J/ApJ/907/10 Initial vs final sample of the VMP HK/HES stars (Limberg+, 2021)
Dynamically Tagged Groups of Very Metal-poor Halo Stars from the HK and
Hamburg/ESO Surveys.
Limberg G., Rossi S., Beers T.C., Perottoni H.D., Perez-Villegas A.,
Santucci R.M., Abuchaim Y., Placco V.M., Lee Y.S., Christlieb N.,
Norris J.E., Bessell M.S., Ryan S.G., Wilhelm R., Rhee J., Frebel A.
<Astrophys. J., 907, 10 (2021)>
=2021ApJ...907...10L 2021ApJ...907...10L
ADC_Keywords: Stars, metal-deficient; Spectra, optical; Abundances, [Fe/H];
Effective temperatures; Radial velocities; Proper motions
Keywords: Milky Way dynamics ; Milky Way evolution ; R-process ;
Population II stars ; Milky Way stellar halo
Abstract:
We analyze the dynamical properties of ∼1500 very metal-poor (VMP;
[Fe/H]≲-2.0) halo stars, based primarily on medium-resolution
spectroscopic data from the HK and Hamburg/ESO surveys. These data,
collected over the past 30yr, are supplemented by a number of
calibration stars and other small samples, along with astrometric
information from Gaia DR2. We apply a clustering algorithm to the 4D
energy-action space of the sample, and identify a set of 38
dynamically tagged groups (DTGs), containing between 5 and 30 member
stars. Many of these DTGs can be associated with previously known
prominent substructures such as Gaia-Sausage/Enceladus (GSE), Sequoia,
Helmi Stream (HStr), and Thamnos. Others are associated with
previously identified smaller dynamical groups of stars and streams.
We identify 10 new DTGs as well, many of which have strongly
retrograde orbits. We also investigate possible connections between
our DTGs and ∼300 individual r-process-enhanced (RPE) stars from a
recent literature compilation. We find that several of these objects
have similar dynamical properties to GSE (5), the HStr (4), Sequoia
(1), and Rg5 (1), indicating that their progenitors might have been
important sources of RPE stars in the Galaxy. Additionally, a number
of our newly identified DTGs are shown to be associated with at least
two RPE stars each (DTG-2:3, DTG-7:2; DTG-27:2). Taken as a whole,
these results are consistent with ultra-faint and/or dwarf spheroidal
galaxies as birth environments in which r-process nucleosynthesis took
place, and then were disrupted by the Milky Way.
Description:
In this work, we have considered the dynamical properties of the very
metal poor (VMP; [Fe/H]≲-2.0) stars primarily selected from the
HK/HES surveys. Over the past three decades, the metal-poor candidates
identified in these surveys have been followed-up with
medium-resolution (1200≲R∼2000) spectroscopy with a wide variety of
telescopes and instruments. The typical spectral coverage of these
spectra are 3500-5000Å, although there was wide variation. The
decisions as to which targets to observe are difficult to quantify,
since many observers contributed to these efforts. In addition, in
some cases, photometric information from independent efforts (HK), or
taken directly from an approximate calibration of the prism spectra
(HES), were obtained in advance of the spectroscopic follow-up.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table5.dat 125 4443 Initial sample of the VMP HK/HES stars
table6.dat 115 1526 Final sample of the VMP HK/HES stars
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See also:
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/349 : StarHorse, Gaia DR2 photo-astrometric distances (Anders+, 2019)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/AJ/90/2089 : Stars of very low metal abundance. I (Beers+, 1985)
J/ApJS/61/667 : Kinematics of Galactic old population (Norris 1986)
J/AJ/103/1987 : Stars of very low metal abundance (Beers+ 1992)
J/AJ/117/981 : Estimation of stellar metal abundance. II. (Beers+, 1999)
J/MNRAS/320/451 : A-G star metallicity (Beers+, 2001)
J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)
J/AJ/130/2804 : Carbon abundances in metal-poor stars (Rossi+, 2005)
J/ApJ/652/1585 : Bright metal-poor stars from HES survey (Frebel+, 2006)
J/ApJ/655/492 : Equivalent widths of 26 metal-poor stars (Aoki+, 2007)
J/A+A/484/721 : HES survey. IV. Candidate metal-poor stars (Christlieb+, 2008)
J/AJ/136/2050 : SEGUE stellar parameter pipeline. II. (Lee+, 2008)
J/ApJ/703/2177 : Metal-poor MS turnoff stars summary (Schlaufman+, 2009)
J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009)
J/ApJ/719/931 : Chemical evolution of the UMi dSph (Cohen+, 2010)
J/ApJ/714/663 : Stellar density map of the Milky Way (de Jong+, 2010)
J/A+A/511/L10 : Abundances and space velocities of 94 stars (Nissen+, 2010)
J/AJ/139/1051 : Carbon-enhanced metal-poor stars in the Galaxy (Placco+, 2010)
J/ApJ/711/573 : Detailed abundances in a halo stellar stream (Roederer+, 2010)
J/AJ/141/90 : SEGUE stellar parameter pipeline. V. (Lee+, 2011)
J/AJ/142/188 : Metal-poor stars from the HES using CH G-band (Placco+, 2011)
J/ApJ/749/77 : MW halo. III. Statistical chemic abundances (Schlaufman+, 2012)
J/ApJ/794/58 : Metal-poor stars in the thick disk of the Galaxy (Beers+, 2014)
J/ApJ/788/180 : Very metal-poor stars in the Milky Way's halo (Carollo+, 2014)
J/ApJ/781/40 : Metal-poor stars HES survey. II. Spectroscopy (Placco+, 2014)
J/ApJ/797/21 : Carbon-enhanced metal-poor stars (Placco+, 2014)
J/AJ/147/136 : Stars of very low metal abundance. VI. Abund. (Roederer+, 2014)
J/MNRAS/448/822 : LAMOST candidate members of star clusters (Xiang+, 2015)
J/AJ/151/82 : 4 brightest red giants in the UFD galaxy Ret2 (Roederer+, 2016)
J/ApJ/835/81 : Bright metal-poor stars from HES Survey. II. (Beers+, 2017)
J/ApJ/838/44 : Abundances of the brightest member of Tuc III (Hansen+, 2017)
J/A+A/618/A93 : Gaia DR2 open clusters in the Milky Way (Cantat-Gaudin+, 2018)
J/A+A/616/A10 : 46 open clusters GaiaDR2 HR diagrams (Gaia Collaboration, 2018)
J/A+A/616/A12 : Gaia DR2 sources in GC and dSph (Gaia Collaboration+, 2018)
J/ApJ/858/92 : RPA Southern Pilot Search of 107 Stars (Hansen+, 2018)
J/ApJ/852/49 : Properties of metal-poor stars in APOGEE DR13 (Hayes+, 2018)
J/ApJS/238/16 : LAMOST-DR3 very metal-poor star catalog (Li+, 2018)
J/AJ/155/256 : Spectroscopic validation RAVE metal-poor stars (Placco+, 2018)
J/AJ/156/179 : Highly r-process-enhanced stars kinematics (Roederer+, 2018)
J/ApJ/868/110 : R-Process Alliance 1st release in Galactic halo (Sakari+, 2018)
J/A+A/623/A128 : Galactic halo CEMP stars abund. & kinematics (Hansen+, 2019)
J/ApJ/882/177 : Abundances of 4 member stars of Tucana III (Marshall+, 2019)
J/ApJ/870/122 : Spectroscopy of low-metallicity star candidates (Placco+, 2019)
J/ApJ/894/34 : Metallicity gradient SDSS & SMSS in halo stars (Dietz+, 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/A+A/638/A76 : StarHorse data for 5 surveys (Queiroz+, 2020)
J/ApJ/891/39 : LAMOST DR3 very metal-poor stars of Galactic halo (Yuan+, 2020)
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- 2MASS 2MASS identifier
18- 30 A13 --- HK HK survey identifier
32- 44 A13 --- HES Hamburg/ESO survey identifier
46- 66 A21 --- OName Other identifier
68- 75 F8.4 deg RAdeg [0.003/360] Right Ascension in decimal degrees
(J2000)
77- 84 F8.4 deg DEdeg [-86/75] Declination in decimal degrees (J2000)
86- 89 F4.1 mag Vmag [5.7/21.1]? Apparent V band magnitude
91- 94 I4 K Teff [4010/6998] Effective temperature
96- 99 F4.2 [cm/s2] logg [0.12/5] log surface gravity
101-105 F5.2 [Sun] [Fe/H] [-4.61/-1.8] Metallicity
107 A1 --- f_[Fe/H] [d] Flag on [Fe/H] (1)
109 A1 --- l_[C/Fe] Limit flag on [C/Fe]
110-114 F5.2 [Sun] [C/Fe] [-2.27/4.92]? log C/Fe abundance
116 A1 --- f_[C/Fe] [d] Flag on [C/Fe] (1)
118 A1 --- l_[C/Fe]c Limit flag on [C/Fe]c
119-123 F5.2 [Sun] [C/Fe]c [-2.27/4.92]? log corrected C/Fe abundance (2)
125 A1 --- f_[C/Fe]c [d] Flag on [C/Fe]c (1)
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Note (1): Flag as follows:
d = CEMP star with Teff≤4500K. The [Fe/H], [C/Fe], and [C/Fe]c
ratios should be taken with caution (Section A.1).
Note (2): Corrected for their evolutionary status (Placco+, 2014, J/ApJ/797/21).
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 2MASS 2MASS identifier
18- 21 I4 km/s RVel [-519/524] Radial velocity (1)
23- 28 F6.1 km/s RVelG [-397/492]? Gaia DR2 radial velocity
30- 34 F5.2 kpc Dist [0.03/17.4] StarHorse distance (2)
36- 39 F4.2 kpc e_Dist [0.0/3.32] Uncertainty in Dist
41- 48 F8.2 mas/yr pmRA [-1115/936] Gaia DR2 proper motion in RA
50- 57 F8.2 mas/yr pmDE [-1836/516] Gaia DR2 proper motion in DE
59- 63 F5.2 10+5km2/s2 E [-2.03/-0.16] Energy
65- 69 F5.2 10+3kpc.km/s JR [0.01/44.4] Radial action
71- 75 F5.2 10+3kpc.km/s Jth [-3.76/4.17] Azimuthal action
77- 80 F4.2 10+3kpc.km/s Jz [0/4.82] Vertical action
82- 85 F4.2 --- e [0.08/0.99] Eccentricity
87- 91 F5.1 deg i [1.6/179] Inclination
93- 99 F7.2 km/s RV [-484/416] Radial velocity
101-107 F7.2 km/s vth [-472/500] Azimuthal velocity
109-115 F7.2 km/s vz [-451/550] Vertical velocity
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Note (1): From the medium-resolution spectroscopy (corrected
to the heliocentric frame).
Note (2): From Anders+, 2019, I/349, as described in Section 2.3.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 30-May-2022