Search Publications
On the type Ia supernovae 2007on and 2011iv: evidence for Chandrasekhar-mass explosions at the faint end of the luminosity-width relationship
Foley, Ryan J.; Ashall, C.; Hoeflich, P. +7 more
Radiative transfer models of two transitional type Ia supernovae (SNe Ia) have been produced using the abundance stratification technique. These two objects - designated SN 2007on and SN 2011iv - both exploded in the same galaxy, NGC 1404, which allows for a direct comparison. SN 2007on synthesized 0.25 M_{⊙} of 56Ni and was less lumino…
Spatial clustering and halo occupation distribution modelling of local AGN via cross-correlation measurements with 2MASS galaxies
Coil, Alison L.; Krumpe, Mirko; Miyaji, Takamitsu +1 more
We present the clustering properties and halo occupation distribution (HOD) modelling of very low redshift, hard X-ray-detected active galactic nuclei (AGN) using cross-correlation function measurements with Two-Micron All Sky Survey galaxies. Spanning a redshift range of 0.007 < z < 0.037, with a median z = 0.024, we present a precise AGN c…
Detailed chemical compositions of the wide binary HD 80606/80607: revised stellar properties and constraints on planet formation
Mustill, A. J.; Yong, D.; Asplund, M. +5 more
Differences in the elemental abundances of planet-hosting stars in binary systems can give important clues and constraints about planet formation and evolution. In this study we performed a high-precision, differential elemental abundance analysis of a wide binary system,
Tracking the iron K α line and the ultra fast outflow in NGC 2992 at different accretion states
Bianchi, S.; Matt, G.; Braito, V. +3 more
The Seyfert 2 galaxy NGC 2992 has been monitored eight times by XMM-Newton in 2010 and then observed again in 2013, while in 2015 it was simultaneously targeted by Swift and NuSTAR. XMM-Newton always caught the source in a faint state (2-10 keV fluxes ranging from 0.3 to 1.6 × 10-11 erg cm-2 s-1), but NuSTAR showed…
Plausible Home Stars of the Interstellar Object ‘Oumuamua Found in Gaia DR2
Buie, Marc W.; Bailer-Jones, Coryn A. L.; Chakrabarti, Sukanya +5 more
The first detected interstellar object, ‘Oumuamua, which passed within 0.25 au of the Sun on 2017 September 9, was presumably ejected from a stellar system. We use its newly determined non-Keplerian trajectory together with the reconstructed Galactic orbits of 7 million stars from Gaia DR2 to identify past close encounters. Such an “encounter” cou…
Chemical content of the circumstellar envelope of the oxygen-rich AGB star R Doradus. Non-LTE abundance analysis of CO, SiO, and HCN
de Koter, A.; Decin, L.; Wyrowski, F. +5 more
Context. The stellar outflows of low- to intermediate-mass stars are characterised by a rich chemistry. Condensation of molecular gas species into dust grains is a key component in a chain of physical processes that leads to the onset of a stellar wind. In order to improve our understanding of the coupling between the micro-scale chemistry and mac…
The GALAH survey: stellar streams and how stellar velocity distributions vary with Galactic longitude, hemisphere, and metallicity
Lewis, Geraint F.; Ting, Yuan-Sen; Buder, Sven +30 more
Using GALAH (GALactic Archaeology with HERMES) survey data of nearby stars, we look at how structure in the planar (u, v) velocity distribution depends on metallicity and on viewing direction within the Galaxy. In nearby stars with distance d ≲ 1 kpc, the Hercules stream is most strongly seen in higher metallicity stars [Fe/H] > 0.2. The Hercul…
Microlensing and Intrinsic Variability of the Broad Emission Lines of Lensed Quasars
Hanslmeier, A.; Muñoz, J. A.; Falco, E. E. +5 more
We study the broad emission lines in a sample of 11 gravitationally lensed quasars with at least two epochs of observation to identify intrinsic variability and to disentangle it from microlensing. To improve our statistical significance and emphasize trends, we also include 15 lens systems with single-epoch spectra. Mg II and C III] emission line…
Mass and Light of Abell 370: A Strong and Weak Lensing Analysis
Schrabback, T.; Vulcani, B.; Hoag, A. +13 more
We present a new gravitational lens model of the Hubble Frontier Fields cluster Abell 370 (z = 0.375) using imaging and spectroscopy from Hubble Space Telescope and ground-based spectroscopy. We combine constraints from a catalog of 909 weakly lensed galaxies and 39 multiply imaged sources comprised of 114 multiple images, including a system of mu…
Low-frequency photospheric and wind variability in the early-B supergiant HD 2905
Grundahl, F.; Fredslund Andersen, M.; Pallé, P. L. +5 more
Context. Despite important advances in space asteroseismology during the last decade, the early phases of evolution of stars with masses above 15 M⊙ (including the O stars and their evolved descendants, the B supergiants) have been only vaguely explored up to now. This is due to the lack of adequate observations for a proper characteriz…