Search Publications
A stellar census in globular clusters with MUSE. A new perspective on the multiple main sequences of ω Centauri
Dreizler, S.; Latour, M.; Brinchmann, J. +3 more
Context. ω Cen is a rare example of a globular cluster where the iron abundance of the stars spans more than one order of magnitude. Many spectroscopic investigations of its red-giant and sub-giant branches have revealed multiple peaks in the iron abundance distribution. The metallicity distribution of main sequence (MS) stars is not well characte…
Broad-line region configuration of the supermassive binary black hole candidate PG1302-102 in the relativistic Doppler boosting scenario
Lu, Youjun; Ge, Junqiang; Ji, Xiang +2 more
PG1302-102 is thought to be a supermassive binary black hole (BBH) system according to the periodical variations of its optical and UV photometry, which may be interpreted as being due to the relativistic Doppler boosting of the emission mainly from the disk around the secondary black hole (BH) modulated by its orbital motion. In this paper, we in…
Globules and pillars in Cygnus X. III. Herschel and upGREAT/SOFIA far-infrared spectroscopy of the globule IRAS 20319+3958 in Cygnus X
Comerón, F.; Schneider, N.; Bontemps, S. +11 more
IRAS 20319+3958 in Cygnus X South is a rare example of a free-floating globule (mass ~240 M⊙, length ~1.5 pc) with an internal H II region created by the stellar feedback of embedded intermediate-mass stars, in particular, one Herbig Be star. In Schneider et al. 2012, (A&A, 542, L18) and Djupvik et al. 2017, (A&A, 599, A37), we …
Evolved massive stars at low-metallicity. IV. Using the 1.6 µm H-bump to identify red supergiant stars: Case study of NGC 6822
Yang, Ming; Bonanos, Alceste Z.; Gao, Jian +9 more
We present a case study in which we used a novel method to identify red supergiant (RSG) candidates in NGC 6822 based on their 1.6 µm H-bump. We collected 32 bands of photometric data for NGC 6822 ranging from the optical to the mid-infrared, derived from Gaia, PS1, LGGS, VHS, UKIRT, IRSF, HAWK-I, Spitzer, and WISE. Using the theoretical spe…
The behaviour of lithium at high metallicity in the Milky Way. Selection effects in the samples and the possible role of atomic diffusion
de Laverny, P.; Charbonnel, C.; Prantzos, N. +1 more
Aims: We revisit large spectroscopic data sets for field stars from the literature to derive the upper Li envelope in the high metallicity regime in our Galaxy.
Methods: We take advantage of Gaia EDR3 data and state-of-the-art stellar models to precisely determine the position of the sample dwarf stars in the Hertzsprung-Russell diagram.…
First MATISSE L-band observations of HD 179218. Is the inner 10 au region rich in carbon dust particles?
Waters, L. B. F. M.; Meisenheimer, K.; Augereau, J. -C. +58 more
Context. Carbon is one of the most abundant components in the Universe. While silicates have been the main focus of solid phase studies in protoplanetary discs (PPDs), little is known about the solid carbon content especially in the planet-forming regions (~0.1-10 au). Fortunately, several refractory carbonaceous species present C-H bonds (such as…
Photoionisation modelling of the X-ray emission line regions within the Seyfert 2 AGN NGC 1068
Bianchi, S.; Mehdipour, M.; Behar, E. +4 more
Aims: We investigate the photoionised X-ray emission line regions (ELRs) within the Seyfert 2 galaxy NGC 1068 to determine if there are any characteristic changes between observations taken 14 years apart.
Methods: We compared XMM-Newton observations collected in 2000 and 2014, simultaneously fitting the reflection grating spectrometer a…
Looking into the cradle of the grave: J22564-5910, a potential young post-merger hot subdwarf
Uzundag, Murat; Pelisoli, Ingrid; Bobrick, Alexey +10 more
Context. We present the discovery of J22564-5910, a new type of hot subdwarf (sdB) which shows evidence of gas present in the system and it has shallow, multi-peaked hydrogen and helium lines which vary in shape over time. All observational evidence points towards J22564-5910 being observed very shortly after the merger phase that formed it.
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Inhomogeneity in the early Galactic chemical enrichment exposed by beryllium abundances in extremely metal-poor stars
Pasquini, L.; Smiljanic, R.; Zych, M. G.
Context. Abundances of beryllium in metal-poor stars scale linearly with metallicity down to [Fe/H] ∼ -3.0. In the stars where Be has been detected at this extremely metal-poor regime, an increased abundance scatter has been previously reported in the literature. This scatter could indicate a flattening of the relation between Be abundances and me…
Evolution of the truncated disc and inner hot-flow of GX 339-4
Chainakun, P.; Young, A. J.; Luangtip, W. +2 more
Aims: We study the changes in geometry of the truncated disc and the inner hot-flow of GX 339-4 by analysing the power spectral density (PSD) extracted from six XMM-Newton observations taken at the very end of an outburst.
Methods: We developed a theoretical model of the PSD of GX 339-4 in the 0.3-0.7 keV (thermal-reverberation-dominated…