Search Publications
Study of chemically peculiar stars - I. High-resolution spectroscopy and K2 photometry of Am stars in the region of M44
Bhatt, B. C.; García, R. A.; Lund, M. N. +30 more
We present a study based on the high-resolution spectroscopy and K2 space photometry of five chemically peculiar stars in the region of the open cluster M44. The analysis of the high-precision photometric K2 data reveals that the light variations in HD 73045 and HD 76310 are rotational in nature and caused by spots or cloud-like co-rotating struct…
Models of metal-poor stars with different initial abundances of C, N, O, Mg, and Si - I. Bolometric corrections derived from new MARCS synthetic spectra and their implications for observed colour-magnitude diagrams
Casagrande, Luca; Edvardsson, Bengt; VandenBerg, Don A. +1 more
New, high-resolution MARCS synthetic spectra have been calculated for more than a dozen mixtures of the metals allowing, in turn, for variations in C:N:O, [CNO/Fe], and enhanced abundances of C, O, Mg, and Si. Bolometric corrections (BCs) for many of the broad-band filters currently in use have been generated from these spectra. Due to improved tr…
Comparing the super-Eddington accretion of SMC X-3 and RX J0209.6-7427 with Swift J0243.6+6124
Weng, Shan-Shan; Liu, Jiren; Vasilopoulos, Georgios +4 more
We study the giant outbursts of SMC X-3 and RX J0209.6-7427 (hereafter RX J0209) to compare their super-Eddington accretion regime with that of Swift J0243.6+6124 (hereafter Swift J0243). The high double-peak profile of SMC X-3 is found to be 0.25 phase offset from that below 2.3 × 1038 erg s-1, which is similar to Swift J024…
Discovery of extreme, roughly daily superflares on the recurrent nova V2487 Oph
Schaefer, Bradley E.; Pagnotta, Ashley; Zoppelt, Seth
V2487 Oph is a recurrent nova with detected eruptions in 1900 and 1998. Startlingly, V2487 Oph shows flares, called 'Superflares', with up to 1.10 mag amplitude, fast rises of under one-minute, always with an initial impulsive spike followed by a roughly exponential tail, typically one-hour durations, and with random event times averaging once-per…
Post maximum light and late time optical imaging polarimetry of type I superluminous supernova 2020znr
Pérez-Fournon, I.; Poidevin, F.; Omand, C. M. B. +5 more
Optical imaging polarimetry was conducted on the hydrogen poor superluminous supernova 2020znr during three phases after maximum light (≈ +34 d, +288 d, and +289 d). After instrumental and interstellar polarization correction, all measurements are consistent with null-polarization detection. Modelling the light curve with a magnetar spin-down mode…
Modelling high-resolution ALMA observations of strongly lensed dusty star-forming galaxies detected by Herschel
Serjeant, Stephen; Dunne, Loretta; Cooray, Asantha +15 more
We present modelling of ~0.1 arcsec resolution Atacama Large Millimetre/submillimetre Array imaging of seven strong gravitationally lensed galaxies detected by the Herschel Space Observatory. Four of these systems are galaxy-galaxy strong lenses, with the remaining three being group-scale lenses. Through careful modelling of visibilities, we infer…
Chemistry and physical properties of the born-again planetary nebula HuBi 1
Morisset, C.; Guerrero, M. A.; Toalá, J. A. +4 more
The central star of the planetary nebula (PN) HuBi 1 has been recently proposed to have experienced a very late thermal pulse (VLTP), but the dilution of the emission of the recent ejecta by that of the surrounding H-rich old outer shell has so far hindered confirming its suspected H-poor nature. We present here an analysis of the optical properti…
Modelling of multimode radially pulsating high-amplitude δ Scuti stars from the OGLE Galactic bulge sample
Smolec, R.; Netzel, H.
Thanks to relatively firm mode identification, possible based only on period ratios, high-amplitude δ Scuti stars pulsating in at least three radial modes are promising targets for asteroseismic inference. In this study, we used the most numerous sample of HADS from the OGLE inner bulge fields that likely pulsate in either three or four radial mod…
Multiwavelength observations of MAXI J1820+070 during its outburst decay and subsequent mini-outburst
Altamirano, D.; Bailyn, C. D.; Özbey Arabacı, M. +3 more
We present results from quasi-simultaneous multiwavelength observations of the Galactic black hole X-ray transient MAXI J1820+070 during the decay of the 2018 outburst and its entire subsequent mini-outburst in March 2019. We fit the X-ray spectra with phenomenological and Comptonizaton models and discuss the X-ray spectral evolution in comparison…
Abundance analysis of APOGEE spectra for 58 metal-poor stars from the bulge spheroid
Schultheis, M.; Minniti, D.; Valentini, M. +19 more
The central part of the Galaxy hosts a multitude of stellar populations, including the spheroidal bulge stars, stars moved to the bulge through secular evolution of the bar, inner halo, inner thick disc, inner thin disc, as well as debris from past accretion events. We identified a sample of 58 candidate stars belonging to the stellar population o…