Related papers: High resolution optical spectroscopy of Plaskett's…
There is a small group of peculiar early-type stars on the main sequence that show different rotation velocities from different spectral lines. This inconsistency might be due to the binary nature of these objects. We aim to verify this…
We identify the bright Am-type star HD 181793 to be a previously-unknown eclipsing, chemically peculiar heartbeat binary, the second of its kind known. The system carries an orbital period of $P = 11.47578275 \pm 0.00000055$ days. We use…
Massive stars continuously enrich the surrounding interstellar medium by supplying it with stellar material driven by their powerful winds. B supergiant stars (BSGs) in particular are a type of massive star characterized by strong winds and…
The chemical composition of stellar photospheres in mass-transferring binary systems is a precious diagnostic of the nucleosynthesis processes that occur deep within stars, and preserves information on the components history. The binary…
We present results from a Hubble Space Telescope (HST) program characterizing the atmospheres of the outer two planets, in the HR8799 system. The images were taken over 15 orbits in three near-infrared medium-band filters - F098M, F127M and…
We present an analysis of nine bright spectroscopic binaries (HD 1585, HD 6613, HD 12390, HD 39923, HD 55201, HD 147430, HD 195543, HD 202699, HD 221643), which have orbital periods of P > 500 days. These well-separated binaries are the…
The detection of pulsational frequencies in stellar photometry is required as input for asteroseismological modelling. The second short run (SRa02) of the CoRoT mission has provided photometric data of unprecedented quality and…
We present the new interpretation of the oscillation spectrum of HD 163899 based on the new determinations of the effective temperature, mass-luminosity ratio and rotational velocity. These new parameters strongly prefer the more massive…
HD170582 is an interacting binary of the Double Periodic Variable (DPV) type, showing ellipsoidal variability with a period of 16.87 days along with a long photometric cycle of 587 days. It was recently studied by Mennickent et al. (2015),…
We present detailed parameter determinations of two chemically normal late A-type stars, HD 32115 and HD 37594, to uncover the reasons behind large discrepancies between two previous analyses of these stars performed with a semi-automatic…
We present a new optical spectroscopic study of the O-type binary HD 165052 based on high- and intermediate-resolution CCD observations. We re-investigated the spectral classification of the binary components, obtaining spectral types of…
Optical images and spectra, both ground based and taken by Hubble Space Telescope (HST), of the young, luminous O-rich supernova remnant in the irregular galaxy NGC 4449 are presented. HST images of the remnant and its local region were…
We present new results from a study of high quality, red spectra of the massive binary star system HD 1383 (B0.5 Ib + B0.5 Ib). We determined radial velocities and revised orbital elements (P = 20.28184 +/- 0.0002 d) and made Doppler…
Powerful astronomical spectra reveal an urgent need for additional work on atomic lines, levels, and oscillator strengths. The star HD 65949 provides some excellent examples of species rarely identified in stellar spectra. For example, the…
HD 65949 is a late B star with exceptionally strong Hg II at 3984[A], but it is not a typical HgMn star. The Re II spectrum is of extraordinary strength. Abundances, or upper limits are derived here for 58 elements based on a model with…
We report spectral time series of the late O-type runaway supergiant HD 188209. Radial velocity variations of photospheric absorption lines with a possible quasi-period ~ 6.4 days have been detected in high-resolution echelle spectra.…
We report observations of the transiting extrasolar planet, HD 209458 b, designed to detect the secondary eclipse. We employ the method of `occultation spectroscopy', which searches in combined light (star and planet) for the disappearance…
Using optical long baseline interferometry, we resolved for the first time the two wide components of HD167971, a candidate hierarchical triple system known to efficiently accelerate particles. Our multi-epoch VLTI observations provide…
We modeled the HeII 4686 line profiles observed in the eta Carinae binary system close to the 2003.5 spectroscopic event, assuming that they were formed in the shocked gas that flows at both sides of the contact surface formed by wind-wind…
Spectroscopic observations of AH Herculis during a deep quiescent state are put forward. We found the object in a rare long minima, allowing us to derive accurately the semi-amplitudes: $K_1 =121 \pm \, 4$ \kms\ and $K_2 =152 \pm 2$ \kms\…