J/ApJ/754/L38 Abundances and radial velocities of M13 giants (Johnson+, 2012)
Oxygen and sodium abundances in M13 (NGC 6205) giants: linking globular
cluster formation scenarios, deep mixing, and post-RGB evolution.
Johnson C.I., Pilachowski C.A.
<Astrophys. J., 754, L38 (2012)>
=2012ApJ...754L..38J 2012ApJ...754L..38J
ADC_Keywords: Abundances ; Stars, giant ; Radial velocities ;
Effective temperatures ; Clusters, globular
Keywords: Galaxy: halo; globular clusters: general; stars: abundances;
globular clusters: individual (M13,NGC 6205); stars: Population II
Abstract:
We present O, Na, and Fe abundances, as well as radial velocities, for
113 red giant branch (RGB) and asymptotic giant branch (AGB) stars in
the globular cluster M13. The abundances and velocities are based on
spectra obtained with the WIYN-Hydra spectrograph, and the
observations range in luminosity from the horizontal branch (HB) to
RGB tip. The results are examined in the context of recent globular
cluster formation scenarios. We find that M13 exhibits many key
characteristics that suggest its formation and chemical enrichment are
well described by current models. Some of these observations include
the central concentration of O-poor stars, the notable decrease in
[O/Fe] (but small increase in [Na/Fe]) with increasing luminosity that
affects primarily the "extreme" population, the small fraction of
stars with halo-like composition, and the paucity of O-poor AGB stars.
In agreement with recent work, we conclude that the most O-poor M13
giants are likely He-enriched and that most (all?) O-poor RGB stars
evolve to become extreme HB and AGB-manqué stars. In contrast, the
"primordial" and "intermediate" population stars appear to experience
standard HB and AGB evolution.
Description:
All observations for this project were obtained on 2011 May 19-20
using the WIYN 3.5m telescope instrumented with the Hydra multifiber
positioner and bench spectrograph. A single spectrograph setup, with
wavelength coverage ranging from 6050 from 6350Å, was used to
obtain high signal-to-noise ratio (S/N>100), moderate resolution
(R∼18000) spectra of 113 RGB and AGB stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 105 113 Basic data and results
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/248 : UBV photometry and proper motions in M13 (Kadla, 1966)
IV/26 : Hercules Messier 13 (M13) photometry (Ludendorff, 1905)
J/AJ/139/2374 : Evolved stars in M13 (Sandquist+, 2010)
J/AJ/137/4282 : Red giant stars in clusters. II. M13 and M92 (Meszaros+, 2009)
J/A+A/505/139 : Abundances of red giants in 17 GCs (Carretta+, 2009)
J/A+A/505/117 : Abundances of red giants in 15 GCs (Carretta+, 2009)
J/ApJ/638/1018 : Equivalent widths for giant stars in M13 and M71 (Yong+, 2006)
J/AJ/129/303 : Abundances of stars in M3 and M13 (Cohen+, 2005)
J/AJ/127/1579 : Abundances of faint M13 stars (Briley+, 2004)
J/A+A/398/541 : VI light-curves of the variable stars in M13 (Kopacki+, 2003)
J/AJ/122/3219 : M3 and M13 CCD BV photometry (Rey+, 2001)
J/AJ/120/1364 : Abundances in M3 and M13 (Cavallo+, 2000)
J/AJ/113/669 : Stars in M13 core (Cohen+ 1997)
J/AJ/113/279 : Proton Capture Chains. II (Kraft+ 1997)
J/AJ/112/545 : Proton capture chains in GCs. I. (Pilachowski+ 1996)
J/A+AS/102/397 : Colour magnitude diagram of M13 (Guarnieri+ 1993)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Name Star name (1)
8- 14 A7 --- AName Alternate name
16- 25 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000) (2)
27- 35 F9.6 deg DEdeg Declination in decimal degrees (J2000) (2)
37- 41 F5.2 mag Vmag [12/15.3] V band magnitude (2)
43- 48 F6.3 mag Kmag [8.3/14.4] 2MASS KS band magnitude
50- 53 F4.2 [Lsun] logL [1.6/3.3] Log of luminosity
55- 58 I4 K Teff [3895/5195] Effective temperature
60- 63 F4.2 [cm/s2] log(g) [0.4/2.5] Log of the surface gravity
65- 69 F5.2 [Sun] [Fe/H] [-1.8/-1.3] Average [Fe/H] metallicity
71- 74 F4.2 km/s Vt [1.3/2.5] Turbulent velocity
76- 80 F5.2 [Sun] [FeI/H] Fe I to H abundance
82- 86 F5.2 [Sun] [FeII/H] ? Fe II to H abundance
88- 92 F5.2 [Sun] [O/Fe] [-1.1/0.8]? O to Fe abundance
94- 98 F5.2 [Sun] [Na/Fe] [-0.7/0.8]? Na to Fe abundance
100-105 F6.1 km/s RVel [-258.3/-230.1] Radial velocity
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Note (1): Star name from
(L): Ludendorf 1905, Cat. IV/26, in Simbad,
(K): Kadla 1966IzPul..24...93K 1966IzPul..24...93K, <Cl* NGC 6205 KAD NNN> in Simbad;
see also Cat. II/248.
Note (2): All coordinates, optical photometry, and membership probabilities
were taken from Cudworth & Monet (1979AJ.....84..774C 1979AJ.....84..774C). To ensure
membership, we only observed targets with P>70%.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 05-Mar-2014