Search Publications
High-resolution radiative transfer modelling of M33
De Looze, Ilse; Baes, Maarten; Smith, Matthew W. L. +4 more
In this work, we characterize the contributions from both ongoing star formation and the ambient radiation field in Local Group galaxy M33, as well as estimate the scale of the local dust-energy balance (i.e. the scale at which the dust is re-emitting starlight generated in that same region) in this galaxy through high-resolution radiative transfe…
Ongoing star formation at the outskirts of Sextans A: spectroscopic detection of early O-type stars
Garcia, Miriam; Herrero, Artemio; Najarro, Francisco +2 more
With both nebular- and stellar-derived abundances of ≲1/10 Z_{⊙ } and low foreground extinction, Sextans A is a prime candidate to replace the Small Magellanic Cloud as reservoir of metal-poor massive stars and reference to study the metal-poor Universe. We report the discovery of two early O-type stars in Sextans A, the earliest O-type stars with…
Revisiting the potassium feature of WASP-31b at high resolution
Nikolov, Nikolay; de Mooij, Ernst J. W.; Gibson, Neale P. +4 more
The analysis and interpretation of exoplanet spectra from time-series observations remains a significant challenge to our current understanding of exoplanet atmospheres, due to the complexities in understanding instrumental systematics. Previous observations of the hot Jupiter WASP-31b using transmission spectroscopy at low resolution have present…
The stellar halo of isolated central galaxies in the Hyper Suprime-Cam imaging survey
Sonnenfeld, Alessandro; Wang, Wenting; Han, Jiaxin +14 more
We study the faint stellar halo of isolated central galaxies, by stacking galaxy images in the HSC survey and accounting for the residual sky background sampled with random points. The surface brightness profiles in HSC r band are measured for a wide range of galaxy stellar masses (9.2 < log10M∗/M⊙ < 11.4) an…
The sdA problem - III. New extremely low-mass white dwarfs and their precursors from Gaia astrometry
Kepler, S. O.; Bell, Keaton J.; Pelisoli, Ingrid +1 more
The physical nature of the sdA stars - cool hydrogen-rich objects with spectroscopic surface gravities intermediate between main-sequence and canonical-mass white dwarfs - has been elusive since they were found in Sloan Digital Sky Survey Data Release 12 spectra. The population is likely dominated by metal-poor A/F stars in the halo with overestim…
Mass function and dynamical study of the open clusters Berkeley 24 and Czernik 27 using ground based imaging and Gaia astrometry
Bisht, D.; Yadav, R. K. S.; Fynbo, J. P. U. +3 more
We present a UBVI photometric study of the open clusters Berkeley 24 (Be 24) and Czernik 27 (Cz 27). The radii of the clusters are determined as 2{^'.}7 and 2{^'.}3 for Be 24 and Cz 27, respectively. We use the Gaia Data Release 2 (GDR2) catalogue to estimate the mean proper motions for the clusters. We found the mean proper …
Spectroscopic detection of multiple populations in the ∼2 Gyr old cluster Hodge 6 in the LMC
Martocchia, S.; Dalessandro, E.; Salaris, M. +8 more
We report the spectroscopic discovery of abundance spreads (i.e. multiple populations) in the ∼2 Gyr old cluster in the LMC, Hodge 6. We use low-resolution VLT FORS2 spectra of 15 member stars in the cluster to measure their CN and CH band strengths at ≃3883 and 4300 Å, respectively, as well as [C/Fe] and [N/Fe] abundances. We find a subpopulation…
Star-disc (mis-)alignment in Rho Oph and Upper Sco: insights from spatially resolved disc systems with K2 rotation periods
Davies, Claire L.
The discovery of close in, giant planets (hot Jupiters) with orbital angular momentum vectors misaligned with respect to the rotation axis of their host stars presents problems for planet formation theories in which planets form in discs with angular momentum vectors aligned with that of the star. Violent, high-eccentricity migration mechanisms pu…
High-energy monitoring of NGC 4593 II. Broad-band spectral analysis: testing the two-corona model
Bianchi, S.; Cappi, M.; Ponti, G. +9 more
It is widely believed that the primary X-ray emission of AGN is due to the Comptonization of optical-UV photons from a hot electron corona, while the origin of the `soft-excess' is still uncertain and matter of debate. A second Comptonization component, called warm corona, was therefore proposed to account for the soft-excess, and found in agreeme…
Detections and constraints on white dwarf variability from time-series GALEX observations
Hermes, J. J.; Shappee, B. J.; Tucker, M. A. +1 more
We search for photometric variability in more than 23 000 known and candidate white dwarfs (WDs), the largest ultraviolet survey compiled for a single study of WDs. We use GPHOTON, a publicly available calibration/reduction pipeline, to generate time-series photometry of WDs observed by GALEX. By implementing a system of weighted metrics, we selec…