Asteroseismology based on high time-resolution and high dispersion spectroscopy

• Project/Area Number: 23540260
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Astronomy
• Research Institution: The University of Tokyo
• Principal Investigator: SHIBAHASHI Hiromoto 東京大学, 理学(系)研究科(研究院), 教授 (30126081)
• Project Period (FY): 2011 – 2013
• Project Status: Completed (Fiscal Year 2013)
• Budget Amount: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000); Fiscal Year 2013: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2012: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2011: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
• Keywords: 星震学 / 脈動星 / 特異星 / B型輝線星 / 分光観測 / データ解析 / スペクトル線 / 恒星大気 / 衝撃波 / 恒星物理学 / 恒星脈動 / 恒星スペクトル / 国際情報交流（英国）

Research Abstract

The vertical wavelengths of the oscillations found in roAp stars are so short that the amplitude and phase of the variation of each spectroscopic line are highly dependent on the level of the line profile. We carried out a numerical simulation of line-profile variation by taking account of the finite thickness of the line-forming layer. We demonstrated how effective this treatment is.
Barycentric corrections made to the timing of Kepler observations break the regular time-sampling of the data. A consequence is that Nyquist aliases are split into multiplets that can be identified by their shape. We provided an analytical derivation of the phenomenon, alongside demonstrations with simulated and real Kepler data.
Observations indicate that a circumstellar disk is formed around a Be star while the stellar rotation is below the break-up velocity. I proposed a working hypothesis to explain this mystery by taking account of the effect of leaky waves upon angular momentum transfer.

Research Products

• [Journal Article] Shock Diagnostics in the Pulsating Proto-Subdwarf V652 Herculis (2014)
  • Author(s): Jeffery, C. S., Montañés-Rodríguez, P., Shibahashi, H., Kurtz, D. W., Elkin, V., and Saio, H
  • Journal Title: Astron. Soc. Pacific Conf. Ser Volume: Vol. 481 Pages: 125-131
• [Journal Article] Finding binaries among Kepler pulsating stars from phase modulation of their pulsations (2014)
  • Author(s): Murphy, S. J., Bedding, T. R., Shibahashi, H., Kurtz, D. W., and Kjeldsen, H
  • Journal Title: Monthly Notices Roy. Astron. Soc Volume: (掲載決定済)
  • Peer Reviewed
• [Journal Article] Finding binaries among Kepler pulsating stars from phase modulation of their pulsations (2014)
  • Author(s): Murphy, S.J., Bedding, T.R., Shibahashi, H., Kurtz, D.W., & Kjeldsen, H.
  • Journal Title: MNRAS Volume: 未定
  • Peer Reviewed
• [Journal Article] (2013)
  • Author(s): Jeffery, C. S., Shibahashi, H., Kurtz, D. W., Elkin, V., Montañés-Rodríguez, P., and Saio, H
  • Journal Title: Astron. Soc. Pacific Conf. Ser Volume: Vol. 479 Pages: 369-376
• [Journal Article] A Working Hypothesis about the Cause of Be Stars: Episodic Outward Leakage of Low-Frequency Modes Excited by the Iron-Peak κ-Mechanism (2013)
  • Author(s): Ishimatsu, H. and Shibahashi, H
  • Journal Title: Astron. Soc. Pacific Conf. Ser Volume: Vol. 479 Pages: 325-333
• [Journal Article] Super-Nyquist asteroseismology with the Kepler Space Telescope (2013)
  • Author(s): Murphy, S. J., Shibahashi, H., and Kurtz, D. W
  • Journal Title: Monthly Notices Roy. Astron. Soc Volume: Vol. 430, Issue 4 Issue: 4 Pages: 2986-2998
  • DOI: 10.1093/mnras/stt105
  • Peer Reviewed
• [Journal Article] Hot DAVs: a probable new class of pulsating white dwarf stars (2013)
  • Author(s): Kurtz, D.W., Shibahashi, H., Dhillon, V.S., Marsh, T.R., Littlefair, S.P., Copperwheat, C.M., Gansicke, B.T., & Parsons, S.G.
  • Journal Title: MNRAS Volume: 432 Issue: 2 Pages: 1632-1639
  • DOI: 10.1093/mnras/stt585
  • Peer Reviewed
• [Journal Article] Establishing Shock Diagnostics in the Pulsating Extreme Helium Star V642 Herculis (2013)
  • Author(s): Jeffery, C.S., Shibahashi, H., Kurtz, D.W., Elkin, V., Montanes-Rodriguez, P., & Saio, H.
  • Journal Title: ASP Conf. Ser. Volume: 479 Pages: 369-376
• [Journal Article] A Working Hypothesis about the Cause of Be Stars: Episodic Outward Leakage of Low-Frequency Modes Excited by the Iron-Peak κ-Mechanism (2013)
  • Author(s): Ishimatsu, H. & Shibahashi, H.
  • Journal Title: ASP Conf. Ser. Volume: 479 Pages: 325-333
• [Journal Article] Super-Nyquist asteroseismology with the Kepler Space Telescope (2013)
  • Author(s): Murphy, S. J., Shibahashi, H., Kurtz, D. W.
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 未定
  • Peer Reviewed
• [Journal Article] FM stars: a Fourier view of pulsating binary stars, a new technique for measuring radial velocities photometrically (2012)
  • Author(s): Shibahashi, H. and Kurtz, D. W
  • Journal Title: Monthly Notices Roy. Astron. Soc Volume: Vol. 422, Issue 1 Issue: 1 Pages: 738-752
  • DOI: 10.1111/j.1365-2966.2012.20654.x
  • Peer Reviewed
• [Journal Article] Numerical Simulations of Line-Profile Variation beyond a Single-Surface Approximation for Oscillations in roAp Stars (2012)
  • Author(s): Nomura, T., Naito, J., and Shibahashi, H
  • Journal Title: Publ. Astron. Soc. Japan Volume: Vol. 64, No. 1 Issue: 1
  • DOI: 10.1093/pasj/64.1.9
  • NAID: 10030386117
  • Peer Reviewed
• [Journal Article] FM stars: a Fourier view of pulsating binary stars, a new technique for measuring radial velocities photometrically (2012)
  • Author(s): Shibahashi, H., Kurtz, D. W.
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 422 Pages: 738-752
  • Peer Reviewed
• [Journal Article] Numerical Simulations of Line-Profile Variation beyond a Single-Surface Approximation for Oscillations in roAp Stars (2012)
  • Author(s): Nomura, T., Naito, J., Shibahashi, H.
  • Journal Title: Publ. Astron. Soc. Japan Volume: 64
  • NAID: 10030386117
  • Peer Reviewed
• [Journal Article] The first evidence for multiple pulsation axes: a new rapidly oscillating Ap star in the Kepler field, KIC 10195926 (2011)
  • Author(s): Kurtz, D. W., Cuhna, M. S., Saio, H., Balona, L. A., Elkin, V. G., Shibahashi, H., Brandao, I. M., Uytterhoeven, K., Frandsen, S., Frimann, S. Hatzes, A. Lueftinger, T. Gruberbauer, M., Kjeldsen, H., Christensen-Dalsgaard, J., and Kawaler, S. D
  • Journal Title: Monthly Notices Roy. Astron. Soc Volume: Vol. 414, Issue 3 Issue: 3 Pages: 2550-2566
  • DOI: 10.1111/j.1365-2966.2011.18572.x
  • Peer Reviewed
• [Presentation] スーパーナイキスト星震学 (2014)
  • Author(s): 柴橋博資
  • Organizer: 日本天文学会 2014 年春季年会
  • Place of Presentation: 三鷹市
• [Presentation] スーパーナイキスト星震学 (2014)
  • Author(s): 柴橋博資
  • Organizer: 日本天文学会2014年春季年会
  • Place of Presentation: 国際基督教大学（東京都）
• [Presentation] A working hypothesis about the cause of Be stars: Episodic outward leakage of low-frequency waves excited by the iron-peak κ-mechanism (2013)
  • Author(s): Shibahashi, H
  • Organizer: IAU Symposium 301
  • Place of Presentation: Wrocraw (Poland)
• [Presentation] Super-Nyquist asteroseismology (2013)
  • Author(s): Shibahashi, H
  • Organizer: Kepler Asteroseismic Science Consortium Sixth Workshop
  • Place of Presentation: Sydney (Australia)
• [Presentation] New kind of pulsator in the DB gap of white dwarfs (2013)
  • Author(s): Shibahashi, H.
  • Organizer: New advances in stellar physics: from microscopic to macroscopic processes
  • Place of Presentation: Roscoff (France)
  • Invited
• [Presentation] ケプラー脈動測光データから連星軌道要素を決める (2013)
  • Author(s): 柴橋博資
  • Organizer: 日本天文学会2013年秋季年会
  • Place of Presentation: 東北大学（宮城県）
• [Presentation] Be 星の星周円盤の生成 (2012)
  • Author(s): 石松宏幸, 柴橋博資
  • Organizer: 日本天文学会 2012 年秋季年会
  • Place of Presentation: 大分市
• [Presentation] Frequency modulated stars (2012)
  • Author(s): Shibahashi, H
  • Organizer: Kepler Asteroseismic Consortium Fifth Workshop
  • Place of Presentation: Balatonalmádi (Hungary)
• [Presentation] Frequency modulated stars (2012)
  • Author(s): Shibahashi, H., Kurtz, D. W.
  • Organizer: Kepler Asteroseismic Science Consortium Fifth Workshop
  • Place of Presentation: Balatonalmadi, Hungary
  • Invited
• [Presentation] The DB gap and a new class of pulsating white dwarfs (2012)
  • Author(s): Shibahashi, H.
  • Organizer: The 40th Liege International Astrophysical Colloquium, Ageing low mass stars: from red giants to white dwarfs
  • Place of Presentation: Liege, Belgium
  • Invited
• [Presentation] Radial velocities from photometry (2012)
  • Author(s): Shibahashi, H.
  • Organizer: IAU GA Special Session 13, Precise Photometry
  • Place of Presentation: Beijing, China
  • Invited
• [Presentation] Super-Nyquist asteroseismology (2012)
  • Author(s): Kurtz, D. W., Murphy, S. J., Shibahashi, H.
  • Organizer: Progress in Physics of the Sun and Stars: A New Era in Helio- and Asteroseismology
  • Place of Presentation: 箱根
  • Invited
• [Presentation] roAp 星におけるスペクトル線プロファイル変動 (2011)
  • Author(s): 内藤純, 柴橋博資
  • Organizer: 日本天文学会 2011 年秋季年会
  • Place of Presentation: 鹿児島市
• [Presentation] Numerical simulations of line-profile variation beyond a single-surface approximation for oscillations in roAp stars (2011)
  • Author(s): Shibahashi, H
  • Organizer: IAU Symposium
  • Place of Presentation: Oxford (UK)
• [Presentation] Traditional approximation for low-frequency modes in rotating stars and a working hypothesis about episodic mass-loss in Be stars (2011)
  • Author(s): Shibahashi, H
  • Organizer: The 20th Stellar Pulsation Conference Series
  • Place of Presentation: Granada (Spain)
• [Presentation] roAp星におけるスペクトル線プロファイル変動 (2011)
  • Author(s): 内藤 純、柴橋 博資
  • Organizer: 日本天文学会2011年秋季年会
  • Place of Presentation: 鹿児島大学
• [Presentation] Numerical Simulations of Line-Profile Variation beyond a Single-Surface Approximation for Oscillations in roAp Stars (2011)
  • Author(s): 柴橋博資
  • Organizer: IAU Symposium "New Horizons in Time Domain Astronomy"
  • Place of Presentation: オックスフォード
• [Presentation] Traditional approximation for low-frequency modes in rotating stars and a working hypothesis about episodic mass loss in Be stars (2011)
  • Author(s): 柴橋博資
  • Organizer: 20th Stellar Pulsation Conference
  • Place of Presentation: グラナダ