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J/A+A/565/A100 NGC 288 hot horizontal branch stars abundances (Moehler+, 2014)
The following files can be converted to FITS (extension .fit or fit.gz)
table1.dat n288abu.dat
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Query from: http://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/A+A/565/A100
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Beginning of ReadMe :J/A+A/565/A100 NGC 288 hot horizontal branch stars abundances (Moehler+, 2014)
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Hot horizontal branch stars in NGC 288 - effects of diffusion and stratification
on their atmospheric parameters.
Moehler S., Dreizler S., LeBlanc F., Khalack V., Michaud G., Richer J.,
Sweigart A.V., Grundahl F.
<Astron. Astrophys. 565, A100 (2014)>
=2014A&A...565A.100M
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ADC_Keywords: Clusters, globular ; Stars, horizontal branch ; Abundances
Keywords: stars: horizontal branch - stars: atmospheres -
techniques: spectroscopic - globular clusters: individual: NGC288
Abstract:
NGC 288 is a globular cluster with a well-developed blue horizontal
branch covering the u-jump that indicates the onset of diffusion. It
is therefore well suited to study the effects of diffusion in blue
horizontal branch (HB) stars. We compare observed abundances with
predictions from stellar evolution models calculated with diffusion
and from stratified atmospheric models. We verify the effect of using
stratified model spectra to derive atmospheric parameters. In
addition, we investigate the nature of the overluminous blue HB stars
around the u-jump. We defined a new photometric index sz from uvby
measurements that is gravity-sensitive between 8000K and 12000K.
Using medium-resolution spectra and Stroemgren photometry, we
determined atmospheric parameters (Teff, logg) and abundances for the
blue HB stars. We used both homogeneous and stratified model spectra
for our spectroscopic analyses. The atmospheric parameters and masses
of the hot HB stars in NGC 288 show a behaviour seen also in other
clusters for temperatures between 9000K and 14000K. Outside this
temperature range, however, they instead follow the results found for
such stars in omega Cen. The abundances derived from our
observations are for most elements (except He and P) within the
abundance range expected from evolutionary models that include the
effects of atomic diffusion and assume a surface mixed mass of
10^-7^M_sun_. The abundances predicted by stratified model
atmospheres are generally significantly more extreme than observed,
except for Mg. When effective temperatures, surface gravities, and
masses are determined with stratified model spectra, the hotter stars
agree better with canonical evolutionary predictions. Our results show
definite promise towards solving the long-standing problem of surface
gravity and mass discrepancies for hot HB stars, but much work is
still needed to arrive at a self-consistent solution.
Description:
Temperatures, surface gravities, and abundances for hot (Teff>9000K)
horizontal branch stars in NGC 288 as derived from medium-resolution
FLAMES-GIRAFFE spectra (resolution about 0.7AA). Effective
temperatures and surface gravities are derived from line profile fits.
The abundances were derived via spectrum synthesis, using the
presviously defined effective temperature and surface gravity. Errors
are about +/-5% in Teff, +/-0.1 in logg, +/-0.2 (He), +/-0.28 (Mg),
+/-0.34 (Si, P, Fe), +/-0.58 (Ti, Mn, Ni). 0.00 means that no
abundance could be determined.
Objects:
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RA (2000) DE Designation(s)
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00 52 45.24 -26 34 57.4 NGC 288 = NGC 288
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