Search Publications
Fundamental parameters and evolutionary status of the magnetic chemically peculiar stars HD 188041 (V1291 Aquilae), HD 111133 (EP Virginis), and HD 204411: spectroscopy versus interferometry
Shulyak, D.; Ryabchikova, T.; Perraut, K. +4 more
The determination of fundamental parameters of stars is one of the main tasks of astrophysics. For magnetic chemically peculiar stars, this problem is complicated by the anomalous chemical composition of their atmospheres, which requires special analysis methods. We present the results of the effective temperature, surface gravity, abundance, and …
From ridges in the velocity distribution to wiggles in the rotation curve
Martinez-Medina, Luis; Pichardo, Barbara; Peimbert, Antonio +1 more
Recently, the Gaiadata release 2 (DR2) showed us the richness in the kinematics of the Milky Way disc. Of particular interest is the presence of ridges covering the stellar velocity distribution, Vϕ-R; as shown by others, it is likely that these ridges are the signature of phase mixing, transient spirals, or the bar. Here, with a Galact…
Progenitor constraints on the Type Ia supernova SN 2014J from Hubble Space Telescope H β and [O III] observations
Graur, Or; Woods, Tyrone E.
Type Ia supernovae are understood to arise from the thermonuclear explosion of a carbon-oxygen white dwarf, yet the evolutionary mechanisms leading to such events remain unknown. Many proposed channels, including the classical single-degenerate scenario, invoke a hot, luminous evolutionary phase for the progenitor, in which it is a prodigious sour…
An efficient approach to extract parameters from star cluster CMDs: fitCMD
Bonatto, Charles
This work presents an approach (fitCMD) designed to obtain a comprehensive set of astrophysical parameters from colour-magnitude diagrams (CMDs) of star clusters. Based on initial mass function (IMF) properties taken from isochrones, fitCMD searches for the values of total (or cluster) stellar mass, age, global metallicity, foreground reddening, d…
On the iron ionization balance of cool stars
Adibekyan, V.; Sousa, S. G.; Santos, N. C. +3 more
High-resolution spectroscopic studies of solar-type stars have revealed higher iron abundances derived from singly ionized species compared to neutral, violating the ionization equilibrium under the assumption of local thermodynamic equilibrium. In this work, we investigate the overabundances of Fe II lines reported in our previous work for a samp…
Chemical abundances in the metal-intermediate GC NGC 6723
Bono, Giuseppe; Alonso-García, Javier; Crestani, Juliana +2 more
We have performed a detailed spectral analysis of the inner halo Galactic globular cluster (GC) NGC 6723 using high-resolution (R{≈ } 22 000-48 000) spectra for for 11 red giant branch stars collected with MIKE (Magellan) and FEROS (MPG/ESO). This globular is located at the minimum of the bimodal metallicity distribution of GCs, which suggests tha…
Puzzling blue dips in the black hole candidate Swift J1357.2 - 0933, from ULTRACAM, SALT, ATCA, Swift, and NuSTAR
Altamirano, D.; Dhillon, V. S.; Charles, P. A. +13 more
We present rapid, multiwavelength photometry of the low-mass X-ray binary Swift J1357.2-0933 during its 2017 outburst. Using several sets of quasi-simultaneous ULTRACAM/NTT (optical), NuSTAR (X-ray), XRT/Swift (X-ray), SALT (optical), and ATCA (radio) observations taken during outburst decline, we confirm the frequent optical dipping that has prev…
A multiwavelength study of a massive, active galaxy at z ∼ 2: coupling the kinematics of the ionized and molecular gas
Loiacono, Federica; Cimatti, Andrea; Talia, Margherita +3 more
We report a multiwavelength study of the massive (M_{\star } ≳ 10^{11} {M}_{\odot }), z ∼ 2 star-forming galaxy GMASS 0953, which hosts an obscured AGN. We combined near-infrared observations of the GNIRS, SINFONI and KMOS spectrographs to study the kinematics of the [O III] λ5007 and H α emission lines. Our analysis shows that GMASS 0953 may host…
Gaia parallax of Milky Way globular clusters - A solution of mixture model
Li, Lu; Shao, Zhengyi
We have established a mixture model approach to derive the parallax of the Milky Way globular clusters. It avoids the problem of cluster membership determination and provides a completely independent astrometrical solution by purely using the parallax data. This method is validated with simulated clusters of Pancino et al.. We have resolved 120 re…
Planetesimals around stars with TESS (PAST) - I. Transient dimming of a binary solar analogue at the end of the planet accretion era
Vanderburg, A.; Winn, J. N.; Ansdell, M. +16 more
We report detection of quasi-periodic (1.5-d) dimming of HD 240779, the solar-mass primary in a 5 arcsec visual binary (also TIC 284730577), by the Transiting Exoplanet Survey Satellite. This dimming, as has been shown for other `dipper' stars, is likely due to occultation by circumstellar dust. The barycentric space motion, lithium abundance, rot…