J/ApJ/923/183ivo://CDS.VizieR/J/ApJ/923/183doi:10.26093/cds/vizier.19230183CDSLi H.2025-02-05T20:12:49Z2023-07-24T12:16:42ZCDS support team

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

cds-question@unistra.frmetallicitychemically-peculiar-starsvisible-astronomyspectroscopyThis work presents a first attempt to apply fuzzy cluster analysis (FCA) to analyzing stellar spectra. FCA is adopted to categorize line indices measured from LAMOST low-resolution spectra, and automatically remove the least metallicity-sensitive indices. The FCA-processed indices are then transferred to the artificial neural network (ANN) to derive metallicities for 147 very metal-poor (VMP) stars that have been analyzed by high-resolution spectroscopy. The FCA-ANN method could derive robust metallicities for VMP stars, with a precision of ~0.2dex compared with high-resolution analysis. The recommended FCA threshold value {lambda} for this test is between 0.9965 and 0.9975. After reducing the dimension of the line indices through FCA, the derived metallicities are still robust, with no loss of accuracy, and the FCA-ANN method performs stably for different spectral quality from [Fe/H]~1.8 down to -3.5. Compared with traditional classification methods, FCA considers ambiguity in groupings and noncontinuity of data, and is thus more suitable for observational data analysis. Though this early test uses FCA to analyze low-resolution spectra, and feeds the input to the ANN method to derive metallicities, FCA should be able to, in the large data era, also analyze slitless spectroscopy and multiband photometry, and prepare the input for methods not limited to ANN, in the field of stellar physics for other studies, e.g., stellar classification, identification of peculiar objects. The literature-collected high-resolution sample can help improve pipelines to derive stellar metallicities, and systematic offsets in metallicities for VMP stars for three published LAMOST catalogs have been discussed.2021ApJ...923..183Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/923/183CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/345 : Gaia DR2 (Gaia Collaboration, 2018)V/164 : LAMOST DR5 catalogs (Luo+, 2019)J/AJ/103/1987 : Stars of very low metal abundance (Beers+ 1992)J/AJ/117/981 : Estimation of stellar metal abundance. II. (Beers+, 1999)J/AJ/128/1177 : Galactic stellar abundances (Venn+, 2004)J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)J/A+A/442/961 : Lithium content of the Gal. Halo stars (Charbonnel+, 2005)J/AJ/132/137 : Abund. of extremely metal-poor carbon stars (Cohen+, 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/A+A/484/721 : HES survey. IV. Cand. metal-poor stars (Christlieb+, 2008)J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)J/A+A/501/519 : Extremely metal-poor turnoff stars abund. (Bonifacio+, 2009)J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009)J/ApJ/743/140 : Abund. (Be,{alpha}) in metal-poor stars (Boesgaard+, 2011)J/ApJ/742/54 : CASH project II. Extremely metal-poor stars (Hollek+, 2011)J/MNRAS/412/843 : SAGA extremely metal-poor stars (Suda+, 2011)J/A+A/548/A34 : Abundances of carbon-enhanced metal-poor stars (Allen+, 2012)J/AJ/145/13 : Metal-poor stars from SDSS/SEGUE. I. Abundances (Aoki+, 2013)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/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013)J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)J/ApJ/797/13 : Abundances of bright metal-poor stars (Schlaufman+, 2014)J/ApJ/807/171 : SkyMapper Survey metal-poor star sp. (Jacobson+, 2015)J/ApJ/798/110 : Equivalent widths of LAMOST metal-poor stars (Li+, 2015)J/ApJ/808/16 : The Cannon: a new approach to determine abund. (Ness+, 2015)J/ApJ/819/110 : Extremely metal-poor gal. in SDSS II. (Sanchez Almeida+ 2016)J/A+A/614/A68 : Carbon-enhanced metal-poor stars sample (Caffau+, 2018)J/A+A/612/A98 : APOGEE full information on classes (Garcia-Dias+, 2018)J/ApJ/858/92 : RPA Southern Pilot Search of 107 Stars (Hansen+, 2018)J/ApJS/238/16 : LAMOST-DR3 very metal-poor star catalog (Li+, 2018)J/ApJ/868/110 : R-Process Alliance: 1st release in Gal. halo (Sakari+, 2018)J/ApJS/245/34 : Abundances for 6 million stars from LAMOST DR5 (Xiang+, 2019)J/ApJ/891/39 : LAMOST very metal-poor stars of the Gal. halo (Yuan+, 2020)http://www.lamost.org/ : LAMOST home pagehttp://jinabase.pythonanywhere.com/ : JINAbase - database for metal-poor starshttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/923/183https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/923/183http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/923/183https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/923/183https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/923/183http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/923/183GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/923/183/table3 (List of the very metal-poor (VMP) stars used)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/923/183/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/923/183/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/923/183/table3?GETtext/xml+votable180.050000true1.5716761110.961623890.0055555555555555566/0 146 154 1533 4253 4269 4714 4783 4909 5246 5310 5406 5458 5723 5768 5827 5886 5973 6058 6274 7456 8197 8200-8201 8205 8244 8266 8395 8864 8930 10149 10368 10376 10382 10425 10430 10820 11072 11432 11490 12639 14385 14956 17745 17749 17757 17850 17879 18132 18193 18663 18683 18797 18847 18850 18883 19000 19061 19070 19073 19210-19211 19485 19602 19652 19901 21854 22451 22685 22755 22766 23097 23207 23220 23428 23467 23876 24062 25577 25722 25772 25813 25832 25836 25853 25870 25906 25938-25939 25980 26025 26027 26048 26057 26147 26164 26191 26214 26220 26225 26232 26284 26292 26380 26462 26530 26534 26565 26581 26829 26886 26927 27024 27035 27065 27105 27131 27237 27322 27589 27644 27659 27948 27973 27986 27989 28054 28097 28223 28484 28540 28594 31337 31398 31420 31427 31543 31642 31737 32034 32302 32312 36811 36813 36824 45038https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/923/183?format=asciiOpticaldefaultJ/ApJ/923/183/table3List of the very metal-poor (VMP) stars usedrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension (J2000)degpos.eq.ra;meta.mainG1[0/8.34] Line index G10.1nmspect.indexfloatFe5335[0/1.74] Line index Fe53350.1nmspect.indexfloatFe5406[0/0.87] Line index Fe54060.1nmspect.indexfloatDEJ2000[-8.6/58.7] Declination (J2000)degpos.eq.dec;meta.mainTeff[4210/6650]? Effective temperature derived from high-resolution spectraKphys.temperature.effectiveintnullablelogg[0.01/5]? Surface gravity derived from high-resolution spectraphys.gravityfloatnullable[Fe/H][-4.8/-2] Metallicity derived from high-resolution spectraphys.abund.ZfloatSNg[21.5/592] SNR at g-band of the LAMOST spectrastat.snrfloatSNr[23.8/913] SNR at r-band of the LAMOST spectrastat.snrfloatFeH-FCA865[-4.3/-0.8] Metallicity derived from LAMOST spectra, FCA clustered, threshold=0.9865phys.abund.FefloatFeH-FCA885[-5.3/0.8] Metallicity derived from LAMOST spectra, FCA clustered, threshold=0.9885phys.abund.FefloatFeH-FCA965[-4.6/-1.9] Metallicity derived from LAMOST spectra, FCA clustered, threshold=0.9965phys.abund.FefloatFeH-FCA975[-4.6/-1.9] Metallicity derived from LAMOST spectra, FCA clustered, threshold=0.9975phys.abund.FefloatFeH-FCA980[-4.9/-1.4] Metallicity derived from LAMOST spectra, FCA clustered, threshold=0.9980phys.abund.FefloatFeH-FCA983[-4.3/-1.2] Metallicity derived from LAMOST spectra, FCA clustered, threshold=0.9983phys.abund.FefloatFeH-FCA985[-4.8/-1.7] Metallicity derived from LAMOST spectra, FCA clustered, threshold=0.9985phys.abund.FefloatFeH-FCA990[-7.6/-1.5] Metallicity derived from LAMOST spectra, FCA clustered, threshold=0.9990phys.abund.FefloatCaHK[0/21.43] Line index CaHK0.1nmspect.indexfloatK24[0/11.34] Line index K240.1nmspect.indexfloatK12[0/8.16] Line index K120.1nmspect.indexfloatK6[0/4.92] Line index K60.1nmspect.indexfloatFe5709[0/0.6] Line index Fe57090.1nmspect.indexfloatFe5782[0/0.68] Line index Fe57820.1nmspect.indexfloatNaD[0/9.88] Line index NaD0.1nmspect.indexfloatFeH-DDPayne[-3.7/-0.9]? Metallicity derived from LAMOST spectra, from DDPaynephys.abund.FefloatnullableFeH-DR5v3[-2.5/-1.37]? Metallicity derived from LAMOST spectra, from official DR5v3phys.abund.FefloatnullableHeI4026[0/0.9] Line index HeI40260.1nmspect.indexfloatHD24[0/10.55] Line index HD240.1nmspect.indexfloatHD12[0/6.57] Line index HD120.1nmspect.indexfloatCN1[0/22] Line index CN10.1nmspect.indexfloatCN2[0/22.95] Line index CN20.1nmspect.indexfloatCa4227[0/2.13] Line index Ca42270.1nmspect.indexfloatG4300[0/8.93] Line index G43000.1nmspect.indexfloatFe4383[0/4.45] Line index Fe43830.1nmspect.indexfloatCa4455[0/0.9] Line index Ca44550.1nmspect.indexfloatHeI4471[0/0.82] Line index HeI44710.1nmspect.indexfloatFe4531[0/2.66] Line index Fe45310.1nmspect.indexfloatHbeta[0.016/7.66] Line index Hbeta0.1nmspect.indexfloatFe5015[0/3.4] Line index Fe50150.1nmspect.indexfloatMg1[0/29.87] Line index Mg10.1nmspect.indexfloatMg2[0.1/7.02] Line index Mg20.1nmspect.indexfloatMgb[0/4.31] Line index Mgb0.1nmspect.indexfloatFe5270[0/1.86] Line index Fe52700.1nmspect.indexfloatFeH-GSN[-2.41/-1.39]? Metallicity derived from LAMOST spectra, from generative spectrum network (GSN)phys.abund.FefloatnullableDR5Display data from the LAMOST DR5 cat. (V/164) within 3"meta.ref.urlcharr_[Fe/H]Reference of high-resolution analyses (see refs.dat file)meta.refcharJ/ApJ/923/183/refsReferencesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRefReference codemeta.notecharBibCodeBibcode of the referencemeta.bib.bibcodecharCommComment (Catalog's reference in VizieR)meta.notechar