J/ApJ/908/79    The r-process Alliance; abundances in 519 stars   (Gudin+, 2021)

The r-process Alliance: chemodynamically tagged groups of halo r-process-enhanced stars reveal a shared chemical-evolution history. Gudin D., Shank D., Beers T.C., Yuan Z., Limberg G., Roederer I.U., Placco V., Holmbeck E.M., Dietz S., Rasmussen K.C., Hansen T.T., Sakari C.M., Ezzeddine R., Frebel A. <Astrophys. J., 908, 79 (2021)> =2021ApJ...908...79G 2021ApJ...908...79G
ADC_Keywords: Milky Way; Stars, metal-deficient; Optical; Abundances, [Fe/H]; Proper motions; Radial velocities Keywords: Dwarf galaxies ; Milky Way stellar halo ; Stellar dynamics ; Stellar abundances ; Stellar populations ; R-process Abstract: We derive dynamical parameters for a large sample of 446 r-process-enhanced (RPE) metal-poor stars in the halo and disk systems of the Milky Way, based on data releases from the R-Process Alliance, supplemented by additional literature samples. This sample represents more than a 10-fold increase in size relative to that previously considered by Roederer et al. and, by design, covers a larger range of r-process-element enrichment levels. We test a number of clustering analysis methods on the derived orbital energies and other dynamical parameters for this sample, ultimately deciding on application of the HDBSCAN algorithm, which obtains 30 individual chemodynamically tagged groups (CDTGs); 21 contain between 3 and 5 stars, and 9 contain between 6 and 12 stars. Even though the clustering was performed solely on the basis of their dynamical properties, the stars in these CDTGs exhibit statistically significant similarities in their metallicity ([Fe/H]), carbonicity ([C/Fe]), and neutron-capture element ratios ([Sr/Fe], [Ba/Fe], and [Eu/Fe]). These results demonstrate that the RPE stars in these CDTGs have likely experienced common chemical-evolution histories, presumably in their parent satellite galaxies or globular clusters, prior to being disrupted into the Milky Way's halo. We also confirm the previous claim that the orbits of the RPE stars preferentially exhibit pericentric distances that are substantially lower than the present distances of surviving ultrafaint dwarf and canonical dwarf spheroidal galaxies, consistent with the disruption hypothesis. The derived dynamical parameters for several of our CDTGs indicate their association with previously known substructures, dynamically tagged groups, and RPE groups. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 113 519 Positions, magnitudes, distances, radial velocities, proper motions for the initial sample table3.dat 90 519 RPA classes, temperatures, and elemental abundances for the initial sample table4.dat 79 446 Derived dynamical parameters for the RPE sample table5.dat 136 206 CDTGs identified from the HDBSCAN algorithm -------------------------------------------------------------------------------- See also: I/337 : Gaia DR1 (Gaia Collaboration, 2016) III/279 : RAVE 5th data release (Kunder+, 2017) I/345 : Gaia DR2 (Gaia Collaboration, 2018) I/349 : StarHorse, Gaia DR2 photo-astrometric distances (Anders+, 2019) J/AJ/90/2089 : Stars of very low metal abundance. I (Beers+, 1985) J/AJ/100/1191 : Giants DDO photometry (Morrison+, 1990) J/AJ/103/1987 : Stars of very low metal abundance (Beers+ 1992) J/ApJS/96/175 : Kinematics of Metal-Poor Stars. I. (Beers+ 1995) J/AJ/120/1841 : Abundances & Kinematics of Halo & Disk Stars (Fulbright 2000) J/ApJ/530/783 : The r-process enriched giant HD 115444 (Westin+, 2000) J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004) J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005) J/ApJ/652/1585 : Bright metal-poor stars from HES survey (Frebel+, 2006) J/ApJ/645/613 : Abundances of HD 221170 (Ivans+, 2006) J/AJ/132/1714 : Photometric and Spectroscopic study of TY Gru (Preston+, 2006) J/A+A/484/721 : HES survey. IV. Candidate metal-poor stars (Christlieb+, 2008) J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008) J/A+A/501/519 : Extremely metal-poor turnoff stars abund. (Bonifacio+, 2009) J/MNRAS/404/1529 : s-process in low-metallicity stars (Bisterzo+, 2010) J/ApJ/724/975 : Heavy elements abundances metal-poor stars (Roederer+, 2010) J/ApJ/742/54 : CASH project II. 14 extremely metal-poor stars (Hollek+, 2011) J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011) J/A+A/548/A34 : Abundances of carbon-enhanced metal-poor stars (Allen+, 2012) J/MNRAS/434/1681 : Extremely metal-poor stars CaII triplet (Carrera+, 2013) J/ApJ/778/56 : Hamburg/ESO Survey extremely metal-poor stars (Cohen+, 2013) J/ApJ/771/67 : Detailed abundances 97 metal-poor stars. II. (Ishigaki+, 2013) J/ApJ/775/L27 : Chemical abundances in a metal-poor RGB star (Johnson+, 2013) J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013) J/A+A/569/A43 : HE 2252-4225 abundance analysis (Mashonkina+, 2014) J/ApJ/797/21 : Carbon-enhanced metal-poor stars (Placco+, 2014) J/AJ/147/136 : Stars very low metal abundance VI Abundances (Roederer+, 2014) J/ApJ/807/171 : SkyMapper Survey metalpoor star spectroscopy (Jacobson+, 2015) J/MNRAS/460/884 : EMBLA survey. Galactic bulge metal-poor stars (Howes+, 2016) J/AJ/151/82 : 4 brightest red giants in UFD galaxy Ret 2 (Roederer+, 2016) J/ApJ/844/18 : RAVEJ203843.2-002333 high-resolution spectro. (Placco+, 2017) J/ApJ/864/43 : Abundances 3 bright extremely metal-poor giants (Cain+, 2018) J/A+A/618/A133 : Non standard s-process massive rotating stars (Choplin+, 2018) J/ApJ/858/92 : RPA Southern Pilot Search of 107 Stars (Hansen+, 2018) J/AJ/156/179 : Highly r-process-enhanced field stars kinema. (Roederer+,2018) J/ApJ/865/129 : Abundance analysis of HD 222925 (Roederer+, 2018) J/ApJ/868/110 : R-Process Alliance 1st release Galactic halo (Sakari+, 2018) J/ApJ/863/89 : Gaia DR2 PMs stars in ultra-faint MW satellites (Simon, 2018) J/ApJ/870/83 : Abundances in ultra-faint dwarf gal. GruI & TriII (Ji+, 2019) J/ApJ/875/89 : Metal-poor stars with APF I LAMOST CEMP stars (Mardini+, 2019) J/A+A/627/A173 : Abundances for 4 metal-poor stars (Valentini+, 2019) J/ApJ/898/40 : 2MASSJ15213995-3538094 abund. from high-res. sp. (Cain+, 2020) J/ApJ/898/150 : High-res. MIKE obs. of metal-poor stars (Ezzeddine+, 2020) J/ApJS/249/30 : R-Process Alliance metal-poor star spectro. (Holmbeck+, 2020) J/ApJ/897/78 : RAVEJ183013.5-455510 equivalent-width measure. (Placco+, 2020) J/A+A/638/A76 : StarHorse data for 5 surveys (Queiroz+, 2020) J/ApJ/905/20 : Metal-poor stars observed with SALT/HRS (Rasmussen+, 2020) J/ApJ/891/39 : LAMOSTDR3 very metal-poor stars of Galactic halo (Yuan+, 2020) J/ApJ/907/10 : Initial vs final sample of VMP HK/HES stars (Limberg+, 2021) Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 28 A28 --- Name Object name 30- 31 I2 h RAh [0/23] Hour of Right Ascension (J2000) 33- 34 I2 min RAm Minute of Right Ascension (J2000) 36- 40 F5.2 s RAs Second of Right Ascension (J2000) 42- 42 A1 --- DE- [±] Sign of the Declination (J2000) 43- 44 I2 deg DEd Degree of Declination (J2000) 46- 47 I2 arcmin DEm Arcminute of Declination (J2000) 49- 52 F4.1 arcsec DEs Arcsecond of Declination (J2000) 54- 58 F5.2 mag Vmag [5.67/16.5]? V band magnitude (1) 60- 64 F5.2 kpc Dist-g [0.01/18.5]? Distance based on Gaia DR2 parallax (2) 66- 70 F5.2 kpc e_Dist-g [0/20]? Uncertainty in Dist-g 71- 72 A2 --- f_Dist-g Flag on Dist-g (3) 75- 79 F5.2 kpc Dist-sh [0.01/15.9]? Distance derived StarHorse (4) 81- 84 F4.2 kpc e_Dist-sh [0/7]? Uncertainty on Dist-sh 85- 86 A2 --- f_Dist-sh Flag on Dist-sh (3) 88- 93 F6.1 km/s RVel [-380/476]? Radial Velocity (5) 95- 95 A1 --- r_RVel Source for RVel (5) 97-104 F8.2 mas/yr pmRA [-1001/4003] proper motion, Right Ascension (6) 106-113 F8.2 mas/yr pmDE [-5817.86/79.78] proper motion, Declination (6) -------------------------------------------------------------------------------- Note (1): V band magnitudes transformed from Gaia G magnitudes using the photometric transformations from Evans+, 2018A&A...616A...4E 2018A&A...616A...4E, Table A.2; specifically, V=G+0.01760+0.006860x(GBP-GRP)+0.1732x(GBP-GRP)2. Note (2): Distance estimates were obtained from inversion of the reported Gaia DR2 parallax, with a positive correction of 0.054mas added to the parallax value, as recommended by Everall+, 2019MNRAS.489..910E 2019MNRAS.489..910E and Schonrich+, 2019MNRAS.487.3568S 2019MNRAS.487.3568S. Note (3): Flags as follows: * = stars with relative distance errors in the range 20%<e=<30% ** = stars with relative distance errors in the range e>30% Note (4): Distance estimates obtained using the Bayesian tool StarHorse (Queiroz+, 2018MNRAS.476.2556Q 2018MNRAS.476.2556Q, 2020, J/A+A/638/76; Anders+, 2019, I/349). Note (5): Radial velocities from Gaia DR2 except when not available the values are supplemented with radial velocities from RAVE DR5, where available (Kunder+, 2017, III/279), as well as from other literature sources as follows : a = Jacobson+, 2015, J/ApJ/807/171 b = Roederer+, 2014, J/AJ/147/136 c = T.C. Beers, private comm. d = Hansen+, 2015ApJ...807..173H 2015ApJ...807..173H e = Beers+, 1992, J/AJ/103/1987 f = Beers & Sommer-Larsen, 1995, J/ApJS/96/175 g = Barklem+, 2005, J/A+A/439/129 h = Ezzeddine+, 2020, J/ApJ/898/150 i = Hansen+, 2018, J/ApJ/858/92 j = Aoki+, 2002PASJ...54..933A 2002PASJ...54..933A k = Bonifacio+, 2009, J/A+A/501/519 l = Kunder+, 2017, J/AJ/153/75 m = Xing+, 2019NatAs...3..631X 2019NatAs...3..631X n = Carrera+, 2013, J/MNRAS/434/1681 o = Cohen+, 2013, J/ApJ/778/56 p = Holmbeck+, 2020, J/ApJS/249/30 q = Aoki+, 2005, J/ApJ/632/611 r = Frebel+, 2006, J/ApJ/652/1585 s = Sakari+, 2018, J/ApJ/868/110 t = Howes+, 2015Natur.527..484H 2015Natur.527..484H u = Howes+, 2016, J/MNRAS/460/884 v = Allende Prieto+, 2000AJ....120.1516A 2000AJ....120.1516A w = Aoki+, 2010ApJ...723L.201A 2010ApJ...723L.201A x = Johnson+, 2011, J/ApJ/732/108 Note (6): Proper motions from Gaia DR2 except 2MASS J10345348-1117221, which is taken from where from Kharchenko & Roeser, 2009, I/280. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 28 A28 --- Name Object name 30- 42 A13 --- Class Dominant neutron capture class (1) 44- 47 I4 K Teff [4150/6650] Stellar effective temperature 49- 53 F5.2 [-] [Fe/H] [-4.04/-1] Log, Fe/H number abundance ratio 55- 59 F5.2 [-] [C/Fe] [-1.75/2.38]? Log, C/Fe number abundance ratio 61- 65 F5.2 [-] [C/Fe]c [-1.75/2.38]? Log, C/Fe number abundance ratio, corrected (2) 67- 67 A1 --- l_[Sr/Fe] Limit flag for [Sr/Fe] 69- 73 F5.2 [-] [Sr/Fe] [-2.87/1.44]? Log, Sr/Fe number abundance ratio 75- 79 F5.2 [-] [Ba/Fe] [-1.99/2.42] Log, Ba/Fe number abundance ratio 81- 85 F5.2 [-] [Eu/Fe] [-0.84/2.83] Log, Eu/Fe number abundance ratio 87- 88 A2 --- Ref Sources for chemical-abundance information (3) 90- 90 I1 --- r_Class [0/1] Source for Class (4) -------------------------------------------------------------------------------- Note (1): Class for dominant neutron capture processes, Table 1, following Beers & Christlieb 2005ARA&A..43..531B 2005ARA&A..43..531B, Frebel+, 2018ARNPS..68..237F 2018ARNPS..68..237F but with the r-I/II division at [Eu/Fe]>+0.7 rather than prior [Eu/Fe]>+1.0 (Holmbeck+, 2020, J/ApJS/249/30) r-I =+0.3=<[Eu/Fe]=<+0.7 and [Ba/Eu]<0.0 r-II =[Eu/Fe]>+0.7 and [Ba/Eu]<0.0 r-I/CEMP-r=[C/Fe]>+0.7 and +0.3=<[Eu/Fe]=<+0.7 and [Ba/Eu]<0.0; r-II/CEMP-r=[C/Fe]>+0.7 and [Eu/Fe]>+0.7 and [Ba/Eu]<0.0; limited-r=[Eu/Fe]<+0.3, [Sr/Ba]>+0.5. Note (2): Corrected for evolutionary status following Placco+, 2014, J/ApJ/797/21. Note (3): Sources for chemical-abundance information as follows: a = Hansen+, 2018, J/ApJ/858/92 b = Holmbeck+, 2020, J/ApJS/249/30 c = Jacobson+, 2015, J/ApJ/807/171 d = Fulbright, 2000, J/AJ/120/1841 e = Roederer+, 2014ApJ...784..158R 2014ApJ...784..158R f = Barklem+, 2005, J/A+A/439/129 g = Sakari+, 2018, J/ApJ/868110 h = Allen+, 2012, J/A+A/548/34 i = Ezzeddine+, 2020, J/ApJ/898/150 j = Hansen+, 2015ApJ...807..173H 2015ApJ...807..173H k = Christlieb+, 2004ApJ...603..708C 2004ApJ...603..708C l = Siqueira Mello+, 2014A&A...565A..93S 2014A&A...565A..93S m = Hansen+, 2012A&A...545A..31H 2012A&A...545A..31H n = Lai+, 2008, J/ApJ/681/1524 o = Rasmussen+, 2020, J/ApJ/905/20 p = Preston+, 2006, J/AJ/132/1714 q = Hollek+, 2011, J/ApJ/742/54 r = Cayrel+, 2004, J/A+A/416/1117 s = Cain+, 2018, J/ApJ/864/43 t = Holmbeck+, 2018ApJ...859L..24H 2018ApJ...859L..24H u = Mardini+, 2019, J/ApJ/875/89 v = Li+, 2015PASJ...67...84L 2015PASJ...67...84L w = Xing+, 2019NatAs...3..631X 2019NatAs...3..631X x = Valentini+, 2019, J/A+A/627/173 y = Hayek+, 2009A&A...504..511H 2009A&A...504..511H z = Ishigaki+, 2013, J/ApJ/771/67 aa = Johnson & Bolte, 2002ApJ...579..616J 2002ApJ...579..616J ab = Cohen+, 2013, J/ApJ/778/56 ac = Westin+, 2000, J/ApJ/530/783 ad = Roederer+, 2010, J/ApJ/724/975 ae = Aoki+, 2005ApJ...632..611A 2005ApJ...632..611A af = Hawkins & Wyse, 2018MNRAS.481.1028H 2018MNRAS.481.1028H ag = Burris+, 2000ApJ...544..302B 2000ApJ...544..302B ah = Honda+, 2004ApJ...607..474H 2004ApJ...607..474H ai = Cain+, 2020, J/ApJ/898/40 aj = Cowan+, 2002ApJ...572..861C 2002ApJ...572..861C ak = Howes+, 2015Natur.527..484H 2015Natur.527..484H al = Johnson+, 2013, J/ApJ/775/L27 am = Placco+, 2020, J/ApJ/897/78 an = Howes+, 2016, J/MNRAS/460/884 ao = McWilliam+, 1995AJ....109.2757M 1995AJ....109.2757M ap = Placco+, 2017, J/ApJ/844/18 aq = Sneden+, 2003ApJ...591..936S 2003ApJ...591..936S ar = Mashonkina+, 2014, J/A+A/569/43 as = Ivans+, 2006, J/ApJ/645/613 at = Ryan+, 1996ApJ...471..254R 1996ApJ...471..254R au = Roederer+, 2018, J/ApJ/865/129 av = Masseron+, 2012ApJ...751...14M 2012ApJ...751...14M aw = Aoki+, 2010ApJ...723L.201A 2010ApJ...723L.201A Note (4): Code as follow: 1 = from papers from the RPA 0 = from other sources -------------------------------------------------------------------------------- Byte-by-byte Description of file: table4.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 28 A28 --- Name Object name 30- 30 A1 --- Flag relative distance errors in the range 20%<e<30% 32- 36 F5.2 10+5km2/s2 Energy [-2.42/-0.08] Specific orbital energy (1) 38- 41 F4.2 --- Ecc [0.04/0.99] Orbit eccentricity (1) 43- 47 F5.2 10+3kpc.km/s Jr [0/84.85] Actions due to oscillations along the orbital radius (1) 49- 53 F5.2 10+3kpc.km/s Jp [-6.1/3.92] Action due to orbital motions (1) 55- 58 F4.2 10+3kpc.km/s Jz [0/3.9] Action due to oscillations along the axis perpendicular to the Galactic plane (1) 60- 64 F5.2 kpc rperi [0.08/18.1] pericentric distance 66- 72 F7.2 kpc rapo [1.63/2057] apocentric distance 74- 79 F6.2 kpc Zmax [0.17/157] Maximum distance from the Galactic plane -------------------------------------------------------------------------------- Note (1): Orbital parameters as derived using the AGAMA package (Vasiliev, 2019MNRAS.482.1525V 2019MNRAS.482.1525V) and the MW2017 potential (McMillan, 2017MNRAS.465...76M 2017MNRAS.465...76M) as follows: E = the specific orbital energy, defined as the full orbital energy of the star divided by its mass; Ecc = orbital eccentricity is obtained from (rapo-rperi)/(rapo+rperi); Jr = the orbital action due to oscillations along the orbital radius, is defined to be non-negative. For a given E, Jr=0 for circular orbits and is large for eccentric orbits. Jp = the action due to orbital motions, is taken to be the reverse projection of the angular momentum on the axis perpendicular to the Galactic plane, Lz. In our adopted coordinate system, positive and negative values of Jp (and Vp) correspond to prograde and retrograde motions about the Milky Wayys center, respectively. Jz = the action due to oscillations along the axis perpendicular to the Galactic plane, is defined to be non-negative. Jz=0 for planar orbits, and is large for orbits with large Zmax. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table5.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 7 A7 --- CDTG Chemo-Dynamically Tagged Group number (1) 9- 10 I2 --- Nstar [3/12] Number of stars in CDTG (1) 12- 15 F4.1 --- CL [12.4/99.8] Confidence level, CDTG (1) 17- 40 A24 --- Name Object Name (1) 42- 42 A1 --- Flag relative distance errors in the range 20%<e<30% 44- 56 A13 --- Class Dominant neutron capture class (2) 58- 62 F5.2 [-] [Fe/H] [-3.2/0.95] Log, Fe/H number abundance ratio 64- 67 F4.2 [-] e_[Fe/H] [0.08/0.7]? Standard deviation CDTG mean [Fe/H] 69- 69 A1 --- l_[C/Fe] Limit flag for [C/Fe] 70- 74 F5.2 [-] [C/Fe] [-0.95/1.78]? Log, C/Fe number abundance ratio 76- 79 F4.2 [-] e_[C/Fe] [0.05/0.6]? Standard deviation CDTG mean [C/Fe] 81- 81 A1 --- l_[C/Fe]c Limit flag for [C/Fe]c 82- 86 F5.2 [-] [C/Fe]c [-0.57/1.78]? Log, C/Fe (corrected) number abundance ratio (3) 88- 91 F4.2 [-] e_[C/Fe]c [0.02/0.6]? Standard deviation CDTG mean [C/Fe]c (3) 93- 93 A1 --- l_[Sr/Fe] Limit flag for [Sr/Fe] 94- 98 F5.2 [-] [Sr/Fe] [-2.87/1.11]? Log, Sr/Fe number abundance ratio 100-103 F4.2 [-] e_[Sr/Fe] [0.09/0.6]? Standard deviation CDTG mean [Sr/Fe] 105-109 F5.2 [-] [Ba/Fe] [-0.85/0.98] Log, Ba/Fe number abundance ratio 111-114 F4.2 [-] e_[Ba/Fe] [0.01/0.6]? Standard deviation CDTG mean [Ba/Fe] 116-120 F5.2 [-] [Eu/Fe] [0.02/1.7] Log, Eu/Fe number abundance ratio 122-125 F4.2 [-] e_[Eu/Fe] [0.02/0.6]? Standard deviation CDTG mean [Eu/Fe] 127-131 F5.2 [-] [Eu/H] [-2.46/-0.29]? Log, Eu/H number abundance ratio 133-136 F4.2 [-] e_[Eu/H] [0.13/0.8]? Standard deviation CDTG mean [Eu/H] -------------------------------------------------------------------------------- Note (1): For each CDTG the data in the first three columns are repeated for each row, including the CDTG sequence number, the number of objects in the group and the confidence level for the group. In addition to listing group objects, the table includes and additional two rows for each CDTG. The first additional row with Name=Avg includes the mean and standard deviation for the elemental abundances in each CDTG with at least 3 measured abundances are listed. When the number of available measured elemental abundances is 4 or more, biweight estimates of these quantities are reported, in order to decrease the influence of potential outliers. The second additional row with Name=CFV provides the cumulative fraction value [0,1] for the elemental abundance in the group Note (2): Class for dominant neutron capture processes, Table 1, following Beers & Christlieb, 2005ARA&A..43..531B 2005ARA&A..43..531B, Frebel+, 2018ARNPS..68..237F 2018ARNPS..68..237F but with the r-I/II division at [Eu/Fe]>+0.7 rather than prior [Eu/Fe]>+1.0 (Holmbeck+, 2020, J/ApJS/249/30) as follows: r-I = +0.3=<[Eu/Fe]=<+0.7 and [Ba/Eu]<0.0; r-II = [Eu/Fe]>+0.7 and [Ba/Eu]<0.0; r-I / CEMP-r = [C/Fe]>+0.7 and +0.3=<[Eu/Fe]=<+0.7 and [Ba/Eu]<0.0; r-II / CEMP-r = [C/Fe]>+0.7 and [Eu/Fe]>+0.7 and [Ba/Eu]<0.0; limited-r = [Eu/Fe]<+0.3, [Sr/Ba]>+0.5. Note (3): Corrected for evolutionary status following Placco+, 2014, J/ApJ/797/21. -------------------------------------------------------------------------------- History: From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 28-Jun-2022
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