J/ApJ/874/148 Metal-poor star RAVE J093730.5-062655 abundances (Sakari+, 2019)
The R-Process Alliance: discovery of a Low-α, r-process-enhanced
metal-poor star in the Galactic halo.
Sakari C.M., Roederer I.U., Placco V.M., Beers T.C., Ezzeddine R.,
Frebel A., Hansen T., Sneden C., Cowan J.J., Wallerstein G., Farrell E.M.,
Venn K.A., Matijevic G., Wyse R.F.G., Bland-Hawthorn J., Chiappini C.,
Freeman K.C., Gibson B.K., Grebel E.K., Helmi A., Kordopatis G., Kunder A.,
Navarro J., Reid W., Seabroke G., Steinmetz M., Watson F.
<Astrophys. J., 874, 148 (2019)>
=2019ApJ...874..148S 2019ApJ...874..148S
ADC_Keywords: Abundances; Equivalent widths; Stars, metal-deficient;
Stars, halo; Spectra, optical
Keywords: Galaxy: formation ; stars: abundances ; stars: atmospheres ;
stars: fundamental parameters ;
stars: individual (RAVE J093730.5-062655)
Abstract:
A new moderately r-process-enhanced metal-poor star, RAVEJ093730.5-062655,
has been identified in the Milky Way halo as part of an ongoing survey
by the R-Process Alliance. The temperature and surface gravity
indicate that J0937-0626 is likely a horizontal branch star. At
[Fe/H]=-1.86, J0937-0626 is found to have subsolar [X/Fe] ratios for
nearly every light, α, and Fe-peak element. The low [α/Fe]
ratios can be explained by an ∼0.6dex excess of Fe; J0937-0626 is
therefore similar to the subclass of "iron-enhanced" metal-poor stars.
A comparison with Milky Way field stars at [Fe/H]=-2.5 suggests that
J0937-0626 was enriched in material from an event, possibly a Type Ia
supernova, that created a significant amount of Cr, Mn, Fe, and Ni and
smaller amounts of Ca, Sc, Ti, and Zn. The r-process enhancement of
J0937-0626 is likely due to a separate event, which suggests that its
birth environment was highly enriched in r-process elements. The
kinematics of J0937-0626, based on Gaia DR2 data, indicate a
retrograde orbit in the Milky Way halo; J0937-0626 was therefore
likely accreted from a dwarf galaxy that had significant r-process
enrichment.
Description:
RAVE J093730.5-062655 was observed at high spectral resolution in 2016
and 2017 using the Astrophysical Research Consortium (ARC) 3.5m
telescope at Apache Point Observatory, as part of the Northern
Hemisphere survey of the R-Process Alliance (RPA;
Sakari+ 2018, J/ApJ/868/110). The ARC Echelle Spectrograph was used in
its default mode, leading to a spectral resolution of R∼31500 and
coverage of nearly the full optical range, from 3800 to 10400Å.
Objects:
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RA (ICRS) DE Designation(s)
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09 37 30.53 -06 26 55.2 RAVE J093730.5-062655 = TYC 4900-1967-1
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 42 200 Line equivalent widths or abundances
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See also:
III/279 : RAVE 5th data release (Kunder+, 2017)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/422/527 : Metal-poor star uvby-beta photometry. X. (Schuster+, 2004)
J/AJ/128/1177 : Galactic stellar abundances (Venn+, 2004)
J/ApJ/636/821 : Abundances of Baade's Window K giants (Fulbright+, 2006)
J/MNRAS/367/1329 : Elemental abundances for 176 stars (Reddy+, 2006)
J/ApJS/168/128 : UBVRcIc photom. of FHB and metal-poor stars (Beers+, 2007)
J/A+A/512/A54 : Teff and Fbol from Infrared Flux Method (Casagrande+, 2010)
J/ApJ/719/931 : Chemical evolution of the UMi dSph (Cohen+, 2010)
J/ApJ/724/341 : Nucleosynthesis of massive metal-free stars (Heger+, 2010)
J/A+A/511/L10 : Abundances and space velocities of 94 stars (Nissen+, 2010)
J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)
J/ApJ/754/91 : Abundances and velocities of NGC 6397 stars (Lovisi+, 2012)
J/ApJ/751/102 : Equivalent widths of 9 RGB in Carina dSph (Venn+, 2012)
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/ApJ/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013)
J/AJ/148/81 : APASS BVgri photometry of RAVE stars. I. (Munari+, 2014)
J/ApJ/797/21 : Carbon-enhanced metal-poor stars (Placco+, 2014)
J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)
J/ApJ/830/93 : Abund. of the Ret II brightest red giant members (Ji+, 2016)
J/AJ/151/82 : The 4 brightest red giants in Ret 2 (Roederer+, 2016)
J/ApJ/847/142 : Ultra-metal-poor stars LTE & NLTE abund. (Ezzeddine+, 2017)
J/ApJ/844/18 : RAVE J203843.2-002333 high-resolution spec. (Placco+, 2017)
J/ApJ/864/43 : Abund. of 3 bright extremely metal-poor giants (Cain+, 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/ApJ/859/L8 : Properties of TriAnd stars (Hayes+, 2018)
J/ApJ/852/99 : Abund. of 3 metal-poor stars in Hor I (Nagasawa+, 2018)
J/AJ/155/256 : Spec. validation of RAVE metal-poor stars (Placco+, 2018)
J/AJ/156/179 : Highly r-process-enhanced field stars (Roederer+, 2018)
J/ApJ/865/129 : Abundance analysis of HD 222925 (Roederer+, 2018)
J/ApJ/868/110 : R-Process Alliance: 1st release in Gal. halo (Sakari+, 2018)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- El Element
4- 5 A2 --- Ion Ionization state (I=neutral; II=ionized)
7- 13 F7.2 0.1nm lambda [3819.6/6678] Spectral line wavelength;
in Angstrom units
15- 18 F4.2 eV ExPot [0/4.45] Excitation potential
20- 25 F6.3 [-] log(gf) [-3.45/0.55] Log statistical weight and
oscillator strength
27- 31 F5.1 10-13m EW [10.6/102]?=-99.9 J0937-0626 equivalent width
in units of milli-Angstroms
33- 38 F6.2 [-] log(eps) [-0.6/5.6]?=-99.9 log(epsilon) abundance
40- 42 A3 --- Meth Analysis type (1)
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Note (1): Analysis type as follows:
SYN = the abundance was determined via spectrum synthesis; in this case,
a logε abundance is given;
EW = an equivalent width analysis was performed, and the measured EW
is given instead of an abundance.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 31-Aug-2020