J/ApJ/897/78 RAVE J183013.5-455510 equivalent-width measurements (Placco+, 2020)
The R-process Alliance: The Peculiar Chemical Abundance Pattern of
RAVE J183013.5-455510
Placco V.M., Santucci R.M., Yuan Z., Mardini M.K., Holmbeck E.M., Wang X.,
Surman R., Hansen T.T., Roederer I.U., Beers T.C., Choplin A., Ji A.P.,
Ezzeddine R., Frebel A., Sakari C.M., Whitten D.D., Zepeda J.
<Astrophys. J., 897, 78 (2020)>
=2020ApJ...897...78P 2020ApJ...897...78P
ADC_Keywords: Stars, metal-deficient; Abundances; Spectra, optical
Keywords: Chemical abundances ; Stellar atmospheres ; Stellar kinematics ;
R-process ; CEMP stars ; Metallicity
Abstract:
We report on the spectroscopic analysis of RAVE-J183013.5-455510, an
extremely metal-poor star, highly enhanced in CNO, and with
discernible contributions from the rapid neutron-capture process.
There is no evidence of binarity for this object. At [Fe/H]=-3.57,
this star has one of the lowest metallicities currently observed, with
18 measured abundances of neutron-capture elements. The presence of
Ba, La, and Ce abundances above the solar system r-process predictions
suggests that there must have been a non-standard source of r-process
elements operating at such low metallicities. One plausible
explanation is that this enhancement originates from material ejected
at unusually high velocities in a neutron star merger event. We also
explore the possibility that the neutron-capture elements were
produced during the evolution and explosion of a rotating massive
star. In addition, based on comparisons with yields from
zero-metallicity faint supernova, we speculate that RAVE-J1830-4555
was formed from a gas cloud pre-enriched by both progenitor types.
From analysis based on Gaia DR2 measurements, we show that this star
has orbital properties similar to the Galactic metal-weak thick-disk
stellar population.
Description:
High-resolution spectroscopy for RAVE J1830-4555 was obtained on 2017
August 14 using the Magellan Inamori Kyocera Echelle (MIKE)
spectrograph, mounted on the 6.5m Magellan-Clay Telescope at Las
Campanas Observatory. The observing setup included a 0.7" slit with
2x2 on-chip binning, yielding a resolving power of R∼37000 (blue
spectrum) and R∼30000 (red spectrum). The S/N is ∼80 per pixel at
3900Å and ∼120 at 5200Å after a total exposure of 2000s. The
MIKE spectrum covers a wide range of optical wavelengths
(∼3300-9000Å), making it ideal for chemical abundance
determinations, in particular for neutron-capture elements.
Objects:
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RA (2000) DE Designation(s)
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18 30 13.54 -45 55 10.1 RAVE J183013.5-455510 = RAVE J183013.5-455510
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 45 257 Equivalent-width measurements
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See also:
III/279 : RAVE 5th data release (Kunder+, 2017)
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
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/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/AJ/136/2050 : SEGUE stellar parameter pipeline. II. (Lee+, 2008)
J/ApJ/724/341 : Nucleosynthesis of massive metal-free stars (Heger+, 2010)
J/ApJ/724/975 : Heavy elements abundances of metal-poor stars (Roederer+, 2010)
J/ApJ/778/56 : Hamburg/ESO Survey extremely metal-poor stars (Cohen+, 2013)
J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)
J/ApJ/773/33 : Chemical analysis of metal-poor subgiant BD+44 493 (Ito+, 2013)
J/ApJ/794/58 : Metal-poor stars in the thick disk of the Galaxy (Beers+, 2014)
J/ApJ/781/40 : Metal-poor stars from HES survey. II. Spectro. (Placco+, 2014)
J/ApJ/797/21 : Carbon-enhanced metal-poor stars (Placco+, 2014)
J/AJ/147/136 : Stars very low metal abundance. VI. Abundances (Roederer+,2014)
J/ApJ/807/171 : SkyMapper Survey metal-poor star spectroscopy (Jacobson+, 2015)
J/ApJ/812/109 : HST & Keck spectroscopy of bright CEMP-s stars (Placco+, 2015)
J/ApJ/824/L19 : Carbon-enhanced metal-poor star BD+44493 EWs (Roederer+, 2016)
J/ApJ/833/20 : Carbon-enhanced metal-poor (CEMP) star abundances (Yoon+, 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/ApJ/864/43 : Abundances of 3 bright extremely metal-poor giants (Cain+,2018)
J/A+A/618/A133 : Non standard s-process massive rotating stars (Choplin+, 2018)
J/ApJ/862/174 : Spectroscopy obs. of RAVE J094921.8-161722 (Gull+, 2018)
J/ApJ/858/92 : RPA Southern Pilot Search of 107 Stars (Hansen+, 2018)
J/ApJS/237/13 : Models and yields of 13-120M☉ massive stars (Limongi+,2018)
J/ApJ/852/99 : Abundances 3 metal-poor stars in Horologium I (Nagasawa+, 2018)
J/AJ/155/256 : Spectroscopic validation RAVE metal-poor stars (Placco+, 2018)
J/AJ/156/179 : Highly r-process-enhanced field stars kine. (Roederer+, 2018)
J/ApJ/865/129 : Abundance analysis of HD 222925 (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 abundances&kinematics (Hansen+, 2019)
J/ApJ/882/40 : Lanthanide fraction distribution of metal-poor stars (Ji+,2019)
J/ApJ/875/89 : Metal-poor stars with APF. I. LAMOST CEMP stars (Mardini+,2019)
J/ApJ/882/27 : Metal-poor stars with APF obs II. MW halo stars (Mardini+,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)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Ion Species
7- 14 F8.3 0.1nm lambda [3360/8335] Wavelength, Angstroms
16- 19 F4.2 eV ExPot [0/4.34]? Excitation potential
21- 26 F6.3 [-] loggf [-9.82/0.76]? Log oscillator strength
28- 30 A3 --- f_EW Flag on EW (1)
32- 37 F6.2 10-13m EW [6.78/162]? Equivalent width
39- 39 A1 --- l_logeps(x) Limit flag on logeps
41- 45 F5.2 [Sun] logeps(x) [-2.85/7.36] Log number abundance of Ion
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Note (1): Flag as follows:
syn = indicates that abundances were derived by spectral synthesis matching
(57 occurrences)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 27-Sep-2021