J/ApJ/923/77ivo://CDS.VizieR/J/ApJ/923/77doi:10.26093/cds/vizier.19230077CDSPace A.B.Walker M.G.Koposov S.E.Caldwell N.Mateo M.,Olszewski E.W.Bailey III J.I.Wang M.-Y.2025-02-28T20:13:06Z2023-07-19T12:53:11ZCDS support team

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

cds-question@unistra.frdwarf-galaxieschemical-abundancesvisible-astronomyspectroscopyradial-velocityThe Fornax dwarf spheroidal galaxy has an anomalous number of globular clusters, five, for its stellar mass. There is a longstanding debate about a potential sixth globular cluster (Fornax 6) that has recently been "rediscovered" in DECam imaging. We present new Magellan/M2FS spectroscopy of the Fornax 6 cluster and Fornax dSph. Combined with literature data we identify ~15-17 members of the Fornax 6 cluster, showing that this overdensity is indeed a star cluster and associated with the Fornax dSph. The cluster is significantly more metal-rich (mean metallicity of [Fe/H]=-0.71+/-0.05) than the other five Fornax globular clusters (-2.5<[Fe/H]{<}-1.4) and more metal-rich than the bulk of Fornax. We measure a velocity dispersion of 5.6_-1.6_^+2.0^kms^-1^ corresponding to an anomalously high mass-to-light of 15<M/L<258 at 90% confidence when calculated assuming equilibrium. Two stars inflate this dispersion and may be either Fornax field stars or as yet unresolved binary stars. Alternatively, the Fornax 6 cluster may be undergoing tidal disruption. Based on its metal-rich nature, the Fornax 6 cluster is likely younger than the other Fornax clusters, with an estimated age of ~2Gyr when compared to stellar isochrones. The chemodynamics and star formation history of Fornax shows imprints of major events such as infall into the Milky Way, multiple pericenter passages, star formation bursts, and/or potential mergers or interactions. Any of these events may have triggered the formation of the Fornax 6 cluster.2021ApJ...923...77Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/923/77CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/202 : Globular Clusters in the Milky Way (Harris, 1997)II/357 : The Dark Energy Survey (DES): Data Release 1 (Abbott+, 2018)I/350 : Gaia EDR3 (Gaia Collaboration, 2020)J/PASP/110/533 : BR photometry of Fornax bright stars (Stetson+ 1998)J/ApJ/521/577 : HST studies of the WLM globular cluster (Hodge+, 1999)J/AJ/132/781 : 2MASS colors of Magellanic cloud star clusters (Pessev+, 2006)J/A+A/459/423 : VI and [Fe/H] of Fornax dSph RGB stars (Battaglia+, 2006)J/AJ/137/3100 : Radial velocities of 4 dSph galaxies (Walker+, 2009)J/A+A/523/A17 : Individual stars in Fornax dSph center (Letarte+, 2010)J/ApJS/191/352 : Abundances in stars of MW dwarf satellites (Kirby+, 2010)J/A+A/538/A100 : Abundances red giants in Carina dSph (Lemasle+, 2012)J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)J/A+A/572/A82 : Abundances in outer parts of Fornax dSph (Hendricks+, 2014)J/MNRAS/448/2717 : Bayesian analysis of resolved stellar sp. (Walker+, 2015)J/ApJ/808/108 : M2FS stellar spectroscopy of Reticulum 2 (Walker+, 2015)J/A+A/585/A86 : Fornax dSph H4 globular cluster stars (Hendricks+, 2016)J/ApJ/817/41 : Abundances of 4 metal-poor red giants in BooII (Ji+, 2016)J/ApJ/819/53 : Magellan/M2FS sp. of Tucana 2 and Grus 1 (Walker+, 2016)J/ApJ/829/26 : Variable stars in Andromeda XXV field. III. (Cusano+, 2016)J/ApJ/837/54 : Variable stars in DDO 216-A1 (Cole+, 2017)J/ApJ/838/83 : RVs, abundances & membership in TriII (Kirby+, 2017)J/A+A/616/A12 : Gaia DR2 sources in GC and dSph (Gaia Collaboration+, 2018)J/ApJ/866/22 : Spectroscopic analysis of Tuc III stream (Li+, 2018)J/ApJ/875/77 : Proper motions of MW satellites with Gaia & DES (Pace+, 2019)J/ApJ/875/L13 : DECam r and i magnitudes in the Fornax 6 cluster (Wang+, 2019)J/A+A/626/A15 : Sculptor Red Giant Branch stars abundances (Hill+, 2019)J/MNRAS/490/3508 : The Southern Stellar Stream Sp. Survey (S^5^) (Li+, 2019)J/A+A/635/A107 : Spectroscopy of the Eri 2 cluster (Zoutendijk+, 2020)J/A+A/638/A104 : Gaia DR2 cand. RR Lyrae of Sgr stream & dwarf (Ramos+, 2020)J/A+A/642/A176 : Chemical evolution of dSph galaxy Sextans (Theler+, 2020)J/ApJ/908/18 : HST stellar photometry of Eridanus II (Simon+, 2021)J/A+A/649/A3 : Gaia EDR3 photometric passbands (Riello+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/923/77https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/923/77http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/923/77https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/923/77https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/923/77http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/923/77GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/923/77/table2 (M2FS stellar spectroscopy of Fornax)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/923/77/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/923/77/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/923/77/table2?GETtext/xml+votable180.050000true40.13920806-35.015186110.005555555555555556Cone search capability for table J/ApJ/923/77/table3 (Combined MMFS and M2FS catalog of Fornax)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/923/77/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/923/77/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/923/77/table3?GETtext/xml+votable180.050000true39.601695-35.497693890.0055555555555555565/8992 6/35882-35883 35886 35972https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/923/77?format=asciiOpticaldefaultJ/ApJ/923/77/table2M2FS stellar spectroscopy of FornaxGaiaGaia EDR3 identifiermeta.id;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000[38.57/41.3] Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-35.6/-33.6] Declination (J2000)degpos.eq.dec;meta.mainHJDHeliocentric Julian Datedtime.epochdoubleS/N[0.27/43.3] Signal-to-Noise ratiostat.snrfloatVLOS[-2452/371.4] Line-of-sight velocitykm/sphys.veloc;pos.heliocentricdoublee_VLOS[0.6/4.8] Uncertainty in VLOSkm/sstat.errorfloatVLOS-Sk[-49.4/96] Skewness measure in VLOSkm/sstat.fit.paramfloatVLOS-Ku[-0.7/11167] Kurtosis measure in VLOSkm/sstat.fit.paramdoubleTeff[4007/7967] Effective temperatureKphys.temperature.effectiveinte_Teff[6/1019] Uncertainty in TeffKstat.error;phys.temperature.effectiveintTeff-Sk[-5.2/4.7] Skewness measure in TeffKstat.fit.paramfloatTeff-Ku[-1.1/72.2] Kurtosis measure in TeffKstat.fit.paramfloatlog(g)[0.03/4.91] Log surface gravitylog(cm.s**-2)phys.gravityfloate_log(g)[0.02/1.6] Uncertainty in log(g)log(cm.s**-2)stat.errorfloatlog(g)-Sk[-5.1/4.2] Skewness measure in log(g)log(cm.s**-2)stat.fit.paramfloatlog(g)-Ku[-1.3/76] Kurtosis measure in log(g)log(cm.s**-2)stat.fit.paramfloatZ[-3.3/0.8] Metallicitylog(Sun)phys.abund.Zfloate_Z[0.05/1.1] Uncertainty in Zlog(Sun)stat.errorfloatZ-Sk[-4/1.7] Skewness measure in Zlog(Sun)stat.fit.paramfloatZ-Ku[-1/18] Kurtosis measure in Zlog(Sun)stat.fit.paramfloatCStar also included in combined MMFS and M2FS catalog (link to Table 3)meta.ref.urlintnullableJ/ApJ/923/77/table3Combined MMFS and M2FS catalog of FornaxNVLOS[1/6] Number of VLOS measurementsmeta.numberintNM2FS[0/3] Number of VLOS measurements in M2FS catalogmeta.numberintVLOS[-268/417] Line-of-sight velocitykm/sphys.veloc;pos.heliocentricfloate_VLOS[0.3/17] Uncertainty in VLOSkm/sstat.errorfloatZ[-3.1/1]? Metallicitylog(Sun)phys.abund.Zfloatnullablee_Z[0.05/1.3]? Uncertainty in Zlog(Sun)stat.errorfloatnullablePdsph[0/1] Dwarf Spheroidal membership probabilitystat.probabilityfloatb_Pdsph[0/1] Lower 16% uncertainty in Pdsphstat.error;stat.minfloatB_Pdsph[0/1] Upper 84% uncertainty in Pdsphstat.error;stat.maxfloatPf6[0/0.995] Fornax 6 globular cluster probabilitystat.fit.goodnessfloatb_Pf6[0/0.992] Lower 16% uncertainty in Pf6stat.error;stat.minfloatB_Pf6[0/0.997] Upper 84% uncertainty in Pf6stat.error;stat.maxfloatSimbadSimbad column added by the CDSmeta.ref.urlcharW09Display data from Walker+ 2009, J/AJ/137/3100 within 3"meta.ref.urlintnullableM2Star also included in M2FS catalog (link to Table 2)meta.ref.urlintnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaGaia EDR3 identifiermeta.id;meta.mainRAJ2000[38.57/41.3] Gaia EDR3 Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-35.6/-33.6] Gaia EDR3 Declination (J2000)degpos.eq.dec;meta.main