Search Publications
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…
Machine learning for fast transients for the Deeper, Wider, Faster programme with the Removal Of BOgus Transients (ROBOT) pipeline
Mahabal, Ashish; Zhang, Jielai; Cooke, Jeff +3 more
The Deeper, Wider, Faster (DWF) programme is optimized to detect fast transients that show luminosity changes on time-scales of sub-second to days using fast cadence simultaneous observations and rapid response follow up. One of the significant bottlenecks in DWF is the time required to assess candidates for rapid follow up and to manually inspect…
Optical and near-infrared data and modelling of nova V5668 Sgr
Lawrence, S. S.; Sokolovsky, K. V.; Diaz, M. +4 more
We present Hubble Space Telescope optical images, Keck-OSIRIS near-infrared (NIR) integral field spectroscopy data cubes and Keck-Near InfraRed Camera-2 (NIRC2) NIR images of nova V5668 Sgr from 2016 to 2019. The observations indicate enhanced emission at the polar caps and equatorial torus for low-ionization lines, and enhanced high-ionization em…
Spatiokinematic models of five nova remnants: correlations between nova shell axial ratio, expansion velocity, and speed class
Guerrero, M. A.; Toalá, J. A.; Santamaría, E. +3 more
We present long-slit intermediate-dispersion spectroscopic observations and narrow-band direct imaging of four classical nova shells, namely T Aur, HR Del, DQ Her, and QU Vul, and the nova-like source CK Vul. These are used to construct models of their nebular remnants using the morphokinematic modelling tool SHAPE to reveal their 3D shape. All th…
Polarization, polarizing efficiency, and grain alignment towards the direction of the cluster NGC 2345
Hoang, Thiem; Pandey, Jeewan C.; Singh, Sadhana
We have investigated the grain alignment and dust properties towards the direction of the cluster NGC 2345 using the multiband optical polarimetric observations. For the majority of the stars, the observed polarization is found to be due to the interstellar medium with average values of maximum polarization and wavelength corresponding to it as 1.…
The transient ultraluminous X-ray source, ULX-4, in M51
Akyuz, A.; Aksaker, N.; Avdan, S. +6 more
We present the results of a temporal and spectral analysis of the transient source ULX-4 in the galaxy M51. The data used were drawn from Chandra, XMM-Newton, and Swift-XRT archives, spanning the years 2000-2019.. The X-ray flux of the source is seen to vary by two orders of magnitudes within a month but a short-term variability was not observed o…
The cycle of metals in the infalling elliptical galaxy NGC 1404
Simionescu, A.; Mernier, F.; Pinto, C. +6 more
Hot atmospheres pervading galaxy clusters, groups, and early-type galaxies are rich in metals, produced during epochs and diffused via processes that are still to be determined. While this enrichment has been routinely investigated in clusters, metals in lower mass systems are more challenging to probe with standard X-ray exposures and spectroscop…
APOGEE detection of N-rich stars in the tidal tails of Palomar 5
Cohen, Roger E.; Majewski, Steven R.; Horta, Danny +15 more
Recent results from chemical tagging studies using Apache Point Observatory Galactic Evolution Experiment data suggest a strong link between the chemical abundance patterns of stars found within globular clusters (GC), and chemically peculiar populations in the Galactic halo field. In this paper, we analyse the chemical compositions of stars withi…