Search Publications
The tilt of the local velocity ellipsoid as seen by Gaia
Evans, N. W.; Belokurov, V.; Schönrich, R. +1 more
The Gaia Radial Velocity Spectrometer (RVS) provides a sample of 7224 631 stars with full six-dimensional phase space information. Bayesian distances of these stars are available from the catalogue of Schönrich, McMillan & Eyer. We exploit this to map out the behaviour of the velocity ellipsoid within 5 kpc of the Sun. We find that the tilt of…
The host galaxies of FeLoBAL quasars at z ∼ 0.9 are not dominated by recent major mergers
Villforth, C.; Hamann, F.; Hamilton, T. +4 more
Theoretical models have suggested an evolutionary model for quasars, in which most of luminous quasars are triggered by major mergers. It is also postulated that reddening as well as powerful outflows indicate an early phase of activity, close to the merger event. We test this model on a sample of quasars with powerful low-ionization outflows seen…
The relation between the turbulent Mach number and observed fractal dimensions of turbulent clouds
Klessen, Ralf S.; Federrath, Christoph; Schneider, Nicola +1 more
Supersonic turbulence is a key player in controlling the structure and star formation potential of molecular clouds (MCs). The three-dimensional (3D) turbulent Mach number, M, allows us to predict the rate of star formation. However, determining Mach numbers in observations is challenging because it requires accurate measurements of the velocity d…
The Pristine survey - VII. A cleaner view of the Galactic outer halo using blue horizontal branch stars
McConnachie, Alan W.; Martin, Nicolas; Venn, Kim A. +11 more
We use the Pristine survey CaHK narrow-band photometry, combined with the Sloan Digital Sky Survey (SDSS)ugr photometry, to provide a cleaner sample of blue horizontal branch stars in the Galactic halo out to large distances. We demonstrate a completeness of 91 per cent and a purity of 93 per cent with respect to available spectroscopic classifica…
Evaluating the evidence of multipolar surface magnetic field in PSR J0108-1431
Arumugasamy, Prakash; Mitra, Dipanjan
PSR J0108-1431 is an old pulsar where the X-ray emission is expected to have a thermal component from the polar cap and a non-thermal component from the magnetosphere. Although the phase-integrated spectra are fit best with a single non-thermal component modelled with a power law (PL) of photon index Γ = 2.9, the X-ray pulse profiles do show the p…
GALEX absolute calibration and extinction coefficients based on white dwarfs
Genest-Beaulieu, C.; Bergeron, P.; Gianninas, A. +3 more
We use 1837 DA white dwarfs with high signal-to-noise ratio spectra and Gaia parallaxes to verify the absolute calibration and extinction coefficients for the Galaxy Evolution Explorer (GALEX). We use white dwarfs within 100 pc to verify the linearity correction to the GALEX data. We find that the linearity correction is valid for magnitudes brigh…
Super-Earths in the TW Hya disc
Pinte, Christophe; Price, Daniel J.; Mentiplay, Daniel
We test the hypothesis that the sub-millimetre thermal emission and scattered light gaps seen in recent observations of TW Hya are caused by planet-disc interactions. We perform global three-dimensional dusty smoothed particle hydrodynamics simulations, comparing synthetic observations of our models with dust thermal emission, CO emission, and sca…
Subdwarf B stars as possible surviving companions in Type Ia supernova remnants
Li, Jiao; Meng, Xiangcun
Although Type Ia supernovae (SNe Ia) are so important in many astrophysical fields, a debate on their progenitor model is still endless. Searching the surviving companion in a supernova remnant (SNR) may distinguish different progenitor models, since a companion still exists in the remnant for the single-degenerate (SD) model, but does not for the…
A rogues gallery of Andromeda's dwarf galaxies - II. Precise distances to 17 faint satellites
Lewis, Geraint F.; Dolphin, Andrew E.; Skillman, Evan D. +8 more
We present new horizontal branch (HB) distance measurements to 17 of the faintest known M31 satellites (-6 ≲ MV ≲ -13) based on deep Hubble Space Telescope (HST) imaging. The colour-magnitude diagrams extend ∼1-2 mag below the HB, which provides for well-defined HBs, even for faint galaxies in which the tip of the red giant branch (TRGB…
HD 99458: First time ever Ap-type star as a δ Scuti pulsator in a short period eclipsing binary?
Sabotta, S.; Paunzen, E.; Skarka, M. +18 more
We present the discovery of a unique object, a chemically peculiar Ap-type star showing δ Scuti pulsations that is bound in an eclipsing binary system with an orbital period shorter than 3 d. HD 99458 is therefore a complex astrophysical laboratory opening doors for studying various, often contradictory, physical phenomena at the same time. It is …