J/MNRAS/535/2189ivo://CDS.VizieR/J/MNRAS/535/2189doi:10.26093/cds/vizier.75352189CDSBarcelo Forteza S.Pascual-Granado J.Suarez J.C.Garcia Hernandez A.,Mirouh G.M.Lares-Martiz M.2025-02-24T20:16:56Z2024-12-10T13:27:01ZCDS support team

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

cds-question@unistra.fra-starsvariable-starsasteroseismologyThe presence of low-amplitude peaks over the noise in the power spectra of {delta} Sct stars is frequently disregarded. These seemingly insignificant peaks, collectively referred to as grass, might contain valuable information about the origin of these stars and the reasons behind the occurrence or absence of a plateau. It is crucial to systematically parameterize the grass phenomenon throughout a comprehensive sample that covers the entire {delta} Sct star parameter range. Thus, we conduct a quantitative study of long-duration, high-duty-cycle TESS light curves, leading to improved detection methods for plateaus and a deeper understanding of their nature. This approach minimizes the impact of unresolved peaks caused by mode variations over time. Additionally, we present appropriate analysis techniques to mitigate window effects and identify and eliminate spurious peaks. We demonstrate here that the grass can be effectively parameterized based on peak density. With such parameterization two distinct regimes are found: the sparse grass regime, characterized by low peak density and the absence of a plateau in the power spectra, and the dense grass regime, characterized by high peak densities and the presence of an observable plateau. Our study is the first rigorous quantification of the emergence of such a plateau in the power spectra of {delta} Sct. Since the grass might be related with fractality, mode variability, and stellar rotation rate, its parameterization opens a new way to analyze these stars.2024MNRAS.535.2189Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/535/2189CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/535/2189https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/535/2189http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/535/2189https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/535/2189https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/535/2189http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/535/2189GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/MNRAS/535/2189/table1Grass parameterization for delta Sct starsSpTypeSpectral type (2)src.spTypecharCommentObject type (2)src.classcharRegimeGrass regimemeta.notecharFileNameName of the table with envelope peaks data in subdirectory envpeaksmeta.id;meta.tablecharSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHD? Henry Draper ID Numbermeta.idintnullableTeffEffective temperature (1)Kphys.temperature.effectiveinte_TeffError of Teff (1)Kstat.error;phys.temperature.effectiveintloggSurface gravity (1)log(cm.s**-2)phys.gravityfloate_loggError of surface gravity (1)log(cm.s**-2)stat.errorfloat[Fe/H]? Metallicity (1)phys.abund.Zfloatnullablevsini? Projected velocity or lower value of vsini interval(2)km/sphys.velocfloatnullablevsini2? Upper value of vsini intervalkm/sphys.veloc.rotat;stat.maxintnullablee_vsini? Error on vsini (2)km/sstat.error;phys.veloc.rotatintnullablenu-lambdaFrequency at minimum peak densityuHzem.freqinte_nu-lambdaError of nu-lambdauHzstat.errorintnu-c? Cut-off frequencyuHzem.freqintnullablee_nu-c? Error of nu-cuHzstat.errorintnullablenu-NHighest frequency detecteduHzem.freq;stat.maxdoubleAmean? Mean amplitude of the plateau(10-6)src.var.amplitudefloatnullablee_Amean? Error of A_mean(10-6)stat.errorfloatnullableXi? Plateau factorstat.fit.paramfloatnullablee_Xi? Error of the plateau factorstat.errorfloatnullablenmean? Mean density of the plateau peaks (in peaks/uHz unit)uHz**-1stat.fit.paramfloatnullablee_nmean? Error of n_mean (in peaks/uHz unit)uHz**-1stat.errorfloatnullableDeltan? Grass density decay (in peaks/uHz unit)uHz**-1stat.fit.paramfloatnullablee_Deltan? Error of {Delta}n (in peaks/uHz unit)uHz**-1stat.errorfloatnullableTICTESS ID numbermeta.id;meta.mainlong