J/A+A/693/A103 V424 Cep Halpna and HeI6678 spectra (Schmutz+, 2025)
A Maia-type candidate was misclassified:
V424 Cep is an eclipsing beta Cep-type pulsator in a triple system.
Schmutz W., Koenigsberger G., Luna-Nino L.F., Paschke A., Richer M.G.
<Astron. Astrophys. 693, A103 (2025)>
=2025A&A...693A.103S 2025A&A...693A.103S (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, eclipsing ; Spectroscopy ; Optical
Keywords: asteroseismology - eclipses - binaries: eclipsing -
binaries: oscillations - stars: individual: V424 Cep -
stars: individual: HD 239652
Abstract:
V424 Cephei is an eclipsing binary system that has been classified as
a Maia variable candidate. These objects are pulsators that apparently
lie outside the theoretical instability strips.
We determine the properties of V424 Cep and identify the nature of the
pulsating variable.
We analyzed photometric data obtained over the past three decades from
TESS, Gaia, Hipparcos, and ground-based observations. Times of minimum
light were determined, and the light curves and spectral energy
distribution were analyzed. We analyzed the radial velocity curves of
the double-lined system obtained from spectroscopy at the Observatorio
Astronomico Nacional on the Sierra San Pedro Martir.
The two eclipses observed in the light curves yield a refined orbital
period P=4.93d, an eccentricity e=0.02, and an apsidal period U=730yr.
The eclipse O-C curve is not linear. Combined with the apsidal period,
this indicates the presence of a third component in the system. This
conclusion was confirmed by a comparison of predicted and observed
absolute fluxes. The masses of the binary pair are 8.7M☉ and
6.3M☉, their radii are 6.0R☉ and 3.5R☉, and the
luminosities are log(L/L☉) 3.80 and 3.11. The TESS light curve
shows oscillations with a dominant period of 0.17d. They are coherent
throughout the orbital cycles with a stable amplitude, except during
the (partial) eclipse of the primary star. This indicates that this is
the pulsator. Its temperature is 21000K. The third-light component
contributes no more than 15% to the total light of the system in the
TESS wavelength band and 20% in the K band.
V424 Cep is not a Maia variable, but rather a beta Cep star. This
result highlights the importance of combining photometric light-curve
solutions with absolute flux models and spectroscopic observations.
Description:
The tables are spectra of V424 Cep as shown in Figs. 5 and 6 with
observational details given in Tables A.2 and A.3.
Objects:
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RA (2000) DE Designation(s)
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21 24 23.25 +56 21 41.6 V424 Cep = HD 239652
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
spm0127.dat 27 690 Halpha spectrum JD 2460479.92406
spm0275.dat 27 690 Halpha spectrum JD 2460480.96816
spm0281.dat 27 690 HeI6678 spectrum JD 2460480.98440
spm0455.dat 27 690 Halpha spectrum JD 2460481.96150
spm0458.dat 27 690 HeI6678 spectrum JD 2460481.97096
spm0605.dat 27 690 Halpha spectrum JD 2460482.96148
spm0609.dat 27 690 HeI6678 spectrum JD 2460482.97185
spm0773.dat 27 690 Halpha spectrum JD 2460483.94786
spm0776.dat 27 690 HeI6678 spectrum JD 2460483.95784
spm0968.dat 27 690 Halpha spectrum JD 2460485.95314
spm0971.dat 27 690 HeI6678 spectrum JD 2460485.96278
spm1135.dat 27 690 Halpha spectrum JD 2460486.91765
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Byte-by-byte Description of file: spm*.dat
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Bytes Format Units Label Explanations
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1- 16 F16.11 0.1nm lambda Wavelength
19- 27 F9.7 --- NFlux Normalised flux
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Acknowledgements:
Werner Schmutz, werner.schmutz(at)pmodwrc.ch
(End) Patricia Vannier [CDS] 01-Dec-2024