Search Publications
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 Canada-France Imaging Survey: Reconstructing the Milky Way Star Formation History from Its White Dwarf Population
Lewis, Geraint F.; Gwyn, Stephen D. J.; McConnachie, Alan W. +15 more
As the remnants of stars with initial masses ≲8 M ⊙, white dwarfs contain valuable information on the formation histories of stellar populations. In this paper, we use deep, high-quality, u-band photometry from the Canada-France Imaging Survey, griz photometry from Pan-STARRS1, as well as proper motions from Gaia DR2, to select 25,156 w…
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…
Spatial variations in the Milky Way disc metallicity-age relation
Feuillet, Diane K.; Lind, Karin; García-Hernández, D. A. +5 more
Stellar ages are a crucial component to studying the evolution of the Milky Way. Using Gaia DR2 distance estimates, it is now possible to estimate stellar ages for a larger volume of evolved stars through isochrone matching. This work presents [M/H]-age and [α/M]-age relations derived for different spatial locations in the Milky Way disc. These re…
Astrometry with the Wide-Field Infrared Space Telescope
Casertano, Stefano; Lu, Jessica R.; Anderson, Jay +15 more
The Wide-Field Infrared Space Telescope (WFIRST) will be capable of delivering precise astrometry for faint sources over the enormous field of view of its main camera, the Wide-Field Imager (WFI). This unprecedented combination will be transformative for the many scientific questions that require precise positions, distances, and velocities of sta…
Feedback from massive stars at low metallicities: MUSE observations of N44 and N180 in the Large Magellanic Cloud
Testi, L.; Evans, C. J.; Kruijssen, J. M. D. +5 more
We present MUSE integral field data of two H II region complexes in the Large Magellanic Cloud: N44 and N180. Both regions consist of a main superbubble and a number of smaller, more compact H II regions that formed on the edge of the superbubble. For a total of 11 H II regions, we systematically analyse the radiative and mechanical feedback from …
A new RASS galaxy cluster catalogue with low contamination extending to z ∼ 1 in the DES overlap region
Smith, M.; D'Andrea, C. B.; Abbott, T. M. C. +63 more
We present the MARD-Y3 catalogue of between 1086 and 2171 galaxy clusters (52 per cent and 65 per cent new) produced using multicomponent matched filter (MCMF) follow-up in 5000 deg2 of DES-Y3 optical data of the ∼20 000 overlapping ROSAT All-Sky Survey source catalogue (2RXS) X-ray sources. Optical counterparts are identified as peaks …
The lowest detected stellar Fe abundance: the halo star SMSS J160540.18-144323.1
Schmidt, B. P.; Da Costa, G. S.; Marino, A. F. +12 more
We report the discovery of SMSS J160540.18-144323.1, a new ultra metal-poor halo star discovered with the SkyMapper telescope. We measure [{Fe}/{H}]= -6.2 ± 0.2 (1D LTE), the lowest ever detected abundance of iron in a star. The star is strongly carbon-enhanced, [{C}/{Fe}] = 3.9 ± 0.2, while other abundances are compatible with an α-enhanced solar…
The First Detection of 13C17O in a Protoplanetary Disk: A Robust Tracer of Disk Gas Mass
Booth, Alice S.; Ilee, John D.; Walsh, Catherine +4 more
Measurements of the gas mass are necessary to determine the planet formation potential of protoplanetary disks. Observations of rare CO isotopologues are typically used to determine disk gas masses; however, if the line emission is optically thick this will result in an underestimated disk mass. With the Atacama Large Millimeter/submillimeter Arra…
High gas-to-dust size ratio indicating efficient radial drift in the mm-faint CX Tauri disk
Tazzari, M.; Facchini, S.; Manara, C. F. +7 more
The large majority of protoplanetary disks have very compact continuum emission (≲15 AU) at millimeter wavelengths. However, high angular resolution observations that resolve these small disks are still lacking, due to their intrinsically fainter emission compared with large bright disks. In this Letter we present 1.3 mm ALMA data of the faint dis…