J/A+A/324/949 Properties of He-rich stars I. (Zboril+ 1997)
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 1997A&A...324..949Z (SIMBAD/NED BibCode)
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)
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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
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File Summary:
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FileName Lrecl Records Explanations
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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 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
(End) Patricia Bauer [CDS] 27-Feb-1997