Search Publications
The X-ray spectral and variability properties of typical radio-loud quasars
Brandt, W. N.; Zhu, S. F.; Timlin, John D.
We present X-ray spectral and long-term variability analyses of an unbiased sample of 361 optically selected radio-loud quasars (RLQs) utilizing sensitive serendipitous X-ray data from the Chandra and XMM-Newton archives. The spectral and temporal properties of RLQs are compared with those of radio-quiet quasars (RQQs) matched in L2500Å…
Isochrone fitting of Galactic globular clusters - III. NGC 288, NGC 362, and NGC 6218 (M12)
Gontcharov, George A.; Mosenkov, Aleksandr V.; Khovritchev, Maxim Yu +6 more
We present new isochrone fits to colour-magnitude diagrams of the Galactic globular clusters NGC 288, NGC 362, and NGC 6218 (M12). We utilize a lot of photometric bands from the ultraviolet to mid-infrared by use of data from the HST, Gaia, unWISE, Pan-STARRS, and other photometric sources. In our isochrone fitting, we use theoretical models and i…
VVV-WIT-08: the giant star that blinked
Smith, Leigh C.; Udalski, Andrzej; Minniti, Dante +11 more
We report the serendipitous discovery of a late-type giant star that exhibited a smooth, eclipse-like drop in flux to a depth of 97 per cent. Minimum flux occurred in 2012 April and the total event duration was a few hundred days. Light curves in V, I, and Ks from the Optical Gravitational Lensing Experiment and VISTA Variables in the V…
SuperWASP variable stars: classifying light curves using citizen science
Thiemann, Heidi B.; Norton, Andrew J.; Kolb, Ulrich C. +2 more
We present the first analysis of results from the SuperWASP variable stars Zooniverse project, which is aiming to classify 1.6 million phase-folded light curves of candidate stellar variables observed by the SuperWASP all sky survey with periods detected in the SuperWASP periodicity catalogue. The resultant data set currently contains >1 millio…
The role of gas kinematics in setting metallicity gradients at high redshift
Federrath, Christoph; Krumholz, Mark R.; Wisnioski, Emily +1 more
In this work, we explore the diversity of ionized gas kinematics (rotational velocity vϕ and velocity dispersion σg) and gas-phase metallicity gradients at 0.1 ≤ z ≤ 2.5 using a compiled data set of 74 galaxies resolved with ground-based integral field spectroscopy. We find that galaxies with the highest and the lowest σ…
Water and deuterium-to-hydrogen ratio in comets
Fulle, Marco
Recent models find that nuclei of comets are a mixture of water-rich and water-poor cm-sized pebbles. We aim to fit the correlation of the deuterium-to-hydrogen ratio, D/H, with the nucleus active area fraction. Pebble parameters, constrained by the Rosetta mission data, depend on where pebbles accreted in the protoplanetary disc. The diversity of…
The COS-legacy survey of C IV absorbers: properties and origins of the intervening systems
Charlton, Jane C.; Savage, Blair D.; Misawa, Toru +4 more
We present here results from a survey of intervening C IV absorbers at z < 0.16 conducted using 223 sightlines from the Hubble Spectroscopic Legacy Archive. Most systems (83%) out of the total sample of 69 have simple kinematics with 1 or 2 C IV components. In the 22 C IV systems with well constrained H I column densities, the temperatures from…
The Deeper, Wider, Faster programme: exploring stellar flare activity with deep, fast cadenced DECam imaging via machine learning
Abbott, T. M. C.; Zhang, J.; Flynn, C. +9 more
We present our 500 pc distance-limited study of stellar flares using the Dark Energy Camera as part of the Deeper, Wider, Faster programme. The data were collected via continuous 20-s cadence g-band imaging and we identify 19 914 sources with precise distances from Gaia DR2 within 12, ~3 deg2, fields over a range of Galactic latitudes. …
Long-term X-ray variability of the symbiotic system RT Cru based on Chandra spectroscopy
Drake, J. J.; Karovska, M.; Danehkar, A. +1 more
RT Cru belongs to the rare class of hard X-ray emitting symbiotics, whose origin is not yet fully understood. In this work, we have conducted a detailed spectroscopic analysis of X-ray emission from RT Cru based on observations taken by the Chandra Observatory using the Low Energy Transmission Grating (LETG) on the High-Resolution Camera Spectrome…
Early science with the Large Millimeter Telescope: a 1.1 mm AzTEC survey of red-Herschel dusty star-forming galaxies
Ivison, R. J.; Omont, A.; Pope, A. +32 more
We present Large Millimeter Telescope (LMT)/AzTEC 1.1 mm observations of ~100 luminous high-redshift dusty star-forming galaxy candidates from the $\sim 600\,$ sq.deg Herschel-ATLAS survey, selected on the basis of their SPIRE red far-infrared colours and with $S_{500\, \mu \rm m}=35-80$ mJy. With an effective $\theta _{\rm FWHM}\approx 9.5\,$arcs…