the nebular photo-…
Heliospheric conditions that affect the interstellar gas inside the heliosphere
Möbius, E.; Bzowski, M.; Lallement, R. +9 more
The interstellar gas that flows through the heliosphere is strongly affected by ionization close to the Sun, in particular solar photoionization, electron impact, and charge exchange. Therefore, the interpretation of any observation of interstellar gas in the inner heliosphere hinges upon the accurate knowledge of these effects and their variation…
An XMM-Newton observation of the massive binary HD 159176
Gosset, E.; Owocki, S. P.; Rauw, G. +4 more
We report the analysis of an XMM-Newton observation of the close binary HD 159176 (O7 V + O7 V). The observed LX/Lbol ratio reveals an X-ray luminosity exceeding by a factor ∼7 the expected value for X-ray emission from single O-stars, therefore suggesting a wind-wind interaction scenario. EPIC and RGS spectra are fitted cons…
Beyond the iron group: Heavy metals in hot subdwarfs
O'Toole, S. J.
We report the discovery of strong photospheric resonance lines of Ga III, Ge IV, Sn IV and Pb IV in the UV spectra of more than two dozen sdB and sdOB stars at temperatures ranging from 22 000 K to 40 000 K. Lines of other heavy elements are also detected, however in these cases more atomic data are needed. Based on these discoveries, we present a…
The X-ray luminosity function of galaxies in the Coma cluster
Finoguenov, A.; Boselli, A.; Gavazzi, G. +3 more
The XMM-Newton survey of the Coma cluster of galaxies covers an area of 1.86 square degrees with a mosaic of 16 pointings and has a total useful integration time of 400 ks. Detected X-ray sources with extent less than 10'' were correlated with cataloged galaxies in the Coma cluster region. The redshift information, which is abundant in …
Optical and near infrared observations of SN 1998bu
Sollerman, J.; Spyromilio, J.; Fransson, C. +3 more
Infrared and optical spectra of SN 1998bu at an age of one year after explosion are presented. The data show evidence for the radioactive decay of 56Co to 56Fe, long assumed to be the powering source for the supernova light curve past maximum light. The spectra provide direct evidence for at least 0.4 solar masses of iron bei…
Signature of oscillations in coronal bright points
Doyle, J. G.; Madjarska, M. S.; O'Shea, E. +1 more
A detailed study of two consecutive bright points observed simultaneously with the Coronal Diagnostic Spectrometer (CDS), the Extreme ultraviolet Imaging Telescope (EIT) and the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO) is presented. The analysis of the evolution of the photospheric magnetic features and …