J/A+A/698/A253 beta Cep star mode identification (Fritzewski+, 2025)
Mode identification and ensemble asteroseismology of 119 beta Cep stars detected
by Gaia light curves and monitored by TESS.
Fritzewski D.J., Vanrespaille M., Aerts C., Gus Z., Hey D., De Ridder J.
<Astron. Astrophys. 698, A253 (2025)>
=2025A&A...698A.253F 2025A&A...698A.253F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, OB ; Stars, variable ; Stars, fundamental ; Photometry ;
Optical ; Asteroseismology
Keywords: asteroseismology - stars: evolution - stars: interiors -
stars: massive - stars: oscillations - stars: rotation
Abstract:
The Gaia mission detected many new candidate beta Cephei (beta Cep)
pulsators, whose variability classification has since been confirmed
from Transiting Exoplanet Survey Satellite (TESS) space photometry of
the nominal mission. We aim to analyse all currently available TESS
data for these beta Cep pulsators, of which 145 are new discoveries,
in order to exploit their asteroseismic potential. Although they are
of critical importance to improve evolution models of massive stars,
beta Cep stars are under-represented in the current space photometry
revolution.
We extracted light curves for 216 stars from the TESS full-frame
images and performed a frequency analysis by means of pre-whitening.
Based on Gaia Data Release 3, we deduced the stellar properties and
compared them to those of known beta Cep stars from the literature. We
developed a methodology for identifying the dominant pulsation modes
of the beta Cep stars from the detection of rotationally split
multiplets and Gaia and TESS amplitude ratios. We used grid modelling
to gain insights into the population of beta Cep stars.
Combining TESS and Gaia, we successfully identified the mode degrees
for 148 stars in our sample. We find the majority to have a dominant
dipole non-radial mode. Many non-radial modes show splittings in their
TESS frequency spectra, which we used to calculate their envelope
rotation, spin parameter, and the level of differential
envelope-to-surface rotation. For the last, we find an upper limit of
about 3. We also provide relative frequency asymmetries within the
multiplets, ranging from -0.15 to 0.15 with most being positive. Based
on grid modelling, we provide mass, convective core mass, and age
distributions for 119 stars.
Our sample enables asteroseismology of beta Cep pulsators as a
population. Our study prepares for future detailed mod- elling based
on individual frequencies of identified modes leading towards a better
understanding of these massive pulsators.
Description:
Table 1: Observational properties of beta Cephei stars observed with
Gaia and TESS. It includes the main frequencies, classification of the
light curves, amplitude ratios, and the derived mode degrees.
Table 2: Asteroseismic model results for the subset of stars with
identified modes. We provide the masses, normalised core hydrogen
fraction, age, and relative core masses.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 205 219 Observational properties of beta Cephei stars
observed with Gaia and TESS
table2.dat 124 119 Asteroseismic model results for the subset of
stars with identified modes
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See also:
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 I10 --- TIC TESS input catalog ID (Cat. IV/39)
12- 30 I19 --- GaiaDR3 Gaia DR3 source_id (Cat. I/355)
32- 40 A9 --- Name Simbad Main identifier
42- 50 F9.5 deg RAdeg Right ascension from Gaia DR3 (ICRS)
at Ep=2016.0 (Cat. I/355)
52- 60 F9.5 deg DEdeg Declination from Gaia DR3 (ICRS)
at Ep=2016.0 (Cat. I/355)
62- 66 F5.2 mag Gmag G magnitude from Gaia DR3 (Cat. I/355)
68- 72 F5.2 [K] logTeff ? log of Gaia ESP-HS effective temperature
from Gaia DR3 astrophysical_parameters
74- 78 F5.2 [Lsun] logL ? log luminosity
80- 82 A3 --- r_logL Reference (1)
84- 88 F5.2 d-1 frotsini ? rotation frequency times sin i
90- 94 F5.2 d-1 e_frotsini ? Uncertainty of frot_sini
96-103 F8.5 d-1 f1 ? Main frequency in TESS
105-112 F8.5 d-1 fGaia Main frequency in Gaia
114-121 F8.5 d-1 fTESS ? Frequncy of zonal mode
123-128 A6 --- LCtype Classification of the light curve (2)
130-135 F6.2 d Pbeat ? Beating period between two main frequencies
in TESS data
137-141 F5.2 --- Avar ? Amplitude variability (Eq 2)
143-146 F4.2 --- aG/aBP Amplitude ratio of main frequency in Gaia G
band light curve relative to Gaia BP band
light curve
148-151 F4.2 --- e_aG/aBP Uncertainty of G band to BP band amplitude
ratio
153-156 F4.2 --- aR/aBP Amplitude ratio of main frequency in Gaia RP
band light curve relative to Gaia BP band
light curve
158-161 F4.2 --- e_aR/aBP Uncertainty of RP band to BP band amplitude
ratio
163-167 F5.2 --- aT/B ? Amplitude ratio of main frequency in TESS
light curve relative to Gaia BP band
light curve
169-173 F5.2 --- e_aT/B ? Uncertainty of TESS band to BP band
amplitude ratio
175 I1 --- l ? Degree of Gaia detected pulsation mode
177-181 F5.2 --- p0 ? Probability of l=0
183-187 F5.2 --- p1 ? Probability of l=1
189-193 F5.2 --- p2 ? Probability of l=2
195-199 F5.2 d-1 splitting ? Strength of rotational splitting
201-205 F5.2 --- asymmetry ? Relative asymmetry in split multiplet
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Note (1): Reference as follows:
1 = Stankov & Handler (2005ApJS..158..193S 2005ApJS..158..193S, Cat. J/ApJS/158/193)
2 = Pigulski & Pojmanski (2008A&A...477..907P 2008A&A...477..907P, Cat. J/A+A/477/907)
3 = Labadie-Bartz et al. (2020AJ....160...32L 2020AJ....160...32L, Cat. J/AJ/160/32)
4 = Shi et al. (2024ApJS..271...28S 2024ApJS..271...28S, Cat. J/ApJS/271/28)
5 = Eze & Handler (2024ApJS..272...25E 2024ApJS..272...25E)
Note (2): The following classes are distinguished:
mono = (Nearly) mono-periodic stars
multi = Clear multi-periodic stars with beating patterns in their
light curves
hybrid = Hybrid pulsators between beta Cep and SPB stars
diff = Light curves that cannot be associated with the other classes
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 I10 --- TIC TESS input catalog ID (Cat. IV/39)
12- 30 I19 --- GaiaDR3 Gaia DR3 source_id (Cat. I/355)
32- 40 A9 --- Name Simbad Main identifier
42- 50 F9.5 deg RAdeg Right ascension from Gaia DR3 (ICRS)
at Ep=2016.0 (Cat. I/355)
52- 60 F9.5 deg DEdeg Declination from Gaia DR3 (ICRS)
at Ep=2016.0 (Cat. I/355)
62- 65 F4.2 --- Xpc Normalised core hydrogen mass fraction
67- 70 F4.2 --- e_Xpc Lower uncertainty of Xc'
72- 75 F4.2 --- E_Xpc Upper uncertainty of Xc'
77- 81 F5.2 Msun Mini Initial mass
83- 86 F4.2 Msun e_Mini Lower uncertainty of Mini
88- 91 F4.2 Msun E_Mini Upper uncertainty of Mini
93- 96 F4.2 [yr] logAge Log age
98-101 F4.2 [yr] e_logAge Lower uncertainty of logAge
103-106 F4.2 [yr] E_logAge Upper uncertainty of logAge
108-112 F5.3 --- Mcore/M Convetive core mass relative to initial mass
114-118 F5.3 --- e_Mcore/M Lower uncertainty of Mcore/M
120-124 F5.3 --- E_Mcore/M Upper uncertainty of Mcore/M
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Acknowledgements:
Dario Fritzewski, dario.fritzewski(at)kuleuven.be
References:
Gaia Collaboration, 2023A&A...674A..36G 2023A&A...674A..36G,
Gaia Data Release 3 Pulsations in main sequence OBAF-type stars.
(End) Patricia Vannier [CDS] 16-Apr-2025