Search Publications
ζ1 + ζ2 Reticuli binary system: a puzzling chromospheric activity pattern
Nuñez, N. E.; González, J. F.; Jofré, E. +4 more
We perform, for the first time, a detailed long-term activity study of the binary system ζ Ret. We use all available HARPS spectra obtained between the years 2003 and 2016. We build a time series of the Mount Wilson S index for both stars, then we analyse these series by using Lomb-Scargle periodograms. The components ζ1 Ret and ζ2…
Infrared outbursts as potential tracers of common-envelope events in high-mass X-ray binary formation
Oskinova, Lidia M.; Bulik, Tomasz; Gómez-Morán, Ada Nebot
Context. Classic massive binary evolutionary scenarios predict that a transitional common-envelope (CE) phase could be preceded as well as succeeded by the evolutionary stage when a binary consists of a compact object and a massive star, that is, a high-mass X-ray binary (HMXB). The observational manifestations of common envelope are poorly constr…
A transiting M-dwarf showing beaming effect in the field of Ruprecht 147
Cochran, William D.; Endl, Michael; Gandolfi, Davide +11 more
We report the discovery and characterization of an eclipsing M5Vdwarf star, orbiting a slightly evolved F7V main sequence star. In contrast to previous claims in the literature, we confirm that the system does not belong to the galactic open cluster Ruprecht 147. We determine its fundamental parameters combining K2 time-series data with spectrosco…
A Runaway Giant in the Galactic Halo
Massey, Philip; Morrell, Nidia; Neugent, Kathryn F. +3 more
New evidence provided by the Gaia satellite places the location of the runaway star J01020100-7122208 in the halo of the Milky Way (MW) rather than in the Small Magellanic Cloud (SMC) as previously thought. We conduct a reanalysis of the star’s physical and kinematic properties, which indicates that the star may be an even more extraordinary find …
The CMB neutrino mass/vacuum energy degeneracy: a simple derivation of the degeneracy slopes
Sutherland, Will
It is well known that estimating cosmological parameters from cosmic microwave background (CMB) data alone results in a significant degeneracy between the total neutrino mass and several other cosmological parameters, especially the Hubble constant H0 and the matter density parameter Ωm. Adding low-redshift measurements such …
Measuring the black hole mass in ultraluminous X-ray sources with the X-ray scaling method
Titarchuk, L.; Satyapal, S.; Gliozzi, M. +1 more
In our recent work, we demonstrated that a novel X-ray scaling method, originally introduced for Galactic black holes (BH), could be reliably extended to estimate the mass of supermassive black holes accreting at moderate to high level. Here, we apply this X-ray scaling method to ultraluminous X-ray sources (ULXs) to constrain their MBH…
Thermal Reaction in Cometary and Pre-cometary Ices: Formation of Thiocarbamate in OCS-CH3NH2 Mixed Ices
Hodyss, Robert; Mahjoub, Ahmed
Cometary ices are rich sources of organic molecules relevant to prebiotic chemistry and may have played a key role in the delivery of the building blocks of life to Earth. Comets endure thermal processing of their surfaces during their orbits around the Sun. Furthermore, icy grain precursors of cometary materials may have experienced heating in th…
Extreme Circumgalactic H I and C III Absorption around the Most Massive, Quenched Galaxies
Ménard, Brice; Smailagić, Marijana; Prochaska, Jason Xavier +2 more
Luminous red galaxies (LRGs) are the most massive galaxies at z ∼ 0.5 and, by selection, have negligible star formation (SF). These objects have halo masses between those of L * galaxies, whose circumgalactic media (CGMs) are observed to have large masses of cold gas, and clusters of galaxies, which primarily contain hot gas. Here, we r…
An Updated Line List for NUV Spectral Synthesis in Evolved Stars: Redetermination of the Beryllium Abundance in the Solar Photosphere
Cunha, Katia; Smith, Verne V.; Carlberg, Joleen K. +1 more
Motivated by the desire to measure beryllium abundances in red giant stars, we have constructed a new line list for synthesizing spectra in the near-ultraviolet. Using the Sun, Arcturus, and Pollux as benchmark stars, we explore potential sources of missing continuous opacity and line absorption. Despite the inclusion of new sources of continuous …
Blue Straggler Stars beyond the Milky Way. II. A Binary Origin for Blue Straggler Stars in Magellanic Cloud Clusters
Deng, Licai; de Grijs, Richard; Li, Chengyuan +1 more
We have analyzed populations of blue straggler stars (BSSs) in 24 Magellanic Cloud (MC) star clusters using multi-passband Hubble Space Telescope images. We compiled a homogeneous BSS database, containing both traditional and evolved BSSs. We uncovered a sublinear correlation between the number of BSSs in the cluster cores and the clusters’ core m…