Search Publications
Tentative identification of urea and formamide in ISO-SWS infrared spectra of interstellar ices
Duvernay, F.; Chiavassa, T.; Dartois, E. +4 more
Laboratory experiments involving vacuum ultraviolet (VUV) irradiation of solid isocyanic acid (HNCO) at 10 K, followed by infrared spectroscopy (FTIR), are used to interpret the complex spectra associated with Interstellar Medium (ISM) dust grains, particularly the spectra associated with the icy phase observed toward dense molecular clouds. The c…
2-10 keV luminosity of high-mass binaries as a gauge of ongoing star-formation rate
Cappi, M.; Franceschini, A.; Braito, V. +4 more
Based on recent work on spectral decomposition of the emission of star-forming galaxies, we assess whether the integrated 2-10 keV emission from high-mass X-ray binaries (HMXBs), L2-10HMXB, can be used as a reliable estimator of ongoing star formation rate (SFR). Using a sample of 46 local (z ⪉ 0.1) star-forming galaxies, and…
Photometric redshifts with the Multilayer Perceptron Neural Network: Application to the HDF-S and SDSS
Popesso, P.; Fontana, A.; Vanzella, E. +8 more
We present a technique for the estimation of photometric redshifts based on feed-forward neural networks. The Multilayer Perceptron (MLP) Artificial Neural Network is used to predict photometric redshifts in the HDF-S from an ultra deep-multicolor catalog. Various possible approaches for the training of the neural network are explored, including t…
The XMM-Newton and BeppoSAX view of the Ultra Luminous Infrared Galaxy MKN 231
Cappi, M.; Franceschini, A.; Piconcelli, E. +11 more
We discuss XMM-Newton and BeppoSAX observations of MKN 231, the lowest-redshift Broad Absorption Line (BAL) QSO known so far and one of the best-studied Ultra Luminous Infrared Galaxies. By combining the XMM-Newton spectral resolution and the high-energy bandpass of BeppoSAX we have been able to study in more detail than previously possible its 0.…
The SUMER spectral atlas of solar coronal features
Curdt, W.; Landi, E.; Feldman, U.
We present a spectral atlas of the solar corona in the far-ultraviolet (FUV) and extreme ultraviolet (EUV) wavelength range. The atlas is based on observations obtained between 670 Å and 1609 Å in first order of diffraction and between 465 and 670 Å in second order with the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrograph o…
The HELLAS2XMM survey. VI. X-ray absorption in the 1df AGN sample through a spectral analysis
Maiolino, R.; Perola, G. C.; Fiore, F. +13 more
The spectroscopic analysis of 117 serendipitous sources in the HELLAS2XMM 1df (1 degree field) survey is described. Of these, 106 sources, of which 86% have a spectroscopic redshift, are used to evaluate the fraction of X-ray absorbed (log NH>22) Active Galactic Nuclei (AGN) in the 2-10 keV flux range 0.8-20×10-14 erg cm
The initial helium abundance of the Galactic globular cluster system
Salaris, M.; Riello, M.; Piotto, G. +1 more
In this paper we estimate the initial He content in about 30% of the Galactic globular clusters (GGCs) from new star counts we have performed on the recently published HST snapshot database of Colour Magnitude Diagrams (Piotto et al. \cite{Piotto02}). More specifically, we use the so-called R-parameter and estimate the He content from a theoretica…
Multi-element abundance Doppler imaging of the rapidly oscillating Ap star HR 3831
Piskunov, N.; Kochukhov, O.; Drake, N. A. +1 more
We investigate magnetic field geometry and surface distribution of chemical elements in the rapidly oscillating Ap star HR 3831. Results of the model atmosphere analysis of the spectra of this star are combined with the Hipparcos parallax and evolutionary models to obtain new accurate estimates of the fundamental stellar parameters: Teff
Mass segregation in young Magellanic Cloud star clusters: Four clusters observed with HST
Bellas-Velidis, I.; Kontizas, M.; Kontizas, E. +2 more
We present the results of our investigation on the phenomenon of mass segregation in young star clusters in the Magellanic Clouds. HST/WFPC2 observations on NGC 1818, NGC 2004 and NGC 2100 in the Large Magellanic Cloud and NGC 330 in the Small Magellanic Cloud have been used for the application of diagnostic tools for mass segregation: i) the radi…
Puzzling wind properties of young massive stars in SMC-N81
Schaerer, D.; Martins, F.; Hillier, D. J. +1 more
We present a quantitative study of massive stars in the High Excitation Blob N81, a compact star forming region in the SMC. The stellar content was resolved by HST, and STIS was used to obtain medium resolution spectra. The qualitative analysis of the stellar properties presented in Heydari-Malayeri et al. (\cite{papI}) is extended using non-LTE s…