J/A+A/639/A63ivo://CDS.VizieR/J/A+A/639/A63doi:10.26093/cds/vizier.36390063CDSGaulme P.Jackiewicz J.Spada F.Chojnowski D.Mosser B.McKeever J.,Hedlund A.Vrard M.Benbakoura M.Damiani C.2022-09-05T13:50:05Z2020-07-13T07:23:25ZCDS support team

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

cds-question@unistra.frspectroscopic-binary-starsgiant-starsasteroseismologystellar-radiistellar-massesOscillating red-giant stars have provided a wealth of asteroseismic information regarding their interiors and evolutionary states, and access to their fundamental properties enable detailed studies of the Milky Way. The objective of this work is to determine what fraction of red-giant stars shows photometric rotational modulation, and understand its origin. One of the underlying questions is the role of close binarity in this population, standing upon the fact that red giants in short-period binary systems (less than 150 days or so) have been observed to display strong rotational modulation. We select a sample of about 4500 relatively bright red giants observed by Kepler, and show that about 370 of them (~8%) display rotational modulation. Almost all have oscillation amplitudes below the median of the sample, while 30 of them are not oscillating at all. Of the 85 of these red giants with rotational modulation chosen for follow-up radial-velocity observation and analysis, 34 show clear evidence of spectroscopic binarity. Surprisingly, 26 of the 30 non-oscillators are in this group of binaries. To the contrary, about 85% of the active red giants with detectable oscillations are not part of close binaries. With the help of stellar masses and evolutionary states computed from the oscillation properties, we shed light on the origin of their activity. It appears that low-mass red-giant branch stars tend to be magnetically inactive, while intermediate-mass ones tend to be highly active. The opposite trends are true for helium-core burning (red clump) stars, whereby the lower-mass clump stars are comparatively more active and the higher-mass ones less so. In other words, we find that low-mass red-giant branch stars gain angular momentum as they evolve to clump stars, while higher-mass ones lose angular momentum. The trend observed with low-mass stars leads to possible scenarios of planet engulfment or other merging events during the shell-burning phase. Regarding intermediate-mass stars, the rotation periods that we measure are long with respect to theoretical expectations reported in the literature, which reinforces the existence of an unidentified sink of angular momentum after the main sequence. This article establishes strong links between rotational modulation, tidal interactions, (surface) magnetic fields, and oscillation suppression. There is a wealth of physics to be studied in these targets not available in the Sun.2020A&A...639A..63Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/639/A63CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/133 : Kepler Input Catalog (Kepler Mission Team, 2009)J/A+A/588/A87 : Seismic global parameters of 6111 KIC (Vrard+, 2016)J/ApJ/866/99 : Revised radii of KIC stars + planets using Gaia DR2https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/639/A63https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/639/A63http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/639/A63https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/639/A63https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/639/A63http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/639/A63GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/639/A63/tablec1 (Asteroseismic and rotational parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/639/A63/tablec1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/639/A63/tablec1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/639/A63/tablec1?GETtext/xml+votable180.050000true291.0558791736.559950.0055555555555555564/922-923 933-935 944-946 5/3645-3647 3683 3704 3706 3729-3731 3760 3788-3789 3792 6/14559 14567 14573 14575 14577-14579 14730-14731 14744 14746-14747 14749-14751 14792 14794-14795 14822 14828 14830-14831 14914-14915 15044-15045 15057 15059-15062 15160-15161 15172-15174 15176 15178 15200 15232https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/639/A63?format=asciidefaultJ/A+A/639/A63/tablec1Asteroseismic and rotational parametersM*? Asteroseismic masssolMassphys.massfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKICKIC numbermeta.id;meta.mainlong2MASS2MASS designationmeta.idcharRAJ2000Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainKpmagKepler magnitudemagphot.mag;em.optfloatTeffGAIA DR2 effective temperatureKphys.temperature.effectiveinte_TeffError on TeffKstat.error;phys.temperature.effectiveintnumax? Oscillation frequency at maximum amplitudeuHzem.freqfloatnullablee_numax? Error on nu maxuHzstat.errorfloatnullableDnu? Oscillation mean large frequency separationuHzem.freq;src.varfloatnullablee_Dnu? Error on DnuuHzstat.errorfloatnullableHmax? Height of oscillation envelope (in ppp^2^/muHz unit)uHz**-1phys.sizedoublenullablee_Hmax? Error on Hgauss (in ppp^2^/muHz unit)uHz**-1stat.errordoublenullablee_M*? Error on M*solMassstat.errorfloatnullableR*? Asteroseismic radiussolRadphys.size.radiusfloatnullablee_R*? Error on R*solRadstat.errorfloatnullablelogg*? Asteroseismic logglog(cm.s**-2)phys.gravityfloatnullablee_logg*? Error on logg*log(cm.s**-2)stat.errorfloatnullableDPi1? Period spacing of dipole mixed modesstime.periodfloatnullablevisl1? Dipole (l=1) mode visibilitystat.fit.paramfloatnullableSph? Photometric index%spect.indexfloatnullableSimbadSimbad column added by the CDSmeta.ref.urlcharProt? Rotation perioddtime.periodfloatnullablevsin90? Stellar equatorial rotation velocitykm/sphys.veloc.rotatfloatnullableNvisitNumber of spectroscopic measurementsmeta.numberintstd(RV)? Standard deviation of radial velocitieskm/sstat.stdev;spect.dopplerVelocfloatnullableFlgact/osc? Activity and oscillation flag (1)meta.codeintnullableFlgVrard16[0/1] Is 1 if the value of DPi1 comes from Vrard et al., 2016, Cat. J/A+A/588/A87meta.codeintevolStatus? Red giant evolutionary state (2)meta.codeintnullable