Search Publications
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…
Optical constants of refractory oxides at high temperatures. Mid-infrared properties of corundum, spinel, and α-quartz, potential carriers of the 13 µm feature
Mutschke, H.; Zeidler, S.; Posch, Th.
Context. Many cosmic dust species, among them refractory oxides, form at temperatures higher than 300 K. Nevertheless, most astrophysical studies are based on the room-temperature optical constants of solids, such as corundum and spinel. A more realistic approach is needed for these materials, especially in the context of modeling late-type stars.…
Kinematics of massive star ejecta in the Milky Way as traced by 26Al
Wang, Wei; Gerhard, Ortwin; Diehl, Roland +5 more
Context. Massive stars form in groups and their winds and supernova explosions create superbubbles up to kpc in size. The fate of their ejecta is of vital importance for the dynamics of the interstellar medium, for chemical evolution models, and the chemical enrichment of galactic halos and the intergalactic medium. However, ejecta kinematics and …
The shape of broad-line profiles in active galactic nuclei
Kollatschny, W.; Zetzl, M.
Aims: We present a study of the broad optical/UV emission line profiles in active galactic nuclei (AGN) to get information on the dominant velocity components (turbulence, rotation, etc.) in the central broad-line region (BLR).
Methods: We introduce line broadening simulations of emission line profiles and compare these results with the …
The spectroscopic evolution of the γ-ray emitting classical nova Nova Mon 2012. I. Implications for the ONe subclass of classical novae
Cheung, C. C.; Shore, S. N.; Starrfield, S. +4 more
Aims: Among the classical novae, the ONe subgroup, distinguished by their large overabundance of neon, are thought to occur on the most massive white dwarfs. Nova Mon 2012 was the first classical nova to be detected as a high energy γ-ray transient, by Fermi-LAT, before its optical discovery. The first optical spectra obtained about 55 days a…
Beginning of activity in 67P/Churyumov-Gerasimenko and predictions for 2014-2015
Tubiana, C.; Snodgrass, C.; Bramich, D. M. +3 more
Context. Comet 67P/Churyumov-Gerasimenko was selected in 2003 as the new target of the Rosetta mission. It has since been the subject of a detailed campaign of observations to characterise its nucleus and activity.
Aims: We present previously unpublished data taken around the start of activity of the comet in 2007/8, before its last perihelio…
Spectroscopic FIR mapping of the disk and galactic wind of M 82 with Herschel-PACS
Lutz, D.; Genzel, R.; Poglitsch, A. +11 more
Context. We present maps of the main cooling lines of the neutral atomic gas ([OI] at 63 and 145 µm and [CII] at 158 µm) and in the [OIII] 88 µm line of the starburst galaxy M 82, carried out with the PACS spectrometer on board the Herschel satellite.
Aims: Our aim is to study the nature of the neutral atomic gas of M 82 and…