J/AJ/161/288 Stellar population in M53 (Gerber+, 2021)
Light element abundances and multiple populations in M53.
Gerber J.M., Friel E.D., Vesperini E.
<Astron. J., 161, 288-288 (2021)>
=2021AJ....161..288G 2021AJ....161..288G (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular; Radial velocities; Photometry, UBV;
Photometry, infrared; Effective temperatures; Abundances
Keywords: Globular star clusters; Stellar evolution; Stellar abundances
Abstract:
We present results from a study of 94 red giant stars in the globular
cluster M53. We use low-resolution spectra to measure the strength of
CN and CH features at ∼3800 and 4300Å, respectively. The strengths
of these features are used to classify stars into a CN-enhanced and
CN-normal population and to measure C and N abundances in all 94
stars. We find the red giant branch stars to be evenly split between
the two populations identified, and observe the presence of
CN-enhanced stars on the asymptotic giant branch. In addition, we
identify five CH star candidates based on the strength of their CN and
CH band features, and the presence of a P-branch in their CH band. We
compare our identification of multiple populations to those based on
the Na-O anticorrelation and pseudo-color indices in Hubble Space
Telescope UV photometry, and find general agreement between all three
methods. Our large sample size also allows us to study the radial
distribution of each population, and we find that the CN-enhanced
population is more centrally concentrated. We use our C and N
measurements to compare the evolutionary changes in these elements as
a function of magnitude between the two populations, and show that
both populations experience similar evolutionary changes to the
surface abundances of C and N. Finally, we calculate C+N+O abundances
for each population and compare them to similar measurements made in
M10; we find that in both clusters, CN-enhanced stars have a slightly
enhanced C+N+O (Δ(C+N+O)∼0.2dex).
Description:
We completed our observations over three observing runs on the WIYN 2
3.5m telescope during 2016 June 9-12, 2017 May 29-June 1, and 2018
April 22-24. We used the blue fibers of the Hydra multi-object
spectrograph, which allows us to observe the near-UV CN band at
3883Å and the CH band at 4300Å.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 113 98 Stars measured in M53
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See also:
VII/195 : Globular Clusters in the Milky Way (Harris, 1996)
J/AJ/116/1775 : BV photometry of M53 (Rey+, 1998)
J/A+A/358/547 : M53 variable stars V light curves (Kopacki, 2000)
J/A+A/505/117 : Abundances of red giants 15 globular clusters (Carretta+, 2009)
J/A+A/505/139 : Abundances of red giants in 17 glob. clusters (Carretta+, 2009)
J/A+A/524/A44 : CN and CH line strengths in 12 globulars (Pancino+, 2010)
J/AJ/142/126 : CN and CH in SDSS Galactic globular clusters (Smolinski+, 2011)
J/A+A/548/A107 : U,V photometry in M2 (NGC 7089) (Lardo+, 2012)
J/AJ/149/53 : RVel of 12 Milky Way globular clusters (Kimmig+, 2015)
J/ApJ/801/125 : Carbon in red giants in GCs and dSph galaxies (Kirby+, 2015)
J/MNRAS/446/3319 : Line list for the NGC 1851 stars (Yong+, 2015)
J/MNRAS/450/815 : Red giants in NGC 5286 (Marino+, 2015)
J/ApJ/824/5 : Chemical abundances in NGC 5024 (M53) (Boberg+, 2016)
J/AJ/156/6 : Light element abund. of RGB & AGB stars in M10 (Gerber+, 2018)
J/MNRAS/475/257 : AGB subpopulations in NGC 6397 (MacLean+, 2018)
J/AJ/157/154 : Abundances of RGs in Galactic globular clusters (Gerber+, 2019)
J/AJ/158/14 : Stellar pop. of globular clusters using APOGEE (Nataf+, 2019)
J/MNRAS/482/5138 : Galactic GC mean pms & velocities (Baumgardt+, 2019)
J/MNRAS/484/2832 : Proper motions Milky Way globular clusters (Vasiliev, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID Identifier
6- 15 F10.6 deg RAdeg [198/199] Right Ascension (J2000) (1)
17- 25 F9.6 deg DEdeg [18/19] Declination (J2000) (1)
27- 29 I3 km/s RVel [-81/29] Heliocentric radial velocity
31- 35 F5.2 mag Vmag [13.78/17.34] Apparent V band magnitude (1)
37- 41 F5.2 mag VMAG [-2.54/1.02] Absolute V band magnitude (2)
43- 47 F5.2 mag Kmag [10.44/100] Apparent 2MASS Ks band magnitude
49- 52 I4 K Teff [4048/5198] Effective temperature
54- 57 F4.2 [cm/s2] logg [0.68/2.73] log surface gravity
59- 64 F6.3 --- S3839 [-0.4/0.21] S(3839) index; see equation 1
66- 71 F6.3 --- DeltaCN [-0.13/0.46] δCN index; see Section 3.1.3
73- 77 F5.3 --- CH [0.13/0.47] CH index; see equation 2
79- 83 F5.2 [-] [C/Fe] [-0.8/0.5] log C/Fe abundance ratio
85- 88 F4.2 [-] [N/Fe] [0.79/1.8] log N/Fe abundance ratio
90- 93 F4.1 [-] [O/Fe] [-0.2/0.4]? log O/Fe abundance ratio (3)
95- 97 F3.1 [-] [Na/Fe] [0.1/0.7]? log Na/Fe abundance ratio (3)
99-111 A13 --- Branch Branch location
113 A1 --- Mem M53 member? (y)es or (n)o
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Note (1): From Rey+, 1998 J/AJ/116/1775.
Note (2): Assumes (m-M)V=16.32; Harris, 1996, VII/195.
Note (3): From Boberg+, 2016, J/ApJ/824/5.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 06-Jul-2021