Inference of the density and velocity structure of rotating/expanding circumstellar discs/winds is of considerable interest in the understanding of stellar mass loss. High resolution line spectropolarimetry creates the possibility of diagnosing such envelope structure much more fully than broad band polarimetry or high resolution spectrometry alone since each element of the scattered spectropolarimetric profile picks out the element of the envelope with the appropriate Doppler shift and provides orientation information on it. This problem has been formulated in detail by Wood, et al (1993) for scattering of a finite width line in a flattened envelope – the spectral shape of the scattered Stokes fluxes being determined by isowavelength–shift contours or surfaces which give the relative wavelength shift of the scattered radiation at different regions in the disc. It was also shown how, in the case of a narrow stellar line scattered in a rotating or expanding flat disc with a simply parametrised density and velocity structure (ignoring the smearing effect of electron thermal motions), it is possible to infer the system inclination and structure model parameters from the resulting spectropolarimetric line profile. This poster presents a method for determining the disc inclination from analysis of the scattered profiles – a parameter which cannot be determined uniquely from spectrometry alone – and thus illustrates the powerful diagnostic potential of high resolution line spectropolarimetry.

High resolution (0.15 Å/pixel) spectropolarimetry across the Hβ emission line of the Be star γ Cas is presented (solid line in Figure B), as well as the intensity profile (Figure A). Earlier observations of the linear polarization across the emission lines (PL) in Be stars (Coyne 1975, Poeckert 1975) found that PL is inversely proportional to the total intensity of the emission line. However, our data clearly show that the width of the polarization profile is much wider than that of the emission line. The dotted line in Figure B gives PL, based on the relationship of: which follows directly from Coyne (1975), where IA is the intensity of the underlying Hβ absorption feature, Itotal the observed intensity profile, and PC the polarization in the adjacent continuum. The underlying stellar profile of Hβ (dotted line in Figure C), adopted from models by Hubeny (1988), gives a good match to the wings of the depolarization profile.

The bright Be star κ Dra (HD 109387, B5 III, v.sini=249 km/s) is one of the rare mid B type stars which have presented FeII emission lines during strong emission phases. Spectroscopic variations were previously reported by many authors over different time scales: years, days and hours. Juza et al. (1991) proposed that κ Dra was the primary component of a binary system with Porb. = 61.55 days. Short-term and long-term variations in the linear optical polarization were also reported by Arsenijevic et al. (1986). We have tried, with our extensive joint material, to search for correlation between long-term spectroscopic and polarimetric variations with the aim of obtaining information on the behaviour of the circumstellar envelope.

The long-term changes of the intrinsic polarization percentage are evident in the stars O And, γ Cas, 88 Her (during the period 1974–1992), κ Dra (1979–1992) and BU Tau (1986–1992). The amplitudes of the polarization percentage variations are not more than a half of the percent. The changes of the position angles are within an interval of about 30 degrees.

Recent observations of rapid variations in optical He I lines, X-rays, and FUV wavelengths in the prototypical classical Be stars λ Eri and star γ Cas hint that the violent processes occur on the surfaces of these stars almost all the time. We suggest that of these phenomena show greater similarities with magnetic flaring than any other process thought to occur on stars.

We have initiated an observational campaign on some bright Be stars in order to investigate the rapid variability in emission lines using a Fabry-Perot spectrometer(λ/δλ = 104; FSR = 21.3Å) at the Nasmyth focus of the 1.22 m JRO telescope at Hyderabad, India. The PMT dark counts were 1 – 2sec-1. Here we report our first observations on four stars.

We simulate the effect due to a latitudinal differential rotation on a HeI λ4471 absorption line. The effect can produce an emission-like reversal in the line core.

In this paper we study the veiling effect and the strength of an extra emission-like component filling partially the HeI λ4471 line of Be stars. It is shown that this component is roughly correlated with the emission in the continuum and in the Hγ line.

In this paper we report the spectroscopic behaviour of 31 Peg in the HeI λ4471, MgII λ4481 and the Hγ lines at four observing dates. The behaviour of the HeI line indicates that perhaps there exists a photospheric activity and/or some exophotospheric perturbing effect acting on the stellar photosphere.

Our aim is to analyze the FeII λ5317 emission line of nine Be stars recorded in 1990, to deduce some constraints on the modeling of their envelope and to compare them to the results obtained in 1985 and 1987 by other authors.

The geometry of Be star envelopes is not directly observable, apart from those very few cases where interferometry has been successful. This is even more true for the kinematical conditions in these envelopes. An indirect measure of kinematics, density law and geometry can be achieved by comparing line widths of photospheric absorption lines (⇔ v* sin i) and circumstellar emission lines (⇔ v(r) sin i). Hitherto existing determinations of line widths have been, however, quite unsatisfactory. The reason is that in these studies Balmer line parameters were used [see Hanuschik (1989) and references therein] which are strongly broadened by radiative transfer and Thomson scattering in addition to kinematic broadening. Because the question of geometry and kinematics is of crucial importance for understanding the Be phenomenon, I have started a new study, using measurements of the Fe ii λ5317 line. This line shows almost optically thin emission and is broadened primarily by kinematics.

For a total of 33 bright Be stars, archival high-dispersion spectrograms obtained by the International Ultraviolet Explorer (IUE) satellite were analyzed together with optical spectrograms in order to study the FeII, FeIII and MgII spectra in the entire 1600 Å to 6500 Å wavelength range. Ultraviolet FeII resonance lines are always found to be in absorption which usually is of interstellar origin. By applying curve-of-growth methods to equivalent widths measured for FeII multiplets UV-1 through UV-8, column densities of interstellar FeII are derived ranging typically between about 1014 and 1015 cm-2. For a few program stars showing shell-type spectra in the optical region, additional FeII resonance absorption lines are detected starting from excited fine-structure levels above the ground state, pointing to FeII absorption occurring in the dense circumstellar envelope in front of these star. Analysis of their equivalent widths is used to infer typical column densities of circumstellar ground state FeII ions of order 1015 cm-2.

Medium resolution (2Å/px) but high s/n spectra of approximately twenty of the brightest blue stars in the young open cluster NGC 330 in the SMC have been obtained with EFOSC1 on the ESO 3.6m telescope, and analyzed in order to determine the atmospheric parameters and the evolutionary status of the stars. LTE and NLTE model atmosphere calculations were used to determine the stellar parameters. The Teff values were derived from fits of the UV continua for all stars where these were available, using Robertson's (1974) B and V photometry to scale the Kurucz model fluxes for metallicity Z = 0.1Z⊙. Luminosities of the sample stars lie in the range 4.0 < log(L*/L⊙) < 5.0 and spectral types between B0 and late-B.

Slitless field Hα spectroscopy with a resolution of 0.2 nm has detected numerous Be stars in 3 young open star clusters in the LMC but only a few each in one Galactic and one LMC cluster. The line widths indicate rapid rotation as is typical of Galactic field Be stars. In NGC 2004 (LMC) their distribution seems inconsistent with the assumption of either very similar equatorial rotation velocities or random orientation of the rotation axes or both, which are believed to be valid for Galactic field Be stars.

Although NLTE model atmospheres have been shown to resolve most of the equivalent width (EW) discrepancies for blue He I lines (Auer and Mihalas 1972, 1973), Wolff and Heasley (1984, 1985) have demonstrated that discrepancies remain for the leading members of the singlet/triplet 2P – nD series, viz. λ6678 and λ5876. These two lines are the strongest nonresonance He I transitions and are important because they respond to thermal changes in the superficial atmosphere (τ~ 10-3) of early B stars. In order to understand the observed rapid variations of the λ6678 line in mild Be stars, we undertook a survey of EWs of λ6678 and λ4388, namely the first and third member of the same series. These two lines have a log gf ratio of 15 but have similar EWs in B star spectra. Our new observations confirm the red line discrepancy noted by WH85 and point to additional EW differences among various groups of B stars not noted hitherto.

Rountree and Sonneborn (1991) developed a system for the classification of ultraviolet B-star spectra, using MK standards drawn from the optical region. The observational material consisted of high-dispersion spectra obtained with the Short Wavelength Prime (SWP) camera on the International Ultraviolet Explorer (IUE) spacecraft. The classification criteria were based exclusively on photospheric absorption lines, primarily lines of C III, Si II, and Si III. The stellar wind lines of Si IV, C IV, and N V were not used in the classification.

Equivalent widths of 16 lines of CI, CII, CIII, CIV, SiII, SiIII, SiIV, AlII, AlIII, FeII, and FeIII, plus centroid and edge velocities of the SiIV and CIV lines, were measured in IUE spectra of 39 Ble–B8e and 18 B1–B8 standard stars. These suggest the following:

1. 1. Certain line ratios of Sill/III, CII/III, A1II/III, and Fell/Ill are very sensitive to spectral type and represent excellent UV criteria for spectral classification.

2. 2. UV line strengths and line ratios show that there are no significant differences between the photospheric line spectra of Be and normal, nonemission stars of corresponding type.

3. 3. Despite the fact that the SilV and CIV wind lines are variable in the Be stars, certain conclusions can be drawn from a statistical “snapshot” study such as this:

   1. a) The SilV and CIV wind lines in the Be stars are correlated with both spectral type and luminosity class in the sense that the hottest stars have the strongest lines, and the giants and subgiants (at least for the B1-B3 stars) have stronger lines than the main-sequence stars, (see Fig. 1 and 2).

   2. b) The SilV wind lines persist to spectral type B8 in both the Be stars and the standard stars but are stronger in the Be stars than in the standards for the earlier types (B1-B3). (See Fig. 1)

   3. c) The CIV wind lines persist to spectral type B8 in the Be stars but only to B3 in the standard stars. They are stronger in the Be stars than in the standards at all spectral types, (see Fig. 2).

   4. d) The equivalent widths of the SilV and CIV wind lines are only very weakly correlated with vsini, if at all, but a threshold in vsini near 150 km s− 1 (as found earlier by Grady et al.) exists below which no large equivalent widths of SilV or CIV may be seen. Assuming that the Be stars are all rapid rotators, such a correlation is essentially a correlation with i and suggests that the winds from Be stars arise preferentially from the equatorial regions. The aforementioned conclusion is supported by a plot of SilV 1394 centroid velocities versus vsini, which shows that stars with large velocity shifts also have large vsini, while those with unshifted lines all have vsini less than about 150 km s− 1. Again, it seems that strong stellar winds are more likely to arise from equatorial than polar regions.

   5. e) Additional evidence that the winds are stronger for Be stars of early type comes from the SilV and CIV centroid velocities, which are much larger for the hotter Be stars. The stars with the strongest lines also tend to have the largest velocity shifts, suggesting that winds with more mass are also faster moving.

   6. f) The SilV and CIV lines in the standard stars, while they may be asymmetric, never show displaced line centers.

   7. g) The edge velocities for both the SilV 1394 and the CIV 1548 Unes increase with earlier spectral type in the Be stars (therefore, stronger winds in the hotter stars), and are considerably higher in the Be stars than in the standard stars, suggesting again that the winds are stronger in the Be stars.

   8. h) Shell stars have weaker CIV absorption and smaller edge and centroid velocities than other Be stars, suggesting that they have weaker winds. Since there is considerable evidence that these are stars with cool, low-velocity disks which axe being viewed edge-on or nearly edge-on, the winds may be inhibited and modified by the denser material in the equatorial regions.

4. 4. Mg II emission is detected in about half of the program Be stars with long wavelength IUE spectra, and seems not to be correlated with spectral type, vsini, or strength of the SilV wind lines. Since the Mgll emission presumably originates in the cool, low velocity envelope and since Mgll emission also correlates with hydrogen Balmer emission in the Be stars, this suggests that there is no strong physical relationship between the stellar winds and the cool disk.

Archival high-dispersion spectrograms obtained by the International Ultraviolet Explorer satellite in the short-wavelength (λλ1150–2000Å) region were inspected and analyzed for a total of 33 Be stars, including one Oe star (HR 6397) and three stars showing shell-type spectra in the optical region (48 Lib, ɛ Cap, o Aqr). The following atomic and ionic transitions were investigated: Hi-Lyα, Cii-UV1, Ciii-UV4, Civ-UV1, Nv-UV1, Siii-UV1…-UV4, Siiii-UV2, Siiv-UV1.

Omicron Andromedae is a multiple system of at least four stars: a B ↔Be star (component A), a spectroscopic binary (components B1–B2) and a close companion (component a). According to several studies (see Hill et al. 1988, 1989):

1. - the distance between A and the B1–B2 system decreased from 0.39″ in 1975 to 0.25″ in 1987 (McAlister and Hartkopf 1988)

2. - the few previous speckle measurements of component a have shown the possibility of a 3.7 years orbit around A, according to the 1975 to 1984 observations (mean distance 0.05″). The calculations with this 3.7 yr orbit lead to the prediction of a maximum distance of 0.77″ at 1992.738, i.e. at the end of september 1992, with a North-South orientation.

During the past six years we have carried through seven multiwavelength, multisite campaigns to investigate the cause for short-term (rapid) photometric and spectroscopic variability in Be stars and assess its importance in driving the mass loss in these objects. These campaigns usually included simultaneous observations in the UV with the IUE and Voyager spacecraft and optical region with ground-based telescopes worldwide (photometry, high resolution spectroscopy, and polarimetry). Typically 10–25 observers from 5–9 countries participated. Stars that have been observed include λ Eri, ω Ori, o And, ∊ Cap, 28 Cyg, η Cen, 48 Lib, ζ Tau, ψ Per, and 2 Vul. We briefly summarize some of the results from the UV study here. Additional results from the ground-based data are given in other papers in this volume by D. Gies, M. Hahula, J. Percy, and D. McDavid.