Search Publications
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 …
On the dynamics of the Small Magellanic Cloud through high-resolution ASKAP H I observations
McClure-Griffiths, N. M.; Dickey, John M.; Staveley-Smith, L. +10 more
We use new high-resolution H I data from the Australian Square Kilometre Array Pathfinder to investigate the dynamics of the Small Magellanic Cloud (SMC). We model the H I gas component as a rotating disc of non-negligible angular size, moving into the plane of the sky, and undergoing nutation/precession motions. We derive a high-resolution (∼10 p…
Photodynamical analysis of the triply eclipsing hierarchical triple system EPIC 249432662
Vanderburg, A.; Haas, M.; Rappaport, S. +16 more
Using Campaign 15 data from the K2 mission, we have discovered a triply eclipsing triple star system: EPIC 249432662. The inner eclipsing binary system has a period of 8.23 d, with shallow ∼3 per cent eclipses. During the entire 80-d campaign, there is also a single eclipse event of a third body in the system that reaches a depth of nearly 50 per …
Radio frequency timing analysis of the compact jet in the black hole X-ray binary Cygnus X-1
Maccarone, T. J.; Gandhi, P.; Casella, P. +5 more
We present simultaneous multiband radio and X-ray observations of the black hole X-ray binary Cygnus X-1, taken with the Karl G. Jansky Very Large Array and the Nuclear Spectroscopic Telescope Array. With these data, we detect clear flux variability consistent with emission from a variable compact jet. To probe how the variability signal propagate…