Life after eruption - II. The eclipsing old nova V728 Scorpii

Scritto il 09 Apr 2013 alle 01:39 in Pubblicazioni

The old nova V728 Sco has been recently recovered via photometric and spectroscopic observations, 150 yr after the nova eruption. The spectral properties pointed to a high-inclination system with a comparatively low mass-transfer rate. In this paper, we show that the object is an eclipsing system with an orbital period of 3.32 h. It has enhanced long-term variability that can be interpreted as `stunted’ dwarf-nova-type outbursts. Using the ingress and egress times of the eclipsed components we calculate the radius of the central object. The latter turns out to be significantly...

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The mystery of T Pyx; the 2011 explosion

Scritto il 06 Apr 2013 alle 01:39 in Pubblicazioni

T Pyx is a recurrent nova which has undergone eruptions on an almost
regular basis every 20 years until reaching a long lasting quiescence
between 1967 and 2011. We observed the long awaited 2011 explosion in
the optical and near infrared with intermediate spectral resolution. In
this paper we report on the change in the spectral type of the nova
(both during its rise and during its fading), as well as the observed
changes in the expansion velocities. We also present an interpretation
of these changes and set them in the general framework of a new
understanding of nova classification.

X-ray luminosity functions of different morphological and X-ray type AGN populations

Scritto il 02 Apr 2013 alle 01:39 in Pubblicazioni

Luminosity functions are one of the most important observational clues when studying galaxy evolution over cosmic time. In this paper we present the X-ray luminosity functions for X-ray detected AGN in the SXDS and GWS fields. The limiting fluxes of our samples are 9.0 ×10<SUP>-15</SUP> and 4.8 ×10<SUP>-16</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP> in the 0.5-7.0 keV band in the two fields, respectively. We carried out analysis in three X-ray bands and in two redshift intervals up to z&leq;1.4. Moreover, we derive the luminosity functions for different optical morphologies and X-ray...

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