J/ApJ/900/146 Abundances in 2 metal-poor GCs, M53 & NGC5053 (Chun+, 2020)
Extratidal stars and chemical abundance properties of two metal-poor globular
clusters M53 (NGC 5024) and NGC 5053.
Chun S.-H., Lee J.-J., Lim D.
<Astrophys. J., 900, 146 (2020)>
=2020ApJ...900..146C 2020ApJ...900..146C
ADC_Keywords: Clusters, globular; Abundances; Effective temperatures;
Infrared sources
Keywords: Globular star clusters ; Stellar abundances
Abstract:
We search for extratidal stars around two metal-poor Galactic globular
clusters, M53 and NGC 5053, using the near-infrared APOGEE spectra.
Applying the t-distributed stochastic neighbor embedding (t-SNE)
algorithm on the chemical abundances and radial velocities results in
identification of two isolated stellar groups composed of cluster
member stars in the t-SNE projection plane. With additional selection
criteria of radial velocity, location in the color-magnitude diagram,
and abundances from a manual chemical analysis, we find a total of
73 cluster member candidates; seven extratidal stars are found beyond
the tidal radii of the two clusters. The extratidal stars around the
clusters tend to be located along the leading direction of the cluster
proper motion, and the individual proper motion of these stars also
seems to be compatible to those of clusters. Interestingly, we find
that one extratidal star of NGC 5053 is located on the southern
outskirts of M53, which is part of common stellar envelope by the
tidal interaction between two clusters. We discuss the nature of this
star in the context of the tidal interaction between two clusters. We
find apparent Mg-Al anticorrelations with a clear gap and spread
(∼0.9dex) in Al abundances for both clusters, and a light Si abundance
spread (∼0.3dex) for NGC 5053. Since all extratidal stars have
Mg-enhanced and Al-depleted features, they could be first-generation
stars of two globular clusters. Our results support that M53 and
NGC5053 originated in dwarf galaxies and are surrounded by extended
stellar substructures of more numerous populations of clusters.
Description:
In this work, we use the spectra of APOGEE DR14
(Majewski+ 2017AJ....154...94M 2017AJ....154...94M) and the data catalog of The Cannon
(Ness+ 2015, J/ApJ/808/16).
Our initial sample consists of 2558 red giant branch (RGB) stars in
the 20°x10° field around M53 (NGC5024) and NGC5053 that are
covered by the APOGEE survey.
The APOGEE survey provides high resolution (R∼22500) H-band spectra
(λ=1.51-1.70um).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 92 65 Stellar parameters, metallicity, and abundances
of M53 and NGC 5053
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See also:
VII/195 : Globular Clusters in the Milky Way (Harris, 1996)
VII/202 : Globular Clusters in the Milky Way (Harris, 1997)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
V/150 : Updated cat. of variable stars in globular clusters (Clement+ 2017)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
III/284 : APOGEE-2 data from DR16 (Johnsson+, 2020)
J/AJ/112/1489 : Spectroscopic survey for binaries in NGC 5053 (Yan+ 1996)
J/A+A/320/776 : Tidal radii of 7 globular clusters (Lehmann+ 1997)
J/A+A/358/547 : M53 variable stars V light curves (Kopacki, 2000)
J/A+A/505/139 : Abundances of red giants in 17 GCs (Carretta+, 2009)
J/A+A/497/497 : Physical param. from JHK flux (Gonzalez-Hernandez+, 2009)
J/MNRAS/402/226 : NGC 5053 variables VrI light curves (Arellano Ferro+, 2010)
J/ApJ/757/164 : Oxygen abundances of dwarf stars (Ramirez+, 2012)
J/A+A/557/A128 : Stellar [Fe/H] and [Na/H] in NGC6752 (Carretta, 2013)
J/ApJ/804/109 : Equivalent widths of RGB stars in NGC 5053 (Boberg+, 2015)
J/AJ/149/153 : Abundances of red giants in 10 GCs (Meszaros+, 2015)
J/ApJ/808/16 : Cannon: a new approach to determine abundances (Ness+, 2015)
J/ApJ/824/5 : Chemical abundances in NGC 5024 (M53) (Boberg+, 2016)
J/AJ/151/144 : ASPCAP weights for APOGEE chemical elements (Garcia+, 2016)
J/MNRAS/465/501 : APOGEE N-rich stars in inner Galaxy (Schiavon+, 2017)
J/ApJS/228/24 : GALAH semi-automated classification scheme (Traven+, 2017)
J/ApJ/865/44 : Abundances of evolved stars from IGRINS. I. (Afsar+, 2018)
J/AJ/156/126 : Stellar abundances from BACCHUS analysis (Jonsson+, 2018)
J/MNRAS/482/5138 : Galactic GC mean proper motions & vel. (Baumgardt+, 2019)
J/A+A/622/A191 : 885 globular cluster giants abundances (Masseron+, 2019)
J/MNRAS/484/2832 : Proper motions of MW globular clusters (Vasiliev, 2019)
J/A+A/637/A98 : Globular cluster escapees in the Gal. halo (Hanke+, 2020)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [2M]
3- 18 A16 --- 2MASS 2MASS identifier (HHMMSSss+DDMMSSs)
20- 23 I4 K Teff [4120/5120] Effective temperature
25- 28 F4.2 [cm/s2] logg [0.5/1.94] log, surface gravity
30- 33 F4.2 km/s vt [1.66/2.09] microturbulent velocity
35- 40 F6.3 [-] FeH [-2.33/-1.8] Metallicity
42- 46 F5.3 [-] e_FeH [0.006/0.14] Uncertainty in FeH
48- 52 F5.3 [-] MgFe [0.005/0.66]? Mg/Fe relative abundance
54- 58 F5.3 [-] e_MgFe [0.014/0.14]? Uncertainty in MgFe
60- 65 F6.3 [-] AlFe [-0.42/1.3]? Al/Fe relative abundance
67- 71 F5.3 [-] e_AlFe [0.01/0.2]? Uncertainty in AlFe
73- 77 F5.3 [-] SiFe [0.2/0.65]? Si/Fe relative abundance
79- 83 F5.3 [-] e_SiFe [0.012/0.18]? Uncertainty in SiFe
85- 92 A8 --- Cluster Cluster surveyed ("M53"=44 occurrences or
"NGC 5053"=21 occurrences)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Jan-2022