Related papers: A representative sample of Be Stars I: Sample Sele…
We present the first part of a spectroscopic and polarimetric study on a sample of 58 Be stars that have been measured since 1998. The aim of the study is to understand the timescales of disk variability, formation and dissipation as a…
We present Be star candidates in the open cluster NGC\,663, identified by H$\alpha$ imaging photometry with the Palomar Transient Factory Survey, as a pilot program to investigate how the Be star phenomena, the emission spectra, extended…
We present H band (1.53 - 1.69 micron) spectra of 57 isolated Be stars of spectral types O9-B9 and luminosity classes III,IV & V. The HI Brackett (n-4) series is seen in emission from Br 11-18, and FeII emission is also apparent for a…
Context. The study of rotational velocity distributions for normal stars requires an accurate spectral characterization of the objects in order to avoid polluting the results with undetected binary or peculiar stars. This piece of…
We present a spectroscopic study of 150 Classical Be stars in 39 open clusters using medium resolution spectra in the wavelength range 3800 - 9000 \AA. One-third of the sample (48 stars in 18 clusters) has been studied for the first time.…
Spectroscopic monitoring of 141 southern field B type stars, 114 of them known to exhibit the Be phenomenon, allowed the estimation of their projected rotational velocities, effective temperatures and superficial gravities from…
We present Balmer lines spectroscopy for a sample of 48 Be stars. For most of them, H$\alpha$ and H$\beta$ have been observed more than two times, in a total period spanning almost two years between 2008 and 2009. Spectral synthesis of the…
In this study, we present the results of the relationship between spectral type (ST) and the projected stellar rotational velocity ($vsini$), utilising a sample of approximately 50,000 single stars across a range of evolutionary stages. The…
We consider three samples of O- and B-type stars from the solar neighborhood 0.6--4 kpc for which we have taken the distances, line-of-sight velocities, and proper motions from published sources. The first sample contains 120 massive…
Be stars are rapidly rotating B-type stars that exhibit Balmer emission lines in their optical spectra. These stars play an important role in studies of stellar evolution and disk structures. In this work, we carried out a systematic search…
A sample of 97 galactic field Be stars were studied by taking into account the effects induced by the fast rotation on their fundamental parameters. All program stars were observed in the BCD spectrophotometric system in order to minimize…
Classical Be stars are rapid rotators of spectral type late O to early A and luminosity class V-III, wich exhibit Balmer emission lines and often a near infrared excess originating in an equatorially concentrated circumstellar envelope,…
We present infra-red (JHK) photometry of 52 isolated Be stars of spectral types O9--B9 and luminosity classes III--V. We describe a new method of reduction, enabling separation of interstellar reddening and circumstellar excess. Using this…
TESS photometry is analyzed for 432 classical Be stars observed in the first year of the mission. The often complex and diverse variability of each object in this sample is classified to obtain an understanding of the behavior of this class…
We present a variability study of 4646 massive stars in the Small Magellanic Cloud (SMC) with known spectral types from the catalog of Bonanos et al. (2010) using the light curves from the OGLE-III database. The goal is to exploit the time…
Light curves and periodograms of 160 B stars observed by the TESS space mission and 29 main-sequence B stars from Kepler and K2 were used to classify the variability type. There are 114 main-sequence B stars in the TESS sample, of which 45…
We show that Be stars belong to a high velocity tail of a single B-type star rotational velocity distribution in the main sequence (MS). We studied 127 galactic field Be stars and obtained their true equatorial velocity at the ZAMS using…
In preparation for the COROT space mission, we determined the fundamental parameters (spectral type, temperature, gravity, vsini) of the Be stars observable by COROT in its seismology fields (64 Be stars). We applied a careful and detailed…
Our goal is to provide a quantification of several spectral classification criteria for O stars. We collected high-spectral resolution spectra of 105 Galactic O-type stars from various archives. We measured equivalent widths of…
Aims. We attempt to determine if a dependency on spectral subtype or vsini exists for stars undergoing phase-changes between B and Be states, as well as for those stars exhibiting variability in H{\alpha} emission. Methods. We analyse the…