J/ApJ/889/27 Abundances of 11 stars in Carina II and III (Ji+, 2020)
Detailed abundances in the ultra-faint Magellanic satellites Carina II and III.
Ji A.P., Li T.S., Simon J.D., Marshall J., Vivas A.K., Pace A.B.,
Bechtol K., Drlica-Wagner A., Koposov S.E., Hansen T.T., Allam S.,
Gruendl R.A., Johnson M.D., McNanna M., Noel N.E.D., Tucker D.L.,
Walker A.R., (the MagLiteS Collaboration)
<Astrophys. J., 889, 27-27 (2020)>
=2020ApJ...889...27J 2020ApJ...889...27J (SIMBAD/NED BibCode)
ADC_Keywords: Spectra, optical; Abundances; Radial velocities; Equivalent widths
Keywords: Local Group; Stellar abundances; Dwarf galaxies
Abstract:
We present the first detailed elemental abundances in the ultra-faint
Magellanic satellite galaxies Carina II (Car II) and Carina III
(CarIII). With high-resolution Magellan/MIKE spectroscopy, we
determined the abundances of nine stars in Car II, including the first
abundances of an RR Lyrae star in an ultra-faint dwarf galaxy (UFD),
and two stars in Car III. The chemical abundances demonstrate that
both systems are clearly galaxies and not globular clusters. The stars
in these galaxies mostly display abundance trends matching those of
other similarly faint dwarf galaxies: enhanced but declining
[α/Fe] ratios, iron-peak elements matching the stellar halo, and
unusually low neutron-capture element abundances. One star displays a
low outlying [Sc/Fe]=-1.0. We detect a large Ba scatter in Car II,
likely due to inhomogeneous enrichment by low-mass asymptotic giant
branch star winds. The most striking abundance trend is for [Mg/Ca] in
Car II, which decreases from +0.4 to -0.4 and indicates clear
variation in the initial progenitor masses of enriching core-collapse
supernovae. So far, the only UFDs displaying a similar [Mg/Ca] trend
are likely satellites of the Large Magellanic Cloud. We find two stars
with [Fe/H]≤-3.5 whose abundances likely trace the first generation
of metal-free Population III stars and are well fit by Population III
core-collapse supernova yields. An appendix describes our new
abundance uncertainty analysis that propagates line-by-line stellar
parameter uncertainties.
Description:
We observed the Magellanic satellite galaxies Carina II and III target
stars with Magellan/MIKE over four separate runs between May 2017 and
Oct 2019. The total integrated time spent on these stars is 34hr.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 89 11 Observations
table2.dat 45 54 Radial velocities
table3.dat 51 11 Stellar parameters
table4.dat 102 2280 Line measurements
table6.dat 56 242 Stellar abundances
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJ/655/492 : Equivalent widths of 26 metal-poor stars (Aoki+, 2007)
J/MNRAS/383/183 : CaII triplet of RGB from VLT/FLAMES obs. (Battaglia+, 2008)
J/ApJ/708/560 : Spectroscopy of UMa II and Coma Ber (Frebel+, 2010)
J/ApJ/719/931 : Chemical evolution of the UMi dSph (Cohen+, 2010)
J/ApJ/723/1632 : Abundance spreads in Bootes I and Segue 1 (Norris+, 2010)
J/ApJ/724/341 : Nucleosynthesis of massive metal-free stars (Heger+, 2010)
J/AJ/140/1694 : Abundances of non-variable red and blue HB stars (For+, 2010)
J/ApJS/197/29 : Chemical compositions of 11 RR Lyrae (For+, 2011)
J/AJ/144/88 : Spectroscopy of 6 LMC & 3 SMC RR Lyrae stars (Haschke+, 2012)
J/ApJ/760/86 : Equivalent widths for 13 NGC2419 RGB stars (Cohen+, 2012)
J/ApJ/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013)
J/ApJ/763/61 : Abundances of 7 red giant members of BootesI (Gilmore+, 2013)
J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)
J/ApJ/778/56 : Hamburg/ESO Survey extremely metal-poor stars (Cohen+, 2013)
J/ApJ/778/149 : Abundances for 3 stars in Sgr dSph (McWilliam+, 2013)
J/A+A/562/A146 : Chemical abundances of 8 metal-poor stars (Ishigaki+, 2014)
J/ApJ/786/74 : EW measurements of 6 Segue 1 red giants (Frebel+, 2014)
J/MNRAS/440/2665 : SDSS J021933.13+200830.2 spectroscopy (Roederer+, 2014)
J/ApJ/797/21 : Carbon-enhanced metal-poor stars (Placco+, 2014)
J/A+A/574/A129 : The First CEMP star in the Sculptor dSph (Skuladottir+, 2015)
J/A+A/586/A120 : Grid of 1D models for Mg line formation (Osorio+, 2016)
J/AJ/151/82 : The 4 brightest red giants in galaxy Ret 2 (Roederer+, 2016)
J/ApJ/826/110 : Boo-127 and Boo-980 high-resolution spectra (Frebel+, 2016)
J/ApJ/830/93 : Abundances of Ret II brightest red giant members (Ji+, 2016)
J/ApJ/833/20 : Carbon-enhanced metal-poor star abundances (Yoon+, 2016)
J/ApJ/838/44 : Abundances of the brightest member of Tuc III (Hansen+, 2017)
J/ApJ/838/83 : Rvel, abundances & membership in TriII (Kirby+, 2017)
J/ApJ/847/142 : Ultra-metal-poor stars abundances (Ezzeddine+, 2017)
J/ApJ/852/99 : Abundances of 3 metal-poor stars in Hor I (Nagasawa+, 2018)
J/ApJ/856/142 : Abundances of metal-poor stars in Sculptor (Chiti+, 2018)
J/ApJ/857/74 : Abundances of 7 new member stars in Tucana II (Chiti+, 2018)
J/ApJ/857/145 : MagLiteS Carina II and Carina III spectroscopy (Li+, 2018)
J/ApJ/863/25 : Deep Megacam obs. of 4 MW satellites (Mutlu-Pakdil+, 2018)
J/ApJ/863/89 : Gaia DR2 PMs in ultra-faint MW satellites (Simon, 2018)
J/ApJ/870/83 : Abundances in GruI & TriII (Ji+, 2019)
J/A+A/622/A60 : Gaia DR2 misclassified RR Lyrae list (Clementini+, 2019)
J/A+A/623/A129 : New satellites of the LMC search (Fritz+, 2019)
J/ApJ/875/77 : Proper motions of MW satellites with Gaia & DES (Pace+, 2019)
J/A+A/627/A177 : Non-LTE analysis of K I in late-type stars (Reggiani+, 2019)
J/ApJ/882/177 : Abundances of 4 member stars of Tucana III (Marshall+, 2019)
J/A+A/631/A80 : Mn lines 3D NLTE formation (Bergemann+, 2019)
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 Star identifier (1)
13 A1 --- f_ID Flag on ID (2)
15- 33 I19 --- Gaia Gaia DR2 identifier
35- 36 I2 h RAh Hour of right ascension (J2000)
38- 39 I2 min RAm Minute of right ascension (J2000)
41- 45 F5.2 s RAs Second of right ascension (J2000)
47 A1 --- DE- Sign of declination (J2000)
48- 49 I2 deg DEd Degree of declination (J2000)
51- 52 I2 arcmin DEm Arcminute of declination (J2000)
54- 57 F4.1 arcsec DEs Arcsecond of declination (J2000)
59- 63 F5.2 mag Gmag [15/18.5] Gaia G-band magnitude
65- 69 F5.2 mag g0mag [15.6/18.4] Dereddened DECam g-band magnitude
from MagLiteS (3)
71- 75 F5.2 mag r0mag [14.6/18.1] Dereddened DECam r-band magnitude
from MagLiteS (3)
77- 79 F3.1 --- Slit [0.5/1] Slit
81- 83 F3.1 h Exp [1/5.5] Exposure time
85- 86 I2 --- SNR4500 [13/38] Signal-to-noise ratio per pixel
at 4500 Å
88- 89 I2 --- SNR6500 [24/80] Signal-to-noise ratio
at 6500 Å
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Note (1): Our star ID numbers are the last four digits of the Gaia source_id.
Note (2): Flag as follows:
a = This star is a variable RRL star. The magnitudes here are the mean
magnitudes found by MagLiteS and Gaia (Torrealba+ 2018MNRAS.475.5085T 2018MNRAS.475.5085T
and Clementini+ 2019, J/A+A/622/A60), where the DECam magnitudes have
been dereddened.
Note (3): g0mag and r0mag are dereddened DECam photometry from MagLiteS,
taken from T. S. Li. et al. (2019, in preparation).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- ID Star identifier (1)
13- 16 I4 yr Obs.Y Year of the observation
18- 19 I2 "month" Obs.M Month of the observation
21- 22 I2 d Obs.D Day of the observation
24- 32 F9.3 d MJD [58092.3/58552.1] Modified Julian Date
of the observation
34- 38 F5.1 km/s RVel [280.8/483.7] Heliocentric radial velocity
40- 41 I2 --- Nord [16/36] Final number of orders used
43- 45 F3.1 km/s sigma [0.3/7] Systematic error
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Note (1): Note that CarII-6544 is likely a binary star and CarII-V3 is an RRL
star, so these have significant velocity variations.
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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 Star identifier
13- 16 I4 K Teff [4330/6100] Effective temperature
18- 20 I3 K e_Teff [152/330] Teff uncertainty
22- 25 F4.2 [cm/s2] logg [0.4/2.7] Log of surface gravity
27- 30 F4.2 [cm/s2] e_logg [0.27/0.5] Logg uncertainty
32- 35 F4.2 km/s Vt [1.75/3.2] Microturbulent velocity
37- 40 F4.2 km/s e_Vt [0.25/0.4] Vt uncertainty
42- 46 F5.2 [Sun] [M/H] [-3.9/-2.1] Metallicity
48- 51 F4.2 [Sun] e_[M/H] [0.06/0.21] [M/H] uncertainty
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- ID Star identifier
13- 19 F7.2 0.1nm lambda [3825.8/7699] Wavelength in Angstrom units
21- 25 F5.1 --- Ion [8/607] Ion code (1)
27- 30 F4.2 --- chi [0/4.5]? Excitation potential
32- 37 F6.2 [-] log(gf) [-10.3/0.6]? log oscillator strength
39- 43 F5.1 0.1nm EW [8/309]? Equivalent width; Angstroms
45 A1 --- f_EW [s] Flag on EW (s=synthesis)
47- 50 F4.1 0.1nm e_EW [1/26]? Uncertainty in EW
52 I1 --- l_logeps [0/1] Upper flag limit on logeps
(1=True,0=False)
54- 58 F5.2 [-] logeps [-3.3/8.8] log abundance
60- 63 F4.2 --- sigma [0.09/9]? Total error;
sigmaStat2+sigmaSys2
65- 68 F4.2 --- sigmaStat [0.01/9]? Statistical error
70- 73 F4.2 --- sigmaSys [0.07/2.4]? Systematic error (2)
75- 79 F5.2 --- sigmaTeff [-0.4/2.4]? Systematic abundance offset
from Teff
81- 85 F5.2 --- sigmalogg [-0.6/0.4]? Systematic abundance offset
from log(g)
87- 91 F5.2 --- sigmavt [-0.4/0.15]? Systematic abundance offset
from vturb
93- 97 F5.2 --- sigma[M/H] [-0.2/0.16]? Systematic abundance offset
from [M/H]
99-102 F4.2 --- sigmacont [0.01/0.8]? Systematic abundance offset
from local continuum allowed to vary
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Note (1): In the format X.Y where X is the atomic number and Y is the
ionization, e.g. 26.0=FeI. Values of 106.0 and 607.0 indicate
the C-H and C-N molecules, respectively.
Note (2): sigmaSys=sigmaTeff2+sigmalogg2+sigmavt2+sigma[M/H]2.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- ID Star identifier
13- 17 A5 --- El Element identifier
19- 21 I3 --- N [1/169] Number of elements used
23 A1 --- l_logeps Limit flag on logeps
25- 29 F5.2 [-] logeps [-3.3/8.8] log abundance
31- 34 F4.2 --- sigmastat [0.01/0.65]? Statistical error
36- 40 F5.2 [-] [X/H] [-5.8/0.04] log [X/H] abundance
42- 45 F4.2 [-] e_[X/H] [0.1/0.8]? Uncertainty in [X/H]
47- 51 F5.2 [-] [X/Fe] [-2.6/2.9] log [X/Fe] abundance
53- 56 F4.2 [-] e_[X/Fe] [0.02/0.7]? Uncertainty in [X/Fe]
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 08-Jul-2021