J/ApJ/881/104 Spectroscopic obs. of RR Lyrae in NGC5139 (Magurno+, 2019)
Chemical compositions of field and globular cluster RR Lyrae stars.
II. Ω Centauri
Magurno+, Magurno D., Sneden C., Bono G., Braga V.F., Mateo M.,
Persson S.E., Preston G., Thevenin F., da Silva R., Dall'Ora M.,
Fabrizio M., Ferraro I., Fiorentino G., Iannicola G., Inno L., Marengo M.,
Marinoni S., Marrese P.M., Martinez-Vazquez C.E., Matsunaga N., Monelli M.,
Neeley J.R., Nonino M., Walker A.R.
<Astrophys. J., 881, 104 (2019)>
=2019ApJ...881..104M 2019ApJ...881..104M
ADC_Keywords: Clusters, globular; Stars, variable; Spectra, optical;
Abundances, [Fe/H]; Radial velocities
Keywords: globular clusters: individual (NGC 5139) ; stars: abundances ;
stars: variables: RR Lyrae ; techniques: spectroscopic
Abstract:
We present a detailed spectroscopic analysis of RR Lyrae (RRL)
variables in the globular cluster NGC5139 (ω Cen). We collected
optical (4580-5330Å), high-resolution (R∼34000), high
signal-to-noise ratio (∼200) spectra for 113 RRLs with the multifiber
spectrograph M2FS at the Magellan/Clay Telescope at Las Campanas
Observatory. We also analyzed high- resolution (R∼26000) spectra for
122 RRLs collected with FLAMES/GIRAFFE at the Very Large Telescope,
available in the ESO archive. The current sample doubles the
literature abundances of cluster and field RRLs in the Milky Way based
on high-resolution spectra. Equivalent-width measurements were used to
estimate atmospheric parameters, iron, and abundance ratios for
α (Mg, Ca, Ti), iron peak (Sc, Cr, Ni, Zn), and s-process (Y)
elements. We confirm that ωCen is a complex cluster,
characterized by a large spread in the iron content:
-2.58≲[Fe/H]≲-0.85. We estimated the average cluster abundance as
<[Fe/H]≥-1.80±0.03, with σ=0.33dex. Our findings also
suggest that two different RRL populations coexist in the cluster. The
former is more metal-poor ([Fe/H]≲-1.5), with almost solar abundance
of Y. The latter is less numerous, more metal-rich, and yttrium
enhanced ([Y/Fe]≳0.4). This peculiar bimodal enrichment only shows up
in the s-process element, and it is not observed among lighter
elements, whose [X/Fe] ratios are typical for Galactic globular
clusters.
Description:
Between 2015 February and April, we collected single-epoch, high
signal-to-noise ratio (S/N∼200), high-resolution spectra of stars in
the globular cluster ωCen.
The spectra were collected with the Michigan/Magellan Fiber System
(M2FS) installed at the Magellan/Clay 6.5m telescope at Las Campanas
Observatory in Chile. The selected spectrograph configuration limits
the spectral coverage to 11 overlapping echelle orders in the range
4580-5330Å. The 95µm slit size allows a spectral resolution
R∼34000.
In addition to our M2FS data, we also analyzed a sample of 560
multi-epoch spectra for RR Lyrae from the European Southern
Observatory (ESO) archive, collected with the multi-object,
medium-high-resolution spectrograph FLAMES/GIRAFFE. We selected from
the archive all the available RRL spectra collected with the HR13
grism, covering the wavelength range 6120-6405Å with a spectral
resolution R∼26400.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 82 113 Photometric parameters and radial velocities for
the sample stars in ωCen, collected with
M2FS.
table2.dat 27 140 Line list and atomic parameters
table6.dat 51 125 Iron abundances for the considered samples of
ωCen RR Lyrae.
table8.dat 102 108 The α, iron-peak, and s-process element
abundances for the considered samples of
ωCen RRLs collected with M2FS
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See also:
J/AJ/110/2319 : Abundances in RR Lyr variables (Clementini+ 1995)
J/ApJ/462/241 : Ca abundance for Omega Cen red giants (Norris+ 1996)
J/AJ/119/1824 : Caby photometry of Ω Centauri (Rey+, 2000)
J/A+A/424/1101 : Variable Stars in the field of ω Cen (Kaluzny+, 2004)
J/AJ/130/2140 : Abundances and velocities globular clusters (Pritzl+, 2005)
J/MNRAS/370/1979 : JHKs photometry of T2Cs globular clusters (Matsunaga+, 2006)
J/A+A/445/503 : Radial velocities in Omega Cen (NGC5139) (Reijns+, 2006)
J/ApJ/640/L43 : Metallicities of RR Lyrae stars in Omega Cen (Sollima+,2006)
J/ApJ/663/1021 : Log of ω Cen scientific images (Castellani+, 2007)
J/ApJ/667/1267 : CrI transition probabilities (Sobeck+, 2007)
J/AJ/133/1447 : Light curves of variable stars ωCen (Weldrake+, 2007)
J/AJ/136/506 : Radial velocities ωCentauri members (Da Costa+, 2008)
J/ApJ/706/1277 : Stromgren photometry in ω Cen (Calamida+, 2009)
J/A+A/505/139 : Abund. red giants in 17 globular clusters (Carretta+, 2009)
J/PASP/121/1378 : Positions variable stars in globular clusters (Samus+, 2009)
J/ApJ/712/L21 : Calcium abundances in 17 globular clusters (Carretta+, 2010)
J/AJ/140/1694 : Abundances of non-variable red and blue HB stars (For+,2010)
J/AN/331/474 : Abundances of metal-poor stars (Frebel, 2010)
J/ApJ/708/560 : Spectroscopy of UMa II and Coma Ber (Frebel+, 2010)
J/ApJ/722/1373 : ω Centauri giants abundances (Johnson+, 2010)
J/A+A/523/A17 : Individual stars in Fornax dSph center (Letarte+, 2010)
J/ApJS/197/29 : Chemical compositions of 11 RR Lyrae (For+, 2011)
J/ApJ/731/64 : Spectroscopy of 300 RGBs in ω Cen (Marino+, 2011)
J/A+A/534/A53 : Equivalent widths of 18 subgiant ωCen (Pancino+, 2011)
J/AJ/144/114 : Radial velocities of 6 field RR Lyrae (Sesar+, 2012)
J/ApJ/751/102 : Equivalent widths of 9 RGB in Carina dSph (Venn+, 2012)
J/ApJS/208/27 : Sun and HD 84937 TiII log(gf) and abundances (Wood+, 2013)
J/ApJS/215/23 : FeI radiative lifetime & branching fract. (Den Hartog+,2014)
J/ApJ/782/59 : Abund. of 8 RRLyrae subclass C variable stars (Govea+, 2014)
J/MNRAS/441/3127 : FeI oscillator strengths for Gaia-ESO (Ruffoni+, 2014)
J/ApJ/791/107 : Parameters of NGC 5139 SGBs stars (Villanova+, 2014)
J/ApJS/211/20 : NiI transition probability measurements (Wood+, 2014)
J/A+A/576/A30 : NIR light-curve templates classical Cepheids (Inno+, 2015)
J/MNRAS/447/2404 : Equivalent width of 21 RR Lyrae stars (Pancino+, 2015)
J/AJ/152/170 : RRLs in globulars.IV. UBVRI photom. Omega Cen (Braga+, 2016)
J/AJ/154/150 : Spectroscopy of RGB stars in ω Centauri (An+, 2017)
J/ApJS/228/10 : Transition probabilities 183 lines of CrII (Lawler+, 2017)
J/ApJ/848/68 : Abundance & RVs of stable & Blazhko RRc stars (Sneden+,2017)
J/AJ/155/137 : RRLs globulars.V. ωCentauri NIR photom. (Braga+, 2018)
J/ApJ/864/57 : Abundances of field & GC RR Lyrae.I. NGC3201 (Magurno+,2018)
J/A+A/618/A134 : Omega Cen lower red giant stars abund. (Mucciarelli+, 2018)
J/ApJ/870/115 : Reddening, dist. modulus & Fe/H of RRLs in wCen (Bono+,2019)
http://www.nist.gov/pml/asd : NIST Atomic Spectra Database (Kramida+, 2018)
http://vald.astro.uu.se/ : VALD database (Ryabchikova+, 2015)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- ID Star identification
7- 8 I2 h RAh [13/13] Hour of Right Ascension (J2000)
10- 11 I2 min RAm [25/27] Minute of Right Ascension (J2000)
13- 17 F5.2 s RAs Second of Rigth Ascension (J2000)
19 A1 --- DE- [-] Sign of the Declination (J2000)
20- 21 I2 deg DEd [47/47] Degree of Declination (J2000)
23- 24 I2 arcmin DEm [14/41] Arcminute of Declination (J2000)
26- 29 F4.1 arcsec DEs Arcsecond of Declination (J2000)
31- 40 F10.8 d Per [0.253/1.013] Period
42- 51 F10.5 d HJD [7077/7126] Heliocentric Julian Date of observing
epoch; HJD-2450000
53- 56 F4.2 --- Phase [0.01/1]? Observing phase
58- 61 A4 --- Type Pulsation category; 44 RRab, 68 RRc or 1 RRd (1)
62 A1 --- f_Type [*] Asterisk marks Blazhko RRLs (19 occurrences)
64- 69 F6.3 mag Vmag [14.05/14.83] Mean V band magnitude
71- 75 F5.3 mag Vamp [0.04/1.27] V band amplitude
77- 82 F6.2 km/s RVel [173/264] Radial velocity
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Note (1): See Braga+, 2016, J/AJ/152/170 and Braga+, 2018, J/AJ/155/137.
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.3 0.1nm lambda [4589/5326] Wavelength (Å)
10- 14 A5 --- Species Species identifier (1)
16- 20 F5.3 eV ExPot [0/4.4] Excitation potential
22- 27 F6.3 [-] loggf [-4.12/0.57] log oscillator strength
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Note (1): Species and their sources as follows:
Mg I = NIST, http://www.nist.gov/pml/asd (3 occurrences)
Ca I = NIST, http://www.nist.gov/pml/asd (1 occurrence)
Sc II = NIST, http://www.nist.gov/pml/asd (2 occurrences)
Ti I = Lawler+, 2013ApJS..205...11L 2013ApJS..205...11L (6 occurrences)
Ti II = Wood+, 2013, J/ApJS/208/27 (17 occurrences)
Cr I = Sobeck+, 2007, J/ApJ/667/1267 (7 occurrences)
Cr II = Lawler+, 2017, J/ApJS/228/10 (11 occurrences)
Fe I = O'Brian+, 1991JOSAB...8.1185O 1991JOSAB...8.1185O ; Den Hartog+, 2014, J/ApJS/215/23
and Ruffoni+, 2014, J/MNRAS/441/3127 (66 occurrences)
Fe II = NIST, http://www.nist.gov/pml/asd (12 occurrences)
Ni I = Wood+, 2014, J/ApJS/211/20 (9 occurrences)
Zn I = VALD, http://vald.astro.uu.se/ (2 occurrences)
Y II = Biemont+, 2011MNRAS.414.3350B 2011MNRAS.414.3350B (4 occurrences)
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Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- ID Star identification
7- 11 F5.2 --- [Fe/H]EW [-2.53/-0.85]? The [Fe/H] for M2FS with EW method
13- 16 F4.2 --- e_[Fe/H]EW [0.01/0.15]? Uncertainty in [Fe/H]EW
18- 22 F5.2 --- [Fe/H]PAP [-2.58/-1.34]? The [Fe/H] for M2FS with PAP method
24- 27 F4.2 --- e_[Fe/H]PAP [0.02/0.52]? Uncertainty in [Fe/H]PAP
29- 33 F5.2 --- [FE/H]GIR [-2.14/-0.76]? GIRAFFE measured [Fe/H]
35- 38 F4.2 --- e_[FE/H]GIR [0.2/0.53]? Uncertainty in [FE/H]GIR
40 I1 --- n [1/7]? Multiplicity of GIRAFFE measurements
42- 46 F5.2 --- [Fe/H] [-2.58/-0.85] The total [Fe/H] (1)
48- 51 F4.2 --- e_[Fe/H] [0.01/0.53] Uncertainty in [Fe/H]tot
--------------------------------------------------------------------------------
Note (1): Weighted mean on the inverse square of the measurement errors.
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Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- ID Star identification
7- 11 F5.2 [-] [Mg/Fe] [-0.07/0.95]? The [Mg/Fe] abundance ratio
13- 16 F4.2 [-] e_[Mg/Fe] [0.03/0.28]? Uncertainty in [Mg/Fe]
18- 21 F4.2 [-] [Ca/Fe] [0.17/0.63]? The [Ca/Fe] abundance ratio
23- 26 F4.2 [-] e_[Ca/Fe] [0.1/0.1]? Uncertainty in [Ca/Fe]
28- 32 F5.2 [-] [Ti/Fe] [-0.0/0.9]? The [Ti/Fe] abundance ratio
34- 37 F4.2 [-] e_[Ti/Fe] [0.02/0.24]? Uncertainty in [Ti/Fe]
39- 42 F4.2 [-] [a/Fe] [0.15/0.54]? The [α/Fe] abundance ratio (1)
44- 47 F4.2 [-] e_[a/Fe] [0.06/0.14]? Uncertainty in [a/Fe]
49- 53 F5.2 [-] [Sc/Fe] [-0.4/0.66]? The [Sc/Fe] abundance ratio
55- 58 F4.2 [-] e_[Sc/Fe] [0.0/0.22]? Uncertainty in [Sc/Fe]
60- 64 F5.2 [-] [Cr/Fe] [-0.34/0.57]? The [Cr/Fe] abundance ratio
66- 69 F4.2 [-] e_[Cr/Fe] [0.02/0.15]? Uncertainty in [Cr/Fe]
71- 75 F5.2 [-] [Ni/Fe] [-0.34/0.33]? The [Ni/Fe] abundance ratio
77- 80 F4.2 [-] e_[Ni/Fe] [0.03/0.2]? Uncertainty in [Ni/Fe]
82- 85 F4.2 [-] [Zn/Fe] [0.1/0.41]? The [Zn/Fe] abundance ratio
87- 90 F4.2 [-] e_[Zn/Fe] [0.01/0.16]? Uncertainty in [Zn/Fe]
92- 96 F5.2 [-] [Y/Fe] [-0.21/1.11]? The [Y/Fe] abundance ratio
98-102 F5.3 [-] e_[Y/Fe] [0.0/0.21]? Uncertainty in [Y/Fe]
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Note (1): Biweight mean of Mg, Ca, and Ti abundances.
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History:
From electronic version of the journal
References:
Magurno et al. Paper I : 2018ApJ...864...57M 2018ApJ...864...57M cat: J/ApJ/864/57
(End) Prepared by [AAS], Coralie Fix [CDS], 26-Jan-2021