Related papers: Spectral and spatial imaging of the Be+sdO binary …
The late-type Be star $\beta$ CMi is remarkably stable compared to other Be stars that have been studied. This has led to a realistic model of the outflowing Be disk by Klement et al. These results showed that the disk is likely truncated…
The Be star $\pi$ Aquarii shows peculiar $\gamma$ Cas-type X-ray emission, likely caused by its outer disk interacting with a low-mass companion, probably a white dwarf. We study the long-term variability of its optical spectra to derive…
We present a detailed analysis of the early post-mass-transfer binary HD 698 (V742 Cas) combining high-resolution optical spectroscopy, long-baseline interferometry, and radiative-transfer modeling. Counter-phased radial-velocity curves…
Classical Cepheid variable stars are crucial calibrators of the cosmic distance scale thanks to a relation between their pulsation periods and luminosities. Their archetype, {\delta} Cephei, is an important calibrator for this relation. In…
We present a series of optical spectroscopic and near-infrared photometric observations of the Be star X Persei, from the beginning of the recent emission phase. Our data show that after the latest extended low state (ELS), both the…
The bright southern binary star beta Centauri (HR 5267) has been observed with the Sydney University Stellar Interferometer (SUSI) and spectroscopically with the ESO CAT and Swiss Euler telescopes at La Silla. The interferometric…
Recent papers published in the last years contributed to resolve the enigma on the hypothetical Be nature of the hot pulsating star $\beta$ Cep. This star shows variable emission in the H$\alpha$ line, typical for Be stars, but its…
We present spectroscopic observations of the Be/X-ray binary X Per obtained during the period December 2017 - January 2020 (MJD~58095 - MJD~58865). In December 2017 the $H\alpha$, $H\beta$, and HeI 6678 emission lines were symmetric with…
The Mercury-Manganese star Phi Her is a well known spectroscopic binary that has been the subject of a recent study by Zavala et al. (2006), in which they resolved the companion using long-baseline interferometry. The total mass of the…
We used archival International Ultraviolet Explorer (IUE) high-dispersion, short wavelength spectra data to search for evidence of the spectra of hot subdwarf companions of six rapidly rotating Be stars in binary systems. We searched for…
We present a detailed visible and near-IR spectro-interferometric analysis of the Be-shell star $\omicron$ Aquarii from quasi-contemporaneous CHARA/VEGA and VLTI/AMBER observations. We measured the stellar radius of $\omicron$ Aquarii as…
W Serpentis is an eclipsing binary system and the prototype of the Serpentid class of variable stars. These are interacting binaries experiencing intense mass transfer and mass loss. However, the identities and properties of both stars in W…
Be stars are rapid rotators surrounded by a gaseous disk envelope whose origin is still under debate. This envelope is responsible for observed emission lines and large infrared excess. To progress in the understanding of the physical…
We confirmed the binary nature of the Be star 7~Vul, derived a~more accurate spectroscopic orbit with an orbital period of (69.4212+/-0.0034) d, and improved the knowledge of the basic physical elements of the system. Analyzing available…
We aim at determining the masses of Cepheids in binary systems, as well as their geometric distances and the flux contribution of the companions. The combination of interferometry with spectroscopy will offer a unique and independent…
Classical Be stars are possible products of close binary evolution, in which the mass donor becomes a hot, stripped O or B-type subdwarf (sdO/sdB), and the mass gainer spins up and grows a disk to become a Be star. While several Be+sdO…
We report on the detection of a planetary companion in orbit around the primary star of the binary system $\gamma$ Cephei. High precision radial velocity measurements using 4 independent data sets spanning the time interval 1981--2002…
A detailed analysis of new and existing photometric, spectroscopic and spatial distribution data of the eccentric binary V731 Cep was performed. Spectroscopic orbital elements of the system were obtained by means of cross-correlation…
We study the Be star $\delta$ Cen circumstellar disk using long-baseline interferometry which is the only observing technique capable of resolving spatially and spectroscopically objects smaller than 5 mas in the H and K b and. We used the…
We present intermediate dispersion optical spectroscopy for seven very low-mass stars in the alpha Per open cluster with spectral types between M3 and M6, including the brown dwarf candidate of Rebolo et al. (1992). Our radial velocity…