J/ApJ/936/L23ivo://CDS.VizieR/J/ApJ/936/L23doi:10.26093/cds/vizier.19369023CDSLuhn J.K.Wright J.T.Henry G.W.Saar S.H.Baum A.C.2024-11-06T20:27:33Z2024-08-09T08:06:16ZCDS support team

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

cds-question@unistra.frhigh-velocity-starsinfrared-photometryvisible-astronomyphotometryHD-166620 was recently identified as a Maunder minimum candidate based on nearly 50 years of CaII H and K activity data from Mount Wilson and Keck HIRES. These data showed clear cyclic behavior on a 17yr timescale during the Mount Wilson survey that became flat when picked up later with Keck HIRES planet-search observations. Unfortunately, the transition between these two data sets-and therefore the transition into the candidate Maunder minimum phase-contained little to no data. Here, we present additional Mount Wilson data not present in Baum et al., along with photometry over a nearly 30yr baseline that definitively traces the transition from cyclic activity to a prolonged phase of flat activity. We present this as conclusive evidence of the star entering a grand magnetic minimum and therefore the first true Maunder minimum analog. We further show that neither the overall brightness nor the chromospheric activity level (as measured by SHK) is significantly lower during the grand magnetic minimum than its activity cycle minimum, implying that an anomalously low mean or instantaneous activity levels are not a good diagnostic or criterion for identifying additional Maunder minimum candidates. Intraseasonal variability in SHK, however, is lower in the star's grand minimum; this may prove a useful symptom of the phenomenon.2022ApJ...936L..23Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/936/L23CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/AJ/111/439 : Chromospheric emission in late-type stars. (Henry+ 1996)J/A+A/417/651 : NEXXUS ROSAT survey of coronal X-ray (Schmitt+, 2004)J/ApJS/152/261 : Chromospheric Ca II emission in nearby stars (Wright+, 2004)J/ApJ/725/875 : Chromospheric activity for CPS stars (Isaacson+, 2010)J/ApJS/225/32 : Extended abundance analysis of cool stars (Brewer+, 2016)J/ApJ/874/107 : HARPS-N solar radial velocities & activity (Milbourne+, 2019)J/ApJ/904/140 : Ruprecht147 members & rot. data 5 other cl. (Curtis+, 2020)J/AJ/163/183 : S-value for 59 Sun-like starswith HIRES and HKP (Baum+, 2022)J/AJ/163/180 : RVel & BV photometry of 9 {gamma} Doradus stars (Henry+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/936/L23https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/936/L23http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/936/L23https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/936/L23https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/936/L23http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/936/L23GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/ApJ/936/L23/table2All SHK activity datarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJD[2439342/2458918] Julian Datedtime.epochdoubleYear[1966/2021] Fractional yearyrtimedoubleSHK[0.14/0.88] The S_HK_ activity indexspect.indexdoubleInstInstrument identifier (1)meta.id;instrcharJ/ApJ/936/L23/table3T4 APT photometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJD[2449094/2459156] Julian Datedtime.epochdoubleYear[1993/2021] Fractional yearyrtimedoublemag[0.76/0.78] Differential magnitude (1)magphot.mag;em.optfloatInstInstrument identifier (2)meta.id;instrchar