Asteroseismology of the β Cephei star 12 (DD) Lacertae

Photometric observations, pulsational frequency analysis and mode identification

G. Handler, M. Jerzykiewicz, E. Rodríguez, K. Uytterhoeven, P. J. Amado, T. N. Dorokhova, N. I. Dorokhov, E. Poretti, J. P. Sareyan, L. Parrao, D. Lorenz, D. Zsuffa, R. Drummond, J. Daszyńska-Daszkiewicz, T. Verhoelst, J. De Ridder, B. Acke, P. O. Bourge, A. I. Movchan, R. Garrido & 11 others M. Paparó, T. Sahin, V. Antoci, S. N. Udovichenko, K. Csorba, R. Crowe, B. Berkey, S. Stewart, D. Terry, D. E. Mkrtichian, C. Aerts

Research output: Contribution to journalArticle

62 Citations (Scopus)

Abstract

We report a multisite photometric campaign for the β Cephei star 12 Lacertae. 750 h of high-quality differential photoelectric Strömgren, Johnson and Geneva time-series photometry were obtained with nine telescopes during 190 nights. Our frequency analysis results in the detection of 23 sinusoidal signals in the light curves. Ten of those correspond to independent pulsation modes, and the remainder are combination frequencies. We find some slow aperiodic variability such as that seemingly present in several β Cephei stars. We perform mode identification from our colour photometry, derive the spherical degree ℓ for the five strongest modes unambiguously and provide constraints on ℓ for the weaker modes. We find a mixture of modes of 0 ≤ℓ≤ 4. In particular, we prove that the previously suspected rotationally split triplet within the modes of 12 Lac consists of modes of different ℓ; their equal frequency splitting must thus be accidental. One of the periodic signals we detected in the light curves is argued to be a linearly stable mode excited to visible amplitude by non-linear mode coupling via a 2:1 resonance. We also find a low-frequency signal in the light variations whose physical nature is unclear; it could be a parent or daughter mode resonantly coupled. The remaining combination frequencies are consistent with simple light-curve distortions. The range of excited pulsation frequencies of 12 Lac may be sufficiently large that it cannot be reproduced by standard models. We suspect that the star has a larger metal abundance in the pulsational driving zone, a hypothesis also capable of explaining the presence of β Cephei stars in the Large Magellanic Cloud.

Original languageEnglish
Pages (from-to)327-338
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Volume365
Issue number1
DOIs
Publication statusPublished - Jan 2006

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asteroseismology
frequency analysis
stars
light curve
coupled modes
photometry
time series
metal
Magellanic clouds
night
telescopes
low frequencies
color

Keywords

  • Stars: early-type
  • Stars: individual: 12 (DD) Lacertae
  • Stars: oscillations
  • Stars: variables: other
  • Techniques: photometric

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Asteroseismology of the β Cephei star 12 (DD) Lacertae : Photometric observations, pulsational frequency analysis and mode identification. / Handler, G.; Jerzykiewicz, M.; Rodríguez, E.; Uytterhoeven, K.; Amado, P. J.; Dorokhova, T. N.; Dorokhov, N. I.; Poretti, E.; Sareyan, J. P.; Parrao, L.; Lorenz, D.; Zsuffa, D.; Drummond, R.; Daszyńska-Daszkiewicz, J.; Verhoelst, T.; De Ridder, J.; Acke, B.; Bourge, P. O.; Movchan, A. I.; Garrido, R.; Paparó, M.; Sahin, T.; Antoci, V.; Udovichenko, S. N.; Csorba, K.; Crowe, R.; Berkey, B.; Stewart, S.; Terry, D.; Mkrtichian, D. E.; Aerts, C.

In: Monthly Notices of the Royal Astronomical Society, Vol. 365, No. 1, 01.2006, p. 327-338.

Research output: Contribution to journalArticle

Handler, G, Jerzykiewicz, M, Rodríguez, E, Uytterhoeven, K, Amado, PJ, Dorokhova, TN, Dorokhov, NI, Poretti, E, Sareyan, JP, Parrao, L, Lorenz, D, Zsuffa, D, Drummond, R, Daszyńska-Daszkiewicz, J, Verhoelst, T, De Ridder, J, Acke, B, Bourge, PO, Movchan, AI, Garrido, R, Paparó, M, Sahin, T, Antoci, V, Udovichenko, SN, Csorba, K, Crowe, R, Berkey, B, Stewart, S, Terry, D, Mkrtichian, DE & Aerts, C 2006, 'Asteroseismology of the β Cephei star 12 (DD) Lacertae: Photometric observations, pulsational frequency analysis and mode identification', Monthly Notices of the Royal Astronomical Society, vol. 365, no. 1, pp. 327-338. https://doi.org/10.1111/j.1365-2966.2005.09728.x
Handler, G. ; Jerzykiewicz, M. ; Rodríguez, E. ; Uytterhoeven, K. ; Amado, P. J. ; Dorokhova, T. N. ; Dorokhov, N. I. ; Poretti, E. ; Sareyan, J. P. ; Parrao, L. ; Lorenz, D. ; Zsuffa, D. ; Drummond, R. ; Daszyńska-Daszkiewicz, J. ; Verhoelst, T. ; De Ridder, J. ; Acke, B. ; Bourge, P. O. ; Movchan, A. I. ; Garrido, R. ; Paparó, M. ; Sahin, T. ; Antoci, V. ; Udovichenko, S. N. ; Csorba, K. ; Crowe, R. ; Berkey, B. ; Stewart, S. ; Terry, D. ; Mkrtichian, D. E. ; Aerts, C. / Asteroseismology of the β Cephei star 12 (DD) Lacertae : Photometric observations, pulsational frequency analysis and mode identification. In: Monthly Notices of the Royal Astronomical Society. 2006 ; Vol. 365, No. 1. pp. 327-338.
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abstract = "We report a multisite photometric campaign for the β Cephei star 12 Lacertae. 750 h of high-quality differential photoelectric Str{\"o}mgren, Johnson and Geneva time-series photometry were obtained with nine telescopes during 190 nights. Our frequency analysis results in the detection of 23 sinusoidal signals in the light curves. Ten of those correspond to independent pulsation modes, and the remainder are combination frequencies. We find some slow aperiodic variability such as that seemingly present in several β Cephei stars. We perform mode identification from our colour photometry, derive the spherical degree ℓ for the five strongest modes unambiguously and provide constraints on ℓ for the weaker modes. We find a mixture of modes of 0 ≤ℓ≤ 4. In particular, we prove that the previously suspected rotationally split triplet within the modes of 12 Lac consists of modes of different ℓ; their equal frequency splitting must thus be accidental. One of the periodic signals we detected in the light curves is argued to be a linearly stable mode excited to visible amplitude by non-linear mode coupling via a 2:1 resonance. We also find a low-frequency signal in the light variations whose physical nature is unclear; it could be a parent or daughter mode resonantly coupled. The remaining combination frequencies are consistent with simple light-curve distortions. The range of excited pulsation frequencies of 12 Lac may be sufficiently large that it cannot be reproduced by standard models. We suspect that the star has a larger metal abundance in the pulsational driving zone, a hypothesis also capable of explaining the presence of β Cephei stars in the Large Magellanic Cloud.",
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T1 - Asteroseismology of the β Cephei star 12 (DD) Lacertae

T2 - Photometric observations, pulsational frequency analysis and mode identification

AU - Handler, G.

AU - Jerzykiewicz, M.

AU - Rodríguez, E.

AU - Uytterhoeven, K.

AU - Amado, P. J.

AU - Dorokhova, T. N.

AU - Dorokhov, N. I.

AU - Poretti, E.

AU - Sareyan, J. P.

AU - Parrao, L.

AU - Lorenz, D.

AU - Zsuffa, D.

AU - Drummond, R.

AU - Daszyńska-Daszkiewicz, J.

AU - Verhoelst, T.

AU - De Ridder, J.

AU - Acke, B.

AU - Bourge, P. O.

AU - Movchan, A. I.

AU - Garrido, R.

AU - Paparó, M.

AU - Sahin, T.

AU - Antoci, V.

AU - Udovichenko, S. N.

AU - Csorba, K.

AU - Crowe, R.

AU - Berkey, B.

AU - Stewart, S.

AU - Terry, D.

AU - Mkrtichian, D. E.

AU - Aerts, C.

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N2 - We report a multisite photometric campaign for the β Cephei star 12 Lacertae. 750 h of high-quality differential photoelectric Strömgren, Johnson and Geneva time-series photometry were obtained with nine telescopes during 190 nights. Our frequency analysis results in the detection of 23 sinusoidal signals in the light curves. Ten of those correspond to independent pulsation modes, and the remainder are combination frequencies. We find some slow aperiodic variability such as that seemingly present in several β Cephei stars. We perform mode identification from our colour photometry, derive the spherical degree ℓ for the five strongest modes unambiguously and provide constraints on ℓ for the weaker modes. We find a mixture of modes of 0 ≤ℓ≤ 4. In particular, we prove that the previously suspected rotationally split triplet within the modes of 12 Lac consists of modes of different ℓ; their equal frequency splitting must thus be accidental. One of the periodic signals we detected in the light curves is argued to be a linearly stable mode excited to visible amplitude by non-linear mode coupling via a 2:1 resonance. We also find a low-frequency signal in the light variations whose physical nature is unclear; it could be a parent or daughter mode resonantly coupled. The remaining combination frequencies are consistent with simple light-curve distortions. The range of excited pulsation frequencies of 12 Lac may be sufficiently large that it cannot be reproduced by standard models. We suspect that the star has a larger metal abundance in the pulsational driving zone, a hypothesis also capable of explaining the presence of β Cephei stars in the Large Magellanic Cloud.

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KW - Stars: early-type

KW - Stars: individual: 12 (DD) Lacertae

KW - Stars: oscillations

KW - Stars: variables: other

KW - Techniques: photometric

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