Search Publications
No evidence for intermediate-mass black holes in the globular clusters ω Cen and NGC 6624
Dreizler, S.; Usher, C.; Kamann, S. +8 more
We compare the results of a large grid of N-body simulations with the surface brightness and velocity dispersion profiles of the globular clusters ω Cen and NGC 6624. Our models include clusters with varying stellar-mass black hole retention fractions and varying masses of a central intermediate-mass black hole (IMBH). We find that an ∼ 45 000 M
The evolutionary status of Cataclysmic Variables: eclipse modelling of 15 systems
Knigge, C.; Gänsicke, B. T.; Dhillon, V. S. +13 more
We present measurements of the component masses in 15 Cataclysmic Variables (CVs) - 6 new estimates and 9 improved estimates. We provide new calibrations of the relationship between superhump period excess and mass ratio, and use this relation to estimate donor star masses for 225 superhumping CVs. With an increased sample of donor masses we revis…
The evolution of galaxy shapes in CANDELS: from prolate to discy
Faber, S. M.; Lin, Lin; Zhang, Haowen +9 more
We model the projected b/a-log a distributions of CANDELS star-forming main-sequence galaxies, where a (b) is the half-light semimajor (semiminor) axis of the galaxy images measured by GALFIT. We find that smaller a galaxies are rounder at all stellar masses M* and redshifts, so we include a when analysing b/a distributions. Approximati…
SkyMapper stellar parameters for Galactic Archaeology on a grand-scale
Wolf, C.; Yong, D.; Casagrande, L. +3 more
The SkyMapper photometric surveys provides uvgriz photometry for several millions sources in the Southern sky. We use DR1.1 to explore the quality of its photometry, and develop a formalism to homogenize zero-points across the sky using stellar effective temperatures. Physical flux transformations, and zero-points appropriate for this release are …
The wide binary fraction of solar-type stars: emergence of metallicity dependence at a < 200 au
Rix, Hans-Walter; El-Badry, Kareem
We combine a catalogue of wide binaries constructed from Gaia DR2 with [Fe/H] abundances from wide-field spectroscopic surveys to quantify how the binary fraction varies with metallicity over separations 50 ≲ s/au ≲ 50 000. At a given distance, the completeness of the catalogue is independent of metallicity, making it straightforward to constrain …
A hypervelocity star with a Magellanic origin
Boubert, Douglas; Erkal, Denis; Evans, N. Wyn +2 more
Using proper motion measurements from Gaia Data Release 2, we probe the origin of 26 previously known hypervelocity stars (HVSs) around the Milky Way. We find that a significant fraction of these stars have a high probability of originating in the Milky Way Galaxy, but there is one obvious outlier. HVS3 is highly likely to be coming almost from th…
The remarkable X-ray variability of IRAS 13224-3809 - I. The variability process
Young, A. J.; Fabian, A. C.; Reynolds, C. S. +17 more
We present a detailed X-ray timing analysis of the highly variable narrow-line Seyfert 1 (NLS1) galaxy IRAS 13224-3809. The source was recently monitored for 1.5 Ms with XMM-Newton, which, combined with 500 ks archival data, makes this the best-studied NLS1 galaxy in X-rays to date. We apply standard time- and Fourier-domain techniques in order to…
New evidence for the ubiquity of prominent polar dust emission in AGN on tens of parsec scales
Asmus, D.
The key ingredient of active galactic nuclei (AGN) unification, the dusty obscuring torus was so far held responsible for the observed mid-infrared (MIR) emission of AGN. However, the best studied objects with Very Large Telescope Interferometer (VLTI)/MID-infrared Interferometric instrument (MIDI) show that instead a polar dusty wind is dominatin…
Interpretation and diversity of exoplanetary material orbiting white dwarfs
Redfield, Seth; Hollands, Mark; Gänsicke, Boris T. +5 more
Nine metal-polluted white dwarfs are observed with medium-resolution optical spectroscopy, where photospheric abundances are determined and interpreted by comparison with Solar system objects. An improved method for making such comparisons is presented, which overcomes potential weaknesses of prior analyses, with numerous sources of error consider…
The K2-HERMES Survey: age and metallicity of the thick disc
Lewis, Geraint F.; Ting, Yuan-Sen; Huber, Daniel +34 more
Asteroseismology is a promising tool to study Galactic structure and evolution because it can probe the ages of stars. Earlier attempts comparing seismic data from the Kepler satellite with predictions from Galaxy models found that the models predicted more low-mass stars compared to the observed distribution of masses. It was unclear if the misma…