Related papers: On the H$\alpha$ emission from the $\beta$ Cephei …
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 analyze high-resolution UV spectra of a small sample of Herbig Ae/Be stars (HAEBES) in order to explore the origin of the $T\sim10^5$ K gas in these stars. The C IV 1548,1550 \AA\ line luminosities are compared to non--simultaneous…
We present the results of the continuation of our magnetic survey with FORS1 at the VLT of a sample of B-type stars consisting of confirmed or candidate beta Cephei stars and Slowly Pulsating B (hereafter SPB) stars, along with a small…
A large number of high-dispersion spectra of classical Cepheids were obtained in the region of the CaII H+K spectral lines. The analysis of these spectra allowed us to detect the presence of a strong Balmer line, H$\epsilon$, for several…
The survey phase of the Kepler Mission includes a number of hot subdwarf B (sdB) stars to search for nonradial pulsations. We present our analysis of two sdB stars that are found to be g-mode pulsators of the V1093 Her class. These two…
We examine 4-yr almost continuous Kepler photometry of 115 B stars. We find that the light curves of 39 percent of these stars are simply described by a low-frequency sinusoid and its harmonic, usually with variable amplitudes, which we…
We present the results of a search for Galactic Beta Cephei stars, which are massive pulsating stars with both pressure modes and mixed modes. Thus, these stars can serve as benchmarks for seismological studies of the interiors of massive…
PSR B1259-63/LS 2883 is a binary system where a 48 ms pulsar orbits a massive Be star with a highly eccentric orbit (e=0.87) with a period of 3.4 years. The system exhibits variable, non-thermal radiation visible from radio to very high…
The nearby B-type star $\rho$ Oph A was recently identified as a rapidly rotating magnetic B-type star with variable radio and X-ray emission consistent with a magnetospheric origin. We present a high-resolution spectropolarimetric time…
A study is presented regarding the nature of several variable stars sampled during a campaign of photometric monitoring from the Abbey Ridge Observatory: 3 eclipsing binaries, 2 semiregulars, a luminous Be star, and a star of uncertain…
For early type magnetic stars slow, at most moderate rotational velocities have been considered an observational fact. The detection of a multi-kilogauss magnetic field in the B2Vpn star with P approx. 0.52d and v sin approx. 300km/s has…
New and existing photometry for the G0 Ia supergiant HD 18391 is analyzed in order to confirm the nature of the variablity previously detected in the star, which lies off the hot edge of the Cepheid instability strip. Small-amplitude…
We present near-infrared H and K-band spectro-interferometric observations of the gaseous disk around the primary Be star in the delta Sco binary system, obtained in 2007 (between periastron passages in 2000 and 2011). Observations using…
PSR B1259-63/LS 2883 is a very high energy (VHE; $E > 100$ GeV) {\gamma}-ray emitting binary consisting of a 48 ms pulsar orbiting around a Be star with a period of $\sim3.4$ years. The Be star features a circumstellar disk which is…
Spectroscopic observations of stars in young open clusters have revealed evidence for a dichotomous distribution of stellar rotational velocities, with 10-30% of stars rotating slowly and the remaining 70-90% rotating fairly rapidly. At the…
A remarkable correlation between the H-alpha emission line and the radio behaviour of LSI+61 303 (V615 Cas, GT 0236+610) over its 4 yr modulation is discovered. The radio outburst peak is shifted by a quarter of the 4 yr modulation period…
PSR B1259-63/SS 2883 is a binary system in which a 48-ms pulsar orbits around a Be star in a high eccentric orbit with a long orbital period of about 3.4 yr. Extensive broadband observational data are available for this system from radio…
$\beta$ Cephei pulsating variable (BCEP) stars are the most massive pulsating variable stars in the main sequence, exhibiting both p- and g-mode pulsations. In this study, we identified 155 BCEP stars or candidates using data from TESS and…
We present the results of recent multicolor photometric and high-resolution spectroscopic observations of the bright Be star Pi Aquarii. Observational data collected from the literature were used to study the star's variations over the last…
We present long slit spectral (375-725 nm) observations of the proposed identification of the transient 66s X-ray pulsar Cep X-4=GS2138+56. Spectra show features typical of Be/X-ray binaries. Superimposed on a weak emission from the IC 1396…