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The true nature of Swift J0746.3-1608: a possible Intermediate Polar showing accretion state changes
Mukai, K.; de Martino, D.; Bernardini, F. +1 more
Optical and X-ray observations suggested that the 9.38 h binary, SWIFT J0746.3-1608 could be a cataclysmic variable (CV) of the magnetic or nova-like type, or a low-mass X-ray binary. Its optical, UV, and X-ray light curves are strongly variable over years. We report on a recent XMM-Newton observation (2018 April 28), when the source had recovered…
Long-term stellar variability in the Galactic Centre region
Minniti, D.; Catelan, M.; Lucas, P. W. +5 more
We report the detection of variable stars within a 11.5 arcmin× 11.5 arcmin region near the Galactic Centre that includes the Arches and Quintuplet clusters, as revealed by the VISTA Variables in the Vía Láctea survey. There are 353 sources that show KS-band variability, of which the large majority (81 per cent) correspond to red giant …
The GALAH survey: a catalogue of carbon-enhanced stars and CEMP candidates
Lewis, Geraint F.; Ting, Yuan-Sen; Buder, Sven +20 more
Swan bands - characteristic molecular absorption features of the C2 molecule - are a spectroscopic signature of carbon-enhanced stars. They can also be used to identify carbon-enhanced metal-poor (CEMP) stars. The GALAH (GALactic Archaeology with Hermes) is a magnitude-limited survey of stars producing high-resolution, high-signal-to-no…
On the possibility of detecting ultrashort period exoplanets with LISA
Wong, Kaze W. K.; Berti, Emanuele; Gabella, William E. +1 more
Cunha, Silva & Lima recently reexamined the possibility of detecting gravitational waves from exoplanets, claiming that three ultrashort period systems would be observable by LISA. We revisit their analysis and conclude that the currently known exoplanetary systems are unlikely to be detectable, even assuming a LISA observation time Tobs<…
Spectroscopic confirmation and modelling of two lensed quadruple quasars in the Dark Energy Survey public footprint
Marchetti, L.; Vaccari, M.; Baker, A. J. +12 more
Quadruply lensed quasars are extremely rare objects, but incredibly powerful cosmological tools. Only few dozen are known in the whole sky. Here we present the spectroscopic confirmation of two new quadruplets WG0214-2105 and WG2100-4452 discovered by Agnello & Spiniello (2018) within the Dark Energy Survey public footprints. We have conducted…
Probing the fluctuating ultraviolet background using the Hubble Frontier Fields
Dayal, Pratika; Choudhury, Tirthankar Roy
In recent years, the rise in the number of Lyman Break Galaxies detected at high redshifts z ≥ 6 has opened up the possibility of understanding early galaxy formation physics in great detail. In particular, the faint-end slope (α) of the ultraviolet luminosity function (UV LF) of these galaxies is a potential probe of feedback effects that suppres…
CPD-64°2731: a massive spun-up and rejuvenated high-velocity runaway star
Katkov, I. Y.; Gvaramadze, V. V.; Castro, N. +4 more
We report the results of our study of the high-velocity ({≈ }160 km s^{-1}) runaway O star CPD-64°2731 and its associated horseshoe-shaped nebula discovered with the Wide-field Infrared Survey Explorer. Spectroscopic observations with the Southern African Large Telescope and spectral analysis indicate that CPD-64°2731 is a fast-rotating main-seque…
A survey for high-mass eclipsing binaries
Chini, R.; Hackstein, M.; Pozo Nuñez, F. +4 more
We report results from a search for Galactic high-mass eclipsing binaries. The photometric monitoring campaign was performed in Sloan r and i with the robotic twin refractor RoBoTT at the Universitätssternwarte Bochum in Chile and complemented by Johnson UBV data. Comparison with the SIMBAD data base reveals 260 variable high-mass stars. Based on …
The MAGIC project - II. Discovery of two new Galactic lithium-rich Cepheids
Kovtyukh, V.; Lemasle, B.; Kniazev, A. +6 more
We report the discovery of two new lithium-rich Cepheids in the Milky Way (A(Li) ≈ 2.9 dex) among the targets of the MAGIC spectroscopic survey with the Southern African Large Telescope spectrographs. The 6707 Å Li feature is usually not detectable in the atmosphere of Cepheids. Only three Cepheids (two in the Milky Way and one in the Large Magell…
ALMA observations of massive molecular gas reservoirs in dusty early-type galaxies
Smith, M.; Dunne, L.; Eales, S. +9 more
Unresolved gas and dust observations show a surprising diversity in the amount of interstellar matter in early-type galaxies. Using Atacama Large Millimetre/submillimeter Array (ALMA) observations we resolve the ISM in z ∼ 0.05 early-type galaxies. From a large sample of early-type galaxies detected in the Herschel Astrophysical Terahertz Large Ar…