J/ApJ/901/23 Gjoll stream stars & detailed abund. of 4 members (Hansen+, 2020)
A chemo-dynamical link between the Gjoll stream and NGC 3201.
Hansen T.T., Riley A.H., Strigari L.E., Marshall J.L., Ferguson P.S.,
Zepeda J., Sneden C.
<Astrophys. J., 901, 23 (2020)>
=2020ApJ...901...23H 2020ApJ...901...23H
ADC_Keywords: Abundances; Equivalent widths; Radial velocities; Milky Way;
Spectra, optical
Keywords: Milky Way dynamics ; Chemical abundances ; Globular star clusters
Abstract:
Recent analysis of the second data release of Gaia has revealed a
number of new stellar streams surrounding the Milky Way. It has been
suggested that one of these streams, Gjoll, is associated with the
globular cluster NGC 3201, but thus far the association has only been
based on kinematics of the stream stars. In this work we identify five
likely stream members in the Gaia data that are bright enough for
high-resolution spectroscopic follow-up with the Harlan J. Smith
telescope at McDonald Observatory. One star is ruled out as a member
based on its radial velocity. Abundance analysis of the remaining four
kinematic members reveals a good chemical match to NGC 3201 for two of
the stars, driven by their similar Al and α-element abundances.
Of the remaining two, one shows no chemical similarity to NGC 3201 and
is likely an unassociated Milky Way halo field star, while the other
exhibits a similar Al abundance but has somewhat lower α-element
abundances. The chemical tagging of stars in the Gjoll stream to
NGC3201 confirms this association and provides direct proof of the
hierarchical formation of the Milky Way.
Description:
The kinematically selected targets brighter than G=15mag were observed
with the Harlan J. Smith 107 in (2.7m) telescope and the TS23 echelle
spectrograph at McDonald Observatory (R∼35000, with full wavelength
coverage over 3600-5800Å). The five stars, Gaia 3254112556278356608,
Gaia 3187390548572555136, Gaia 2990142148280216960,
Gaia 3259158764894232192 and Gaia 3258976074166599680, were observed
over four separate runs from 2019 November to 2020 February.
The measured radial velocities rejected Gaia 3258976074166599680 as a
member while confirming the kinematic membership for the other four stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 98 166 Known and suspected Gjoll stream stars
table5.dat 66 317 EW and atomic data for FeI and FeII lines used
for parameter determination
table6.dat 82 148 Individual line abundances
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
J/A+A/404/187 : Equivalent widths for metal-poor stars (Gratton+, 2003)
J/A+A/505/139 : Abundances of red giants in 17 GCs (Carretta+, 2009)
J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)
J/ApJ/778/149 : Abundances for 3 stars in Sgr dSph (McWilliam+, 2013)
J/ApJ/801/69 : Iron EWs for NGC3201 giant star members (Mucciarelli+, 2015)
J/MNRAS/446/3319 : Line list for the NGC 1851 stars (Yong+, 2015)
J/AJ/156/18 : APOGEE: companions of evolved stars (Price-Whelan+, 2018)
J/MNRAS/478/4513 : GALAH Survey DR2 (Buder+, 2018)
J/A+A/616/A12 : Gaia DR2 sources in GC and dSph (Gaia Collaboration+, 2018)
J/ApJ/864/57 : Abund. of field & GC RR Lyrae. I. NGC3201 (Magurno+, 2018)
J/A+A/616/A7 : Gaia DR2 RV standard stars catalog (Soubiran+, 2018)
J/MNRAS/486/2995 : GD-1 stellar stream (Malhan+, 2019)
J/AJ/158/223 : Pal 5 stellar stream RR Lyrae members (Price-Whelan+, 2019)
J/ApJ/883/84 : 2 metal-poor stars in Sylgr stream (Roederer+, 2019)
J/ApJ/885/3 : Membership in 12 stellar streams from DES (Shipp+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- Gaia Gaia DR2 source identifier (1)
21- 27 F7.3 deg RAdeg [56.8/152.3] Right Ascension (J2000)
29- 35 F7.3 deg DEdeg [-48.1/8.8] Declination (J2000)
37- 42 F6.3 mag Gmag [13.1/19.7] Apparent Gaia DR2 magnitude
44- 48 F5.3 mag GB-GR [0.49/1.3] Gaia DR2 (GBP-GRP) color index
50- 54 F5.2 mas plx [-0.45/1.57] Gaia DR2 parallax
56- 59 F4.2 mas e_plx [0.02/0.7] Uncertainty in plx
61- 65 F5.2 mas/yr pmRA [8.2/24.9] Proper motion along RA * cos(DE)
67- 70 F4.2 mas/yr e_pmRA [0.03/1.2] Uncertainty in pmRA
72- 77 F6.2 mas/yr pmDE [-24.8/-2.1] Proper motion along DE
79- 82 F4.2 mas/yr e_pmDE [0.03/1.1] Uncertainty in pmDE
84- 90 F7.2 km/s HRV [-150.6/112.1]? Heliocentric radial velocity (1)
92- 95 F4.2 km/s e_HRV [0.6/4.4]? Uncertainty in HRV (1)
96 A1 --- r_HRV [*] * = from Ibata+ 2019ApJ...872..152I 2019ApJ...872..152I
98 A1 --- I19 In Ibata+ (from Ibata+ 2019ApJ...872..152I 2019ApJ...872..152I)?
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Note (1): The first 9 sources have spectroscopic followup from either this work
or Ibata+ 2019ApJ...872..152I 2019ApJ...872..152I
The rest do not have any spectroscopic followup and hence no HRV
values are provided.
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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- 4 A4 --- --- [Gaia]
6- 24 I19 --- Gaia Gaia DR2 source identifier
26- 30 A5 --- Ion Species identifier ("Fe I" or "Fe II")
32- 38 F7.2 0.1nm lambda [4067.97/8387.77] Wavelength; Angstroms
40- 44 F5.3 eV ExPot [0/4.8] Excitation potential
46- 50 F5.2 [-] log(gf) [-4.97/0.65] log oscillator strength
52- 56 F5.1 0.1nm EW [12.8/141.2] Equivalent width
58- 61 F4.1 0.1nm e_EW [2.9/11.3] Uncertainty in EW
63- 66 F4.2 [-] log(e) [5.5/6.8] log abundance
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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- 5 A5 --- Ion Species identifier
7- 13 F7.2 0.1nm lambda [3783.53/7836.13] Wavelength; Angstroms
15- 18 F4.2 eV ExPot [0/5.08]? Excitation potential
20- 24 F5.2 [-] log(gf) [-5.7/0.32]? log oscillator strength
26- 31 F6.2 0.1nm EW3 [19.4/166.5]? Gaia 32541125 equivalent width
33 A1 --- f_EW3 s = derived synthesis analysis
35- 39 F5.2 [-] log(e)3 [-0.01/7.4]? Gaia 32541125 log abundance
41- 46 F6.2 0.1nm EW7 [22.1/200.3]? Gaia 31873905 equivalent width
48 A1 --- f_EW7 s = derived synthesis analysis
50- 54 F5.2 [-] log(e)7 [-0.4/6.9]? Gaia 31873905 log abundance
56- 61 F6.2 0.1nm EW8 [15.8/223.3]? Gaia 29901421 equivalent width
63 A1 --- f_EW8 s = derived synthesis analysis
65- 68 F4.2 [-] log(e)8 [0.07/6.5]? Gaia 29901421 log abundance
70- 75 F6.2 0.1nm EW2 [10.3/171.1]? Gaia 32591587 equivalent width
77 A1 --- f_EW2 s = derived synthesis analysis
79- 82 F4.2 [-] log(e)2 [0.3/6.1]? Gaia 32591587 log abundance
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 05-Jan-2022