Search Publications
The virtual observatory service TheoSSA: Establishing a database of synthetic stellar flux standards. I. NLTE spectral analysis of the DA-type white dwarf G191-B2B
Rauch, T.; Werner, K.; Kruk, J. W. +1 more
Context. Hydrogen-rich, DA-type white dwarfs are particularly suited as primary standard stars for flux calibration. State-of-the-art NLTE models consider opacities of species up to trans-iron elements and provide reliable synthetic stellar-atmosphere spectra to compare with observations.
Aims: We will establish a database of theoretical spec…
Unveiling the nature of INTEGRAL objects through optical spectroscopy. X. A new multi-year, multi-observatory campaign
Palazzi, E.; Minniti, D.; Masetti, N. +18 more
Within the framework of our program (running since 2004) of identification of hard X-ray INTEGRAL sources through optical spectroscopy, we present the results concerning the nature of 33 high-energy objects. The data were acquired with the use of six telescopes of different sizes and from one on-line archive. The results indicate that the majority…
X-ray spectral variability of seven LINER nuclei with XMM-Newton and Chandra data
González-Martín, O.; Márquez, I.; Masegosa, J. +1 more
Context. One of the most distinctive features in active galactic nuclei (AGN) is the variability of their emission. Variability has been discovered at X-ray, UV, and radio frequencies on timescales from hours to years. Among the AGN family and according to theoretical studies, low-ionization nuclear emission line region (LINER) nuclei would be obj…
Mid- to far-infrared properties of star-forming galaxies and active galactic nuclei
Elbaz, D.; Morrison, G.; Helou, G. +19 more
We study the mid- to far-IR properties of a 24 µm-selected flux-limited sample (S24> 5 mJy) of 154 intermediate redshift (⟨ z ⟩ ~ 0.15), infrared luminous galaxies, drawn from the 5 Milli-Jansky Unbiased Spitzer Extragalactic Survey. By combining existing mid-IR spectroscopy and new Herschel SPIRE submm photometry from the Hers…
DIGIT survey of far-infrared lines from protoplanetary discs. II. CO
Henning, Thomas; Bouwman, Jeroen; van Dishoeck, Ewine F. +11 more
CO is an important component of a protoplanetary disc as it is one of the most abundant gas phase species. Furthermore, observations of CO transitions can be used as a diagnostic of the gas, tracing conditions in both the inner and outer disc. We present Herschel/PACS spectroscopy of a sample of 22 Herbig Ae/Be (HAEBEs) and eight T Tauri stars (TT…
Tidal disruption of a super-Jupiter by a massive black hole
Walter, R.; Nikołajuk, M.
Aims: A strong, hard X-ray flare was discovered (IGR J12580+0134) by INTEGRAL in 2011, and is associated to NGC 4845, a Seyfert 2 galaxy never detected at high-energy previously. To understand what happened we observed this event in the X-ray band on several occasions.
Methods: Follow-up observations with XMM-Newton, Swift, and MAXI are …
AGN host galaxies at redshift z ≈ 0.7: peculiar or not?
Heymans, C.; Taylor, A. N.; Gray, M. E. +21 more
Aims: We perform a quantitative morphological comparison between the hosts of active galactic nuclei (AGN) and quiescent galaxies at intermediate redshifts (z ≈ 0.7). The imaging data are taken from the large HST/ACS mosaics of the GEMS and STAGES surveys. Our main aim is to test whether nuclear activity at this cosmic epoch is triggered by m…
Indication for an intermediate-mass black hole in the globular cluster NGC 5286 from kinematics
Kissler-Patig, M.; de Zeeuw, P. T.; Neumayer, N. +6 more
Context. Intermediate-mass black holes (IMBHs) fill the gap between stellar-mass black holes and supermassive black holes (SMBHs). The existence of the latter is widely accepted, but there are only few detections of intermediate-mass black holes (102 - 105M⊙) so far. Simulations have shown that intermediate-mass bl…
Fragmentation and dynamical collapse of the starless high-mass star-forming region IRDC 18310-4
Smith, R.; Henning, Th.; Krause, O. +9 more
Context. Because of their short evolutionary time-scales, the earliest stages of high-mass star formation prior to the existence of any embedded heating source have barely been characterized until today.
Aims: We study the fragmentation and dynamical properties of a massive starless gas clump at the onset of high-mass star formation.
Met…
Vertical settling and radial segregation of large dust grains in the circumstellar disk of the Butterfly Star
Stapelfeldt, K. R.; Wolf, S.; Pontoppidan, K. M. +4 more
Context. Circumstellar disks are considered to be the environment for the formation of planets. The growth of dust grains in these disks is the first step in the core accretion-gas capture planet formation scenario. Indicators and evidence of disk evolution can be traced in spatially resolved images and the spectral energy distribution (SED) of th…