Search Publications
Dust in active galactic nuclei. Mid-infrared T-ReCS/Gemini spectra using the new RedCan pipeline
Esquej, P.; Telesco, C.; Díaz-Santos, T. +6 more
Context. The unified model of active galactic nuclei (AGN) claims that the properties of AGN depend on the viewing angle of the observer with respect to a toroidal distribution of dust surrounding the nucleus. Both the mid-infrared (MIR) attenuation and continuum luminosity are expected to be related to dust associated with the torus. Therefore, i…
Quiet Sun magnetic fields observed by Hinode: Support for a local dynamo
Solanki, S. K.; Lagg, A.; Buehler, D.
Context. The Hinode mission has revealed copious amounts of horizontal flux covering the quiet Sun. Local dynamo action has been proposed to explain the presence of this flux.
Aims: We sought to test whether the quiet Sun flux detected by Hinode is due to a local or the global dynamo by studying long-term variations in the polarisation signal…
Ca II H+K fluxes from S-indices of large samples: a reliable and consistent conversion based on PHOENIX model atmospheres
Schmitt, J. H. M. M.; Schröder, K. -P.; Mittag, M.
Context. Historic stellar activity data based on chromospheric line emission using O.C. Wilson's S-index reach back to the 1960ies and represent a very valuable data resource both in terms of quantity and time-coverage. However, these data are not flux-calibrated and are therefore difficult to compare with modern spectroscopy and to relate to quan…
Planck intermediate results. III. The relation between galaxy cluster mass and Sunyaev-Zeldovich signal
Böhringer, H.; Kneissl, R.; Dahle, H. +183 more
We examine the relation between the galaxy cluster mass M and Sunyaev-Zeldovich (SZ) effect signal DA2 Y500 for a sample of 19 objects for which weak lensing (WL) mass measurements obtained from Subaru Telescope data are available in the literature. Hydrostatic X-ray masses are derived from XMM-Newton archive data,…
An interferometric study of the Fomalhaut inner debris disk. III. Detailed models of the exozodiacal disk and its origin
Absil, O.; Augereau, J. -C.; Ertel, S. +15 more
Context. Debris disks are thought to be extrasolar analogs to the solar system planetesimal belts. The star Fomalhaut harbors a cold debris belt at 140 AU comparable to the Edgeworth-Kuiper belt, as well as evidence of a warm dust component, unresolved by single-dish telescopes, which is suspected of being a bright analog to the solar system's zod…
Accurate determination of accretion and photospheric parameters in young stellar objects: The case of two candidate old disks in the Orion Nebula Cluster
Robberto, M.; Da Rio, N.; Testi, L. +5 more
Context. Current planet formation models are largely based on the observational constraint that protoplanetary disks have a lifetime of ~3 Myr. Recent studies, however, report the existence of pre-main-sequence stars with signatures of accretion (strictly connected with the presence of circumstellar disks) and photometrically determined ages of 30…
Baade-Wesselink distances to Galactic and Magellanic Cloud Cepheids and the effect of metallicity
Groenewegen, M. A. T.
Context. The metallicity dependence of the Cepheid period-luminosity (PL) relation is of importance in establishing the extragalactic distance scale.
Aims: The aim of this paper is to investigate the metallicity dependence of the PL relation in V and K, based on a sample of 128 Galactic, 36 Large Magellanic Cloud (LMC), and 6 Small Magellanic…
Peripheral downflows in sunspot penumbrae
Solanki, S. K.; Lagg, A.; van Noort, M. +1 more
Context. Sunspot penumbrae show high-velocity patches along the periphery.
Aims: The high-velocity downflow patches are believed to be the return channels of the Evershed flow. We aim to investigate their structure in detail using Hinode SOT/SP observations.
Methods: We employ Fourier interpolation in combination with spatially coupled h…
No anticorrelation between cyclotron line energy and X-ray flux in 4U 0115+634
Klochkov, D.; Wolff, M. T.; Wilms, J. +18 more
We report on an outburst of the high mass X-ray binary 4U 0115+634 with a pulse period of 3.6 s in 2008 March/April as observed with RXTE and INTEGRAL. During the outburst the neutron star's luminosity varied by a factor of 10 in the 3-50 keV band. In agreement with earlier work we find evidence of five cyclotron resonance scattering features at ~…
On the self-regulation of intense star-formation in galaxies at z = 1-3
Boulanger, F.; Lehnert, M. D.; Di Matteo, P. +3 more
We have analyzed the properties of the Hα and [Nii]λ6583 rest-frame optical emission lines of a sample of 53 intensely star forming galaxies at z = 1.3 to 2.7 observed with SINFONI on the ESO-VLT. Similar to previous authors, we find large velocity dispersions in the lines, σ = few 10-250 km s-1. Our data agree well with simulations whe…