Be stars vary on many timescales, from hours to decades. A long time base of observations to analyze certain phenomena in these stars is therefore necessary. Collecting all existing and future Be star spectra into one database has thus emerged as an important tool for the Be star community. Moreover, for statistical studies, it is useful to have centralized information on all known Be stars via an up-to-date catalog. These two goals are what the Be Star Spectra (BeSS, http://basebe.obspm.fr) database proposes to achieve. The database contains an as-complete-as-possible catalog of known Be stars with stellar parameters, as well as spectra of Be stars from all origins (any wavelength, any epoch, any resolution, etc.). It currently contains over 54,000 spectra of more than 600 different Be stars among the ~2000 Be stars in the catalog. A user can access and query this database to retrieve information on Be stars or spectra. Registered members can also upload spectra to enrich the database. Spectra obtained by professional as well as amateur astronomers are individually validated in terms of format and science before being included in BeSS. In this paper, we present the database itself as well as examples of the use of BeSS data in terms of statistics and the study of individual stars.

https://iopscience.iop.org/article/10.1088/0004-6256/142/5/149/pdf

The Be Star Spectra (BeSS) Database

We derived photospheric parameters, mass-loss rates, and wind velocities of Galactic O6-O7 stars by analyzing high-resolution spectra in the far-UV and UV ranges with line-blanketed, hydrodynamic, non-LTE spherical models. We combined spectra from the Far Ultraviolet Spectroscopic Explorer (FUSE) in the range 905-1187 A and International Ultraviolet Explorer (IUE) archival spectra (1150-3250 A) and used the WM-BASIC code of Pauldrach et al. to compute model spectra. Lines in the FUSE range include high ionization stages (e.g., O VI) and lower abundance non-CNO elements (e.g., P V). Analyzed in addition to the N IV, N V, Si IV, and C IV lines in the IUE range, these features play a crucial role in uniquely constraining the stellar parameters, assessing the presence of shocks in the wind, and quantifying the effects of the resulting soft X-rays on the wind ionization. The effective temperatures derived from the consistent analysis of the far-UV and UV spectra are significantly (≈6000 K or 15% on average, or between 4000 and 8000 K) lower than most values previously derived for some of our targets and lower than typical values assigned to their spectral types from different compilations. This result has great implications for our understanding of the evolution of massive stars and the characterization of young stellar populations, as well as for energy balance calculations of H II regions.

/pdf/the-effective-temperatures-of-mid-o-stars-17k6ad9x1r.pdf

The Effective Temperatures of Mid-O Stars*

The initial success of the Rigidly Rotating Magnetosphere (RRM)
model application to the B2Vp star sigma Ori E by Townsend,
Owocki and Groote triggered a renewed era of observational
monitoring of this archetypal object. We utilize
high-resolution spectropolarimetry and the magnetic Doppler
imaging (MDI) technique to simultaneously determine the
magnetic configuration, which is predominately dipolar, with a
polar strength Bd = 7.3–7.8 kG and a smaller non-axisymmetric
quadrupolar contribution, as well as the surface distribution
of abundance of He, Fe, C, and Si. We describe a revised RRM
model that now accepts an arbitrary surface magnetic field
configuration, with the field topology from the MDI models used
as input. The resulting synthetic H alpha emission and
broad-band photometric observations generally agree with
observations, however, several features are poorly fit. To
explore the possibility of a photospheric contribution to the
observed photometric variability, the MDI abundance maps were
used to compute a synthetic photospheric light curve to
determine the effect of the surface inhomogeneities. Including
the computed photospheric brightness modulation fails to
improve the agreement between the observed and computed
photometry. We conclude that the discrepancies cannot be
explained as an effect of inhomogeneous surface abundance.
Analysis of the UV light variability shows good agreement
between observed variability and computed light curves,
supporting the accuracy of the photospheric light variation
calculation. We thus conclude that significant additional
physics is necessary for the RRM model to acceptably reproduce
observations of not only sigma Ori E, but also other similar
stars with significant stellar wind-magnetic field
interactions.

Revisiting the rigidly rotating magnetosphere model for σ Ori E – II. Magnetic Doppler imaging, arbitrary field RRM, and light variability

This paper deals with the denition of the input fluxes used for the calibration of the IUE Final Archive. The method adopted consists in the determination of the shape of the detector's sensitivity curves using IUE low resolution observations with model fluxes of the DA white dwarf G191{B2B. A scale factor was then determined so that the IUE observations of some bright OAO{2 standards match the original measurements from Meade (1978) in the spectral region 2100{2300 A. The ultraviolet fluxes of six standard stars used as input for the Final Archive photometric calibration together with the model fluxes of G191{B2B normalized to the OAO{2 scale are given. A comparison with the independent FOS calibration shows that the IUE flux scale for the Ultraviolet is 7.2% lower. We consider this mainly to be caused by the dierent normalization procedures. It is shown that the present flux calibration applies to spectra processed with the INES low resolution extraction software.

/pdf/the-ines-system-iv-the-iue-absolute-flux-scale-4tziwlji8e.pdf

The INES system - IV. The IUE absolute flux scale

We present a spectroscopic survey of known and candidate $\gamma$\,Doradus stars. The high-resolution, high signal-to-noise spectra of 52 objects were collected by five different spectrographs. The spectral classification, atmospheric parameters (\teff, $\log g$, $\xi$), $v\sin i$ and chemical composition of the stars were derived. The stellar spectral and luminosity classes were found between G0-A7 and IV-V, respectively. The initial values for \teff\ and \logg\ were determined from the photometric indices and spectral energy distribution. Those parameters were improved by the analysis of hydrogen lines. The final values of \teff, \logg\ and $\xi$ were derived from the iron lines analysis. The \teff\ values were found between 6000\,K and 7900\,K, while \logg\,values range from 3.8 to 4.5\,dex. Chemical abundances and $v\sin i$ values were derived by the spectrum synthesis method. The $v\sin i$ values were found between 5 and 240\,km\,s$^{-1}$. The chemical abundance pattern of $\gamma$\,Doradus stars were compared with the pattern of non-pulsating stars. It turned out that there is no significant difference in abundance patterns between these two groups. Additionally, the relations between the atmospheric parameters and the pulsation quantities were checked. A strong correlation between the $v\sin i$ and the pulsation periods of $\gamma$\,Doradus variables was obtained. The accurate positions of the analysed stars in the H-R diagram have been shown. Most of our objects are located inside or close to the blue edge of the theoretical instability strip of $\gamma$\,Doradus.

/pdf/spectroscopic-survey-of-g-doradus-stars-i-comprehensive-1wxhibt3be.pdf

Spectroscopic survey of γ Doradus stars – I. Comprehensive atmospheric parameters and abundance analysis of γ Doradus stars

We describe here the structure under which the IUE Project will leave its archive at the completion of the distribution system and final data processing, within the INES systemThe INES system is a total system, which comprises both the data in their final bulk processing mode for direct application to scientific analysis, as well as the software driving the distributed service for data retrieval directly by the end userAs a consequence of the expected long-term usage and support needs, it has been designed to require minimum maintenance costs and will not suffer single point failures because of the distributed nature Integration of the INES system in a more general multi-wavelength archive for specialized analysis is anticipated tobe relatively easy, so further evolution of the data availabilitywill be driven fully by the users community and will evolve as thedata needs of the community develop The long term responsibilitywill be transferred from ESA to the astronomical community throughthe establishment of the INES Principal Centre at the LAEFF Instituteof INTA in Spain

I. Skillen

Papers

INES: Astronomy Data Distribution for the Future