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J/A+A/324/949       Properties of He-rich stars I.     (Zboril+ 1997)
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Properties of He-rich stars I. Their evolutionary state and helium abundance
       Zboril M., North P., Glagolevskij Yu.V., Betrix F.
      <Astron. Astrophys. 324, 949 (1997)>
      =1997A&A...324..949Z      (SIMBAD/NED BibCode)
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ADC_Keywords: Stars, peculiar
Keywords: stars: abundances - stars: atmospheres - stars: chemically peculiar -
          stars: fundamental parameters

Abstract:
    A determination of the surface gravity and an abundance analysis of
    helium in a sample of 17 He-rich and 5 normal, reference stars is
    presented. These results are derived from low resolution CCD spectra,
    but each star was measured at least 6 times in order to obtain a
    significant average spectrum for the spectroscopic variables. The
    helium abundances derived from the models used are very close to 0.1
    for normal, reference stars and are larger for the others, clearly
    indicating the He-rich phenomenon in them. NLTE effects, errors on the
    microturbulence value or on the surface gravity do not influence the
    estimated helium abundances. Nevertheless, synthesized Geneva colours
    are affected by the He-rich peculiarity, especially the [U-B] index
    which systematically changes by -0.025 mag per 0.1 of He abundance for
    the coolest stars in the sample. We cannot confirm the correlation
    between the evolutionary state and the helium abundance reported
    previously (Zboril et al. 1994, in "International Conference on CP and
    Magnetic Stars.", Tatranska Lomnica, eds. J. Zverko and J. Ziznovsky,
    p. 105), although we used a more reliable technique of log(g)
    determination. All He-rich objects lie within the main sequence: their
    surface gravities are all inside the range 4.1<logg<4.5, with no more
    than three objects having logg<4.25. We find a significant spread of
    helium abundances in this range of surface gravities, from the solar
    value ~0.1 up to about 0.4. Some of the programme stars (including
    reference stars) present emission in their Balmer lines and therefore
    some kind of stellar activity. Strong helium overabundance often
    coexists with emission and stellar activity.

Objects:
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       RA   (2000)   DE    Designation(s)
    ----------------------------------------------------------
    05 32 00.4 -00 17 04   HD 36485 = HR 1851
    05 35 21.8 -04 29 38   HD 37017 = HR 1890
    05 38 47.1 -02 35 40   HD 37479 = HR 1932
    05 40 56.3 -01 30 26   HD 37776 = BD-01 1005
    06 37 46.6 +12 46 05   HDE 260858 = BD+12 1223
    06 47 53.8 +04 40 01   HDE 264111 = HD 264111 = BD+04 1447
    07 12 02.2 -27 43 05   CoD-27 3748 = SAO 173185
    07 14 48.7 -26 46 22   HD 56139 = HR 2749
    07 23 19.6 -36 20 25   HD 58260 = CD-36 3578
    07 33 02.1 -23 56 03   HD 60344 = CD-23 5673
    07 53 03.7 -49 36 47   HD 64740 = HR 3089
    08 01 35.1 -50 36 21   HD 66522 = CD-50 3111
    08 11 01.6 -37 17 32   HD 68450 = HR 3219
    08 49 39.7 -46 50 51   CoD-46 4639 = CPD-46 3093
    10 42 14.2 -64 27 59   HD 92938 = HR 4196
    11 06 05.8 -59 56 59   HD 96446 = CD-59 3544 = CPD-59 3038
    11 35 37.6 -63 15 54   CPD-62 2124 = LSS 2394
    12 08 21.6 -50 43 20   HD 105435 = HR 4621
    12 28 02.5 -50 13 49   HD 108483 = HR 4743
    12 46 17.2 -68 06 28   HD 110879 = HR 4844
    13 58 40.8 -44 48 11   HD 121790 = HR 5249
    14 06 02.8 -41 10 45   HD 122980 = HR 5285
    14 14 58.5 -46 17 19   HD 124448 = CD-45 9033
    15 06 55.9 -52 01 47   HD 133518 = CD-51 8745
    ----------------------------------------------------------

File Summary:
--------------------------------------------------------------------------------
  FileName      Lrecl  Records   Explanations
--------------------------------------------------------------------------------
ReadMe             80        .   This file
table1             29      160   Journal of the spectroscopic observations
table1.tex         79      148   LaTeX version of the table
table1.ps          72      375   Postscript version of the table
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Byte-by-byte Description of file: table1
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   Bytes Format Units   Label     Explanations
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   1- 11  A11   ---     Name      Star name (1)
  13- 23  F11.3 d       HJD       Heliocentric Julian date (2)
  25- 28  I4    s       Texp      Exposure time
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Note (1): The stars HD 105435 and HD 121790 are rotational velocity standards
           from Slettebak et al., 1975ApJS...29..137S
Note (2): The epochs are heliocentric Julian dates corresponding to the middle
           of the exposure.
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Acknowledgements: Pierre North <Pierre.North@obs.unige.ch>
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(End)                                         Patricia Bauer [CDS]   27-Feb-1997