Search Publications
Chemo-dynamics and asteroseismic ages of seven metal-poor red giants from the Kepler field
Monty, Stephanie; Freeman, Ken C.; Stello, Dennis +5 more
In this work, we combine information from solar-like oscillations, high-resolution spectroscopy, and Gaia astrometry to derive stellar ages, chemical abundances, and kinematics for a group of seven metal-poor red giants and characterize them in a multidimensional chrono-chemo-dynamical space. Chemical abundance ratios were derived through classica…
Non-parametric spherical Jeans mass estimation with B-splines
Vasiliev, Eugene; Valluri, Monica; Rehemtulla, Nabeel
Spherical Jeans modelling is widely used to estimate mass profiles of systems from star clusters to galactic stellar haloes to clusters of galaxies. It derives the cumulative mass profile, M(<r), from kinematics of tracers of the potential under the assumptions of spherical symmetry and dynamical equilibrium. We consider the application of Jean…
The velocity distribution of white dwarfs in Gaia EDR3
McMillan, Paul J.; Hobbs, David; Wimarsson, John +1 more
Using a penalized maximum likelihood, we estimate, for the first time, the velocity distribution of white dwarfs in the solar neighbourhood. Our sample consists of 129 675 white dwarfs within 500 pc in Gaia Early Data Release 3. The white dwarf velocity distributions reveal a similar structure to the rest of the solar neighbourhood stars, reflecti…
The Galactic high mass X-ray binary population with Fermi-LAT
Chadwick, Paula M.; Harvey, Max; Rulten, Cameron B.
We search for γ-ray emission from 114 Galactic high-mass X-ray binaries, including four well studied catalogued sources, in 12.5 yr of Fermi-LAT data in conjunction with the 10-yr point source catalogue. Where a γ-ray excess appears to be spatially coincident with an X-ray binary, further investigation is performed to ascertain whether this excess…
Quantifying the cool ISM in radio AGNs: evidence for late-time retriggering by galaxy mergers and interactions
Daddi, E.; Morganti, R.; Tadhunter, C. N. +5 more
We use deep Herschel observations of the complete 2Jy sample of powerful radio active galactic nuclei (AGNs) in the local Universe (0.05 < z < 0.7) to probe their cool interstellar medium (ISM) contents and star-forming properties, comparing them against other samples of nearby luminous AGNs and quiescent galaxies. This allows us to investig…
Periodic stellar variability from almost a million NGTS light curves
Jackman, James A. G.; Wheatley, Peter J.; Bayliss, Daniel +25 more
We analyse 829 481 stars from the Next Generation Transit Survey (NGTS) to extract variability periods. We utilize a generalization of the autocorrelation function (the G-ACF), which applies to irregularly sampled time series data. We extract variability periods for 16 880 stars from late-A through to mid-M spectral types and periods between ~0.1 …
Wide binaries from the H3 survey: the thick disc and halo have similar wide binary fractions
Conroy, Charlie; Ting, Yuan-Sen; Cargile, Phillip +8 more
Due to the different environments in the Milky Way's disc and halo, comparing wide binaries in the disc and halo is key to understanding wide binary formation and evolution. By using Gaia Early Data Release 3, we search for resolved wide binary companions in the H3 survey, a spectroscopic survey that has compiled ~150 000 spectra for thick-disc an…
The puzzling story of flare inactive ultra fast rotating M dwarfs - I. Exploring their magnetic fields
Ramsay, Gavin; Hakala, Pasi; Doyle, Lauren +2 more
Stars which are rapidly rotating are expected to show high levels of activity according to the activity-rotation relation. However, previous TESS studies have found ultra fast rotating (UFR) M dwarfs with periods less than 1 d displaying low levels of flaring activity. As a result, in this study, we utilize VLT/FORS2 spectro-polarimetric data of 1…
Properties of shocked dust grains in supernova remnants
De Looze, I.; Gomez, H. L.; Barlow, M. J. +3 more
Shockwaves driven by supernovae both destroy dust and reprocess the surviving grains, greatly affecting the resulting dust properties of the interstellar medium (ISM). While these processes have been extensively studied theoretically, observational constraints are limited. We use physically motivated models of dust emission to fit the infrared (IR…
Quasi-periodic whispers from a transient ULX in M 101: signatures of a fast-spinning neutron star?
Soria, Roberto; Pintore, Fabio; Esposito, Paolo +7 more
We have studied the unusual time variability of an ultraluminous X-ray source in M 101, 4XMM J140314.2 + 541806 (henceforth, J1403), using Chandra and XMM-Newton data. Over the last two decades, J1403 has shown short-duration outbursts with an X-ray luminosity ~1-3 × 1039 erg s-1, and longer intervals at luminosities ~0.5-1 ×…