J/A+A/549/A41 Horizontal branch stars in 47 Tuc and M5 (Gratton+, 2013)
The Na-O anticorrelation in horizontal branch stars. III. 47 Tuc and M 5.
Gratton R.G., Lucatello S., Sollima A., Carretta E., Bragaglia A.,
Momany Y., D'Orazi V., Cassisi S., Pietrinferni A., Salaris M.
<Astron. Astrophys. 549, A41 (2013)>
=2013A&A...549A..41G 2013A&A...549A..41G
ADC_Keywords: Clusters, globular ; Abundances ; Stars, horizontal branch
Keywords: stars: abundances - stars: evolution - stars: Population II -
globular clusters: individual: 47 Tucanae -
globular clusters: individual: M5
Abstract:
To check the impact of the multiple population scenario for globular
clusters on their horizontal branch (HB), we present an analysis of
the composition of 110 red HB (RHB) stars in 47 Tucanae and of 61 blue
HB (BHB) and 30 RHB stars in M5. In 47 Tuc we found tight relations
between the colours of the stars and their abundances of p-capture
elements. This strongly supports the idea that the He content - which
is expected to be closely correlated with the abundances of p-capture
elements - is the third parameter (after overall metallicity and age)
that determines the colour of HB stars. However, the range in He
abundance must be small (ΔY<0.03) in 47 Tuc to reproduce our
observations; this agrees with previous analyses. There is possibly a
correlation between the abundances of p- and n-capture elements in 47
Tuc. If confirmed, this might suggest that asymptotic giant branch
stars of moderate mass contributed to the gas from which
second-generation stars formed. Considering the selection effects in
our sample (which does not include stars warmer than 11000K and RR
Lyrae variables, which were excluded because we could not obtain
accurate abundances with the adopted observing procedure) is important
to understand our results for M5. In this case, we find that, as
expected, RHB stars are Na-poor and O-rich, and likely belong to the
primordial population. There is a clear correlation of the [Na/O]
ratio and N abundance with colour along the BHB. A derivation of the
He abundance for these stars yields a low value of Y=0.22±0.03. This
is expected because HB stars of a putative He-rich population in this
cluster should be warmer than 11000K, and would accordingly not have
been sampled by our analysis. However, we need some additional source
of scatter in the total mass loss of stars climbing up the red giant
branch to reproduce our results for M5. Finally, we found a C-star on
the HB of 47Tuc and a Ba-rich, fast-rotating, likely binary star on
the HB of M5. These stars are among the brightest and coolest HB
stars.
Description:
Tables with basic data and abundances for 110 HB stars in 47 Tuc and
92 Horizontal-Branch (HB) stars in M5. The observations were made with
the GIRAFFE fibre-fed spectrograph at the VLT in March 2011 (47 Tuc)
and June 2011 (M5).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 94 110 Basic data for programme stars in 47 Tuc
table3.dat 98 91 Basic data for programme stars in M5
table4.dat 93 110 Abundances of Fe, O, Na, Al in 47 Tuc
table5.dat 102 110 Abundances of other elements in 47 Tuc
table6.dat 90 91 Elemental abundances in HB stars of M5
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See also:
J/A+A/534/A123 : Horizontal branch stars in NGC 2808 (Gratton+, 2011)
J/A+A/539/A19 : Horizontal branch stars in NGC 1851 (Gratton+, 2012)
Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Name Star designation
8- 9 I2 h RAh Right ascension (J2000.0)
11- 12 I2 min RAm Right ascension (J2000.0)
14- 19 F6.3 s RAs Right ascension (J2000.0)
21 A1 --- DE- Declination sign (J2000.0)
22- 23 I2 deg DEd Declination (J2000.0)
25- 26 I2 arcmin DEm Declination (J2000.0)
28- 32 F5.2 arcsec DEs Declination (J2000.0)
34- 35 I2 --- S/N12 S/N of the Giraffe spectrograph
in HR12 configuration
37- 39 I3 --- S/N19 ? S/N Giraffe spectrograph
in HR19 configuration
41- 45 F5.1 km/s HRV ? Heliocentric radial velocity
47- 50 F4.1 km/s FWHM ? FWHM of spectral lines
52- 56 F5.3 mag Bmag B magnitude
58- 62 F5.3 mag Vmag V magnitude
64- 68 F5.3 mag Kmag ? K magnitude
70- 75 F6.3 mag (B-V)0 Dereddened B-V colour index
77- 82 F6.3 mag (V-K)0 ? Dereddened V-K colour index
84- 88 I5 K Teff Effective temperature
90- 93 F4.2 [cm/s2] logg Log surface gravity
95- 98 F4.2 km/s vt ? Microturbulence velocity
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Name Star designation
8- 9 I2 --- o_[Fe/H]1 Number of FeI lines
11- 15 F5.2 [Sun] [Fe/H]1 Value of [Fe/H] from FeI lines
17- 21 F5.2 [Sun] e_[Fe/H]1 rms of [Fe/H] from FeI lines
23- 24 I2 --- o_[Fe/H]2 Number of Fe II lines
26- 30 F5.2 [Sun] [Fe/H]2 Value of [Fe/H] from FeII lines
32- 36 F5.2 [Sun] e_[Fe/H]2 ? rms of [Fe/H] from FeII lines
38- 42 F5.2 [Sun] [N/Fe] ? Value of [N/Fe] from CN lines
44- 45 I2 --- o_[O/Fe] ? Number of OI lines
47- 51 F5.2 [Sun] [O/Fe] ? Value of [O/Fe] from OI lines
53- 57 F5.2 [Sun] e_[O/Fe] ? rms of [O/Fe] from OI lines
59- 60 I2 --- o_[Na/Fe] Number of NaI lines
62- 66 F5.2 [Sun] [Na/Fe] Value of [Na/Fe] from NaI lines
68- 72 F5.2 [Sun] e_[Na/Fe] rms of [Na/Fe] from NaI lines
74- 78 F5.2 [Sun] [Mg/Fe] ? Value of [Mg/Fe] from MgI lines
80- 81 I2 --- o_[Al/Fe] ? Number of AlI lines
83- 87 F5.2 [Sun] [Al/Fe] ? Value of [Al/Fe] from AlI lines
89- 93 F5.2 [Sun] e_[Al/Fe] ? rms of [Al/Fe] from AlI lines
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Name Star designation
8- 9 I2 --- o_[Si/Fe] Number of SiI lines
11- 15 F5.2 [Sun] [Si/Fe] ? Value of [Si/Fe] from SiI lines
17- 21 F5.2 [Sun] e_[Si/Fe] ? rms of [Si/Fe] from SiI lines
23- 24 I2 --- o_[Ca/Fe] Number of CaI lines
26- 30 F5.2 [Sun] [Ca/Fe] Value of [Ca/Fe] from CaI lines
32- 36 F5.2 [Sun] e_[Ca/Fe] ? rms of [Ca/Fe] from CaI lines
38- 39 I2 --- o_[Ti/Fe] Number of TiI lines
41- 45 F5.2 [Sun] [Ti/Fe] Value of [Ti/Fe] from TiI lines
47- 51 F5.2 [Sun] e_[Ti/Fe] rms of [Ti/Fe] from TiI lines
53- 54 I2 --- o_[V/Fe] Number of VI lines
56- 60 F5.2 [Sun] [V/Fe] ? Value of [V/Fe] from VI lines
62- 66 F5.2 [Sun] e_[V/Fe] ? rms of [V/Fe] from VI lines
68- 69 I2 --- o_[Mn/Fe] Number of MnI lines
71- 75 F5.2 [Sun] [Mn/Fe] Value of [Mn/Fe] from MnI lines
77- 81 F5.2 [Sun] e_[Mn/Fe] rms of [Mn/Fe] from MnI lines
83- 84 I2 --- o_[Ni/Fe] Number of NiI lines
86- 90 F5.2 [Sun] [Ni/Fe] Value of [Ni/Fe] from NiI lines
92- 96 F5.2 [Sun] e_[Ni/Fe] rms of [Ni/Fe] from NiI lines
98-102 F5.2 [Sun] [Ba/Fe] Value of [Ba/Fe] from BaII lines
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Name Star designation
8- 9 I2 --- o_[Fe/H]1 ? Number of FeI lines
11- 15 F5.2 [Sun] [Fe/H]1 ? Value of [Fe/H] from FeI lines
17- 21 F5.2 [Sun] e_[Fe/H]1 ? rms of [Fe/H] from FeI lines
23- 24 I2 --- o_[Fe/H]2 ? Number of FeII lines
26- 30 F5.2 [Sun] [Fe/H]2 ? Value of [Fe/H] from FeII lines
32- 36 F5.2 [Sun] e_[Fe/H]2 ? rms of [Fe/H] from FeII lines
38- 42 F5.2 [Sun] [N/Fe] ? Value of [N/Fe] from CN lines
44- 48 F5.2 [Sun] [O/Fe] ? Value of [O/Fe] from OI lines
50- 54 F5.2 [Sun] [Na/Fe] Value of [Na/Fe] from NaI lines
56- 60 F5.2 [Sun] [Mg/Fe] ? Value of [Mg/Fe] from MgI and MgII lines
62- 66 F5.2 [Sun] [Si/Fe] ? Value of [Si/Fe] from SiI lines
68- 72 F5.2 [Sun] [Ca/Fe] ? Value of [Ca/Fe] from CaI lines
74- 78 F5.2 [Sun] [Mn/Fe] ? Value of [Mn/Fe] from MnI lines
80- 84 F5.2 [Sun] [Ni/Fe] ? Value of [Ni/Fe] from NiI lines
86- 90 F5.2 [Sun] [Ba/Fe] ? Value of [Ba/Fe] from BaII lines
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Acknowledgements:
Raffaele Gratton, raffaele.gratton(at)oapd.inaf.it
References:
Gratton et al., Paper I 2011A&A...534A.123G 2011A&A...534A.123G, Cat. J/A+A/534/123
Gratton et al., Paper II 2012A&A...539A..19G 2012A&A...539A..19G, Cat. J/A+A/539/A19
(End) Raffaele Gratton [INAF, Italy], Patricia Vannier [CDS] 17-Oct-2012