Photometric sample of early B-type pulsators in eclipsing binaries observed with TESS

Asteroseismology coupled with eclipsing binary modelling shows a great potential in improving the efficiency of measurements or calibrations of the interior mixing profile in massive stars. This helps, for instance in treating the challenging and mysterious discrepancies between observations and models of its stellar structure and evolution. This paper discusses the findings in our work titled"$\beta$ Cephei pulsators in eclipsing binaries observed with TESS", which aimed to compile a comprehensive catalogue of $\beta$ Cep pulsators in eclipsing binaries. Seventy eight (78) pulsators of the $\beta$ Cep type in eclipsing binaries among which are 59 new discoveries were reported. Here, we also report a fresh analysis of eight additional stars which were outside the scope of the earlier mentioned work. Six $\beta$ Cep pulsators in eclipsing binaries are reported, among which 5 are new discoveries and 1 is a confirmation of a candidate earlier suggested in literature. Our sample allows for future ensemble asteroseismic modelling of massive pulsators in eclipsing binaries to treat the discrepancy between observations and models.


Introduction
Asteroseismology is the study of the interior structure of stars via their pulsations (e.g., Gough, 1985).Massive stars also show pulsations and offer unique opportunities to constrain their properties via asteroseismology (Aerts et al., 2010).Three classes of massive pulsators exist, among which are β Cephei stars.Beta Cephei stars are main sequence stars with masses of approximately 9 -17 M ⊙ (e.g., Stankov & Handler, 2005).They have low radial order pressure (p), gravity (g) and mixed modes, pulsation amplitudes up to a few tenths of magnitudes and pulsation periods of several hours (approximately 2 to 6 hours) (e.g., Stankov & Handler, 2005).Studying massive pulsators in eclipsing binaries proves to be very beneficial as it combines the strengths of asteroseismology arXiv:2404.11178v1[astro-ph.SR] 17 Apr 2024 and eclipsing binary modelling to probe the stars.Unfortunately, the number of such reported systems is much smaller compared to that of their low mass counterparts (Kirk et al., 2016;Pedersen et al., 2019).This, however, impedes a more holistic asteroseismic study of massive stars.
The present paper discusses the findings in the work titled β Cephei pulsators in eclipsing binaries observed with TESS by Eze & Handler (ApJS, submitted), which aimed to compile a comprehensive catalogue of early B-type (B0 -B3) pulstators in eclipsing binaries observed by TESS with a particular focus on β Cep pulsators, to probe the evolution and properties of massive stars by harnessing the combined potentials of eclipsing binary stars and asteroseismology.In this paper, we also conduct a fresh analysis of eight additional stars which were outside the scope of our earlier mentioned work.Here, we briefly describe the analysis in Sect.2, discuss the results in Sect. 3 and conclude in Sect. 4.

Analysis
A total of 8055 stars of spectral types B0 -B3 were analyzed in our referenced paper (see the paper for the details of the analysis and results).Here, as already pointed out, we also analyzed eight additional stars of spectral types O8 -B0 and B3 -B5.The analysis was done using the methods described in details in the referenced work.The result is shown in Table 1.
We examined the TESS light curves (Ricker et al., 2015) of the targets for independent pulsations via successive prewhitening of their Fourier spectra using the Period04 software (Lenz & Breger, 2005) and accounted for blends in their TESS pixels using Eleanor (Feinstein et al., 2019) and TESS-Localize (Higgins & Bell, 2022).In each case, we removed the effect of binarity by subtracting the harmonic binary model from the light curves before the pulsation analysis.The orbital periods of the stars with their analytical uncertainties are also determined using the Period04 program (Lenz & Breger, 2005).The binned phase diagrams and Fourier spectra of the stars' TESS light curves are shown in Figures 1 and 2 respectively.

Results and discussion
Eze & Handler (ApJS, submitted) reported 78 pulsators of the β Cephei type in eclipsing binaries, 59 of which are new discoveries.Ten ellipsoidal variables with β Cep pulsating components are also reported in the paper.Here, we report three definite and three candidate β Cep pulsators in eclipsing binaries as shown in Table 1.The stars adjudged candidates have nearby contaminators and signals that are too weak to be localized.They are denoted with ′ ?′ in their variability in Table 1.The binarity and β Cep variability are reported for the first time here for the stars TIC 2323229 (HD 330666; Sp. type: B8), TIC 155286121 (HD 319702; Sp. type: O8III), TIC 237173297 (HD 329034; Sp. type:

Conclusion
In this paper, we report the findings from our work which analyzed 8055 stars for β Cep pulsations in eclipsing binaries and that resulted in 78 pulsators of the β Cephei type in eclipsing binaries, among which 59 are new discoveries.Here, six β Cep pulsators in eclipsing binaries are also reported, five of which are new additional discoveries and one is a confirmation of a candidate earlier mentioned in literature.The present paper adds a few stars to the sample of β Cep pulsators, reported until date, for a more general and homogeneous in depth asteroseismic analysis of massive stars.We have already started follow  up of some of the most interesting candidates.The spectroscopic observations of some of the candidates have been conducted using four different instruments among which is Skalnate Pleso Observatory (SPO).Four β Cep pulsators in eclipsing binaries listed in the referenced work were observed using the echelle spectrograph at SPO and are currently under analysis.
obtained from the Mikulski Archive for Space Telescopes (MAST).This paper also made use of the SIMBAD data base and the VizieR catalogue access tool operated at CDS, Strasbourg, France;the SAO/NASA Astrophysics Data System.It also made use of data from the European Space Agency (ESA) mission Gaia1 , processed by the Gaia Data Processing and Analysis Consortium (DPAC2 ).Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.

Figure 1 .
Figure1.Binned Phase diagrams of light curves of the additional new definite and candidate β Cep pulsators in eclipsing binaries after prewhitening the strongest pulsations.TIC 336660284 is not included in Figure1as it has insufficient data (an incomplete orbital cycle) to be accurately phased but showed first primary eclipse at 1606.35(30) BTJD.TIC 2323229, TIC 140309502 and TIC 443410592 are definite β Cep pulsators in eclipsing binaries whereas TIC 155286121, TIC 237173297 and TIC 336660284 are candidate β Cep pulsators in eclipsing binaries.

Figure 2 .
Figure 2. Fourier spectra of the additional new definite and candidate β Cep pulsators in eclipsing binaries after removing the orbital light variations.Whereas TIC 2323229, TIC 140309502 and TIC 443410592 are definite β Cep pulsators in eclipsing binaries, TIC 155286121, TIC 237173297 and TIC 336660284 are candidates.

Table 1 .
The lists of the additional new definite and candidate β Cep pulsators in eclipsing binaries not reported in the earlier work.F d is the dominant β Cep pulsational frequency in c/d, A is the amplitude of the dominant pulsational frequency in mmag and S/N is the signal-to-noise ratio of the dominant frequency