J/ApJ/882/40ivo://CDS.VizieR/J/ApJ/882/40doi:10.26093/cds/vizier.18820040CDSJi A.P.Drout M.R.Hansen T.T.2021-09-10T14:20:48Z2021-03-01T11:04:51ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frchemical-abundanceschemically-peculiar-starsneutron-starsMultimessenger observations of the neutron star merger GW170817 and its kilonova proved that neutron star mergers can synthesize large quantities of r-process elements. If neutron star mergers in fact dominate all r-process element production, then the distribution of kilonova ejecta compositions should match the distribution of r-process abundance patterns observed in stars. The lanthanide fraction (X_La_) is a measurable quantity in both kilonovae and metal-poor stars, but it has not previously been explicitly calculated for stars. Here we compute the lanthanide fraction distribution of metal-poor stars ([Fe/H]{<}-2.5) to enable comparison to current and future kilonovae. The full distribution peaks at log X_La_~-1.8, but r-process-enhanced stars ([Eu/Fe]>0.7) have distinctly higher lanthanide fractions: logX_La_>~-1.5. We review observations of GW170817 and find general consensus that the total logX_La_=-2.2+/-0.5, somewhat lower than the typical metal-poor star and inconsistent with the most highly r-enhanced stars. For neutron star mergers to remain viable as the dominant r-process site, future kilonova observations should be preferentially lanthanide-rich (including a population of ~10% with logX_La_>-1.5). These high-X_La_ kilonovae may be fainter and more rapidly evolving than GW170817, posing a challenge for discovery and follow-up observations. Both optical and (mid-)infrared observations will be required to robustly constrain kilonova lanthanide fractions. If such high-X_La_ kilonovae are not found in the next few years, that likely implies that the stars with the highest r-process enhancements have a different origin for their r-process elements.2019ApJ...882...40Jhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/882/40CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/530/783 : The r-process enriched giant HD 115444 (Westin+, 2000)J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)J/ApJ/617/1091 : La and Eu abundances in 85 stars (Simmerer+, 2004)J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)J/ApJ/645/613 : Abundances of HD 221170 (Ivans+, 2006)J/AJ/132/85 : Equivalent width of 33 metal-poor RHB (Preston+, 2006)J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)J/A+A/516/A46 : HE 2327-5642 abundance analysis (Mashonkina+, 2010)J/ApJ/724/975 : Heavy elements abund. of metal-poor stars (Roederer+, 2010)J/ApJ/711/573 : Abundances in a halo stellar stream (Roederer+, 2010)J/ApJ/742/54 : CASH project II. Extremely metal-poor stars (Hollek+, 2011)J/A+A/548/A34 : Abundances of carbon-enhanced metal-poor stars (Allen+, 2012)J/ApJ/778/56 : Hamburg/ESO Survey extremely metal-poor stars (Cohen+, 2013)J/ApJ/771/67 : Abundances for 97 metal-poor stars. II. (Ishigaki+, 2013)J/ApJ/775/L27 : Chemical abundances in a metal-poor RGB star (Johnson+, 2013)J/ApJ/787/10 : Solar s-process contrib. with GCE model (Bisterzo+, 2014)J/ApJ/797/44 : Evolution and nucleosynthesis of AGB stars (Fishlock+, 2014)J/A+A/569/A43 : HE 2252-4225 abundance analysis (Mashonkina+, 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/807/171 : SkyMapper Survey metal-poor star spectrosc. (Jacobson+, 2015)J/ApJ/798/110 : Equivalent widths of LAMOST metal-poor stars (Li+, 2015)J/MNRAS/460/884 : EMBLA survey. Galactic bulge metal-poor stars (Howes+, 2016)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/838/44 : Abundances of the brightest member of Tuc III (Hansen+, 2017)J/A+A/607/A91 : CS 29497-004 abundances (Hill+, 2017)J/ApJ/844/18 : RAVE J203843.2-002333 high-resolution spec. (Placco+, 2017)J/ApJ/851/L21 : UV-NIR obs. compilation of GW170817 (Villar+, 2017)J/ApJ/869/50 : Barium abundances of red giant branch stars (Duggan+, 2018)J/ApJ/858/92 : RPA Southern Pilot Search of 107 Stars (Hansen+, 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)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/882/40https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/882/40http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/882/40https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/882/40https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/882/40http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/882/40GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/882/40/table4 (Star data table)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/882/40/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/882/40/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/882/40/table4?GETtext/xml+votable180.050000true2.21592925.4380850.0055555555555555566/51 5886 7456 8244 10173 10249 10453 10476 11302 16451 16462 16503 16514 16540 16566 16569 16609 16663 16665 16854 17095 17181 17197 17203 17241 17380 17406 17412 17420 17448 17578 17642 17683 17938 18086 18132 18452 18545 18579 18587 18634 18847 18850 18964 18968 18972 19070 19083 19209 19211 19484 21034 21089 22635 22662 23056 23304 24685 24887 24999 25302 25413 25479 25482 25540 25579 25608 25630 25639 25641 25658 25710 25722 25733 25772 25853 25879 25959 26019 26242 26292 26347 26366 26995 27131 27763 28740 28998 30031 30858 30874 31377 31383 31398 31404 31427 31451 32468 33019 33249 33261 33464 33470 33526 33633 33653 33695 33696 34019 34232 34574 34595 34600 34708 34990 35079 35112 35390 35695 36135 36193 36295 36365 36628 36642 36690 36691 36788 36843 38841 38868 38919 38953 40027 40959 41307 41335 42104 42307 43261 43367 43503 44208 44427 44545 44570 44575 44890 45017 45309 45397 45401 45406 45408 45504 45612 45679 45718 45796 45797 45808 45825 46023 46080 46090 46155 46311 46490 46506 46580 46646 46676 46691 46722 46751 46780 46813 46851 46902 46958 47012 47190 47204 47216 47217 47353 47458 47649 47699 47802 47852 47955 48221 48363 48388 48451 48485 48501 48518 48764 48798 48824 48937 49001 49081 49136https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/882/40?format=asciidefaultJ/ApJ/882/40/table4Star data tableSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarStar (1)meta.id;meta.maincharRefReference (see refs.dat file)meta.ref;pos.framecharNel[3/33] Number of elementsmeta.numberint[Fe/H][-4.1/-2.3] Abundance, [Fe/H]phys.abund.Fefloat[Sr/Fe][-1.6/1.8]? Abundance, [Sr/Fe]phys.abundfloatnullable[Ba/Fe][-1.7/2.3] Abundance, [Ba/Fe]phys.abundfloat[Eu/Fe][-0.6/2.8] Abundance, [Eu/Fe]phys.abundfloatlogXLa-A07[-3.1/-1]? log, X_La_ fraction, Arnould et al. (2007PhR...450...97A) (2)phys.abund.Z;arith.ratiofloatnullablelogXLa-S08[-3.5/-1.1]? log, X_La_ fraction, Sneden et al. (2008ARA&A..46..241S) (2)phys.abund.Z;arith.ratiofloatnullableSampleSample (3)src.samplechar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/ApJ/882/40/refsReferencesCatVizieR catalog referencemeta.id;meta.datasetcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRefReference codemeta.note;meta.maincharprimaryBibCodeBibcode of the referencemeta.bib.bibcodecharAuthFirst author's namemeta.bib.authorchar