J/A+A/708/A106 PG 1159-035 multi-colour photometry (Ranaivomanana+, 2026)
BlackGEM observations of compact pulsating stars.
Mode identification for the DOV PG 1159-035 using multi-colour photometry.
Ranaivomanana 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.
<Astron. Astrophys. 708, A106 (2026)>
=2026A&A...708A.106R 2026A&A...708A.106R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable - Stars, white dwarf ; Photometry ; Optical
Keywords: methods: data analysis - methods: statistical -
techniques: photometric - subdwarfs - stars: variables: general -
stars: white dwarfs
Abstract:
While 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.
Description:
Time-series photometric measurements of PG 1159-035 obtained with the
BlackGEM telescope array in the q, u, and i bands. The table contains
observation time (MJD), calibrated magnitudes, and associated
uncertainties.
Objects:
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RA (ICRS) DE Designation(s)
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12 01 45.97 -03 45 40.6 PG 1159-035 = V* GW Vir
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
bg-lc.dat 53 815 Time-series photometric measurements of PG 1159-035
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Byte-by-byte Description of file: bg-lc.dat
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Bytes Format Units Label Explanations
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1- 18 F18.12 d MJD Observation time (MJD)
20- 29 F10.7 mag mag Magnitude in Filter
31- 51 F21.19 mag e_mag Magnitude in Filter uncertainty
53 A1 --- Filter [qui] Filter
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Acknowledgements:
Princy Ranaivomanana, rtprincy(at)gmail.com
(End) Patricia Vannier [CDS] 05-Mar-2026