Search Publications
A phenomenological model for the X-ray spectrum of nova V2491 Cygni
Kaastra, J. S.; Costantini, E.; Ness, J. -U. +3 more
The X-ray flux of nova V2491 Cyg reached a maximum some forty days after optical maximum. The X-ray spectrum at that time, obtained with the RGS of XMM-Newton, shows deep, blue-shifted absorption by ions of a wide range of ionization. We show that the deep absorption lines of the X-ray spectrum at maximum, and those observed nine days later, are w…
IRAS 11472-0800: an extremely depleted pulsating binary post-AGB star
Hrivnak, B. J.; Gorlova, N.; Van Winckel, H. +2 more
Aims: We focus here on one particular and poorly studied object, IRAS 11472-0800. It is a highly evolved post-asymptotic giant branch (post-AGB) star of spectral type F, with a large infrared excess produced by thermal emission of circumstellar dust.
Methods: We deployed a multi-wavelength study that includes the analyses of optical and …
Optical identification of X-ray source 1RXS J180431.1-273932 as a magnetic cataclysmic variable
Masetti, N.; Parisi, P.; Nucita, A. A.
The X-ray source 1RXS J180431.1-273932 has been proposed as a new member of the symbiotic X-ray binary (SyXB) class of systems, which are composed of a late-type giant that loses matter to an extremely compact object, most likely a neutron star. In this paper, we present an optical campaign of imaging plus spectroscopy on selected candidate counte…
Li I spectra in the 4.65-8.33 micron range: high-Lstates and oscillator strengths
Civiš, S.; Kubelík, P.; Ferus, M. +2 more
Context. Infrared (IR) astronomy capacities have rapidly developed in recent years thanks to several ground- and space-based facilities. To take advantage of these capabilities efficiently, a large amount of atomic data (such as line wavenumber, excited-level energy values, and oscillator strengths) are needed. These data are incomplete, in partic…
High resolution IR observations of the starburst ring in NGC 7552. One ring to rule them all?
Schaerer, D.; Brandl, B. R.; van der Werf, P. P. +2 more
Aims: Approximately 20% of all spiral galaxies display starburst activity in nuclear rings of a few hundred parsecs in diameter. It is our main aim to investigate how the starburst ignites and propagates within the ring, leading to the formation of massive stellar clusters.
Methods: We observed the ring galaxy NGC 7552 with the mid-infra…
Star-galaxy separation in the AKARI NEP deep field
Pearson, C. P.; Ohyama, Y.; Takagi, T. +10 more
Context. It is crucial to develop a method for classifying objects detected in deep surveys at infrared wavelengths. We specifically need a method to separate galaxies from stars using only the infrared information to study the properties of galaxies, e.g., to estimate the angular correlation function, without introducing any additional bias.
…
Three quasi-stellar objects acting as strong gravitational lenses
Djorgovski, S. G.; Stern, D.; Faure, C. +8 more
We report the discovery of three new cases of quasi-stellar objects (QSOs) acting as strong gravitational lenses on background emission line galaxies: SDSS J0827+5224 (zQSO = 0.293, zs = 0.412), SDSS J0919+2720 (zQSO = 0.209, zs = 0.558), SDSS J1005+4016 (zQSO = 0.230, zs = 0.441). …
The continuum intensity as a function of magnetic field. II. Local magnetic flux and convective flows
Solanki, S. K.; Borrero, J. M.; Kobel, P.
Context. To deepen our understanding of the role of small-scale magnetic fields in active regions (ARs) and in the quiet Sun (QS) on the solar irradiance, it is fundamental to investigate the physical processes underlying their continuum brightness. Previous results showed that magnetic elements in the QS reach larger continuum intensities than in…
The spectroscopic orbits and physical parameters of GG Carinae
Ferrer, O. E.; Quiroga, C.; Brandi, E. +3 more
Aims: GG Car is an eclipsing binary classified as a B[e] supergiant star. The aims of our study are to improve the orbital elements of the binary system in order to obtain the actual orbital period of this system. We also compare the spectral energy distribution of the observed fluxes over a wide wavelength range with a model of a circumstell…
New insights on Stephan's Quintet: exploring the shock in three dimensions
Vílchez, J. M.; Petropoulou, V.; López-Martín, L. +2 more
Aims: We study the ionized gas emission from the large scale shock region of Stephan's Quintet (SQ).
Methods: We carried out integral field unit (IFU) optical spectroscopy on three pointings in and near the SQ shock. We used Potsdam MultiAperture Spectrometer (PMAS) on the 3.5 m Calar Alto telescope to obtain measures of emission lines t…