J/A+A/347/69 Abundances of halo early-type stars (Rolleston+, 1999)
Early-type stars in the Galactic halo from the Palomar-Green Survey.
II: A sample of distant, apparently young Population I stars
Rolleston W.R.J., Hambly N.C., Keenan F.P., Dufton P.L., Saffer R.A.
<Astron. Astrophys. 347, 69 (1999)>
=1999A&A...347...69R 1999A&A...347...69R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, early-type ; Equivalent widths ; Abundances
Keywords: stars: abundances - stars: atmospheres - stars: early-type -
stars: kinematics
Abstract:
We present echelle (R∼40,000) spectroscopic observations for a sample
of apparently normal, high Galactic latitude, early-type stars drawn
from the Palomar-Green Survey. The metal-line spectra show evidence
for rotational velocity broadening with values of vsini≤300km/s. In
conjunction with Kurucz model atmospheres, we derive stellar
photospheric abundances that are consistent with a Population I
chemical composition; differential abundances with respect to Galactic
disk Population I stars indicate no abundance differences outside the
estimated errors. From a comparison of the derived atmospheric
parameters with recent theoretical evolutionary models, we derive
distance and age estimates for individual stars. Using kinematical
considerations, we conclude that all these objects are `runaway'
stars, formed in the Galactic disk and subsequently ejected, possibly
by supernovae explosions or dynamical interactions.
Objects:
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RA (2000) DE Designation(s)
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08 58 21.0 +29 12 12 PG 0855+294
09 37 04.0 +14 18 24 PG 0934+145
09 58 14.4 +28 52 26 PG 0955+291
12 07 57.4 +22 31 47 PG 1205+228
22 21 59.1 +09 37 31 PG 2219+094
22 32 08.5 +10 14 25 PG 2229+099
23 48 22.4 +24 23 06 PG 2345+241
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table4.dat 74 17 Equivalent width for the non-diffuse helium and
metal lines (PG 0855+294 to PG 2219+094)
table5.dat 38 61 Equivalent width for the non-diffuse helium and
metal lines (PG 2229+099 and PG 2345+241)
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.2 0.1nm Line Wavelength of spectral line
10- 15 A6 --- Species Ionization stage of element
18- 20 I3 0.1pm EW0855 ? Equivalent width for PG 0855+294
22- 26 F5.2 --- A0855 ? LTE abundances for PG 0855+294 in 12+log(X/H)
30- 32 I3 0.1pm EW0934 ? Equivalent width for PG 0934+145
34- 38 F5.2 --- A0934 ? LTE abundances for PG 0934+145 in 12+log(X/H)
42- 44 I3 0.1pm EW0955 ? Equivalent width for PG 0955+291
46- 50 F5.2 --- A0955 ? LTE abundances for PG 0955+291 in 12+log(X/H)
54- 56 I3 0.1pm EW1205 ? Equivalent width for PG 1205+228
58- 62 F5.2 --- A1205 ? LTE abundances for PG 1205+228 in 12+log(X/H)
66- 68 I3 0.1pm EW2219 ? Equivalent width for PG 2219+094
70- 74 F5.2 --- A2219 ? LTE abundances for PG 2219+094 in 12+log(X/H)
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.2 0.1nm Line Wavelength of spectral line
10- 15 A6 --- Species Ionization stage of element
18- 20 I3 0.1pm EW2229 ? Equivalent width for PG 2229+099
22- 26 F5.2 --- A2229 ? LTE abundances for PG 2229+099 in 12+log(X/H)
30- 32 I3 0.1pm EW2345 ? Equivalent width for PG 2345+241
34- 38 F5.2 --- A2345 ? LTE abundances for PG 2345+241 in 12+log(X/H)
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Acknowledgements: Robert Rolleston
References:
Hambly et al., Paper I. 1997ApJS..111..419H 1997ApJS..111..419H
(End) Patricia Bauer [CDS] 29-Apr-1999