J/A+A/672/A69 MeerLICHT phot. of hot sub-luminous stars (Ranaivomanana+, 2023)
Identifying and characterising the population of hot sub-luminous stars with
multi-colour MeerLICHT data.
Ranaivomanana P., Johnston C., Groot P.J., Aerts C., Lees R., IJspeert L.,
Bloemen S., Klein-Wolt M., Woudt P., Kording E., Le Poole R., Pieterse D.
<Astron. Astrophys. 672, A69 (2023)>
=2023A&A...672A..69R 2023A&A...672A..69R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, dwarfs ; Stars, variable ; Photometry ; Optical
Keywords: surveys - subdwarfs - stars: variables: general -
Hertzsprung Russell and C-M diagrams - techniques: photometric -
methods: data analysis
Abstract:
Colour-magnitude diagrams reveal a population of blue (hot)
subluminous objects with respect to the main sequence. These hot
subluminous stars are the result of evolutionary processes that
require stars to expel their obscuring, hydrogen-rich envelopes to
reveal the hot helium core. As such, these objects offer a direct
window into the hearts of stars that are otherwise inaccessible to
direct observation.
We showcase MeerLICHT's capabilities of detecting faint hot subdwarfs
and identifying the dominant frequency in the photometric variability
of these compact hot stars, in comparison to their Gaia DR3 data. We
hunt for oscillations as an essential ingredient for future
asteroseismology to accurately probe their stellar interior.
Comparative MeerLICHT and Gaia colour-magnitude diagrams are presented
as a way to select hot subdwarfs from our sample. A dedicated
frequency determination technique is developed and applied to the
selected candidates to determine their dominant variability using
time-series data from MeerLICHT and Gaia DR3. We explore the power of
both datasets in determining the dominant frequency.
Using the g-i colour, MeerLICHT offers a colour-magnitude diagram that
is comparable in quality to that of Gaia DR3. The former, however, is
more sensitive to fainter objects. The MeerLICHT colour-colour
diagrams allow for the study of different stellar populations. The
frequency analysis of MeerLICHT and Gaia DR3 data demonstrates the
superiority of our MeerLICHT multi-colour photometry to estimate the
dominant frequency compared to the sparse Gaia DR3 data.
MeerLICHT's multiband photometry leads to the discovery of
high-frequency faint subdwarfs. Continued observations tuned to
asteroseismology will allow for mode identification using the method
of amplitude ratios. Our MeerLICHT results are a proof-of-concept for
the capacity of the BlackGEM instrument currently in commissioning at
ESO's La Silla Observatory in Chile.
Description:
A full list of 610 sdB candidates, similar to Table A.1 of the paper.
Note that, here, the first column is different from the first column
of Table A.1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 67 610 A full list of the candidates with their
derived periods
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [1/610] Source identifier
5- 13 F9.5 deg RAdeg Right ascension (ICRS) at Ep=2016.0
15- 23 F9.5 deg DEdeg Declination (ICRS) at Ep=2016.0
25- 29 F5.2 mag qmag ?=99.99 MeerLICHT q-band magnitude
31- 35 F5.2 mag umag ?=99.99 MeerLICHT u-band magnitude
37- 41 F5.2 mag imag ?=99.99 MeerLICHT i-band magnitude
43- 45 I3 --- Nq Number of observations in the q-band
47- 49 I3 --- Nu Number of observations in the u-band
51- 53 I3 --- Ni Number of observations in the i-band
55- 62 F8.4 d Per Derived period
64- 65 I2 --- SNR Signal-to-noise ratio
67 I1 --- Class [0/2] Preliminary variability classification (1)
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Note (1): Preliminary variability classification of MeerLICHT candidates flagged
as VARIABLE in Gaia DR3 data (class 1 and 2) as follows:
0 = unclassified object
1 = eclipsing binary
2 = sinusoidal
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Acknowledgements:
Princy Ranaivomanana, princy.ranaivomanana(at)ru.nl
(End) Patricia Vannier [CDS] 08-Feb-2023