The Gaia mission is delivering a large number of astrometric orbits for binary stars. By combining these with spectroscopic orbits for systems with two observable spectra (SB2), it is possible to derive the masses of both components. However, to get masses with a good accuracy requires accurate spectroscopic orbits, which is the major aim of the present paper. A subsidiary aim is to discover SB2 systems hiding among known SB1, and even though this search may often prove unsuccessful, the acquired radial velocities may be used anyway to improve the existing spectroscopic orbits. New radial velocities for 58 binary systems from the Ninth Catalogue of Spectroscopic Binary Orbits (SB9), obtained using the high-resolution HERMES spectrograph installed on the 1.2 m Mercator telescope, were used to possibly identify hitherto undetected SB2 systems. For SB1 systems with inaccurate orbits, these new radial-velocity measurements were used to improve the orbital accuracy. This paper provides 51 orbits (41 SB1 and 10 SB2) that have been improved with respect to the solution listed in the SB9 catalogue, out of the 58 SB9 orbits studied, which belong to 56 stellar systems. Among them, there are five triple and four quadruple systems. Despite the high resolution of HERMES, HIP 115142 A is the only system which we detected as a new SB2 system. The B component of the visual binary HIP 92726 has now been found to be a spectroscopic system as well, which makes HIP 92726 a newly discovered quadruple system (SB1+SB1). The high HERMES resolution allowed us moreover to better isolate the signature of the secondary component of HIP 12390, HIP 73182 and HIP 111170. More accurate masses have thus been derived for them. Among the 30 SB also present in Gaia Data Release 3 (DR3) and with periods shorter than the Gaia DR3 time span (1000 d), only 5 were flagged as binaries by DR3.
We report on our search for spectroscopic binaries among a sample of AGB stars. Observations were carried out in the framework of the monitoring of radial velocities of (candidate) binary stars performed at the Mercator 1.2m telescope, using the HERMES spectrograph. We found evidence for duplicity in UV Cam, TU Tau, BL Ori, VZ Per, T Dra, and V Hya. This short communication focus on V Hya, found to behave like RV Tau of the b subtype, which are binaries surrounded by a disc.
In order to clarify the properties of the secondary clump star HD 226808 (KIC 5307747), we combined four years of data from Kepler space photometry with high-resolution spectroscopy of the High Efficiency and Resolution Mercator Échelle Spectrograph mounted on the Mercator telescope. The fundamental atmospheric parameters, radial velocities, rotation velocities, and elemental abundance for Fe and Li were determined by analyzing line strengths and fitting-line profiles, based on a 1D local thermodynamic equilibrium model atmosphere. Second, we analyzed a photometric light curve obtained by Kepl…
Elemental abundances of extrinsic carbon stars provide insight into the poorly understood origin and evolution of elements in the early Galaxy. In this work, we present the results of a detailed spectroscopic analysis of four potential carbon star candidates from the Hamburg/ESO Survey (HES) HE~0457$-$1805, HE~0920$-$0506, HE~1241$-$0337, and HE~1327$-$2116. This analysis is based on the high-resolution spectra obtained with Mercator/HERMES (R$\sim$86,000) and SUBARU/HDS (R$\sim$50,000). Although the abundances of a few elements, such as, Fe, C, and O are available from medium-resolution spect…
The K2 eclipsing binary candidates EPIC 211982753 (hereinafter called EPIC2753) and EPIC 211915147 (hereinafter called EPIC5147) are characterized with the help of photometric and high-resolution spectroscopic data. The light curve analysis uses the R-band photometric data from the 1.3-m Devasthal Fast Optical Telescope (DFOT, India), ASAS-3 and K2 observations. High-resolution echelle spectra are collected using the HERMES spectrograph at the 1.2-m MERCATOR telescope (La Palma, Spain). The synthetic light and radial velocity curves are generated with the help of the modeling package PHOEBE 1.…
GALAH+ is a magnitude-limited survey of high resolution stellar spectra obtained by the HERMES spectrograph at the Australian Astronomical Observatory. Its third data release provides reduced spectra with new derivations of stellar parameters and abundances of 30 chemical elements for 584,015 dwarfs and giants, 88% of them in the Gaia magnitude range 11 < G < 14. Here we use these improved values of stellar parameters to build a library of observed spectra which is useful to study variations of individual spectral lines with stellar parameters. This and other improvements are used to derive ra…
We study the $δ$ Scuti -- red giant binary KIC9773821, the first double-pulsator binary of its kind. It was observed by \textit{Kepler} during its four-year mission. Our aims are to ascertain whether the system is bound, rather than a chance alignment, and to identify the evolutionary state of the red giant via asteroseismology. An extension of these aims is to determine a dynamical mass and an age prior for a $δ$ Sct star, which may permit mode identification via further asteroseismic modelling. We determine spectroscopic parameters and radial velocities (RVs) for the red giant component usin…
Determining ages of stars for reconstructing the history of the Milky Way remains one of the most difficult tasks in astrophysics. This involves knowing when it is possible to relate the stellar mass with its age and when it is not. The young $α-$rich (YAR) stars present such a case in which we are still not sure about their ages because they are relatively massive, implying young ages, but their abundances are $α-$enhanced, which implies old ages. We report the results from new observations from a long-term radial-velocity-monitoring campaign complemented with high-resolution spectroscopy, as…
