The Kepler Cepheid V1154 Cyg revisited: Light curve modulation and detection of granulation

A. Derekas, E. Plachy, L. Molnár, Sódor, J. Benkő, L. Szabados, Zs Bognár, B. Csák, Gy M. Szabó, R. Szabó, A. Pál

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

We present a detailed analysis of the bright Cepheid-type variable star V1154 Cygni using 4 yr of continuous observations by the Kepler space telescope.We detected 28 frequencies using the standard Fourier transform method.We identified modulation of the main pulsation frequency and its harmonics with a period of ~159 d. This modulation is also present in the Fourier parameters of the light curve and the O - C diagram. We detected another modulation with a period of about 1160 d. The star also shows significant power in the low-frequency region that we identified as granulation noise. The effective time-scale of the granulation agrees with the extrapolated scalings of red giant stars. Non-detection of solar-like oscillations indicates that the pulsation inhibits other oscillations.We obtained new radial velocity observations that are in a perfect agreement with previous years data, suggesting that there is no high-mass star companion of V1154 Cygni. Finally, we discuss the possible origin of the detected frequency modulations.

Original languageEnglish
Pages (from-to)1553-1562
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Volume464
Issue number2
DOIs
Publication statusPublished - 2017

Fingerprint

light curve
oscillation
modulation
Fourier transform
red giant stars
solar oscillations
companion stars
variable stars
diagram
timescale
radial velocity
frequency modulation
diagrams
telescopes
low frequencies
harmonics
scaling
stars
oscillations
detection

Keywords

  • Stars: individual: V1154 Cyg
  • Stars: variables: Cepheids
  • Techniques: photometric
  • Techniques: spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

The Kepler Cepheid V1154 Cyg revisited : Light curve modulation and detection of granulation. / Derekas, A.; Plachy, E.; Molnár, L.; Sódor, ; Benkő, J.; Szabados, L.; Bognár, Zs; Csák, B.; Szabó, Gy M.; Szabó, R.; Pál, A.

In: Monthly Notices of the Royal Astronomical Society, Vol. 464, No. 2, 2017, p. 1553-1562.

Research output: Contribution to journalArticle

Derekas, A. ; Plachy, E. ; Molnár, L. ; Sódor, ; Benkő, J. ; Szabados, L. ; Bognár, Zs ; Csák, B. ; Szabó, Gy M. ; Szabó, R. ; Pál, A. / The Kepler Cepheid V1154 Cyg revisited : Light curve modulation and detection of granulation. In: Monthly Notices of the Royal Astronomical Society. 2017 ; Vol. 464, No. 2. pp. 1553-1562.
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AU - Sódor,

AU - Benkő, J.

AU - Szabados, L.

AU - Bognár, Zs

AU - Csák, B.

AU - Szabó, Gy M.

AU - Szabó, R.

AU - Pál, A.

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N2 - We present a detailed analysis of the bright Cepheid-type variable star V1154 Cygni using 4 yr of continuous observations by the Kepler space telescope.We detected 28 frequencies using the standard Fourier transform method.We identified modulation of the main pulsation frequency and its harmonics with a period of ~159 d. This modulation is also present in the Fourier parameters of the light curve and the O - C diagram. We detected another modulation with a period of about 1160 d. The star also shows significant power in the low-frequency region that we identified as granulation noise. The effective time-scale of the granulation agrees with the extrapolated scalings of red giant stars. Non-detection of solar-like oscillations indicates that the pulsation inhibits other oscillations.We obtained new radial velocity observations that are in a perfect agreement with previous years data, suggesting that there is no high-mass star companion of V1154 Cygni. Finally, we discuss the possible origin of the detected frequency modulations.

AB - We present a detailed analysis of the bright Cepheid-type variable star V1154 Cygni using 4 yr of continuous observations by the Kepler space telescope.We detected 28 frequencies using the standard Fourier transform method.We identified modulation of the main pulsation frequency and its harmonics with a period of ~159 d. This modulation is also present in the Fourier parameters of the light curve and the O - C diagram. We detected another modulation with a period of about 1160 d. The star also shows significant power in the low-frequency region that we identified as granulation noise. The effective time-scale of the granulation agrees with the extrapolated scalings of red giant stars. Non-detection of solar-like oscillations indicates that the pulsation inhibits other oscillations.We obtained new radial velocity observations that are in a perfect agreement with previous years data, suggesting that there is no high-mass star companion of V1154 Cygni. Finally, we discuss the possible origin of the detected frequency modulations.

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KW - Stars: variables: Cepheids

KW - Techniques: photometric

KW - Techniques: spectroscopic

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