J/ApJ/959/141 Chemical abundances of Cet II brightest star (Webber+, 2023)
Chemical analysis of the brightest star of the Cetus II ultrafaint dwarf galaxy
candidate.
Webber K.B., Hansen T.T., Marshall J.L., Simon J.D., Pace A.B.,
Mutlu-Pakdil B., Drlica-Wagner A., Martinez-Vazquez C.E., Aguena M.,
Allam S.S., Alves O., Bertin E., Brooks D., Carnero Rosell A.,
Carretero J., da Costa L.N., De Vicente J., Doel P., Ferrero I.,
Friedel D., Frieman J., Garcia-Bellido J., Giannini G., Gruen D.,
Gruendl R.A., Hinton S.R., Hollowood D.L., Honscheid K., Kuehn K.,
Mena-Fernandez J., Menanteau F., Miquel R., Ogando R.L.C., Pereira M.E.S.,
Pieres A., Plazas Malagon A.A., Sanchez E., Santiago B., Smith J.A.,
Smith M., Suchyta E., Tarle G., To C., Weaverdyck N., Yanny B.
<Astrophys. J., 959, 141 (2023)>
=2023ApJ...959..141W 2023ApJ...959..141W
ADC_Keywords: Abundances; Galaxies, dwarf; Equivalent widths; Spectra, optical;
Photometry, ugriz; Radial velocities
Keywords: Chemical abundances ; Stellar abundances
Abstract:
We present a detailed chemical abundance analysis of the brightest
star in the ultrafaint dwarf (UFD) galaxy candidate Cetus II from
high-resolution Magellan/MIKE spectra. For this star,
DES_J011740.53-173053, abundances or upper limits of 18 elements from
carbon to europium are derived. Its chemical abundances generally
follow those of other UFD galaxy stars, with a slight enhancement of
the α-elements (Mg, Si, and Ca) and low neutron-capture element
(Sr, Ba, and Eu) abundances supporting the classification of Cetus II
as a likely UFD. The star exhibits lower Sc, Ti, and V abundances than
Milky Way (MW) halo stars with similar metallicity. This signature is
consistent with yields from a supernova originating from a star with a
mass of ∼11.2M☉. In addition, the star has a potassium abundance
of [K/Fe]=0.81, which is somewhat higher than the K abundances of MW
halo stars with similar metallicity, a signature that is also present
in a number of UFD galaxies. A comparison including globular clusters
and stellar stream stars suggests that high K is a specific
characteristic of some UFD galaxy stars and can thus be used to help
classify objects as UFD galaxies.
Description:
High-resolution spectral data were obtained for DES_J011740.53-173053
with the MIKE echelle spectrograph at Las Campanas Observatory in
Chile in 2017 August and November.
A color-magnitude diagram of the Cetus II (Cet II) ultrafaint dwarf
(UFD) galaxy member stars (Pace+ 2022ApJ...940..136P 2022ApJ...940..136P) is shown in
Figure 1 (including J0117).
The spectra were obtained using a 0.7" slit with 2x2 pixel binning and
cover a wavelength range of 3350-5000Å in the blue and
4900-9500Å in the red, with resolutions of R∼35000 at blue
wavelengths and ∼28000 at red wavelengths, respectively.
Objects:
------------------------------------------------------------
RA (ICRS) DE Designation(s)
------------------------------------------------------------
01 17 40.9 -17 30 54.5 J0117 = DES J011740.53-173053.1
------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 114 2 Observing details and stellar data
table2.dat 46 218 Data for atomic lines used in analysis and
individual line EW measurements
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See also:
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
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/667/1267 : CrI transition probabilities (Sobeck+, 2007)
J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)
J/A+A/512/A54 : Teff & Fbol from Infrared Flux Method (Casagrande+, 2010)
J/ApJ/708/560 : Spectroscopy of UMa II and Coma Ber (Frebel+, 2010)
J/ApJ/724/341 : Nucleosynthesis of massive metal-free stars (Heger+, 2010)
J/ApJ/723/1632 : Abundance spreads in Bootes I and Segue 1 (Norris+, 2010)
J/ApJS/194/35 : Atomic transition probabilities of Mn (Den Hartog+, 2011)
J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)
J/ApJ/760/86 : Equivalent widths for 13 NGC2419 RGB stars (Cohen+, 2012)
J/ApJ/750/76 : R-process peaks elements in HD 160617 (Roederer+, 2012)
J/ApJ/769/40 : Potassium abundance in red giants of GCs (Carretta+, 2013)
J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)
J/ApJ/763/61 : Abund. of 7 red giant members of BootesI (Gilmore+, 2013)
J/ApJS/208/27 : Sun and HD 84937 TiII log(gf) and abundances (Wood+, 2013)
J/ApJ/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013)
J/ApJS/215/23 : FeI radiative lifetime (Den Hartog+, 2014)
J/ApJ/786/74 : EW measurements of 6 Segue 1 red giants (Frebel+, 2014)
J/A+A/562/A146 : Chemical abundances of 8 metal-poor stars (Ishigaki+, 2014)
J/ApJS/215/20 : Vanadium log(gf) & transition probabilities (Lawler+, 2014)
J/ApJ/797/21 : Carbon-enhanced metal-poor stars (Placco+, 2014)
J/MNRAS/440/2665 : SDSS J021933.13+200830.2 spectroscopy (Roederer+, 2014)
J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)
J/MNRAS/441/3127 : FeI oscillator strengths for Gaia-ESO (Ruffoni+, 2014)
J/ApJS/214/18 : VII log(gf) values, and V abundance in HD 84937 (Wood+ 2014)
J/ApJS/211/20 : NiI transition probability measurements (Wood+, 2014)
J/ApJS/220/13 : Co I transition probabilities (Lawler+, 2015)
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/817/41 : Abundances of 4 metal-poor red giants in BooII (Ji+, 2016)
J/ApJS/225/24 : NuGrid stellar data set I. Yields (Pignatari+, 2016)
J/AJ/151/82 : The 4 brightest red giants in Ret 2 (Roederer+, 2016)
J/ApJ/817/53 : Fe abundances analysis in HD84937 (Sneden+, 2016)
J/ApJ/838/44 : Abund. of the brightest member of Tuc III (Hansen+, 2017)
J/ApJS/228/10 : Transition prob. for 183 lines of Cr II (Lawler+, 2017)
J/ApJ/857/74 : Abundances of 7 new member stars in Tucana II (Chiti+, 2018)
J/ApJ/855/83 : Abundances of VMP stars in Sagittarius (Hansen+, 2018)
J/ApJ/859/75 : NGC 5824 giant star members from VLT (Mucciarelli+, 2018)
J/ApJ/870/83 : Abundances in the UFD gal. GruI & TriII (Ji+, 2019)
J/MNRAS/490/3508 : The Southern Stellar Stream Sp. Survey (S5) (Li+, 2019)
J/ApJ/882/177 : Abundances of 4 member stars of Tucana III (Marshall+, 2019)
J/ApJ/875/77 : PMs 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/890/119 : Iron abundances in 3 very metal-poor stars (Cowan+, 2020)
J/ApJ/893/47 : MW satellite census. I. DES & PS1 (Drlica-Wagner+, 2020)
J/ApJ/897/183 : Abundances of 3 stars in Grus II galaxy (Hansen+, 2020)
J/AJ/160/181 : Chemical abundances in red giants with Magellan (Ji+, 2020)
J/ApJ/889/27 : Abundances of 11 stars in Carina II and III (Ji+, 2020)
J/ApJ/900/106 : Vanadium abundances for 255 metal-poor stars (Ou+, 2020)
J/A+A/641/A127 : 13 dsph and ultra-faint galaxies analysis (Reichert+, 2020)
J/other/Nat/583.768 : 2050 red giants CaII EWs (Wan+, 2020)
J/ApJ/916/81 : Grus I and Indus II deep DES photometry (Cantu+, 2021)
J/ApJ/921/67 : High-dis. sp. of 8 Phoenix stream red giants (Casey+, 2021)
J/MNRAS/501/2279 : Stars in the Sagittarius stream (Vasiliev+, 2021)
J/AJ/165/55 : Chemical abundances for 5 stars in Tucana II (Chiti+, 2023)
J/AJ/165/100 : Stellar param. and abundances in Reticulum II (Ji+, 2023)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 21 A21 --- Name Star name
23- 27 A5 --- ID Abbreviated ID used in the paper
29- 30 I2 h RAh Hour of right ascension (J2000)
32- 33 I2 min RAm Minute of right ascension (J2000)
35- 38 F4.1 s RAs Second of right ascension (J2000)
40 A1 --- DE- Sign of declination (J2000)
41- 42 I2 deg DEd Degree of declination (J2000)
44- 45 I2 arcmin DEm Arcminute of declination (J2000)
47- 50 F4.1 arcsec DEs Arcsecond of declination (J2000)
52- 57 F6.3 mag gmag0 [16.443] Dereddened DES g-band magnitude
59- 64 F6.3 mag rmag0 [15.716] Dereddened DES r-band magnitude
66- 71 F6.3 mag imag0 [15.818] Dereddened DES i-band magnitude
73- 78 F6.3 mag zmag0 [16.014] Dereddened DES z-band magnitude
80- 92 F13.5 d HJD Heliocentric Julian Date at the beginning
of the exposure
94- 99 A6 s ExpTime Exposure times
101- 102 I2 --- S/N [15/21] Signal-to-noise ratio per pixel
at 4500Å
104- 109 F6.2 km/s HRV [-81.9/-81.38] Heliocentric radial velocity
111- 114 F4.2 km/s e_HRV [0.51/0.52] HRV uncertainty
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Ion Species identifier
7- 13 F7.2 0.1nm lambda [3845.47/7698.96] Wavelength; Angstroms
15- 18 F4.2 eV chi [0/5.1] Excitation potential
20- 24 F5.2 [-] loggf [-4.76/0.64] log oscillator strength
26- 31 F6.2 10-13m EW [14/269]? Equivalent width; milli-Angstroms
33- 37 F5.2 10-13m e_EW [2/17]? Uncertainty in EW
39- 43 F5.2 [Sun] log(e) [-2.34/6.13] log number abundance relative
to solar
45- 46 I2 --- Ref [1/22] Reference code number (1)
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Note (1): Reference code as follows:
1 = Kramida et al. 2018APS..DMPM01004K
2 = Pehlivan Rhodin et al. 2017A&A...598A.102P 2017A&A...598A.102P
3 = Yu & Derevianko 2018ADNDT.119..263Y 2018ADNDT.119..263Y
4 = Lawler & Dakin 1989JOSAB...6.1457L 1989JOSAB...6.1457L
using HFS from Kurucz & Bell 1995all..book.....K 1995all..book.....K
5 = Lawler et al. 2013ApJS..205...11L 2013ApJS..205...11L
6 = Wood et al. 2013ApJS..208...27W 2013ApJS..208...27W
7 = Pickering et al. 2001ApJS..132..403P 2001ApJS..132..403P with corrections
given in Pickering et al. 2002ApJS..138..247P 2002ApJS..138..247P
8 = Lawler et al. 2014ApJS..215...20L 2014ApJS..215...20L for loggf values and HFS;
9 = Wood et al. 2014ApJS..214...18W 2014ApJS..214...18W for loggf values
and HFS, when available;
10 = Sobeck et al. 2007ApJ...667.1267S 2007ApJ...667.1267S
11 = Lawler et al. 2017ApJS..228...10L 2017ApJS..228...10L
12 = Den Hartog et al. 2011ApJS..194...35D 2011ApJS..194...35D for
both log(gf) value and HFS;
13 = O'Brian et al. 1991JOSAB...8.1185O 1991JOSAB...8.1185O
14 = Den Hartog et al. 2014ApJS..215...23D 2014ApJS..215...23D
15 = Belmonte et al. 2017ApJ...848..125B 2017ApJ...848..125B
16 = Ruffoni et al. 2014AJ....147..136R 2014AJ....147..136R
17 = Den Hartog et al. 2019ApJS..243...33D 2019ApJS..243...33D
18 = Melendez & Barbuy 2009A&A...497..611M 2009A&A...497..611M
19 = Lawler et al. 2015ApJS..220...13L 2015ApJS..220...13L for log(gf) values and HFS;
20 = Wood et al. 2014ApJS..211...20W 2014ApJS..211...20W
21 = Roederer & Lawler 2012ApJ...750...76R 2012ApJ...750...76R
22 = Kramida et al. (2018APS..DMPM01004K), using HFS/IS from
McWilliam 1998AJ....115.1640M 1998AJ....115.1640M when available.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 29-Jan-2026