Search Publications
Diagnosing solar wind origins using in situ measurements in the inner heliosphere
Matteini, L.; Horbury, T. S.; Stansby, D.
Robustly identifying the solar sources of individual packets of solar wind measured in interplanetary space remains an open problem. We set out to see if this problem is easier to tackle using solar wind measurements closer to the Sun than 1 au, where the mixing and dynamical interaction of different solar wind streams is reduced. Using measuremen…
A discontinuity in the Teff-radius relation of M-dwarfs
Jordán, Andrés; Espinoza, Néstor; Brahm, Rafael +7 more
We report on 13 new high-precision measurements of stellar diameters for low-mass dwarfs obtained by means of near-infrared long-baseline interferometry with PIONIER at the Very Large Telescope Interferometer. Together with accurate parallaxes from Gaia DR2, these measurements provide precise estimates for their linear radii, effective temperature…
Clouds in arms
Belokurov, Vasily A.; Erkal, Denis
We use astrometry and broad-band photometry from Data Release 2 of the ESA's Gaia mission to map out low surface-brightness features in the stellar density distribution around the Large and Small Magellanic Clouds. The LMC appears to have grown two thin and long stellar streams in its Northern and Southern regions, highly reminiscent of spiral arm…
Rotational modulation in TESS B stars
Handler, G.; Wade, G. A.; Cantiello, M. +6 more
Light curves and periodograms of 160 B stars observed by the Transiting Exoplanet Survey Satellite (TESS) space mission and 29 main-sequence B stars from Kepler and K2 were used to classify the variability type. There are 114 main-sequence B stars in the TESS sample, of which 45 are classified as possible rotational variables. This confirms previo…
The spiral pattern rotation speed of the Galaxy and the corotation radius with Gaia DR2
Dias, W. S.; Monteiro, H.; Lépine, J. R. D. +1 more
In this work we revisit the issue of the rotation speed of the spiral arms and the location of the corotation radius of our Galaxy. This research was performed using homogeneous data set of young open clusters (age < 50 Myr) determined from Gaia Data Release 2 (DR2) data. The stellar astrometric membership was determined using proper motions an…
Disentangling the spatial substructure of Cygnus OB2 from Gaia DR2
Lennon, D. J.; Herrero, A.; Wright, N. J. +2 more
For the first time, we have explored the spatial substructure of the Cygnus OB2 association using parallaxes from the recent second Gaia data release. We find significant line-of-sight substructure within the association, which we quantify using a parametrized model that reproduces the observed parallax distribution. This inference approach is nec…
Galaxy structure with strong gravitational lensing: decomposing the internal mass distribution of massive elliptical galaxies
Tam, Sut-Ieng; Nightingale, James W.; Cooper, Andrew P. +4 more
We investigate how strong gravitational lensing can test contemporary models of massive elliptical (ME) galaxy formation, by combining a traditional decomposition of their visible stellar distribution with a lensing analysis of their mass distribution. As a proof of concept, we study a sample of three ME lenses, observing that all are composed of …
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…