Search Publications
On the lack of correlation between [O III]/[O II] and Lyman continuum escape fraction
Ryan-Weber, E. V.; Nanayakkara, T.; Sawicki, M. +9 more
We present the first results of our pilot study of eight photometrically selected Lyman-continuum (LyC) emitting galaxy candidates from the COSMOS field and focus on their optical emission line ratios. Observations were performed in the H and K bands using the Multi-Object Spectrometer for Infra-Red Exploration (MOSFIRE) instrument at the Keck Obs…
The search for multiple populations in Magellanic Clouds clusters - V. Correlation between cluster age and abundance spreads
Martocchia, S.; Dalessandro, E.; Salaris, M. +13 more
In our HST photometric survey, we have been searching for multiple stellar populations (MPs) in Magellanic Clouds (MCs) massive star clusters which span a significant range of ages (∼1.5-11 Gyr). In the previous papers of the series, we have shown that the age of the cluster represents one of the key factors in shaping the origin of the chemical a…
Modelling the spectral energy distribution of super-Eddington quasars
Done, Chris; Kubota, Aya
We develop a broad-band spectral model, AGNSLIM, to describe super-Eddington black hole accretion disc spectra. This is based on the slim disc emissivity, where radial advection keeps the surface luminosity at the local Eddington limit, resulting in L(r) ∝ r-2 rather than the r-3 expected from the Novikov-Thorne (standard, su…
The age of the Galactic stellar halo from Gaia white dwarfs
Hambly, N. C.; Rowell, N.; Bergeron, P. +3 more
We use 156 044 white dwarf candidates with ≥5σ significant parallax measurements from the Gaia mission to measure the velocity dispersion of the Galactic disc; (σU, σV, σW) = (30.8, 23.9, 20.0) km s-1. We identify 142 objects that are inconsistent with disc membership at the >5σ level. This is the lar…
Kinematics with Gaia DR2: the force of a dwarf
Anders, F.; Chiappini, C.; Santiago, B. X. +10 more
We use Gaia DR2 astrometric and line-of-sight velocity information combined with two sets of distances obtained with a Bayesian inference method to study the 3D velocity distribution in the Milky Way disc. We search for variations in all Galactocentric cylindrical velocity components (Vϕ, VR, and Vz) with Galactic …
Scattered light shadows in warped protoplanetary discs
Pinte, Christophe; Mentiplay, Daniel; Alexander, Richard +2 more
3D hydrodynamic numerical simulations have demonstrated that the structure of a protoplanetary disc may be strongly affected by a planet orbiting in a plane that is misaligned to the disc. When the planet is able to open a gap, the disc is separated into an inner, precessing disc and an outer disc with a warp. In this work, we compute infrared sca…
The Pisces Plume and the Magellanic wake
Carballo-Bello, Julio A.; Erkal, Denis; Belokurov, Vasily +5 more
Using RR Lyrae stars in the Gaia Data Release 2 and Pan-STARRS1 we study the properties of the Pisces overdensity, a diffuse substructure in the outer halo of the Milky Way. We show that along the line of sight, Pisces appears as a broad and long plume of stars stretching from 40 to 110 kpc with a steep distance gradient. On the sky Pisces's elong…
Lessons from the curious case of the `fastest' star in Gaia DR2
Evans, N. W.; Koposov, S. E.; Seabroke, G. +6 more
Gaia DR2 5932173855446728064 was recently proposed to be unbound from the Milky Way based on the -614.3± 2.5 km s^{-1} median radial velocity given in Gaia DR2. We obtained eight epochs of spectroscopic follow-up and find a very different median radial velocity of -56.5 ± 5.3 km s^{-1}. If this difference were to be explained by binarity, then the…
The Gaia ultracool dwarf sample - II. Structure at the end of the main sequence
Caballero, J. A.; Sarro, L. M.; Marocco, F. +4 more
We identify and investigate known late M, L, and T dwarfs in the Gaia second data release. This sample is being used as a training set in the Gaia data processing chain of the ultracool dwarfs work package. We find 695 objects in the optical spectral range M8-T6 with accurate Gaia coordinates, proper motions, and parallaxes which we combine with p…
Testing asteroseismology with Gaia DR2: hierarchical models of the Red Clump
Chaplin, William J.; Davies, Guy R.; García, Rafael A. +8 more
Asteroseismology provides fundamental stellar parameters independent of distance, but subject to systematics under calibration. Gaia DR2 has provided parallaxes for a billion stars, which are offset by a parallax zero-point (ϖzp). Red Clump (RC) stars have a narrow spread in luminosity, thus functioning as standard candles to calibrate …