Search Publications
Radio-loudness in black hole transients: evidence for an inclination effect
Motta, S. E.; Casella, P.; Fender, R. P.
Accreting stellar-mass black holes appear to populate two branches in a radio:X-ray luminosity plane. We have investigated the X-ray variability properties of a large number of black hole low-mass X-ray binaries, with the aim of unveiling the physical reasons underlying the radio-loud/radio-quiet nature of these sources, in the context of the know…
The Cygnus Loop's distance, properties, and environment driven morphology
Blair, William P.; Raymond, John C.; Fesen, Robert A. +2 more
The Cygnus Loop is among the brightest and best studied evolved Galactic supernova remnants. However, its distance has remained uncertain thus undermining quantitative understanding about many of its fundamental properties. Here we present moderate-dispersion spectra of three stars with projected locations toward the remnant. Spectra of these star…
K2-260 b: a hot Jupiter transiting an F star, and K2-261 b: a warm Saturn around a bright G star
Kuzuhara, M.; Tamura, M.; Alonso, R. +45 more
We present the discovery and confirmation of two new transiting giant planets from the Kepler extended mission K2. K2-260 b is a hot Jupiter transiting a V = 12.7 F6V star in K2 Field 13, with a mass and radius of M⋆ = 1.39_{-0.06}^{+0.05} M_{⊙} and R⋆ = 1.69 ± 0.03 R_{⊙}. The planet has an orbital period of P = 2.627 d, and …
PAHs and star formation in the H II regions of nearby galaxies M83 and M33
Tielens, A. G. G. M.; Peeters, E.; Stock, D. J. +3 more
We present mid-infrared (MIR) spectra of H II regions within star-forming galaxies M83 and M33. Their emission features are compared with Galactic and extragalactic H II regions, H II-type galaxies, starburst galaxies, and Seyfert/LINER type galaxies. Our main results are as follows: (i) the M33 and M83 H II regions lie in between Seyfert/LINER ga…
Wide binaries in Tycho-Gaia II: metallicities, abundances and prospects for chemical tagging
Agüeros, Marcel A.; Andrews, Jeff J.; Chanamé, Julio
From our recent catalogue based on the first Gaia data release (TGAS), we select wide binaries in which both stars have been observed by the Radial Velocity Experiment (RAVE) or the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). Using RAVE and LAMOST metallicities and RAVE Mg, Al, Si, Ti and Fe abundances, we find that the dif…
Cas A and the Crab were not stellar binaries at death
Kochanek, C. S.
The majority of massive stars are in binaries, which implies that many core collapse supernovae should be binaries at the time of the explosion. Here we show that the three most recent, local (visual) SNe (the Crab, Cas A and SN 1987A) were not stellar binaries at death, with limits on the initial mass ratios of q = M2/M1 ≲ 0…
Can magnetic fields suppress convection in the atmosphere of cool white dwarfs? A case study on WD2105-820
Gänsicke, B. T.; Jordan, S.; Tremblay, P. -E. +3 more
Around 10 per cent of white dwarfs exhibit global magnetic structures with fields ranging from 1 kG to hundreds of MG. Recently, the first radiation magnetohydrodynamics simulations of the atmosphere of white dwarfs showed that convection should be suppressed in their photospheres for magnetic fields with strengths B ≳ 50 kG. These predictions are…
A Gaia study of the Hyades open cluster
Ventura, Paolo; Zari, Eleonora; de Bruijne, Jos +2 more
We present a study of the membership of the Hyades open cluster, derive kinematically modelled parallaxes of its members, and study the colour-absolute magnitude diagram of the cluster. We use Gaia DR1 Tycho-Gaia Astrometric Solution (TGAS) data complemented by Hipparcos-2 data for bright stars not contained in TGAS. We supplement the astrometric …
WASP-128b: a transiting brown dwarf in the dynamical-tide regime
Smalley, Barry; Hellier, Coel; Triaud, Amaury H. M. J. +15 more
Massive companions in close orbits around G dwarfs are thought to undergo rapid orbital decay due to runaway tidal dissipation. We report here the discovery of WASP-128b, a brown dwarf discovered by the WASP survey transiting a G0V host on a 2.2 d orbit, where the measured stellar rotation rate places the companion in a regime where tidal interact…
Primeval very low-mass stars and brown dwarfs - IV. New L subdwarfs, Gaia astrometry, population properties, and a blue brown dwarf binary
Rebolo, R.; Zapatero Osorio, M. R.; Martín, E. L. +13 more
We present 27 new L subdwarfs and classify five of them as esdL and 22 as sdL. Our L subdwarf candidates were selected with the UKIRT Infrared Deep Sky Survey and Sloan Digital Sky Survey. Spectroscopic follow-up was carried out primarily with the OSIRIS spectrograph on the Gran Telescopio Canarias. Some of these new objects were followed up with …