J/ApJ/778/56 Hamburg/ESO Survey extremely metal-poor stars (Cohen+, 2013)
Normal and outlying populations of the Milky Way stellar halo at [Fe/H]←2.
Cohen J.G., Christlieb N., Thompson I., McWilliam A., Shectman S.,
Reimers D., Wisotzki L., Kirby E.
<Astrophys. J., 778, 56 (2013)>
=2013ApJ...778...56C 2013ApJ...778...56C
ADC_Keywords: Stars, metal-deficient ; Stars, carbon ; Radial velocities ;
Abundances ; Equivalent widths ; Surveys
Keywords: Galaxy: abundances; Galaxy: formation; Galaxy: halo
Abstract:
From detailed abundance analysis of >100 Hamburg/ESO candidate
extremely metal-poor (EMP) stars we find 45 with [Fe/H]←3.0dex. We
identify a heretofore unidentified group: Ca-deficient stars with
sub-solar [Ca/Fe] ratios and the lowest neutron-capture abundances;
the Ca-deficient group comprises ∼10% of the sample, excluding Carbon
stars. Our radial velocity distribution shows that the carbon-enhanced
stars with no s-process enhancements, CEMP-no, and which do not show
C2 bands are not preferentially binary systems. Ignoring Carbon
stars, approximately 15% of our sample are strong (≥5σ)
outliers in one or more elements between Mg and Ni; this rises to ∼19%
if very strong (≥10σ) outliers for Sr and Ba are included.
Examples include: HE0305-0554 with the lowest [Ba/H] known;
HE1012-1540 and HE2323-0256, two (non-velocity variable) C-rich stars
with very strong [Mg,Al/Fe] enhancements; and HE1226-1149, an
extremely r-process rich star.
Description:
HIRES observations commenced in 2000 September at the Keck I Telescope
and continued at a rapid pace through late 2007, extending at a slower
pace until early 2012 (3250-5990Å and 3880-8360Å).
MIKE/Magellan observations began in 2003 and continued through 2008.
MIKE observations have a spectral resolution of 42000 in the blue
camera and 32000 in the red camera with full spectral coverage.
The total sample of extremely metal-poor (EMP) candidates with high
dispersion spectra and detailed abundance analyses presented here,
including those from the Keck Pilot Project (Cohen et al.
2002AJ....124..470C 2002AJ....124..470C; Carretta et al. 2002AJ....124..481C 2002AJ....124..481C) and a few
stars selected from the HK Survey (Beers et al. 1985, J/AJ/90/2089 and
1992, J/AJ/103/1987), is 122 stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 71 146 Sample of 122 candidate extremely metal poor (EMP)
stars, mostly from the HES, and log of HIRES/Keck
and Mike/Magellan
table2a.dat 40 34 Abundances for EMP stars
table2b.dat 50 77 Radial velocity for EMP stars with multiple
spectra from HIRES
table3.dat 50 119 Nominal and adopted stellar parameters
table6.dat 40 109 Slopes of linear fits to abundances of
individual FeI lines
table7.dat 32 425 Atomic data for lines used
table8.dat 37 31586 Equivalent widths
table10.dat 34 3244 Relative abundances
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See also:
J/ApJ/762/27 : Most metal-poor stars. III. [Fe/H]≤-3.0 stars (Yong+, 2013)
J/ApJ/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013)
J/ApJ/762/25 : The most metal-poor stars in HES and SDSS. I. (Norris+, 2013)
J/ApJ/755/89 : Metallicities of damped Lyα systems (Rafelski+, 2012)
J/A+A/541/A143 : NLTE Corrections of the Ca lines (Spite+, 2012)
J/ApJ/749/77 : MW halo. III. Statistical abundances (Schlaufman+, 2012)
J/MNRAS/418/284 : s-process in low-metallicity stars. II. (Bisterzo+, 2011)
J/MNRAS/412/843 : SAGA extremely metal-poor stars (Suda+, 2011)
J/A+A/530/A15 : Abundances of 94 stars (Nissen+, 2011)
J/ApJ/731/4 : Galactic halo as seen by the CFHTLS (Sesar+, 2011)
J/A+A/528/A92 : HERES VI. Galactic chemical evolution of Si & C (Zhang+, 2011)
J/ApJ/724/341 : Nucleosynthesis of massive metal-free stars (Heger+, 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/A+A/509/A93 : Carbon-enhanced metal-poor stars (Masseron+, 2010)
J/A+A/501/519 : Extremely metal-poor stars abundances (Bonifacio+, 2009)
J/ApJS/182/80 : Rare earth abundances (Sneden+, 2009)
J/AJ/137/272 : Space velocities orbits in the Milky Way halo (Roederer+ 2009)
J/A+A/484/721 : HES survey. IV. Candidate metal-poor stars (Christlieb+, 2008)
J/ApJS/168/128 : UBVRcIc photometry of FHB and metal-poor stars (Beers+, 2007)
J/ApJ/658/367 : Abundances of carbon stars in Galactic halo (Komiya+, 2007)
J/ApJ/652/1585 : Bright metal-poor stars from HES survey (Frebel+, 2006)
J/AJ/132/137 : Abundances of extremely metal-poor carbon stars (Cohen+, 2006)
J/AJ/132/85 : Equivalent width of 33 metal-poor RHB (Preston+, 2006)
J/MNRAS/367/1329 : Elemental abundances for 176 stars (Reddy+, 2006)
J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)
J/A+A/433/185 : Detailed abundance analysis of F and G dwarfs (Bensby+, 2005)
J/AJ/127/1545 : Abundance ratios of 4 stars in Pal 12 (Cohen+, 2004)
J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)
J/AJ/124/1144 : Orbits of single-lined spectroscopic binaries (Latham, 2002)
J/A+A/375/366 : Carbon stars from the Hamburg/ESO survey (Christlieb+ 2001)
J/A+A/358/77 : Hamburg/ESO survey for bright QSOs. III. (Wisotzki+, 2000)
J/AJ/119/1448 : Improved properties for cool stars (Houdashelt+, 2000)
J/A+A/275/101 : Chemical evolution of the galactic disk I. (Edvardsson+ 1993)
J/AJ/103/1987 : Stars of very low metal abundance (Beers+ 1992)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- ID Source identifier (G2)
13- 14 I2 h RAh Hour of Right Ascension (J2000)
16- 17 I2 min RAm Minute of Right Ascension (J2000)
19- 23 F5.2 s RAs Second of Right Ascension (J2000)
25 A1 --- DE- Sign of the Declination (J2000)
26- 27 I2 deg DEd Degree of Declination (J2000)
29- 30 I2 arcmin DEm Arcminute of Declination (J2000)
32- 33 I2 arcsec DEs Arcsecond of Declination (J2000)
35- 39 F5.2 mag Vmag [9.8/16.6] The V band magnitude
41 A1 --- u_Vmag [d] HES magnitude (1)
43- 49 A7 "MM/YYYY" Date UT date of the observation
51- 56 I6 s Exp [240/18000] Exposure time
58 A1 --- l_S/N Limit flag on S/N
59- 61 I3 --- S/N [35/150] Signal-to-noise (2)
63 A1 --- Mod Spectrograph mode (3)
65- 71 F7.1 km/s HRV [-1164/373] Heliocentric radial velocity
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Note (1): d = magnitude adopted from the HES (b-band) in absence of a better
source.
Note (2): SNR per spectral resolution element in the continuum near 5300
Angstroms. (HIRES: spectral resolution 36000. MIKE 42000 blue camera,
32000 red camera).
Note (3): Mode as follows:
O = HIRES prior to detector upgrade;
B = HIRES-B after upgrade;
R = HIRES-R after upgrade;
M = Mike/Magellan.
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Byte-by-byte Description of file: table2a.dat
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Bytes Format Units Label Explanations
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1 I1 --- C [1/3] Star C-type (G1)
3- 13 A11 --- ID Source identifier (G2)
17- 21 F5.2 [Sun] [Fe/H]1 [-4.1/-2.1] Metallicity from HIRES
23- 26 A4 --- l_[C/Fe] [≤ ] Limit flag on [C/Fe]
28- 31 F4.1 [Sun] [C/Fe] ? Abundance of [C/Fe]
33- 36 I4 K Teff1 [4600/6750]? Effective temperature
38 A1 --- s [0+] s-rich flag: + = High [Ba/Fe];
0 = normal [Ba/Fe])
40 A1 --- Notes Individual notes (4)
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Note (4): Notes as follows:
c = Spectrum shows double lines.
d = Lucatello et al (2003AJ....125..875L 2003AJ....125..875L) gives an orbit for this close
binary with period 3.14 days and with full amplitude of RVel of 104km/s.
e = HE0058-0244 is a rediscovery of CS22183-015, see
Johnson and Bolte (2002ApJ...579L..87J 2002ApJ...579L..87J) and
Tsangarides et al (2004MmSAI..75..772T 2004MmSAI..75..772T).
g = Andersen, Hansen and Nordstrom (2013, in preparation) found this star
to be a long period binary.
h = Andersen, Hansen and Nordstrom (2013, in preparation) have determined
a period of 289 days for this binary.
j = HE2356-0410 is a rediscovery of CS22957-27, previously known binary
with RVel range -62 to -78km/s (Preston & Sneden 2001AJ....122.1545P 2001AJ....122.1545P).
k = HE2344-2800 is a rediscovery of CS22966-048.
l = HE2323-0256 is a rediscovery of CS22949-037.
m = Double lined (Cohen et al. 2002AJ....124..470C 2002AJ....124..470C).
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Byte-by-byte Description of file: table2b.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 I1 --- C [1/3] Star C-type (G1)
3- 13 A11 --- ID Source identifier (G2)
15 A1 --- Rem Individual remarks (1)
17- 24 A8 --- Inst Instrument remark
26- 32 A7 "MM/YYYY" Date Observation UT date
36- 41 F6.1 km/s RV [-288/295] Radial velocity
43- 46 F4.2 km/s e_RV [0.06/1.1]? Radial velocity uncertainty
48- 50 A3 --- Ref Reference (2)
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Note (1): Flag as follows:
e = HE0058-0244 is a rediscovery of CS22183-015, see
Johnson and Bolte (2002ApJ...579L..87J 2002ApJ...579L..87J) and
Tsangarides et al (2004MmSAI..75..772T 2004MmSAI..75..772T).
f = MIKE/Magellan spectrum.
g = Andersen, Hansen and Nordstrom (2013, in preparation) found this star
to be a long period binary.
h = Andersen, Hansen and Nordstrom (2013, in preparation) have determined
a period of 289 days for this binary.
i = A spectrum with low SNR.
j = HE2356-0410 is a rediscovery of CS22957-27, previously known binary
with RVel range -62 to -78km/s (Preston & Sneden 2001AJ....122.1545P 2001AJ....122.1545P).
k = HE2344-2800 is a rediscovery of CS22966-048.
l = HE2323-0256 is a rediscovery of CS22949-037.
Note (2): Reference as follows:
B05 = Barklem et al. (2005, J/A+A/439/129)
F07 = Frebel et al. (2007ApJ...658..534F 2007ApJ...658..534F)
D95 = DuPont; McWilliam et al. (1995AJ....109.2757M 1995AJ....109.2757M)
A01 = AAT, Norris, Ryan and Beers (2001ApJ...561.1034N 2001ApJ...561.1034N)
D02 = Depagne et al. (2002A&A...390..187D 2002A&A...390..187D)
N13 = HIRES/Keck, Norris et al. (2013, J/ApJ/762/25)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- ID Source identifier (G2)
12- 13 A2 --- Ana [ST de] Note on the analysis (5)
16- 19 I4 K NTeff [4592/6730] Nominal effective temperature (6)
21- 23 I3 K e_NTeff ? Error in NTeff (7)
25- 28 F4.2 [cm/s2] Nlog(g) [1/5] Nominal surface gravity (6)
30- 33 I4 K Teff [4592/6750] Adopted effective temperature
35- 38 F4.2 [cm/s2] log(g) Adopted surface gravity
41- 43 F3.1 km/s vt [0.4/2.5] Microturbulent velocity
45- 50 F6.2 [Sun] [Fe/H] [-4.1/-1.9] Metallicity (8)
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Note (5): Remarks on the analysis, as follows:
S = spectra re-analyzed in early 2012 with the updated code of Sobeck et al.
(2011AJ....141..175S 2011AJ....141..175S)
T = Tailored model atmosphere (see section 6.3)
d = See Keck Pilot Project analyses, (Cohen et al. 2002AJ....124..470C 2002AJ....124..470C;
Carretta et al. 2002AJ....124..481C 2002AJ....124..481C; Lucatello et al 2003AJ....125..875L 2003AJ....125..875L).
e = The HIRES spectrum of this star suggests that it is on the horizontal
branch, not the RGB.
Note (6): The nominal Teff and log(g) are based solely on the available
photometry, specifically the mean of that deduced from each of V-I,
V-J, V-K. There are two possible solutions for stars near the main
sequence turnoff; the one adopted is given.
Note (7): Dispersion about the mean for the values (maximum of three) of Teff.
Note (8): Value from our high-resolution analysis adopting [Fe/H](Sun)=7.45dex.
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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- 11 A11 --- ID Source identifier (G2)
13- 14 I2 --- N [7/91] Number of FeI lines
16- 21 F6.3 --- f-chi ? Fit of abundance vs χ (excitation potential)
d[log(ε(Fe)]/dχ (dex/eV)
23- 28 F6.3 --- f-EW ? Fit of abundance vs equivalent width
d[log(ε(Fe)]/d(Wλ/λ)
30- 40 E11.4 --- f-lam ? Fit of abundance vs λ
d[log(ε(Fe)]/d(λ) (dex/Å)
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 0.1nm lambda [3189/7776] Wavelength in Angstroms
9- 13 F5.1 --- Elem Element code (G3)
15 A1 --- f_Elem [c] c = UV OH lines
17- 20 F4.2 eV ExPot [0/9.2] Excitation potential χ
22- 28 F7.3 [-] log(gf) [-10.3/0.8] Log of the oscillatory strength
30- 32 I3 --- Nst [1/109] Number of stars detected (2)
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Note (2): Upper limits are also included.
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- ID Source identifier
13- 19 F7.2 0.1nm lambda [3189/7776] Wavelength in Angstroms
21- 25 F5.1 --- Elem [3/106] Element code (G3)
27- 32 F6.1 10-13m EW [-211.3/560.3]? Equivalent width (mÅ) (1)
34- 37 A4 --- n_EW "syn" indicates synthesis used (1)
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Note (1): Negative values indicate upper limits.
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Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- ID Source identifier
13- 16 F4.1 --- Elem Element code (G3)
18 A1 --- f_Elem [e] C from synthesis of G band of CH
20- 24 F5.2 [-] [X/Fe] [-4.1/3.2]? Log abundance ratio relative to FeI (1)
26- 29 F4.2 [-] e_[X/Fe] ? Uncertainty in [X/Fe] (2)
31- 34 I4 --- Nl [-4/100]? Number of lines measured (3)
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Note (1): Except for FeI, where we give [Fe/H] from FeI lines only.
Note (2): The rms dispersion for the lines of this species around the
mean abundance ratio.
Note (3): A species with an upper limit for its relative abundance is indicated
by setting the number of lines to its negative value. Num←1 means
several lines were searched for, but none were firmly detected.
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Global Notes:
Note (G1): Carbon type as follows:
1 = C-Stars with C2;
2 = C-rich, no C2;
3 = C-normal.
Note (G2): Some IDs of the published table6 are very likely in error,
and were changed at CDS:
* BS16545-008 changed into BS16545-089;
* BS16945-005 changed into BS16945-054;
* HE1432-819 changed into HE1432-1819;
* HE1434-442 changed into HE1434-1442
* HE1439-420 changed into HE1439-1420.
Note (G3): Element code: atomic number plus ionization stage/10),
e.g. 26.0 = FeI, 26.1 = FeII.
History:
From electronic version of the journal
15-Jun-2015: Insert into VizieR
15-Feb-2019: HE0132-2429 misprint in Tables 1, 2a, 8 and 10 corrected for
HE0132-2439.
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 22-Apr-2015