Within the hierarchical framework for galaxy formation, minor merging and tidal interactions are expected to shape all large galaxies to the present day. As a consequence, most seemingly normal disk galaxies should be surrounded by spatially extended stellar 'tidal features' of low surface brightness. As part of a pilot survey for such interaction signatures, we have carried out ultra deep, wide field imaging of 8 isolated spiral galaxies in the Local Volume, with data taken at

We present extensive optical spectroscopy of the early-type magnetic star HD 191612 (O6.5f?pe-O8fp). The Balmer and He I lines show strongly variable emission which is highly reproducible on a well-determined 538-d period. He II absorptions and metal lines (including many selective emission lines but excluding He II λ4686 Å emission) are essentially constant in line strength, but are variable in velocity, establishing a double-lined binary orbit with P orb = 1542 d, e = 0.45. We conduct a model-atmosphere analysis of the spectrum, and find that the system is consistent with a ∼O8 giant with a ∼B1 main-sequence secondary. Since the periodic 538-d changes are unrelated to orbital motion, rotational modulation of a magnetically constrained plasma is strongly favoured as the most likely underlying 'clock'. An upper limit on the equatorial rotation is consistent with this hypothesis, but is too weak to provide a strong constraint.

We present the results of recent multicolor photometric and high-resolution spectroscopic observations of the bright Be star Aqr. Observational data collected from the literature were used to study the star's variations over the last four decades. The star is identified with the IR sources F22227+0107 in the IRAS Faint Point Source Catalog and MSX5 G066.0066À44.7392 in the MSX Catalog. The variations in near-IR brightness of Aqr are found to be among the largest reported for Be stars. Since 1996, the star has shown only weak signs of circumstellar emission, which has allowed us to refine the fundamental stellar parameters: A V ¼ 0:15 mag, T eff ¼ 24;000 K, log g ¼ 3:9, and M V ¼ À2:95 mag. A weak emission component of the H line has been detected during the recent quasi-normal star phase. From analysis of the H line profiles, we find antiphased radial velocity variations of the emission component and the photospheric absorption, with a period of 84.1 days and semiamplitudes of 101.4 and 16.7 km s À1 , respectively. This result suggests that Aqr may be a binary system consisting of stars with masses of M 1 sin 3 i ¼ 12:4 M , M 2 sin 3 i ¼ 2:0 M . We also estimate the orbital inclination angle to be between 50 and 75 . We suggest that the photometric, spectroscopic, and polarimetric variations observed during the second half of the 20th century may be due to variable mass transfer between the binary components.

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Context. One way to understand the still mysterious Be phenomenon is to study the time variations of particular Be stars with a long observational history. ζ Tau is one obvious candidate. Aims. Using our rich series of spectral and photometric observations and a critical compilation of available radial velocities, spectrophotometry of Hα, and UBV photometry, we characterize the pattern of time variations of ζ Tau over about a century. Our goal is to find the true timescales of its variability and confront them with the existing models related to various aspects of the Be phenomenon. Methods. Spectral reductions were carried out using the IRAF and SPEFO programs. The HEC22 program was used for both photometric reductions and transformations to UBV. Orbital solutions were derived with the latest publicly available version of the program FOTEL, period analyses employed both the PDM and Fourier techniques -programs HEC27 and PERIOD04.

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ABSTRACT. A new polarimeter called AnyPol has been used at Limber Observatory for 4 yr to monitor annually the broadband linear polarization of a sample of bright northern Be stars. This is the fourth report on a program started in 1985 at McDonald Observatory and the Ðrst one to come entirely from the new installation. Although no variability was detected at the 3 p level during the current reporting period, analysis of the full 13 yr data set is beginning to reveal hints of long-term variability that may provide clues for understanding the Be phenomenon.

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