Search Publications
A high-resolution spectroscopic search for multiple populations in the 2 Gyr old cluster NGC 1846
Da Costa, G. S.; Mackey, A. D.; Nordlander, T. +1 more
We present detailed C, O, Na, Mg, Si, Ca, Ti, V, Fe, Zr, Ba, and Eu abundance measurements for 20 red giant branch (RGB) stars in the Large Magellanic Cloud (LMC) star cluster NGC 1846 ([Fe/H] = -0.59). This cluster is 1.95 Gyr old and lies just below the supposed lower age limit (2 Gyr) for the presence of multiple populations in massive star clu…
M dwarf stars in the b294 field from the VISTA Variables in the Vía Láctea (VVV)
Minniti, Dante; Alonso-García, Javier; Saito, Roberto K. +4 more
M dwarf stars are the dominant stellar population in the Milky Way, and they are important for a wide variety of astrophysical topics. The Gaia mission has delivered a superb collection of data, nevertheless, ground-based photometric surveys are still needed to study faint objects. Therefore, the present work aims to identify and characterize M dw…
The magnetic, spectroscopic, and photometric variability of the Wolf-Rayet star WR 55
Hubrig, S.; Cikota, A.; Schöller, M. +2 more
Studies of magnetic fields in the most evolved massive stars, the Wolf-Rayet stars, are of special importance because they are progenitors of certain types of supernovae. The first detection of a magnetic field of the order of a few hundred gauss in the WN7 star WR 55, based on a few FORS2 low-resolution spectropolarimetric observations, was repor…
Into the Mystic: ALMA ACA observations of the Mystic Mountains in Carina
Reiter, Megan; Klaassen, P. D.; McLeod, A. F. +2 more
We present new observations of the Mystic Mountains cloud complex in the Carina Nebula using the ALMA Atacama Compact Array (ACA) to quantify the impact of strong UV radiation on the structure and kinematics of the gas. Our Band 6 observations target CO, 13CO, and C18O; we also detect DCN J=3-2 and 13CS J=5-4. A de…
Radio multifrequency observations of Abell 781 with the WSRT
Venturi, T.; Dallacasa, D.; Bernardi, G. +4 more
The Main galaxy cluster in the Abell 781 system is undergoing a significant merger and accretion process with peripheral emission to the north and south-eastern flanks of the merging structure. Here we present a full polarimetric study of this field, using radio interferometric data taken at 21 and 92 cm with the Westerbork Synthesis Radio Telesco…
Optical counterparts of two candidate ultraluminous X-ray sources in NGC 4536
Avdan, S.; Vinokurov, A.; Shablovinskaya, E. S. +7 more
Archival XMM-Newton, Chandra, and Hubble Space Telescope(HST) data have been used to study the X-ray and optical properties of two candidate ultraluminous X-ray sources in NGC 4536. In order to search for potential optical counterparts, relative astrometry between Chandra and HST was improved, and as a result, optical counterparts were detected fo…
Identifying and characterizing ultracool dwarfs ejected from post-encounter disintegrating systems
Carballo-Bello, Julio A.; Gromadzki, Mariusz; Marocco, Federico +3 more
Disintegrating multiple systems have been previously discovered from kinematic studies of the Hipparcos catalogue. They are presumably the result of dynamical encounters taking place in the Galactic disc between single/multiple systems. In this paper, we aim to expand the search for such systems, to study their properties, as well as to characteri…
Timing the X-ray pulsating companion of the hot subdwarf HD 49798 with NICER
Mereghetti, Sandro; Rigoselli, Michela; Malacaria, Christian +1 more
HD 49798 is a hot subdwarf of O spectral type in a 1.55 d orbit with the X-ray source RX J0648.0-4418, a compact object with a spin period of $13.2\,$s. We use recent data from the Neutron Star Interior Composition Explorer instrument, joined with archival data from XMM-Newton and ROSAT, to obtain a phase-connected timing solution spanning ~30 yr.…
Behaviour of molecular hydrogen emission in three solar flares
Fletcher, Lyndsay; Mulay, Sargam M.; Labrosse, Nicolas +1 more
We have systematically investigated ultraviolet (UV) emission from molecular hydrogen (H2) using the Interface Region Imaging Spectrograph (IRIS), during three X-ray flares of C5.1, C9.7, and X1.0 classes on 2014 October 25. Significant emission from five H2 spectral lines appeared in the flare ribbons, interpreted as photoex…
Modelling gas around galaxy pairs and groups using the Q0107 quasar triplet
Tejos, Nicolas; Beckett, Alexander; Morris, Simon L. +3 more
We examine to what extent disc and outflow models can reproduce observations of H I gas within a few virial radii of galaxies in pairs and groups. Using highly sensitive HST/COS and FOS spectra of the Q0107 quasar triplet covering Ly α for z≲1, as well as a deep galaxy redshift survey including VIMOS, DEIMOS, GMOS, and MUSE data, we test simple di…