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We follow, using both optical spectroscopy and photometry, the ‘‘ textbook ’’ colliding-wind WR+O binary WR 140 through and between the periastron passages of 1993 and 2001. An extensive collection of high-quality spectra allows us to derive precise orbital elements for both components simultaneously. We confirm the extremely high eccentricity of the system, e ¼ 0:881 � 0:005, find an excellent match of the newly derived period to the previous estimates, P ¼ 2899:0 � 1:3 days, and improve the accuracy of the time of periastron passage, T0 ¼ HJD 2; 446; 147:4 � 3:7. Around periastron, at orbital phases � � 0:995 1:015, additional emission components appear on the tops of the broad Wolf-Rayet emission lines of relatively low ionization potential. The phase-dependent behavior of these excess line emissions points to their origin in the wind-wind collision zone, which allows us to place some limits on the orbital inclination of the system, i ¼ 50 � � 15 � , and half-opening angle of the bow shock cone, � ¼ 40 � � 15 � . The relatively sudden appearance and disappearance of the extra emission components probably signify a rapid switch from an adiabatically to a radiatively dominated regime and back again. Multiyear UBV photometry provides one more surprise: in 2001 at � ¼ 0:02 0:06, the system went through a series of rapid, eclipse-like events. Assuming these events to be related to an episode of enhanced dust formation at periastron, we estimate the characteristic size of the dust grains to be a � 0:07 lm. Subject headings: binaries: spectroscopic — stars: early-type — stars: individual (WR 140) — stars: Wolf-Rayet On-line material: machine-readable tables

The definition of Be stars (Jaschek et al. 1981) as non-supergiant B stars which at least once have shown some emission in the Balmer lines implies a vast phenomenology whose characteristics, the evolution of their understanding and the questions which still remain open have been widely reviewed in the last five IAU colloquia and symposia on these stars (Slettebak 1976; Jaschek & Groth 1982; Slettebak & Snow 1987; Balona et al. 1994; Smith et al. 2000). The outstanding physical problems related to them can roughly be summarized into two groups of global questions: a) what is the nature of the central stars and when does the Be phenomenon occur during their evolutionary span?; b) what is the structure of their circumstellar envelopes (CE) and how are they produced?, Facultad de Ciencias Astronómicas y Geofísicas (FCAG)

We study the continuum flux excess at λ4471 by comparing the observed He I λ4471 line profiles with non-LTE model line profiles. Assuming that emission of the Hγ line is formed nearly in the same regions of the circumstellar envelope as those where the visible continuum flux excess rises, we estimate the continuum opacity needed to account for the veiling of the He I λ4471 line. The flux excess so derived is then studied as a function of the stellar aspect angle in an attempt to determine the degree of incidence of the envelope geometry near the central star on the continuum flux of Be stars.

66 Oph has shown recurrent short-lived outbursts nicely detected from ground-based and space (Hipparcos) photometry.Spectroscopic observations of He I 6678 and Hα lines were performed in June 1997 and June 1998. Search for short-term periodicities was done in He I 6678 line profiles as in equivalent width EW, radial velocity of the line centroid, and V and R components. At least two frequencies were present: ν = 4.0 c/d and ν = 2.2 c/d. The phase distribution of these frequencies over the line profile corresponds in the nrp frame to g-modes with ℓ ~ 3 − 4 and ℓ = 2 respectively.

Applying the SAC (self absorption curve) method to χ Oph (HD 148184) we conclude that Fell emission lines are optically thick. We estimate the excitation temperature of the permitted Fe II line formation region and the dimensions of this region. We conclude that this region may possibly have a non-uniform density structure.

We analyze a series of spectroscopic observations of the Hβ and Fe II λ4924Å lines of the Be-shell star Pleione (HD23862), which entered a new Be phase since 1988. Their evolution show that the Hβ-emitting envelope expands regularly from 1987 to 1996 (r/r*=8.6 to 25.0), then diminishes slightly in 1997-98 (r/r*=20.0). The Fe II-emitting envelope expands regularly between 1987 and 1998 (r/r*=6.7 to 13.4), but remains always inside the Hβ-one. The evolution of the emitting envelope of Pleione is similar to the one observed between 1954 and 1972, and this one should decrease regularly in the next years, if the former scenario is repeated.

The recent cycle of the V/R ratio and RV variations in ζ Tau has been found similar to that reported by Delplace (1970). As a rule, in both cycles, singly-ionized metallic shell lines display discrete components when the descending branch of RV curve of Balmer lines crosses the stellar RV value; a narrow sharp feature is mainly superimposed on a broad and bluer one, both being slowly varying over some months; very weak additional components are suspected on stronger Fe II lines. On another hand, in the ascending branch of RV curve (RV ≥ RVstar), secondary shell components varying in intensity are conspicuous on V and R emissions of the first Balmer lines.

The analysis of high S/N spectra and photometric data of 60 Cyg shows that: (1) Pronounced long-term variations in spectra are accompanied with light variations. (2) The medium-term variations of RV could indicate that 60 Cyg is a spectroscopic binary. (3) Two independent structures dominate the rapid variability of both spectrum and light of the star.

Correlations between long-term spectrophotometric and optical spectroscopic variations are investigated in some Be stars. Using spectrophotometric variations as a function of time and a compilation of spectroscopic measurements, we investigated temporal variations of emission and shell line parameters. In some cases time lags between spectroscopic and spectrophotmetric variations could be estimated. We could not find precise relations between the spectroscopic and spectrophotometric behaviours, but a number of tendencies could be derived which give information on physical parameters of circumstellar envelopes in Be stars.

We publish here the second part of our spectroscopic survey at high dispersion of some known and suspected lambda Bootis stars with a view to detecting circumstellar shell features. Eight stars of our sample exhibit such features. These stars are fast rotators, a result which is in line with Holweger and Rentzsch-Holm's study (1995). The analysis of the photometric data has allowed us to confirm the exclusion of a few stars misclassified from the lambda Bootis group.

Aims. What is the origin of the large-amplitude variability in Wolf-Rayet WN8 stars in general and WR123 in particular? A dedicated spectroscopic campaign targets the ten-hour period previously found in the high-precision photometric data obtained by the MOST satellite. Methods. In June-August 2003 we obtained a series of high signal-to-noise, mid-resolution spectra from several sites in the {\lambda}{\lambda} 4000 - 6940 A^{\circ} domain. We also followed the star with occasional broadband (Johnson V) photometry. The acquired spectroscopy allowed a detailed study of spectral variability on timescales from \sim 5 minutes to months. Results. We find that all observed spectral lines of a given chemical element tend to show similar variations and that there is a good correlation between the lines of different elements, without any significant time delays, save the strong absorption components of the Hei lines, which tend to vary differently from the emission parts. We find a single sustained periodicity, P \sim 9.8 h, which is likely related to the relatively stable pulsations found in MOST photometry obtained one year later. In addition, seemingly stochastic, large-amplitude variations are also seen in all spectral lines on timescales of several hours to several days., Comment: 6 pages, 4 figures, 2 tables, data available on-line, accepted in A&A Research Notes

Photometric observations of o And collected from 1994 to 1998 are presented. Neither multimodal pulsations nor rotational modulation seems able to explain completely the complex light curves, but a model based on the pulsations together with some type of magnetic activity could be applicable.

HD 45677 and HD 50138 were observed sporadically in the BCD system (1) from 1959 to 1980. The photospheric component of the Balmer discontinuity (BD) in both stars has remained unchanged for the whole observing period. The uneven energy distribution near the BD of HD 45677 makes difficult its luminosity class determination. Hence, we derived two extreme luminosity classes. The (λ1, D) (mean position and value of the BD respectively) and the corresponding fundamental parameters of the studied B[e] stars are given in Table 1: Open image in new window

Allowing for systematic differences in the counting of Be Stars due to their overluminosity, changes produced by their fast rotation on spectral types and time spent in the main sequence, a difference between the IMF (Be) and IMF(B) appears, which indicates that the appearance of the Be phenomenon may relay on differences in the initial star formation conditions.

Rough indications that v sin i is correlated with peculiar velocities exist only in the range of early-type Be Stars. Further corrections of space velocities of Be Stars for systematic movements of stellar groups to which they belong, as well as identifications of coeval stars have to be performed in order to decide whether the high rotation of some of them could be the consequence of gravitational encounters.

Distributions of true rotational velocities as a function of spectral type for different luminosity class groups of B and Be Stars are compared. While the distributions for B stars differ clearly from one luminosity class to another, those of Be Stars differ less, which indicates that due to rotational effects many Be Stars are considered more evolved than they actually are. Be Stars ‘select’ a narrow range of true rotational velocities to display the Be phenomenon and those of latter spectral types rotate only marginally faster than the early ones.

Fast rotation is expected to flatten the star and to produce non uniform temperature and density distributions (i.e. gravitational darkening). While the flattening mostly increases the absolute flux level of the energy distribution, gravitational darkening makes an equator-on star apparently cooler than a star seen through the pole. Both effects (Collins et al. 1991) influence the colours and the location of the star in the HR diagram but also, in a more subtle way, its spectral line profiles. More particularly, in early B type stars, gravitational darkening tends to privilege at the poles the formation of the ions with the highest ionization potentials and directly affects line formation. Consequently, most spectral line shapes - and especially the weakest ones - become aspect angle dependent which in several cases may play a role in the fundamental parameter determination procedures or even in the determination of stellar chemical abundances.

Three spectra of Pleione (1981, 1987-88, 1994), obtained in the blue wavelength range, show strong long-term changes which indicate that the surrounding shell, first rather cool and close to the central star, then expands gradually in the equatorial plane of the star and towards the poles. From 1981 to 1987-88, the spectrum of Pleione is that of the central star, with a cool shell which globally mimics a late-type star. The year 1994 is marked by a pure and stronger Be spectrum, with no shell line.

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.

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): the distance between A and the B1-B2 system decreased from 0.39“ in 1975 to 0.25” in 1987 (McAlister and Hartkopf 1988) 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.

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 analyse 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.

Observations carried out for 5 years on o And show that 65 to 85% of its light variations can be described by a double wave: A sin (2πt/P1 + ϕ1) + B sin (2πt/P2 + ϕ2) + C with P1 ≈ 1.6 d = 2P2. When determined independently, P1 and P2 are always found in a 2:1 ratio (within 1%), while they can vary together by as much as 4%. The peak to peak amplitudes of this double-wave fit lay between 40 and 140 mmag (and can even be reduced to less than 10 mmag - our 1987 observations). The rest of the light variations do not show any permanent period or behavior, although a ∼ 2.3 d. (i.e. ≈ 3P1/2) period is frequently detected. Sometimes a marginal ∼ 6 d. period or time constant has been detected.In spite of the quality of our photometric data, the precision on the periods and amplitudes obtained over a few nights is never increased by longer observations: our phase diagrams show significant irregular displacements around the average double-wave analytical solution if we include longer data strings (Fig. 1). This phenomenon was already apparent in our 1992 study (Sareyan et al., 1998): the star shows real irregular behaviour superimposed onto its double-wave “mean” light curve; these changes may show up as a progressive, or sometimes abrupt, modification of the shape of the double-wave light curve (Fig. 1).

Omicron Andromedae is a multiple system composed of at least four components. The main component “A” is a variable Be star (B5II-III). The variations of this star are multiform: the circumstellar emission and absorption can vary drastically and can even disappear and reappear later, whereas changes in magnitude are also observed (see e.g. Sareyan et al., 1998). Rapid Spectroscopic and photometric variations are observed as well. As explained below, the rapid Spectroscopic variations of the Hα line observed in 1992 during a phase of moderate emission are very special (Briot et al., 2001). Then the emission of о And increased, so another program of observations of the Hα line was performed to investigate its rapid variations during different emission phases. We present here some preliminary results.

Results of the preliminary investigation of the monitoring of line-profile variations of the Be star 60 Cyg are reported. At least three apparent absorption or emission bumps moving from blue to red were detected.

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.

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.

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.

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

Longitude-coordinated high-precision photometry has been obtained a few weeks before the beginning of a strong Be and shell phase (1988) in HR 8762 (o And). The star showed variations of a few millimagnitudes in amplitude; i.e., just over the detection threshold. The classical 1.57-day double-wave period is still detected, showing that it probably never fades out completely, whatever the phase of the star. These variations can be interpreted as normal photospheric activity in a regular rotating B star. Although the variations of HR 8762 during our campaign were quite small, we could detect their amplitudes at a level of a few mmag.We still have to check whether they are still “in phase” with previous photometric observations: if this is the case, it means that in the “spot” hypothesis, these (superficial?) features would remain in the same position on the photosphere, changing only in surface area and/or brightness with the star's activity.

HD 184279 (V1294 Aql) has presented in the past an emission spectrum on the first terms of the Balmer series, and shell absorptions on the hydrogen and neutral helium lines. Their variations have been reported by Merrill (1952), Merrill and Lowen (1953) and Svolopoulos (1975). Ballereau and Hubert-Delplace (1982) evidenced long-term V/R variations with an amplitude of ∼100 km s-1. Short-term photometric variations are irregular (Tempesti and Patriarca, 1976), while long-term variations are correlated with radial velocity (RV) of shell lines (Horn et al., 1982). Ballereau and Chauville (in preparation) extended the spectroscopic observations until 1984 and confirmed the pseudo-periodic variations, the last half-period ranging over 3.4 years (April 1, 1980-August 1, 1983).

This research was supported by the National Research Council of Canada through Grant No. A6025. Permanent address of R. H. Tipping: Department of Physics, Memorial University of Newfoundland, St. John's, Newfoundland, Canada, A1C 5S7

The C2 b3Σg− → a3Πu Ballik-Ramsay system has been studied through emission flame spectra recorded with a Fourier transform interferometer. The 14 bands 0-0, 1-0, 1-1, 2-0, 2-1, 3-0, 3-1, 3-2, 4-1, 4-2, 5-2, 5-3, 6-3, and 7-4 were identified in the 4850- 9900-cm−1 spectral range. They have been reduced to molecular constants using an iterative, nonlinear, least-squares method. Rotational perturbations, observed in the b3Σg−v = 0, 1, 2, 5, and 6 levels, have been reduced. Dunham coefficients are obtained for both the b3Σg− and a3Πu states.

The OD infrared spectrum, emitted in a flame of deuterium and oxygen, has been recorded for the first time in the 2-μm spectral range with a Fourier Transform spectrometer. A simultaneous fit of the ir 2-0, 3-1, 4-2, 5-3, 3-0, 4-1 vibration-rotation bands, of the uv data (0-0, 1-1, 2-2, 0–1 bands of the A 2 Σ + → X 2 Π transition) and of the microwave data, gives accurate molecular constants for the ground-state vibrational levels up to v = 5. The classical “unique perturber approach” and the effective Hamiltonian of Brown for 2 Π states, have been successively used for the reduction of the spectroscopic data.

The determination of the inherent quadrupole moments of the even uranium isotopes 234, 236, 238, based on Optical Relative Isotope shift measurements, was effectuated. These values are in fair agreement with the values of the quadrupole moments deduced from nuclear electric-quadrupole transition probabilities.

High resolution spectrograms of the two well known Be binary systems ζ Tau and KX And were obtained , in the IR ( 2-2.5µ ), with the Fourier Transform Spectrometer of the CFHT. They do not reveal evidence of a cool giant companion.

The analysis of 149 radial velocities of V923 Aql from 1927 to 1987 revealed that the observed RV variations arise from a superpositon of cyclic long-term velocity variations of variable amplitude and cycle length/20≦2K≦65 km.s-1, 1800d≦P≦2400d/ and an orbital motion with a period of 214.75 days and an amplitude 2K=12.4 km.s-1. The binary system consists of a B5–7 e primary and low-mass /about 0.5 M⊙/ secondary separated some 250 R⊙. Both, the long orbital period and low mass ratio are typical of /interacting/ binaries containing a Be star. The observed cycle length of the long-term changes are very similar to those observed for ζ Tau, the only Be binary with the long-term variations known to date. V923 Aql thus becomes the second representative of binary Be stars, for which it is conceivable to interpret the long-term variations by an elongated envelope, revolving due to the attractive force of the secondary, and formed by the process of mass transfer from the secondary to primary, as predicted by the binary model of the Be phenomenon.

With the objective of investigating the wind±wind collision phenomenon and supporting contemporaneous X-ray observations, we have organized a large-scale, coordinated optical monitoring campaign of the massive, highly eccentric O9III1B1III binary Iota Orionis. Successfully separating the spectra of the components, we refine the orbital elements and confirm the rapid apsidal motion in the system. We also see strong interaction between the components during periastron passage and detect phase-locked variability in the spectrum of the secondary star. However, we find no unambiguous signs of the bow shock crashing on the surface of the secondary, despite the predictions of hydrodynamic simulations. Combining all available photometric data, we find rapid, phase-locked variations and model them numerically, thus restricting the orbital inclination to 50 8& i & 708

11 Cam (HD 32343 = HR 1622) is a so-called “pole-on” Be star known for its long term variations, already noted by Merrill and Burwell (1943). Recent determinations of visual magnitude and spectral type are V = 5.222 and B2.5Ve (Rufener, 1981). The Balmer line profiles, especially Hα, have been frequently studied; Briot (1971), for instance, measured 40 and 4.9 Å equivalent widths for Hα and Hβ respectively; the Hα/Hβ peak to continuum ratio is 6.43/2.02 according to Gray and Marlborough (1974) who give v sin i = 131 km s-1, close to the value of 140 km s-1 adopted by Kogure (1968).

At first we examine the main characteristics of 3 well-known shell stars (EW Lac, ζ Tau, 48 Lib) before and during their variable shell phase (long time scale V/R and RV cycles). For that we have investigated a) recent studies of our Meudon working group, based on long sequences of spectroscopic observations (Hubert et al. 1983, 1986a; Mon 1984) b) previous data found in the literature c) additional information by a reexamination of line profiles obtained from our material. For ζ Tau and 48 Lib the selected cycles have been chosen among the most representative ones in the history of their respective shell episode. For EW Lac, which entered an active phase in 1977, we have studied the only recently observed cycle of shell feature variations. A summary of the 3 V/R shell stars characteristics during 1) the pre variable shell phase 2) the variable shell phase is reported elsewhere (Hubert et al. 1986b); we only give here general trends of it, Table 1.

The 3 nu 2 band of CH3D has been detected in spectra of Titan recorded at 1.6 microns with the Fourier Transform Spectrometer (FTS) at the 4 m telescope of the Kitt Peak National Observatory (NOAO). We have obtained a value of the CH3D/CH4 mixing ratio of 6.6 (+6.6 or -3.3) x 10 to the -4 from a comparison between the observed Titan spectra and synthetic spectra. This value is approx. 2 times higher than the value measured on Uranus (de Bergh et al. 1986) and approx. 6 times higher than on Jupiter and on Saturn (Courtin et al. 1984; de Bergh et al. 1986). It corresponds to D/H of 1.65 (+1.65 or -0.8) x 10 the -4, nominally 8 times higher than the most commonly accepted value for the protosolar D/H = 2 x 10 to the -5 (Geiss and Reeves 1981). The value we find on Titan for D/H in methane is comparable to the D/H ratio measured in terrestrial H2O.

Deuterium in the atmosphere of Uranus has been studied only via measurements of the exceedingly weak dipole lines of hydrogen-deuteride (HD) seen in the visible region of the spectrum. The other sensitive indicator of deuterium in the outer solar system is monodeuterated methane (CH3D) but the two bands normally used ot study this molecule, NU sub 2 near 2200 1/cm and NU sub 6 near 1161 1/cm, have not been detected in Uranus.

The analysis of 149 radial velocities of V923 Aql from 1927 to 1987 revealed that the observed RV variations arise from a superpositon of cyclic long-term velocity variations of variable amplitude and cycle length / 20≦2K≦65 km.s-1, 1800d≦P≦2400d/ and an orbital motion with a period of 214.75 days and an amplitude 2K=12.4 km.s-1. The binary system consists of a B5-7 e primary and low-mass /about 0.5 M⊙/ secondary separated some 250 R⊙. Both, the long orbital period and low mass ratio are typical of /interacting/ binaries containing a Be star. The observed cycle length of the long-term changes are very similar to those observed for ɽTau, the only Be binary with the long-term variations known to date. V923 Aql thus becomes the second representative of binary Be stars, for which it is conceivable to interpret the long-term variations by an elongated envelope, revolving due to the attractive force of the secondary, and'formed by the process of mass transfer from the secondary to primary, as predicted by the binary model of the Be phenomenon.