Context. From a long-term Doppler monitoring campaign of 373 giant stars, we have identified ten giants with periodic radial velocity variations that are challenging to associate with planets. Similar cases in the literature are attributed to poorly understood intrinsic processes.Aims. Our goal is to confirm or refute the presence of planets around these ten evolved stars. Additionally, we evaluate the reliability and sensitivity of planet-confirmation metrics when applied to giant stars and...

HR 5907 (HD 142184) stands out among magnetic OB stars for its rapid rotation, exceptionally hard X-ray emission, and strong magnetic field. High-frequency (>5 GHz) radio emission from the star exhibits an approximately flat spectrum that can be attributed to gyrosynchrotron emission from a dense centrifugal magnetosphere. In a survey of radio emission from massive stars at sub-GHz frequencies, we noticed remarkable low-frequency radio emission from this star, characterized by high...

Context: Many telescopes use an iodine (I$_2$) absorption cell to measure precise radial velocities (RVs), but their data reduction pipelines are all tailored to their respective instrumental characteristics and not openly accessible.Aims: For existing and future projects dedicated to measuring precise RVs, we have created an open-source, flexible data reduction software to extract RVs from échelle spectra via the I$_2$ cell method. The software, called pyodine, is completely written in...

Fundamental stellar parameters such as mass and radius are some of the most important building blocks in astronomy, both when it comes to understanding the star itself, but also when it comes to deriving properties of the exoplanets they host. Asteroseismology of solar-like oscillations allows us to determine these parameters with high precision. Here we investigate the solar-like oscillations of the subgiant gamCep A, which harbours a giant planet on a wide orbit. We do this utilising both...

Here we report an ensemble study of 214 A- and F-type stars observed by Kepler, exhibiting the so-called hump and spike periodic signal, explained by Rossby modes (r modes) - the hump - and magnetic stellar spots or overstable convective (OsC) modes- the spike, respectively. We determine the power confined in the non-resolved hump features and find additional gravity modes (g modes) humps always occurring at higher frequencies than the spike. Furthermore, we derive projected...

We present a detailed analysis of an eclipsing double-lined binary FX UMa based on $\it TESS$ photometry and newly acquired spectroscopic observations. The radial velocities and atmospheric parameters for each component star are obtained from the $\it SONG$ high-resolution spectra. Combined with the radial-velocity measurements, our light-curve modeling yields absolute masses and radii of the two components. The Fourier amplitude spectrum of the residual light curve reveals a total of 103...

Aims: This work aims to better understand the role of wide brown dwarf companions in planetary systems. Methods: We obtained high-resolution spectra of six bright stars with co-moving wide substellar companions with the high-resolution SONG, CARMENES, and STELLA spectrographs. We used these spectra to derive radial velocities together with a complete set of physical stellar parameters. We then investigated radial velocity signals and discuss the fraction of planets in such systems. We also...

We present the discovery of a highly irradiated and moderately inflated ultrahot Jupiter, TOI-1431 b/MASCARA-5 b (HD 201033 b), first detected by NASA's Transiting Exoplanet Survey Satellite mission (TESS) and the Multi-site All-Sky CAmeRA (MASCARA). The signal was established to be of planetary origin through radial velocity measurements obtained using SONG, SOPHIE, FIES, NRES, and EXPRES, which show a reflex motion of $K=294.1\pm1.1$ m s$^{-1}$. A joint analysis of the TESS and...

We present the study on continuous high-resolution spectroscopic observations of two long-period single-lined RS Canum Venaticorum (RS CVn) binary stars IM Pegasi (IM Peg) and $\sigma$ Geminorum ($\sigma$ Gem), obtained with the Hertzsprung SONG telescope during the 2015–2016 season. Chromospheric activity indicators H$_{\alpha}$, Na i D$_{1}$, D$_{2}$ doublet, He i D$_{3}$, and H$_{\beta}$ lines have been analyzed by using the spectral subtraction technique. The...

The GOLF instrument has flown aboard SoHO for almost 25 years but aging of the instrument has now strongly affected its performance, especially in the low-frequency p-mode region. SoHO's situation is nominal and, except for the SoHO 1998 vacation weeks, GOLF has been working since 11th April 1996 without severe incident in its third operating mode (the first two operating modes are not available anymore due to damage in the optical system motorisation). However, after such a long time of...