Search Publications
A non-LTE spectral analysis of the 3He and 4He isotopes in the HgMn star κ Cancri
Przybilla, Norbert; Maza, Natalia L.; Nieva, María-Fernanda
Aims: We present a pilot study on non-local thermodynamic equilibrium (NLTE) line-formation computations for the isotopes 3He and 4He in the mercury-manganese star κ Cancri. The impact of NLTE effects on the determination of isotopic abundances and the vertical stratification of helium in the atmosphere is investigated. …
Probing large-scale structure with large samples of X-ray selected AGN. I. Baryonic acoustic oscillations
Sunyaev, Rashid; Gilfanov, Marat; Hütsi, Gert +1 more
We investigate the potential of large X-ray-selected AGN samples for detecting baryonic acoustic oscillations (BAO). Though AGN selection in X-ray band is very clean and efficient, it does not provide redshift information, and thus needs to be complemented with an optical follow-up. The main focus of this study is (i) to find the requirements need…
Segmentation of coronal features to understand the solar EUV and UV irradiance variability
Chitta, L. P.; Verbeeck, C.; Giono, G. +8 more
Context. The study of solar irradiance variability is of great importance in heliophysics, the Earth's climate, and space weather applications. These studies require careful identifying, tracking and monitoring of active regions (ARs), coronal holes (CHs), and the quiet Sun (QS).
Aims: We studied the variability of solar irradiance for a peri…
Phase resolved X-ray spectroscopy of HDE 228766: Probing the wind of an extreme Of+/WNLha star
Nazé, Y.; Rauw, G.; Manfroid, J. +3 more
Context. HDE 228766 is a very massive binary system hosting a secondary component, which is probably in an intermediate evolutionary stage between an Of supergiant and an WN star. The wind of this star collides with the wind of its O8 II companion, leading to relatively strong X-ray emission.
Aims: Measuring the orbital variations of the line…
Dust correction factors over 0 < z < 3 in massive star-forming galaxies derived from a stacking analysis of Herschel data
Oteo, I.
We use a stacking analysis in Herschel/PACS to study the accuracy of several dust-correction factors that are typically employed to estimate the total star-formation rate (SFR) of high-redshift, massive, star-forming (SF) galaxies. We also analyze what stacking suggests about the relation between SFR and stellar mass and the redshift evolution of …
Energy and helicity budgets of solar quiet regions
Georgoulis, M. K.; Tziotziou, K.; Tsiropoula, G. +1 more
Aims: We investigate the free magnetic energy and relative magnetic helicity budgets of solar quiet regions.
Methods: Using a novel nonlinear force-free method that requires single solar vector magnetograms we calculated the instantaneous free magnetic energy and relative magnetic helicity budgets in 55 quiet-Sun vector magnetograms.
Smooth X-ray variability from ρ Ophiuchi A+B. A strongly magnetized primary B2 star?
Goodman, Alyssa; Sciortino, Salvatore; Wolk, Scott J. +1 more
X-rays from massive stars are ubiquitous yet not clearly understood. In an XMM-Newton observation devoted to observing the first site of star formation in the ρ Ophiuchi dark cloud, we detect smoothly variable X-ray emission from the B2IV+B2V system of ρ Ophiuchi. We tentatively assign the emission to the primary component. The light curve of the …
The zCOSMOS redshift survey: evolution of the light in bulges and discs since z ~ 0.8
Kneib, J. -P.; Cimatti, A.; Ilbert, O. +52 more
We studied the chronology of galactic bulge and disc formation by analysing the relative contributions of these components to the B-band rest-frame luminosity density at different epochs. We present the first estimate of the evolution of the fraction of rest-frame B-band light in galactic bulges and discs since redshift z ∼ 0.8. We performed a bul…
The giant H ii region NGC 588 as a benchmark for 2D photoionisation models
Morisset, C.; Monreal-Ibero, A.; Relaño, M. +3 more
Aims: We use optical integral field spectroscopy and 8 µm and 24 µm mid-IR observations of the giant H ii region NGC 588 in the disc of M33 as input and constraints for two-dimensional tailor-made photoionisation models under different geometrical approaches. We do this to explore the spatial distribution of gas and dust in the in…
Characterizing SL2S galaxy groups using the Einstein radius
Blakeslee, J. P.; Cabanac, R.; Fernández-Trincado, J. G. +11 more
Aims: We aim to study the reliability of RA (the distance from the arcs to the center of the lens) as a measure of the Einstein radius in galaxy groups. In addition, we want to analyze the possibility of using RA as a proxy to characterize some properties of galaxy groups, such as luminosity (L) and richness (N).
Me…