J/A+A/708/A106ivo://CDS.VizieR/J/A+A/708/A106CDSRanaivomanana P.Johnston C.Uzundag M.Groot P.J.Kupfer T.,Bloemen S.Vreeswijk P.M.van Roestel J.C.J.Pieterse D.L.A.Paice J.,Kosakowski A.Ramsay G.Aerts C.2026-03-31T09:27:23Z2026-03-31T10:23:02ZCDS support team

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

cds-question@unistra.frphotometryvisible-astronomyWhile space-based telescopes offer unparalleled precision for asteroseismology, ground-based observations remain crucial for identifying compact pulsator candidates and enabling their pulsational study through multi-colour photometry. The BlackGEM telescope array, with its high-cadence multi-colour photometry survey, significantly enhances the detection and characterisation possibilities for compact pulsators that tend to be much fainter than dwarfs or giant pulsators. Using BlackGEM multi-colour photometry of the hot pre-white dwarf PG 1159-035, we demonstrate its capability to detect short, multi-periodic pulsations with amplitudes down to a few milli-magnitudes. The primary aim of this study is to establish the feasibility of pulsation mode identification in hot subdwarfs and white dwarfs via mode amplitude-ratio analysis derived from BlackGEM multi-colour observations. Pulsation frequencies were extracted from our target using iterative pre-whitening analysis. To validate our data-driven mode identification concept using multi-colour photometry, we used the well-studied hot pre-white dwarf PG 1159-035, with previously identified pulsation modes, as a prototypical object that served for validation. The pre-whitening analysis using BlackGEM's standard q-, u-, and i-band light curves of PG 1159-035 revealed pulsation frequencies of l=1 and l=2 modes, consistent with values obtained from the literature. Using the frequencies identified from the q band, amplitudes in the i and u bands could be estimated. Subsequent amplitude ratio calculations resulted in discernible distributions for the l=1 and l=2 modes. The future assembly of more BlackGEM amplitude ratios for well-known white dwarfs with already identified modes will lead to density estimators suitable for identifying newly detected modes in known or as-yet-undiscovered pulsators. Our proof-of-concept study paves the way for large-scale asteroseismic analyses of optically faint compact pulsating stars using ground-based facilities, such as BlackGEM. As BlackGEM continues its observations, a substantial number of these objects will be observed as part of a regular survey, enabling a robust characterisation of their pulsation modes in the context of population studies.2026A&A...708A.106Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/708/A106CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/708/A106https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/708/A106http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/708/A106https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/708/A106https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/708/A106http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/708/A106GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/708/A106/bg-lcTime-series photometric measurements of PG 1159-035recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDObservation time (MJD)dtime.epochdoublemagMagnitude in Filtermagphot.magdoublee_magMagnitude in Filter uncertaintymagstat.error;phot.magdoubleFilter[qui] Filtermeta.id;instr.filterchar