Search Publications
Beyond spheroids and discs: classifications of CANDELS galaxy structure at 1.4 < z < 2 via principal component analysis
Papovich, Casey; Barro, Guillermo; Grogin, Norman A. +15 more
Important but rare and subtle processes driving galaxy morphology and star formation may be missed by traditional spiral, elliptical, irregular or Sérsic bulge/disc classifications. To overcome this limitation, we use a principal component analysis (PCA) of non-parametric morphological indicators (concentration, asymmetry, Gini coefficient, M…
Low-ionization structures in planetary nebulae - I. Physical, kinematic and excitation properties
Gonçalves, Denise R.; Akras, Stavros
Though the low-ionization small-scale structures (LISs) such as knots, filaments and jets of planetary nebulae (PNe) are known for ∼30 yr, some of their observational properties are not well established. In consequence, our ability to include them in the wider context of the formation and evolution of PNe is directly affected. Why most structures …
Carbon to oxygen ratios in extrasolar planetesimals
Gänsicke, Boris T.; Koester, Detlev; Farihi, Jay +1 more
Observations of small extrasolar planets with a wide range of densities imply a variety of planetary compositions and structures. Currently, the only technique to measure the bulk composition of extrasolar planetary systems is the analysis of planetary debris accreting on to white dwarfs, analogous to abundance studies of meteorites. We present me…
SN 2015U: a rapidly evolving and luminous Type Ibn supernova
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Kelly, Patrick L. +7 more
Supernova (SN) 2015U (also known as PSN J07285387+3349106) was discovered in NGC 2388 on 2015 Feb. 11. A rapidly evolving and luminous event, it showed effectively hydrogen-free spectra dominated by relatively narrow helium P-Cygni spectral features and it was classified as an SN Ibn. In this paper, we present photometric, spectroscopic, and spect…
The white dwarf binary pathways survey - I. A sample of FGK stars with white dwarf companions
Gänsicke, B. T.; Rebassa-Mansergas, A.; Parsons, S. G. +3 more
The number of spatially unresolved white dwarf plus main-sequence star binaries has increased rapidly in the last decade, jumping from only ∼30 in 2003 to over 3000. However, in the majority of known systems the companion to the white dwarf is a low-mass M dwarf, since these are relatively easy to identify from optical colours and spectra. White d…
Strong gravitational lensing and the stellar IMF of early-type galaxies
Charlot, Stéphane; Saha, Prasenjit; Bruzual, Gustavo +3 more
Systematic variations of the initial mass function (IMF) in early-type galaxies, and their connection with possible drivers such as velocity dispersion or metallicity, have been much debated in recent years. Strong lensing over galaxy scales combined with photometric and spectroscopic data provides a powerful method to constrain the stellar mass-t…
The treatment of mixing in core helium burning models - II. Constraints from cluster star counts
Campbell, Simon W.; Constantino, Thomas; Lattanzio, John C. +1 more
The treatment of convective boundaries during core helium burning is a fundamental problem in stellar evolution calculations. In the first paper of this series, we showed that new asteroseismic observations of these stars imply they have either very large convective cores or semiconvection/partially mixed zones that trap g modes. We probe this mix…
Shapley Supercluster Survey: ram-pressure stripping versus tidal interactions in the Shapley supercluster
Bourdin, H.; Mazzotta, P.; Haines, C. P. +4 more
We present two new examples of galaxies undergoing transformation in the Shapley supercluster core. These low-mass (M_{star }∼ 0.4-1× 10^{10} M⊙) galaxies are members of the two clusters SC 1329-313 (z ∼ 0.045) and SC 1327-312 (z ∼ 0.049). Integral-field spectroscopy complemented by imaging in the ugriK bands and in Hα narrow band is us…
Warm absorbers in X-rays (WAX), a comprehensive high-resolution grating spectral study of a sample of Seyfert Galaxies - II. Warm absorber dynamics and feedback to galaxies
Dewangan, Gulab C.; Guainazzi, Matteo; Laha, Sibasish +2 more
This paper is a sequel to the extensive study of warm absorber (WA) in X-rays carried out using high-resolution grating spectral data from XMM-Newton satellite (WAX-I). Here we discuss the global dynamical properties as well as the energetics of the WA components detected in the WAX sample. The slope of WA density profile (n ∝ r-α) esti…
A free-form mass model of the Hubble Frontier Fields cluster AS1063 (RXC J2248.7-4431) with over one hundred constraints
Broadhurst, Tom; Zheng, Wei; Lam, Daniel +5 more
We derive a free-form mass distribution for the massive cluster AS1063 (z = 0.348) using the completed optical imaging from the Hubble Frontier Fields programmme. Based on a subset of 11 multiply lensed systems with spectroscopic redshift, we produce a lens model that is accurate enough to secure new multiply lensed systems, totalling over a 100 a…