TY  - JOUR
A1  - Campos, Fabiola
A1  - Pelisoli, Ingrid Domingos
A1  - Kamann, Sebastian
A1  - Husser, T. -O.
A1  - Dreizler, S.
A1  - Bellini, A.
A1  - Robinson, E. L.
A1  - Nardiello, Domenico
A1  - Piotto, G.
A1  - Kepler, S. O.
A1  - Istrate, A. G.
A1  - Winget, D. E.
A1  - Montgomery, M. H.
A1  - Dotter, A.
T1  - Outliers
BT  - multicolour photometry guiding the search for evolved binary systems in the globular cluster 47 Tucanae
JF  - Monthly notices of the Royal Astronomical Society
N2  - We use Hubble Space Telescope multicolour photometry of the globular cluster 47 Tucanae to uncover a population of 24 objects with no previous classification that are outliers from the single-star model tracks in the colour-magnitude diagram and yet are likely cluster members. By comparing those sources with evolutionary models and X-ray source catalogues, we were able to show that the majority of those sources are likely binary systems that do not have any X-ray source detected nearby, most possibly formed by a white dwarf and a main-sequence star and a small number of possible double-degenerate systems.
KW  - binaries: general
KW  - Hertzsprung-Russell and colour-magnitude diagrams
KW  - white dwarfs
KW  - globular clusters: individual: 47 Tuc
Y1  - 2018
U6  - https://doi.org/10.1093/mnras/sty2591
SN  - 0035-8711
SN  - 1365-2966
VL  - 481
IS  - 4
SP  - 4397
EP  - 4409
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Fusillo, Nicola Pietro Gentile
A1  - Tremblay, Pier-Emmanuel
A1  - Gänsicke, Boris T.
A1  - Manser, Christopher J.
A1  - Cunningham, Tim
A1  - Cukanovaite, Elena
A1  - Hollands, Mark
A1  - Marsh, Thomas
A1  - Raddi, Roberto
A1  - Jordan, Stefan
A1  - Toonen, Silvia
A1  - Geier, Stephan Alfred
A1  - Barstow, Martin
A1  - Cummings, Jeffrey D.
T1  - A Gaia Data Release 2 catalogue of white dwarfs and a comparison with SDSS
JF  - Monthly notices of the Royal Astronomical Society
N2  - We present a catalogue of white dwarf candidates selected from the second data release of Gaia (DR2). We used a sample of spectroscopically confirmed white dwarfs from the Sloan Digital Sky Survey (SDSS) to map the entire space spanned by these objects in the Gaia Hertzsprung–Russell diagram. We then defined a set of cuts in absolute magnitude, colour, and a number of Gaia quality flags to remove the majority of contaminating objects. Finally, we adopt a method analogous to the one presented in our earlier SDSS photometric catalogues to calculate a probability of being a white dwarf (PWD) for all Gaia sources that passed the initial selection. The final catalogue is composed of 486641 stars with calculated PWD from which it is possible to select a sample of ≃260000 high-confidence white dwarf candidates in the magnitude range 8 < G < 21. By comparing this catalogue with a sample of SDSS white dwarf candidates, we estimate an upper limit in completeness of 85 per cent for white dwarfs with G ≤ 20 mag and Teff >7000 K, at high Galactic latitudes (|b| > 20°). However, the completeness drops at low Galactic latitudes, and the magnitude limit of the catalogue varies significantly across the sky as a function of Gaia’s scanning law. We also provide the list of objects within our sample with available SDSS spectroscopy. We use this spectroscopic sample to characterize the observed structure of the white dwarf distribution in the H–R diagram.
KW  - catalogues
KW  - surveys
KW  - white dwarfs
Y1  - 2018
U6  - https://doi.org/10.1093/mnras/sty3016
SN  - 0035-8711
SN  - 1365-2966
VL  - 482
IS  - 4
SP  - 4570
EP  - 4591
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Reindl, Nicole
A1  - Geier, Stephan Alfred
A1  - Ostensen, R. H.
T1  - Discovery of two bright DO-type white dwarfs
JF  - Monthly notices of the Royal Astronomical Society
N2  - We discovered two bright DO-type white dwarfs, GALEXJ053628.3+544854 (J0536+5448) and GALEXJ231128.0+292935(J2311+2929), which rank among the eight brightest DO-type white dwarfs known. Our non-LTE model atmosphere analysis reveals effective temperatures and surface gravities of T-eff = 80000 +/- 4600K and log g = 8.25 +/- 0.15 for J0536+5448 and T-eff = 69400 +/- 900K and log g = 7.80 +/- 0.06 for J2311+2929. The latter shows a significant amount of carbon in its atmosphere (C = 0.003(-0.002)(+0.005), by mass), while for J0536+5448 we could derive only an upper limit of C < 0.003. Furthermore, we calculated spectroscopic distances for the two stars and found a good agreement with the distances derived from the Gaia parallaxes.
KW  - stars: abundances
KW  - stars: atmospheres
KW  - white dwarfs
Y1  - 2018
U6  - https://doi.org/10.1093/mnras/sty1875
SN  - 0035-8711
SN  - 1365-2966
VL  - 480
IS  - 1
SP  - 1211
EP  - 1217
PB  - Oxford Univ. Press
CY  - Oxford
ER  -