Search Publications
A 33 hour period for the Wolf-Rayet/black hole X-ray binary candidate NGC 300 X-1
Ehle, M.; Wilms, J.; Pollock, A. M. T. +4 more
Context: NGC 300 X-1 is the second extragalactic candidate, after IC 10 X-1, in the rare class of Wolf-Rayet/compact object X-ray binary systems exemplified in the Galaxy by Cyg X-3. From a theoretical point of view, accretion onto a black hole in a detached system is possible for large orbital periods only if the mass of the relativistic object i…
A search for ultra-compact dwarf galaxies in the Centaurus galaxy cluster
Infante, L.; Hilker, M.; Kissler-Patig, M. +2 more
Aims:Our aim is to extend the investigations of ultra-compact dwarf galaxies (UCD) beyond the well studied Fornax and Virgo clusters.
Methods: We measured spectroscopic redshifts of about 400 compact object candidates with 19.2 < V < 22.4 mag in the central region of the Centaurus galaxy cluster (d = 43 Mpc), using 3 pointings with VIMOS…
Molecular gas in NUclei of GAlaxies (NUGA). VII. NGC 4569, a large scale bar funnelling gas into the nuclear region
Tacconi, L. J.; Hunt, L. K.; Krips, M. +8 more
This work is part of the NUGA survey of CO emission in nearby active galaxies. We present observations of NGC 4569, a member of the Virgo Cluster. We analyse the molecular gas distribution and kinematics in the central region and we investigate a possible link to the strong starburst present at the nucleus. 70% of the [ 1.1±0.2] ×109 M<…
The XMM large scale structure survey: optical vs. X-ray classifications of active galactic nuclei and the unified scheme
Maccagni, D.; Chiappetti, L.; Ebrero, J. +25 more
Aims:Our goal is to characterize AGN populations by comparing their X-ray and optical classifications within the framework of the standard orientation-based unified scheme.
Methods: We present a sample of 99 spectroscopically identified (R ≤ 22 mag) X-ray selected point sources in the XMM-LSS survey which are significantly detected (≥3σ) in th…
The XMM-Newton serendipitous survey. IV. Optical identification of the XMM-Newton medium sensitivity survey (XMS)
Pérez-Fournon, I.; Motch, C.; Bromage, G. E. +54 more
Aims:X-ray sources at intermediate fluxes (a few × 10-14 erg cm-2 s-1) with a sky density of ~100 deg-2 are responsible for a significant fraction of the cosmic X-ray background at various energies below 10 keV. The aim of this paper is to provide an unbiased and quantitative description of the X-ray sou…
Identification of Ne VIII lines in H-deficient (pre-) white dwarfs: a new tool to constrain the temperature of the hottest stars
Rauch, T.; Werner, K.; Kruk, J. W.
For the first time, we have identified Ne VIII absorption lines in far-UV spectra of the hottest known (T_eff ⪆ 150 000 K) hydrogen-deficient (pre-) white dwarfs of spectral type PG1159. They are of photospheric origin and can be matched by synthetic non-LTE line profiles. We also show that a number of UV and optical emission lines in these stars …
PPAK integral field spectroscopy survey of the Orion nebula. Data release
Alves, J.; Sánchez, S. F.; Martín-Gordón, D. +3 more
Aims:We present a low-resolution spectroscopic survey of the Orion nebula. The data are released for public use. We show the possible applications of this dataset analyzing some of the main properties of the nebula.
Methods: We perform an integral field spectroscopy mosaic of an area of ~5 arcmin× 6 arcmin centered on the Trapezium region of t…
Structure and dynamics of the class I young stellar object L1489 IRS
Hogerheijde, M. R.; Jørgensen, J. K.; Brinch, C. +1 more
Context: During protostellar collapse, conservation of angular momentum leads to the formation of an accretion disc. Little is known observationally about how and when the velocity field around the protostar shifts from infall-dominated to rotation-dominated.
Aims: We investigate this transition in the low-mass protostar L1489 IRS, which is kn…
A nanoflare model of quiet Sun EUV emission
Solanki, S. K.; Pauluhn, A.
Nanoflares have been proposed as the main source of heating of the solar corona. However, detecting them directly has so far proved elusive, and extrapolating to them from the properties of larger brightenings gives unreliable estimates of the power-law exponent α characterising their distribution. Here we take the approach of statistically modell…
The AGB stars of the intermediate-age LMC cluster NGC 1846. Variability and age determination
Lebzelter, T.; Wood, P. R.
Aims:We investigate variability and we model the pulsational behaviour of AGB variables in the intermediate-age LMC cluster NGC 1846.
Methods: Our own photometric monitoring has been combined with data from the MACHO archive to detect 22 variables among the cluster's AGB stars and to derive pulsation periods. According to the global parameters…