J/A+A/548/A55 C and O isotopic ratios in Arcturus and Aldebaran (Abia+ 2012)
Carbon and oxygen isotopic ratios in Arcturus and Aldebaran:
Constraining the parameters for non-convective mixing on the RGB.
Abia C., Palmerini S., Busso M., Cristallo S.
<Astron. Astrophys. 548, A55 (2012)>
=2012A&A...548A..55A 2012A&A...548A..55A
ADC_Keywords: Stars, giant ; Stars, late-type ; Abundances
Keywords: stars: abundances - stars: individual: Arcturus -
stars: individual: Aldebaran - stars: late type
Abstract:
We re-analyzed the carbon and oxygen isotopic ratios in the
atmospheres of the two bright K giants Arcturus (α Boo) and
Aldebaran (α Tau). These stars are in the evolutionary stage
following the first dredge-up (FDU). Previous determinations (dating
back more than 20 years) of their 16O/18O ratios showed a rough
agreement with FDU expectations; however, the estimated 16O/17O
and 12C/13C ratios were lower than in the canonical predictions
for red giants. Today these anomalies are interpreted as signs of the
occurrence of non-convective mixing episodes. We therefore
re-investigated this problem to verify whether the observed data can
be reproduced in this scenario and if the fairly well determined
properties of the two stars can help us in fixing the uncertain
parameters that characterize non-convective mixing and in constraining
its physical nature.
Description:
CNO abundances, C and O isotopic ratios and equivalent diffusive
coefficients (D) are given for the calculated extra-mixing models. For
Arcturus we used the electronic version of the Infrared Atlas Spectrum
by Hinkle et al. (1995, Cat. J/PASP/107/1042; resolution 0.01cm-1),
and for Aldebaran we used a spectrum obtained on February 6, 1980 at
the KPNO 4m Coude telescope using a Fourier transform spectrometer,
kindly provided by K. Hinkle (resolution 0.016cm-1)
The first 2 rows of table4 report the CNO abundances and isotopic
ratios resulting from the observations. The other rows give the CNO
abundances and isotopic ratios accounted for by the FDU in the three
stellar models considered of 1.3Mo, 1.2Mo and 1.08Mo (see the paper
for more details).
Objects:
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RA (J2000) DE Designation(s)
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04 35 55.24 +16 30 33.5 Aldebaran = alpha tau
14 15 39.67 +19 10 56.7 Arcturus = alpha Boo
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 119 52 CNO abundances, C and O isotopic ratios and
equivalent diffusive coefficients for the observed
and calculated extra-mixing models.
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See also:
J/PASP/107/1042 : Infrared Arcturus Atlas (Hinkle+ 1995)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Name of star (Arcturus or Aldebaran),
or FDU (First Dredge Up) for model
11- 14 F4.2 Msun M ? Mass used for the model (empty for observed)
16- 19 F4.2 [---] Delta ? Mixing Depth Δ (1)
25- 29 F5.3 10-6Msun/yr dM6 ? Mixing (circulation) rate
36- 39 F4.2 [---] A(C) Carbon Abundance logε(C)
41- 44 F4.2 [---] e_A(C) ? Error on A(C) (observed values only)
47- 50 F4.2 [---] A(N) Nitrogen Abundance logε(N)
58- 61 F4.2 [---] A(O) Oxygen Abundance logε(O)
69- 73 F5.2 --- 12/13C Carbon Isotopic Ratio 12C/13C
75- 76 F2.0 --- e_12/13C ? Mean error on 12/13C (observed values only)
80- 83 I4 --- 16/17O Oxygen Isotopic Ratio 16O/17O
85- 87 I3 --- e_16/17O ? Mean error on 16/17O (observed values only)
91- 94 I4 --- 16/18O Oxygen Isotopic Ratio 16O/18O
96- 98 I3 --- e_16/18O ? Mean error on 16/18O (observed values only)
102-105 F4.2 --- 17/18O Oxygen Isotopic Ratio 17O/18O
107-110 F4.2 --- e_17/18O ? Mean error on 17/18O (observed values only)
113-119 E7.2 cm2/s D ? Equivalent diffusive coefficient
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Note (1): the parameter Δ is given for models only;
it is defined as Δ=log(TH/TP) where:
TP = the temperature of the deepest layers attained by mass transport
TH = the temperature at which the maximum energy from H-burning
in the shell is released.
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(End) Carlos Abia [Univ. Granada], Francois Ochsenbein [CDS] 30-Oct-2012