Search Publications
Feature-tailored spectroscopic analysis of the supernova remnant Puppis A in X-rays
Luna, G. J. M.; Giacani, E.; Smith, M. J. S. +2 more
We introduce a distinct method for performing spatially resolved spectral analysis of astronomical sources with highly structured X-ray emission. The method measures the surface brightness of neighboring pixels to adaptively size and shape each region, thus the spectra from the bright and faint filamentary structures evident in the broadband image…
The fundamental parameters of the roAp star HD 24712. A rapidly oscillator at the red edge of the instability strip
Shulyak, D.; ten Brummelaar, T. A.; Perraut, K. +4 more
Context. There is still a debate about the nature of the mechanism that causes the pulsation excitation of the rapidly oscillating Ap stars that oscillate above the highest theoretically acoustic frequency. HD 24712 is a good test case for such a study because it is bright, its parallax accurately determined, and its frequency spectrum is well kno…
Stellar twins determine the distance of the Pleiades
Casey, Andrew R.; Hawkins, Keith; Jofré, Paula +5 more
Since the release of the Hipparcos catalogue in 1997, the distance to the Pleiades open cluster has been heavily debated. The distance obtained from Hipparcos and those by alternative methods differ by 10 to 15%. As accurate stellar distances are key to understanding stellar structure and evolution, this dilemma puts the validity of some stellar e…
High-resolution HI and CO observations of high-latitude intermediate-velocity clouds
Kerp, J.; Winkel, B.; Ben Bekhti, N. +1 more
Context. Intermediate-velocity clouds (IVCs) are HI halo clouds that are likely related to a Galactic fountain process. In-falling IVCs are candidates for the re-accretion of matter onto the Milky Way.
Aims: We study the evolution of IVCs at the disk-halo interface, focussing on the transition from atomic to molecular IVCs. We compare an atom…
The XMM spectral catalog of SDSS optically selected Seyfert 2 galaxies
Jiménez-Andrade, E. F.; Ranalli, P.; Georgantopoulos, I. +6 more
We present an X-ray spectroscopic study of optically selected (SDSS) Seyfert 2 (Sy2) galaxies. The goal is to study the obscuration of Sy2 galaxies beyond the local universe, using good quality X-ray spectra in combination with high S/N optical spectra for their robust classification. We analyzed all available XMM-Newton archival observations of n…
The spatially resolved correlation between [NII] 205 µm line emission and the 24 µm continuum in nearby galaxies
Ibar, E.; De Looze, I.; Cormier, D. +12 more
A correlation between the 24 µm continuum and the [Nii] 205 µm line emission may arise if both quantities trace the star formation activity on spatially-resolved scales within a galaxy, yet has so far only been observed in the nearby edge-on spiral galaxy NGC 891. We therefore assess whether the [Nii] 205-24 µm emission correlati…
Distribution of star formation rates during the rapid assembly of NGC 1399 as deduced from its globular cluster system
Hilker, M.; Pflamm-Altenburg, J.; Kroupa, P. +1 more
Ultra-compact dwarf galaxies (UCDs) share many properties with globular clusters (GCs) and are found in similar environments. Here, a large sample of UCDs and GCs around NGC 1399, the central giant elliptical of the Fornax galaxy cluster, is used to infer their formation history and also to shed light on the formation of NGC 1399 itself. We assume…
XMMSL1J063045.9-603110: a tidal disruption event fallen into the back burner
Campana, Sergio; Mainetti, Deborah; Colpi, Monica
Black holes at the centre of quiescent galaxies can be switched on when they accrete gas that is gained from stellar tidal disruptions. A star approaching a black hole on a low angular momentum orbit may be ripped apart by tidal forces, which triggers raining down of a fraction of stellar debris onto the compact object through an accretion disc an…
Highly ionized disc and transient outflows in the Seyfert galaxy IRAS 18325-5926
Iwasawa, K.; Fabian, A. C.; Reynolds, C. S. +3 more
We report on strong X-ray variability and the Fe K-band spectrum of the Seyfert galaxy IRAS 18325-5926 obtained from the 2001 XMM-Newton EPIC pn observation with a duration of ~120 ks. While the X-ray source is highly variable, the 8-10 keV band shows larger variability than that of the lower energies. Amplified 8-10 keV flux variations are associ…
Warm ISM in the Sagittarius A Complex. I. Mid-J CO, atomic carbon, ionized atomic carbon, and ionized nitrogen sub-mm/FIR line observations with the Herschel-HIFI and NANTEN2/SMART telescopes
Stutzki, J.; Güsten, R.; Requena-Torres, M. A. +3 more
Aims: We investigate the spatial and spectral distribution of the local standard of rest (LSR) velocity resolved submillimetre emission from the warm (25-90 K) gas in the Sgr A Complex, located in the Galactic centre.
Methods: We present large-scale submillimetre heterodyne observations towards the Sgr A Complex covering ~300 arcmin…