Search Publications
Nuclear activity in nearby galaxies. Mid-infrared imaging with the VLT
Pantin, E.; Siebenmorgen, R.; Moorwood, A. +7 more
Aims: Dust enshrouded activity can be studied ideally by mid-infrared (MIR) observations. To explore the active galactic nuclei (AGN) versus star forming origin of the nuclear MIR emission of galaxies, observations of high spatial resolution are required. We report on 11.3 µm observations with VISIR at the VLT, which reach 0.35'' spatial res…
XMM-Newton and Chandra observations of the globular cluster NGC 6388
Guainazzi, M.; Nucita, A. A.; Carpano, S. +2 more
Context: By studying the optical brightness surface density of the globular cluster NGC 6388, it has been recently proposed that it harbors a central intermediate-mass black hole with mass ≃ 5.7×103 M⊙.
Aims: We expect that the compact object in the center of NGC 6388 emits radiation in the X-ray band as a consequence of …
Multi-conjugate adaptive optics images of the Trapezium cluster
Martín, E. L.; Huélamo, N.; Bouy, H. +3 more
Context: Multi-conjugate adaptive optics (MCAO) combine the advantages of both standard adaptive optics, which provide high contrast and high spatial resolution, and of wide field imaging (≈1'). Up to recently, MCAO for astronomy was limited to laboratory experiments. In this paper, we present the first scientific results obtained with the first M…
A coronal explosion on the flare star CN Leonis
Liefke, C.; Schmitt, J. H. M. M.; Reiners, A. +4 more
We present simultaneous high-temporal and high-spectral resolution observations of the nearby flare star CN Leo at optical and soft X-ray wavelengths. During our observing campaign a major flare occurred, raising the star's instantaneous energy output by almost three orders of magnitude. The flare shows the often observed impulsive behavior, with …
Combined Chandra, XMM-Newton, and Hubble Space Telescope observations of the Galactic globular cluster NGC 2808
Knigge, C.; Long, K. S.; Servillat, M. +6 more
Aims: Using new Chandra X-ray observations and existing XMM-Newton X-ray and Hubble far ultraviolet observations, we aim to detect and identify the faint X-ray sources belonging to the Galactic globular cluster
Methods: We present a Chandra X-r…
Discovery of photospheric Ca X emission lines in the far-UV spectrum of the hottest known white dwarf (KPD 0005+5106)
Rauch, T.; Werner, K.; Kruk, J. W.
For the first time, we have identified photospheric emission lines in the far-UV spectrum of a white dwarf. They were discovered in the Far Ultraviolet Spectroscopic Explorer spectrum of the hot (T eff ≈ 200 000 K) DO white dwarf KPD 0005+5106 and they stem from extremely highly ionized calcium (Ca X λλ 1137, 1159 Å). Their photospheric…
2XMM J083026+524133: the most X-ray luminous cluster at redshift 1
Schwope, A.; Hoeft, M.; Lamer, G. +2 more
Aims: In the distant universe X-ray luminous clusters of galaxies are rare objects. Large area surveys are therefore needed to probe the high luminosity end of the cluster population at redshifts z ⪆ 1.
Methods: We correlated extended X-ray sources from the second XMM-Newton source catalogue (2XMM) with the SDSS in order to identify new cluste…
Zeeman-tomography of the solar photosphere. Three-dimensional surface structures retrieved from Hinode observations
Carroll, T. A.; Kopf, M.
Aims:The thermodynamic and magnetic field structure of the solar photosphere is analyzed by means of a novel 3-dimensional spectropolarimetric inversion and reconstruction technique.
Methods: On the basis of high-resolution, mixed-polarity magnetoconvection simulations, we used an artificial neural network (ANN) model to approximate the nonlin…
On the combination of ACE data with numerical simulations to determine the initial characteristics of a CME
Poedts, S.; Chané, E.; van der Holst, B.
Aims: Our goal is to combine the Advanced Composition Explorer (ACE) data with numerical simulations to determine the initial characteristics of the halo coronal mass ejection (CME), which was observed on April 4, 2000.
Methods: The evolution of a CME from the Sun to 1 AU is simulated in the framework of 2.5 D (axi-symmetric) ideal Magnetohydr…
Intensity oscillations and heating of the coronal X-ray bright points from Hinode/XRT
Kariyappa, R.; Varghese, B. A.
Aims: Our aim is to investigate the intensity oscillations in coronal X-ray Bright Points (XBPs).
Methods: We analysed a 7 h long time sequence of the soft X-ray images obtained on April 14, 2007 with a 2 min cadence using the X-Ray Telescope (XRT) on-board the Hinode mission. We use SSW in IDL to derive the time series of 14 XBPs and 2 backgr…