Search Publications
A critical re-evaluation of the Thorne-Żytkow object candidate HV 2112
Beasor, Emma R.; Davies, Ben; Cabrera-Ziri, Ivan +1 more
It has been argued in the literature that the star HV 2112 in the Small Magellanic Cloud (SMC) is the first known example of a Thorne-Żytkow object (TŻO), a red supergiant with a degenerate neutron core. This claim is based on the star having a high luminosity (log (L/L⊙) ≳ 5), an extremely cool effective temperature, and a surface enri…
The AGN luminosity fraction in merging galaxies
Smith, Howard A.; Zezas, Andreas; Hayward, Christopher C. +7 more
Galaxy mergers are key events in galaxy evolution, often causing massive starbursts and fueling active galactic nuclei (AGNs). In these highly dynamic systems, it is not yet precisely known how much starbursts and AGNs, respectively, contribute to the total luminosity, at what interaction stages they occur, and how long they persist. Here we estim…
A radial velocity survey of the Carina Nebula's O-type stars
Smith, Nathan; Kiminki, Megan M.
We have obtained multi-epoch observations of 31 O-type stars in the Carina Nebula using the CHIRON spectrograph on the CTIO/SMARTS 1.5-m telescope. We measure their radial velocities to 1-2 km s-1 precision and present new or updated orbital solutions for the binary systems HD 92607, HD 93576, HDE 303312, and HDE 305536. We also compile…
Copper abundance from Cu I and Cu II lines in metal-poor star spectra: NLTE versus LTE
Korotin, S. A.; Andrievsky, S. M.; Zhukova, A. V.
We have checked the consistency between the copper abundance derived in six metal-poor stars using ultraviolet (UV) Cu II lines, which are assumed to form in the local thermodynamic equilibrium (LTE), and UV Cu I lines, treated in the non-local thermodynamic equilibrium (NLTE). The stars in our programme cover the atmospheric parameters that are t…
Extended Dust Emission from Nearby Evolved Stars
Kemper, Francisca; Cami, Jan; Scicluna, Peter +6 more
We present James Clerk Maxwell Telescope Sub-millimetre Common-User Bolometer Array 2 (SCUBA-2) 450 and 850 {µ} m observations of 14 asymptotic giant branch stars (9 O-rich, 4 C-rich, and 1 S-type) and one red supergiant in the solar neighbourhood. We combine these observations with Herschel/PACS observations at 70 and 160 {µ} m and ob…
Cold dark energy constraints from the abundance of galaxy clusters
Allen, Steven W.; Rapetti, David; Heneka, Caroline +3 more
We constrain cold dark energy of negligible sound speed using galaxy cluster abundance observations. In contrast to standard quasi-homogeneous dark energy, negligible sound speed implies clustering of the dark energy fluid at all scales, allowing us to measure the effects of dark energy perturbations at cluster scales. We compare those models and …
Masses of the components of SB2 binaries observed with Gaia - IV. Accurate SB2 orbits for 14 binaries and masses of three binaries*
Mazeh, T.; Halbwachs, J. -L.; Arenou, F. +7 more
The orbital motion of non-contact double-lined spectroscopic binaries (SB2s), with periods of a few tens of days to several years, holds unique, accurate information on individual stellar masses, which only long-term monitoring can unlock. The combination of radial velocity measurements from high-resolution spectrographs and astrometric measuremen…
Imaging radial velocity planets with SPHERE
Moutou, C.; Brandner, W.; Messina, S. +37 more
We present observations with the planet finder Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) of a selected sample of the most promising radial velocity (RV) companions for high-contrast imaging. Using a Monte Carlo simulation to explore all the possible inclinations of the orbit of wide RV companions, we identified the systems wit…
Update of membership and mean proper motion of open clusters from UCAC5 catalogue
Assafin, M.; Dias, W. S.; Monteiro, H.
We present mean proper motions and membership probabilities of individual stars for optically visible open clusters, which have been determined using data from the UCAC5 catalogue. This follows our previous studies with the UCAC2 and UCAC4 catalogues, but now using improved proper motions in the GAIA reference frame. In the present study results w…
Disc instabilities and nova eruptions in symbiotic systems: RS Ophiuchi and Z Andromedae
Hameury, J. -M.; Lasota, J. -P.; Bollimpalli, D. A.
Using the disc instability model for dwarf novae and soft X-ray transients, we investigate the stability of accretion discs in long-period binary systems. We simulate outbursts resulting from this thermal-viscous instability for two symbiotic systems, RS Ophiuchi and Z Andromedae. The outburst properties deduced from our simulations suggest that, …