Search Publications
Spectroscopic and photometric study of the eclipsing interacting binary V495 Centauri
Mennickent, R. E.; Djurašević, G.; Curé, M. +2 more
Double Periodic Variables (DPV) are among the new enigmas of semidetached eclipsing binaries. These are intermediate-mass binaries characterized by a long photometric period lasting on average 33 times the orbital period. We present a spectroscopic and photometric study of the DPV V495 Cen based on new high-resolution spectra and the ASAS V-band l…
Testing asteroseismic radii of dwarfs and subgiants with Kepler and Gaia
Casagrande, L.; Silva Aguirre, V.; Bojsen-Hansen, M. +2 more
We test asteroseismic radii of Kepler main-sequence and subgiant stars by deriving their parallaxes which are compared with those of the first Gaia data release. We compute radii based on the asteroseismic scaling relations as well as by fitting observed oscillation frequencies to stellar models for a subset of the sample, and test the impact of u…
Optical spectroscopy of the blue supergiant Sk-69° 279 and its circumstellar shell with SALT
Berdnikov, L. N.; Gvaramadze, V. V.; Kniazev, A. Y. +1 more
We report the results of optical spectroscopy of the blue supergiant Sk-69° 279 and its circular shell in the Large Magellanic Cloud (LMC) with the Southern African Large Telescope (SALT). We classify Sk-69° 279 as an O9.2 Iaf star and analyse its spectrum by using the stellar atmosphere code CMFGEN, obtaining a stellar temperature of ≈30 kK, a lu…
K2-263 b: a 50 d period sub-Neptune with a mass measurement using HARPS-N
Bouchy, F.; Johnson, J. A.; Vanderburg, A. +32 more
This paper reports on the validation and mass measurement of K2-263 b, a sub-Neptune orbiting a quiet G9V star. Using K2 data from campaigns C5 and C16, we find this planet to have a period of 50.818947 ± 0.000094 d and a radius of 2.41 ± 0.12 R⊕. We followed this system with HARPS-N to obtain 67 precise radial velocities (RVs). A combi…
Layers in the Central Orion nebula
O'Dell, C. R.
The existence of multiple layers in the inner Orion nebula has been revealed using data from an Atlas of spectra at 2 arcsec and 12 km s-1 resolution. These data were sometimes grouped over Samples of 10 arcsec×10 arcsecto produce high signal-to-noise spectra and sometimes grouped into sequences of pseudo-slit Spectra of 12^''.
Dynamical properties and acceleration of hierarchical dust in the vicinity of comet 67P/Churyumov-Gerasimenko
Blum, J.; Hartogh, P.; Rezac, L. +4 more
A significant fraction of cometary dust grains leaving the nucleus surface are extremely porous and fluffy particles as revealed by recent observation from the Rosetta mission. In this paper our aim is to investigate the dynamics of such grains when subjected to a gas flow, representing the cometary outgassing. We perform numerical experiments to …
An ultrafast inflow in the luminous Seyfert PG1211+143
King, A. R.; Pounds, K. A.; Lobban, A. +1 more
Blueshifted absorption lines in the X-ray spectra of an active galactic nucleus (AGN) show that ultrafast outflows with typical velocities v ∼ 0.1c are a common feature of these luminous objects. Such powerful AGN winds offer an explanation of the observed M-σ relation linking the mass of the supermassive black hole and the velocity dispersion in …
X-ray versus infrared selection of distant galaxy clusters: a case study using the XMM-LSS and SpARCS cluster samples
Muzzin, A.; Wilson, G.; Yee, H. K. C. +3 more
We present a comparison of two samples of z> 0.8 galaxy clusters selected using different wavelength-dependent techniques and examine the physical differences between them. We consider 18 clusters from the X-ray-selected XMM Large Scale Structure (LSS) distant cluster survey and 92 clusters from the optical-mid-infrared (MIR)-selected Spitzer A…
The vertical metallicity gradients of mono-age stellar populations in the Milky Way with the RAVE and Gaia data
Cropper, Mark; Lin, Jane; Casagrande, Luca +3 more
We investigate the vertical metallicity gradients of five mono-age stellar populations between 0 and 11 Gyr for a sample of 18 435 dwarf stars selected from the cross-matched Tycho-Gaia Astrometric Solution and Radial Velocity Experiment (RAVE) Data Release 5. We find a correlation between the vertical metallicity gradients and age, with no vertic…
New Cepheid variables in the young open clusters Berkeley 51 and Berkeley 55
Negueruela, I.; Roche, P.; Tabernero, H. M. +3 more
As part of a wider investigation of evolved massive stars in Galactic open clusters, we have spectroscopically identified three candidate classical Cepheids in the little-studied clusters Berkeley 51, Berkeley 55, and NGC 6603. Using new multi-epoch photometry, we confirm that Be 51 #162 and Be 55 #107 are bona fide Cepheids, with pulsation period…