J/ApJ/961/227ivo://CDS.VizieR/J/ApJ/961/227CDSLee J.-W.2026-05-28T08:16:51Z2026-05-28T09:09:46ZCDS support team

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

cds-question@unistra.frglobular-star-clustersgiant-starsphotometryvisible-astronomychemical-abundancespopulation-ii-starsWe perform a comparative study of the ex situ second-parameter pair globular clusters (GCs) M30 and M92, having similar metallicities but different horizontal branch morphologies. We obtain similar mean primordial carbon abundances for both clusters. However, M92 shows a large dispersion in carbon due to a more extended C-N anticorrelation, while M30 exhibits a higher primordial nitrogen abundance, suggesting that they have different chemical enrichment histories. Our new results confirm our previous result that M92 is a metal-complex GC showing a bimodal metallicity distribution. We also find that the metal-rich group of stars in M92 shows a helium enhancement as large as {Delta}Y~0.05 from the red giant branch bump V magnitudes, which can also be supported by (i) a lack of bright red giant branch stars, (ii) synthetic evolutionary horizontal branch population models and (iii) the more extended spatial distribution due to different degree of the diffusion process from their lower masses. We reinterpret the [Eu/Fe] measurements by others, finding that the two metallicity groups of stars in M92 have significantly different [Eu/Fe] abundances with small scatters. This strongly suggests that they formed independently out of well-mixed interstellar media in different environments. We suggest that M92 is a more complex system than a normal GC, most likely a merger remnant of two GCs or an even more complex system. In the Appendix, we address the problems with the recently developed color-temperature relations and the usage of broadband photometry in the populational taggings.2024ApJ...961..227Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/961/227CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)VII/195 : Globular Clusters in the Milky Way (Harris, 1996)VII/202 : Globular Clusters in the Milky Way (Harris, 1997)J/ApJ/518/262 : CCD VIc Photometry of M30 Stars (Sandquist+, 1999)J/A+A/505/117 : Abund. of red giants in 15 globular clusters (Carretta+, 2009)J/AJ/142/22 : Heavy-element dispersion in M92 (Roederer+, 2011)J/ApJ/786/14 : He abundances in M30 and NGC 6397 (Mucciarelli+, 2014)J/ApJS/219/7 : Ca,by photometry in globular clusters. I. M22 (Lee, 2015)J/MNRAS/478/1520 : Milky Way globular clusters data (Baumgardt+, 2018)J/MNRAS/485/3042 : UBVRI photometry in 48 globular clusters (Stetson+, 2019)J/ApJ/958/45 : Keck/HIRES spectroscopy obs. of stars in M92 (Kirby+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/961/227https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/961/227http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/961/227https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/961/227https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/961/227http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/961/227GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/961/227/table1 (Photometric data of red giant branch (RGB) stars in M30 and M92)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/961/227/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/961/227/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/961/227/table1?GETtext/xml+votable180.050000true325.07913208-23.181360240.0055555555555555566/9664 9666 48434 48440https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/961/227?format=asciiOpticaldefaultJ/ApJ/961/227/table1Photometric data of red giant branch (RGB) stars in M30 and M92recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintClusterCluster Name ("M30": 271 occurrences or "M92": 592 occurrences)meta.id.parentcharID[18/9624] Star number within Clustermeta.id.part;meta.mainintVmag[12.12/17.1] V-band magnitudemagphot.mag;em.opt.Vfloatb-y[0.43/0.91] Color, Stromgren b-ymagphot.color;em.opt.B;em.opt.VfloatcnJWL[-0.15/-0.012] Photometric index, CN{lambda}3883 (1)spect.indexfloatchJWL[-0.71/-0.52] Photometric index, CH{lambda}4250 (1)spect.indexfloatnhJWL[-1.24/0.41] Photometric index, NH{lambda}3360 (1)spect.indexfloathkJWL[0.23/0.91] Photometric index, CaII H&K (1)spect.indexfloat[Fe/H]hk[-2.6/-2.1] Photometric iron abundance (metallicity) from hkJWL (2)phys.abund.Fefloat[C/Fe]ch[-0.84/0.36] Photometric carbon abundance from chJWL (2)phys.abundfloat[N/Fe]nh[-0.4/1.8] Photometric nitrogen abundance from nhJWL (2)phys.abundfloatRAJ2000[259.1/325.3] Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-23.3/43.3] Declination (J2000)degpos.eq.dec;meta.main