J/MNRAS/492/3143ivo://CDS.VizieR/J/MNRAS/492/3143doi:10.26093/cds/vizier.74923143CDSTrust O.Jurua E.De Cat P.Joshi S.2024-08-20T20:15:38Z2023-06-12T15:04:53ZCDS support team

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

cds-question@unistra.fra-starseffective-temperaturestellar-radiivisible-astronomyFrequency analysis of long-term ultraprecise photometry can lead to precise values of rotation frequencies of rotating stars with 'hump and spike' features in their periodograms. Using these features, we computed the rotation frequencies and amplitudes. The corresponding equatorial rotational velocity (V_rot_) and spot size were estimated. On fitting the autocorrelation functions of the light curves with the appropriate model, we determined the star-spot decay time-scale. The V_rot_ agrees well with the projected rotational velocity (vsini) in the literature. Considering a single circular and black spot, we estimate its radius from the amplitude of the 'spike'. No evidence for a significant difference in the average 'spike' amplitude and spot radius was found for Am/Fm and normal A stars. Indeed, we derived an average value of ~21+/-2 and ~19+/-2ppm for the photometric amplitude and of 1.01+/-0.13 and 1.16+/-0.12R_E_ for the spot radius (where R_E_ is the Earth radius), respectively. We do find a significant difference for the average spot decay time-scale, which amounts to 3.6+/-0.2 and 1.5+/-0.2d for Am/Fm and normal A stars, respectively. In general, spots on normal A stars are similar in size to those on Am/Fm stars, and both are weaker than previously estimated. The existence of the 'spikes' in the frequency spectra may not be strongly dependent on the appearance of star-spots on the stellar surface. In comparison with G, K, and M stars, spots in normal A and Am/Fm stars are weak, which may indicate the presence of a weak magnetic field.2020MNRAS.492.3143Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/492/3143CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/133 : Kepler Input Catalog (Kepler Mission Team, 2009)I/345 : Gaia DR2 (Gaia Collaboration, 2018)J/MNRAS/431/2240 : Activity in A-type stars from Kepler (Balona, 2013)J/AJ/151/13 : LAMOST-Kepler MKCLASS spectral classification (Gray+, 2016)J/ApJS/220/19 : LAMOST obs. in the Kepler field. I. (De Cat+, 2015)J/ApJS/229/30 : Revised stellar properties of Q1-17 Kepler targetshttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/492/3143https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/492/3143http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/492/3143https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/492/3143https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/492/3143http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/492/3143GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/492/3143/tablea1 (List of normal A stars with 'hump and spike' features in the frequency spectra)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/492/3143/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/492/3143/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/492/3143/tablea1?GETtext/xml+votable180.050000true292.587455337.31724670.005555555555555556Cone search capability for table J/MNRAS/492/3143/tablea2 (List of Am/Fm stars with 'hump and spike' features in the frequency spectra)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/492/3143/tablea2?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/492/3143/tablea2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/492/3143/tablea2?GETtext/xml+votable180.050000true292.383166738.39938890.0055555555555555565/3646 3683 3688 3690 3780 6/14559 14579 14582-14583 14588-14589 14730-14731 14744 14746 14750-14751 14756-14757 14759 14764-14765 14768 14770 14772-14773 14775-14776 14779-14781 14783 14792 14794 14816 14824-14826 14918 14926 14930-14933 14935 14937-14938 14950 14959 14962 14967 15105 15107 15109-15110 15115 15118-15119 15124 15128-15129 15131-15132 15135-15136 15138-15139 15143 15145 15150 15154 15156 15168 15171-15172 15200https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/492/3143?format=asciiOpticaldefaultJ/MNRAS/492/3143/tablea1List of normal A stars with 'hump and spike' features in the frequency spectraKICKIC object identifiermeta.id;meta.mainintSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintfrotRotation frequencyd**-1em.freq;src.vardoubleArotPhotometric amplitudemmagsrc.var.amplitudefloate_ArotError on Arotmmagstat.errorfloatfhar? Frequency equivalent to 2*frotd**-1em.freq;src.vardoublenullableAhar? Amplitude associated to fharmmagsrc.var.amplitudefloatnullablee_Ahar? Error on Aharmmagstat.errorfloatnullableTeffEffective temperature (1)Kphys.temperature.effectiveinte_TeffError on TeffKstat.error;phys.temperature.effectiveintloggSurface gravitylog(cm.s**-2)phys.gravityfloate_loggError on logglog(cm.s**-2)stat.errorfloatlogLLogarithm of the luminosity (2)log(solLum)phys.luminosityfloate_logLError on logLlog(solLum)stat.errorfloatRRadius (3)solRadphys.size.radiusfloate_RError on RsolRadstat.errorfloatVrotEquatorial rotational velocitykm/sphys.veloc.rotatinte_VrotError on Vrotkm/sstat.errorintvsini? Projected rotational velocitykm/sphys.veloc.rotatintnullableRspotRadius of the spot (4)(6.3781x10+6m)phys.size.radiusfloate_RspotError on Rspot(6.3781x10+6m)stat.errorfloatPACF? Stellar rotation perioddtime.periodfloatnullablee_PACF? Error on PACFdstat.errorfloatnullabletauDecay time-scale of the dominant active regiondtime.scalefloate_tau? Error on taudstat.errorfloatnullable_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/MNRAS/492/3143/tablea2List of Am/Fm stars with 'hump and spike' features in the frequency spectraSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKICKIC object identifiermeta.id;meta.mainintfrotRotation frequencyd**-1em.freq;src.vardoubleArotPhotometric amplitudemmagsrc.var.amplitudefloate_ArotError on Arotmmagstat.errorfloatfhar? Frequency equivalent to 2*frotd**-1em.freq;src.vardoublenullableAhar? Amplitude associated to fharmmagsrc.var.amplitudefloatnullablee_Ahar? Error on Aharmmagstat.errorfloatnullableTeffEffective temperature (1)Kphys.temperature.effectiveinte_TeffError on TeffKstat.error;phys.temperature.effectiveintloggSurface gravitylog(cm.s**-2)phys.gravityfloate_loggError on logglog(cm.s**-2)stat.errorfloatlogLLogarithm of the luminosity (2)log(solLum)phys.luminosityfloate_logLError on logLlog(solLum)stat.errorfloatRRadius (3)solRadphys.size.radiusfloate_RError on RsolRadstat.errorfloatVrotEquatorial rotational velocitykm/sphys.veloc.rotatinte_VrotError on Vrotkm/sstat.errorintvsini? Projected rotational velocitykm/sphys.veloc.rotatintnullableRspotRadius of the spot (4)(6.3781x10+6m)phys.size.radiusfloate_RspotError on Rspot(6.3781x10+6m)stat.errorfloatPACF? Stellar rotation perioddtime.periodfloatnullablee_PACF? Error on PACFdstat.errorfloatnullabletauDecay time-scale of the dominant active regiondtime.scalefloate_tau? Error on taudstat.errorfloatnullable_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main