000001970 001__ 1970
000001970 005__ 20160701171656.0
000001970 0247_ $$2DOI$$a10.1051/0004-6361:20031450
000001970 037__ $$aASTROimport-127
000001970 100__ $$aBriquet, M.
000001970 245__ $$aHe and Si surface inhomogeneities of four Bp variable stars
000001970 260__ $$c2004
000001970 520__ $$aWe present ground-based multi-colour Geneva photometry and high-resolution spectra of four variable B-type stars: HD 105382, HD 131120, HD 138769 and HD 55522. All sets of data reveal monoperiodic stars. A comparison of moment variations of two spectral lines, one silicon line and one helium line, allows us to exclude the pulsation model as being the cause of the observed variability of the four stars. We therefore delete the four stars from the list of candidate slowly pulsating B stars. We attribute the line-profile variations to non-homogeneous distributions of elements on the stellar surface and we derive abundance maps for both elements on the stellar surface by means of the Doppler Imaging technique. We confirm HD 131120 to be a He-weak star and we classify HD 105382, HD 138769 as new He-weak stars. HD 55522 has the solar helium abundance but the mean abundance value of He varies by 0.8 dex during the stellar rotation. For HD 131120 and HD 105382, helium is enhanced in regions of the stellar surface where silicon is depleted and depleted in regions where silicon is enhanced. Based on observations obtained with the Swiss photometric telescope and ESO's CAT/CES telescope, both situated at La Silla, Chile. Appendix A, Tables 1 and 2 and Figs. 9, 11, 13 are only available in electronic form at http://www.edpsciences.org 
000001970 700__ $$a Aerts, C.
000001970 700__ $$a Lüftinger, T.
000001970 700__ $$a De Cat, P.
000001970 700__ $$a Piskunov, N. E.
000001970 700__ $$a Scuflaire, R.
000001970 773__ $$c273-283$$pAstronomy and Astrophysics$$v413$$y2004
000001970 85642 $$ahttp://esoads.eso.org/abs/2004A%26A...413..273B
000001970 905__ $$apublished in
000001970 980__ $$aREFERD