Search Publications
A method to calculate the local density distribution of the Galaxy from the Tycho-Gaia Astrometric Solution data
Kipper, Rain; Tenjes, Peeter; Tempel, Elmo
New and more reliable distances and proper motions of a large number of stars in the Tycho-Gaia Astrometric Solution (TGAS) catalogue allow us to calculate the local matter density distribution more precisely than earlier. We devised a method to calculate the stationary gravitational potential distribution perpendicular to the Galactic plane by co…
A multi-wavelength analysis of the diffuse H II region G25.8700+0.1350
Reynoso, E. M.; Dorda, R.; Cichowolski, S. +2 more
We present a multi-wavelength investigation of the H II region G25.8700+0.1350, located in the inner part of the Galaxy. In radio continuum emission, the region is seen as a bright arc-shaped structure. An analysis of the H I line suggests that G25.8700+0.1350 lies at a distance of 6.5 kpc. The ionized gas is bordered by a photodissociation region…
Measuring size evolution of distant, faint galaxies in the radio regime
Muxlow, T. W. B.; Wrigley, N.; Knudsen, K. K. +5 more
We measure the evolution of sizes for star-forming galaxies as seen in 1.4 GHz continuum radio for z = 0-3. The measurements are based on combined VLA+MERLIN data of the Hubble Deep Field, and using a uv-stacking algorithm combined with model fitting to estimate the average sizes of galaxies. A sample of ∼1000 star-forming galaxies is selected fro…
Variability search in M 31 using principal component analysis and the Hubble Source Catalogue
Hatzidimitriou, D.; Gavras, P.; Bonanos, A. Z. +4 more
Principal component analysis (PCA) is being extensively used in Astronomy but not yet exhaustively exploited for variability search. The aim of this work is to investigate the effectiveness of using the PCA as a method to search for variable stars in large photometric data sets. We apply PCA to variability indices computed for light curves of 18 1…
OMEGA - OSIRIS mapping of emission-line galaxies in A901/2 - IV. Extinction of star formation estimators with inclination
Chies-Santos, Ana L.; Wolf, Christian; Aragón-Salamanca, Alfonso +6 more
We study the effect of inclination on the apparent brightness of star-forming galaxies in spectral passbands that are commonly used as star formation indicators. As diagnostics we use mass-to-light ratios in three passbands: the UV continuum at 280 nm, the Hα emission line, and the FIR 24µ band. We include a study of inclination trends in th…
Probing the rotational velocity of Galactic WO stars with spectropolarimetry
Crowther, P. A.; Maund, J. R.; Ignace, R. +3 more
Oxygen sequence Wolf-Rayet stars (WO) are thought to be the final evolution phase of some high-mass stars, as such they may be the progenitors of Type Ic SNe as well as potential progenitors of broad-lined Ic and long gamma-ray bursts. We present the first spectropolarimetric observations of the Galactic WO stars WR93b and WR102 obtained with FORS…
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…
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…
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…