J/A+A/413/159 Galactic abundance gradient. V. (Andrievsky+, 2004)
The Galactic abundance gradient from Cepheids.
V. Transition zone between 10 and 11 kpc.
Andrievsky S.M., Luck R.E., Martin P., Lepine J.R.D.
<Astron. Astrophys., 413, 159-172 (2004)>
=2004A&A...413..159A 2004A&A...413..159A
ADC_Keywords: Stars, variable ; Abundances, peculiar
Keywords: stars: abundances - Galaxy: abundances - Galaxy: evolution -
stars: variables: Cepheids
Abstract:
This paper reports on the spectroscopic investigation of 12 Cepheids
which are situated in the crucial region of galactocentric distances
from 9kpc to 12kpc, where according to our previous results
(Andrievsky et al., 2002, Cat. J/A+A/392/491; Luck et al.,
2003A&A...401..939L 2003A&A...401..939L) the radial metallicity distribution experiences
an obvious change. In particular, the wriggle in the iron abundance
distribution is found to fall approximately at galactocentric
distances 10-11kpc (assuming galactocentric distance of the Sun kpc).
Within the transition zone from 10 to 11kpc the relative-to-solar
iron abundance decreases approximately to -0.2dex. The new sample of
stars, analyzed in present paper, gives results supporting the
previous conclusion about the multimodal character of the metallicity
distribution in galactic disc. Using a quite simple consideration of
galactic chemical evolution we show that the observed distribution can
be explained in the framework of a model which includes the spiral
arms. In particular, the wriggle feature associated with 11 kpc can be
interpreted as a change of metallicity level in the vicinity of the
galactic corotation resonance.
Description:
The observations were carried out on 1-5 February 2003 with the 3.6-m
Canada-France-Hawaii Telescope.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 56 13 Star positions and magnitudes (from Simbad)
tablea1.dat 34 299 Individual elemental abundances for program stars
tablea1.tex 136 208 LaTeX version of the table
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See also:
J/A+A/381/32 : Galactic Cepheid abundances. I. (Andrievsky+, 2002)
J/A+A/392/491 : Galactic abundance gradient. III. (Andrievsky+, 2002)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Object name
15- 16 I2 h RAh Right ascension (J2000.0)
18- 19 I2 min RAm Right ascension (J2000.0)
21- 24 F4.1 s RAs Right ascension (J2000.0)
26 A1 --- DE- Declination sign (J2000.0)
27- 28 I2 deg DEd Declination (J2000.0)
30- 31 I2 arcmin DEm Declination (J2000.0)
33- 34 I2 arcsec DEs Declination (J2000.0)
38- 42 F5.2 mag Bmag ? B magnitude
44- 48 F5.2 mag Vmag ? V magnitude
50- 70 A21 --- SpType Spectral type
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Star name
10- 14 F5.2 --- Ion Ion atomic number (1)
16- 20 F5.2 [Sun] [M/H] ? Relative-to-solar abundance
22- 25 F4.2 [Sun] e_[M/H] ? rms uncertainty on [M/H]
27- 28 I2 --- Nline ? Number of lines used
30- 33 F4.2 --- (M/H) ? Absolute abundance (in the scale log(H)=12.00)
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Note (1): Ion atomic number:
6.00=C, 8.00=O, 11.00=Na, 14.00=Si, 14.01=Si+ 16.00=S,
20.00=Ca, 21.00=Sc, 21.01=Sc+ 22.00=Ti, 23.00=V, 24.00=Cr,
24.01=Cr+ 25.00=Mn, 26.00=Fe, 26.01=Fe+ 27.00=Co, 28.00=Ni,
40.01=Zr+ 57.01=La+ 58.01=Ce+ 60.01=Nd+ 63.01=Eu+
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Acknowledgements:
Sergei Andrievsky
References:
Andrievski et al., Paper I 2002A&A...381...32A 2002A&A...381...32A, Cat. J/A+A/381/32
Andrievski et al., Paper II 2002A&A...384..140A 2002A&A...384..140A
Andrievski et al., Paper III 2002A&A...392..491A 2002A&A...392..491A, Cat. J/A+A/392/491
Luck et al., Paper Iv 2003A&A...401..939L 2003A&A...401..939L
(End) Patricia Bauer [CDS] 22-Dec-2003