Search Publications
Dust grain size evolution in local galaxies: a comparison between observations and simulations
Saintonge, A.; De Looze, I.; Smith, M. W. L. +13 more
The evolution of the dust grain size distribution has been studied in recent years with great detail in cosmological hydrodynamical simulations taking into account all the channels under which dust evolves in the interstellar medium. We present a systematic analysis of the observed spectral energy distribution of a large sample of galaxies in the …
Long-term photometric monitoring and spectroscopy of the white dwarf pulsar AR Scorpii
Dhillon, V. S.; Pelisoli, Ingrid; Breedt, E. +14 more
AR Scorpii (AR Sco) is the only radio-pulsing white dwarf known to date. It shows a broad-band spectrum extending from radio to X-rays whose luminosity cannot be explained by thermal emission from the system components alone, and is instead explained through synchrotron emission powered by the spin-down of the white dwarf. We analysed NTT/ULTRACAM…
Evidence for C and Mg variations in the GD-1 stellar stream
Balbinot, Eduardo; Cabrera-Ziri, Ivan; Lardo, Carmela
Dynamically cold stellar streams are the relics left over from globular cluster dissolution. These relics offer a unique insight into a now fully disrupted population of ancient clusters in our Galaxy. Using a combination of Gaia eDR3 proper motions, optical and near-UV colours, we select a sample of likely Red Giant Branch stars from the GD-1 str…
Model-independent redshift estimation of BL Lac objects through very-high-energy observations
Bhatt, Nilay; Malik, Zahoor; Sahayanathan, Sunder +3 more
The very-high-energy (VHE) gamma-ray spectral indices of blazars show a strong correlation with the source redshift. The absence of any such correlation in low-energy gamma-rays and X-rays indicates the presence of extragalactic background light (EBL)-induced absorption of VHE gamma-rays. By employing a linear regression analysis, this observation…
The protoplanetary disc around HD 169142: circumstellar or circumbinary?
Pinte, C.; Ménard, F.; Bayo, A. +12 more
Stellar binaries represent a substantial fraction of stellar systems, especially among young stellar objects. Accordingly, binaries play an important role in setting the architecture of a large number of protoplanetary discs. Binaries in coplanar and polar orientations with respect to the circumbinary disc are stable configurations and could induc…
Optical counterparts of ULXs in NGC 1672
Akyuz, A.; Allak, S.; Sonbas, E. +1 more
In this work, we deploy archival data from Hubble Space Telescope, Chandra, XMM-Newton, and Swift-XRT, to probe the nature of nine candidate ultraluminous X-ray sources (ULXs) in NGC 1672. Specifically, our study focuses on using the precise source positions obtained via improved astrometry based on Chandra and Hubble Space Telescope observations …
A multi-wavelength view of distinct accretion regimes in the pulsating ultraluminous X-ray source NGC 1313 X-2
Done, C.; Kaaret, P.; Soria, R. +7 more
NGC 1313 X-2 is one of the few known pulsating ultraluminous X-ray sources (PULXs), and so is thought to contain a neutron star that accretes at highly super-Eddington rates. However, the physics of this accretion remains to be determined. Here, we report the results of two simultaneous XMM-Newton and HST observations of this PULX taken to observe…
Models for metal-poor stars with different initial abundances of C, N, O, Mg, and Si. II. Application to the colour-magnitude diagrams of the globular clusters 47 Tuc, NGC 6362, M 5, M 3, M 55, and M92
Casagrande, Luca; Edvardsson, Bengt; VandenBerg, Don A.
Stellar models for -2.5 ≤ [Fe/H] ≤-0.5 that have been computed for variations in the C:N:O abundance ratio (for two different values of [CNO/Fe]) are compared with HST Wide Field Camera 3 (WFC3) observations of the globular clusters (GCs) 47 Tuc, NGC 6362, M 5 M 3, M 55, and M 92. The bolometric corrections (BCs) used to transpose the models to th…
Low-metallicity globular clusters in the low-mass isolated spiral galaxy NGC 2403
Forbes, Duncan A.; Romanowsky, Aaron J.; Brodie, Jean P. +4 more
The globular cluster (GC) systems of low-mass late-type galaxies, such as NGC 2403, have been poorly studied to date. As a low mass galaxy (M* = 7 × 109 M⊙), cosmological simulations predict NGC 2403 to contain few, if any, accreted GCs. It is also isolated, with a remarkably undisturbed HI disc. Based on candidate…
Dynamo activity of the K dwarf KOI-883 from transit photometry mapping
Marsden, S. C.; Carter, B. D.; Valio, A. +1 more
The Kepler mission target star KOI-883 is notable in being a low-mass K2V dwarf with moderately fast 8.99-d rotation and hosting a single transiting hot Jupiter in a 2.69-d orbit. This combination thus presents a particular opportunity to study star-spot activity by using the many deep planetary transits apparent in the light curve to map the stel…