Search Publications
Mass-invariance of the iron enrichment in the hot haloes of massive ellipticals, groups, and clusters of galaxies
Urdampilleta, I.; Simionescu, A.; Kaastra, J. S. +7 more
X-ray measurements find systematically lower Fe abundances in the X-ray emitting haloes pervading groups (kT ≲ 1.7 keV) than in clusters of galaxies. These results have been difficult to reconcile with theoretical predictions. However, models using incomplete atomic data or the assumption of isothermal plasmas may have biased the best-fitting Fe a…
Ground-based detection of G star superflares with NGTS
Jackman, James A. G.; Wheatley, Peter J.; Günther, Maximilian N. +19 more
We present high cadence detections of two superflares from a bright G8 star (V = 11.56) with the Next Generation Transit Survey (NGTS). We improve upon previous superflare detections by resolving the flare rise and peak, allowing us to fit a solar flare inspired model without the need for arbitrary break points between rise and decay. Our data als…
SDSS J211852.96-073227.5: a new γ-ray flaring narrow-line Seyfert 1 galaxy
Komossa, S.; Yang, Hui; Jin, Chichuan +6 more
We report on the identification of a new γ-ray-emitting narrow-line Seyfert 1 (NLS1) galaxy, SDSS J211852.96-073227.5 (hereinafter J2118-0732). The galaxy, at a redshift of 0.26, is associated with a radio source of flat/inverted spectrum at high radio frequencies. The analysis of its optical spectrum obtained in the Sloan Digital Sky Survey (SDSS…
Galactic outflows, star formation histories, and time-scales in starburst dwarf galaxies from STARBIRDS
McQuinn, Kristen B. W.; Skillman, Evan D.; Kelley, Tyler +2 more
Winds are predicted to be ubiquitous in low-mass, actively star-forming galaxies. Observationally, winds have been detected in relatively few local dwarf galaxies, with even fewer constraints placed on their time-scales. Here, we compare galactic outflows traced by diffuse, soft X-ray emission from Chandra Space Telescope archival observations to …
Stellar ages and masses in the solar neighbourhood: Bayesian analysis using spectroscopy and Gaia DR1 parallaxes
Ting, Yuan-Sen; Dotter, Aaron; Lin, Jane +1 more
We present a Bayesian implementation of isochrone fitting in deriving stellar ages and masses, incorporating absolute K magnitude (M_K) derived from 2MASS photometry and Gaia DR1 parallax and differentiation between initial bulk metallicity and present-day surface metallicity, with allowance for incorporating further constraints (e.g. asteroseismo…
KiDS-i-800: comparing weak gravitational lensing measurements from same-sky surveys
Heymans, C.; Wolf, C.; Lidman, C. +21 more
We present a weak gravitational lensing analysis of 815 deg2 of i-band imaging from the Kilo-Degree Survey (KiDS-i-800). In contrast to the deep r-band observations, which take priority during excellent seeing conditions and form the primary KiDS data set (KiDS-r-450), the complementary yet shallower KiDS-i-800 spans a wide range of obs…
On the production of He, C, and N by low- and intermediate-mass stars: a comparison of observed and model-predicted planetary nebula abundances
Balick, B.; Henry, R. B. C.; Stephenson, B. G. +2 more
The primary goal of this paper is to make a direct comparison between the measured and model-predicted abundances of He, C, and N in a sample of 35 well-observed Galactic planetary nebulae (PNe). All observations, data reductions, and abundance determinations were performed in house to ensure maximum homogeneity. Progenitor star masses (M ≤ 4 M
Unmasking the hidden NGTS-3Ab: a hot Jupiter in an unresolved binary system
Smalley, Barry; Gibson, Neale P.; Wheatley, Peter J. +36 more
We present the discovery of NGTS-3Ab, a hot Jupiter found transiting the primary star of an unresolved binary system. We develop a joint analysis of multicolour photometry, centroids, radial velocity (RV) cross-correlation function (CCF) profiles, and their bisector inverse slopes (BIS) to disentangle this three-body system. Data from the Next Gen…
Star formation in the outskirts of DDO 154: a top-light IMF in a nearly dormant disc
Meurer, Gerhardt R.; Lagos, Claudia D. P.; Kroupa, Pavel +3 more
We present optical photometry of Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS)/Wide Field Camera (WFC) data of the resolved stellar populations in the outer disc of the dwarf irregular galaxy DDO 154. The photometry reveals that young main sequence (MS) stars are almost absent from the outermost H I disc. Instead, most are cluster…
Generation of a circumstellar gas disc by hot Jupiter WASP-12b
Frank, Adam; Dobbs-Dixon, Ian; Fossati, Luca +3 more
Observations of transiting extra-solar planets provide rich sources of data for probing the in-system environment. In the WASP-12 system, a broad depression in the usually bright Mg II h&k lines has been observed, in addition to atmospheric escape from the extremely hot Jupiter WASP-12b. It has been hypothesized that a translucent circumstella…