Search Publications
Ultraviolet and visual flux and line variations of one of the least variable Bp stars HD 64740
Skarka, M.; Krtička, J.; Janík, J. +4 more
Context. The light variability of hot magnetic chemically peculiar stars is typically caused by the flux redistribution in spots with peculiar abundance. This raises the question why some stars with surface abundance spots show significant rotational light variability, while others do not.
Aims: We study the Bp star HD 64740 to investigate ho…
The XMM-Newton SSC survey of the Galactic plane
Motch, C.; Pakull, M.; Barcons, X. +17 more
Many different classes of X-ray sources contribute to the Galactic landscape at high energies. Although the nature of the most luminous X-ray emitters is now fairly well understood, the population of low-to-medium X-ray luminosity (LX = 1027-34 erg s-1) sources remains much less studied, our knowledge being mostly …
Accretion disk wind as explanation for the broad-line region structure in NGC 5548
Kollatschny, W.; Zetzl, M.
Context. Supermassive black holes in the centers of active galactic nuclei (AGN) are surrounded by broad-line regions (BLRs). The broad emission lines seen in the AGN spectra are emitted in this spatially unresolved region.
Aims: We intend to obtain information on the structure and geometry of this BLR based on observed line profiles.
Me…
A 0535+26 in the April 2010 outburst: probing the accretion regime at work
Müller, D.; Klochkov, D.; Santangelo, A. +1 more
Context. A number of accreting X-ray pulsars experience spectral changes, both on the long time scales and on the time scales of the neutron star spin period. The sources seem to form two distinct groups that differ by the type of the spectral variations with flux. Such a bimodality probably reflects two different regimes of accretion that may res…
Morphology with light profile fitting of confirmed cluster galaxies at z = 0.84
Demarco, R.; Lidman, C.; Rosati, P. +3 more
We perform a morphological study of 124 spectroscopically confirmed cluster galaxies in the redshift (z) = 0.84 galaxy cluster RX J0152.7-1357. Our classification scheme includes color information, visual morphology, and one- and two-component light profile fitting derived from Hubble Space Telescope riz imaging. We adopt a modified version of a d…
Anchors for the cosmic distance scale: the Cepheids U Sagittarii, CF Cassiopeiae, and CEab Cassiopeiae
Kovtyukh, V.; Bonatto, C.; Moni Bidin, C. +11 more
New and existing X-ray, UBVJHKsW(1 - 4), and spectroscopic observations were analyzed to constrain fundamental parameters for M 25, NGC 7790, and dust along their sight-lines. The star clusters are of particular importance because they host the classical Cepheids U Sgr, CF Cas, and the visual binary Cepheids CEa and CEb Cas. …
Herschel survey of brown dwarf disks in ρ Ophiuchi
Pinte, C.; Könyves, V.; Ábrahám, P. +6 more
Context. Young brown dwarfs are known to possess circumstellar disks, a characteristic that is fundamental to the understanding of their formation process, and raises the possibility that these objects harbour planets.
Aims: We want to characterise the far-IR emission of disks around the young brown dwarf population of the ρ Ophiuchi cluster …
APEX/SABOCA observations of small-scale structure of infrared-dark clouds . I. Early evolutionary stages of star-forming cores
Henning, Thomas; Beuther, Henrik; Ragan, Sarah E.
Infrared-dark clouds (IRDCs) harbor the early phases of cluster and high-mass star formation and are comprised of cold (~20 K), dense (n > 104 cm-3) gas. The spectral energy distribution (SED) of IRDCs is dominated by the far-infrared and millimeter wavelength regime, and our initial Herschel study examined IRDCs at the pe…
Determination of the far-infrared dust opacity in a prestellar core
Juvela, M.; White, G. J.; André, Ph. +5 more
Context. Mass estimates of interstellar clouds from far-infrared and submillimetre mappings depend on the assumed dust absorption cross-section for radiation at those wavelengths.
Aims: The aim is to determine the far-IR dust absorption cross-section in a starless, dense core located in Corona Australis. The value is needed for determining of…
Active asteroid belt causes the UXOR phenomenon in RZ Piscium
Grinin, V. P.; Müller, A.; de Wit, W. J. +3 more
We report the discovery of mid-infrared excess emission in the young object RZ Psc. The excess constitutes ~8% of its Lbol and is well fit by a single 500 K blackbody, implying a dust-free region within ~0.7 AU for optically thick dust. The object displays dust obscuration events (UXOR behaviour) on a time scale that suggests dusty mate…