Asteroseismic measurement of surface-to-core rotation in a main-sequence A star, KIC 11145123

Kurtz, D. W.; Saio, Hideyuki; Takata, Masasuke; Shibahashi, Hiromoto; Murphy, Simon J.; Sekii, T.

doi:10.1093/mnras/stu1329

Cited by 228 publications

(379 citation statements)

References 30 publications

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“…The vr sin i = 1 km s −1 predicted by Kurtz et al (2014) is well-supported. We therefore suggest that the difference between our measured va sin i and their prediction is significant for exploring macroturbulence and the pulsational velocity fields in the atmosphere of this star.…”

Section: Investigating Line Broadening and The Rotational Velocitymentioning

confidence: 55%

“…The exceptionally long rotation period near 100 d of KIC 11145123 derived asteroseismically by Kurtz et al (2014) to predict a surface equatorial rotation velocity of veq = 1 km s −1 , implying v sin i 1 km s −1 . However, observational measures of v sin i are made from line broadening, which includes macroturbulent broadening, as well as pulsational broadening from both the p modes and the g modes in this star.…”

Section: Rotation Velocitymentioning

confidence: 93%

“…Solar abundances from Asplund et al (2009) dure that gives some real information on the evolutionary state and structure of the star. In their discovery paper of the core-to-surface rotation of KIC 11145123, Kurtz et al (2014) tried to find asteroseismic stellar models that best fitted the pulsation frequencies -particularly the g-mode series of frequencies and some of the p-mode frequencies. This suggested to Kurtz et al (2014) that the star is near the terminal-age main-sequence, has enhanced helium abundance, and perhaps low metallicity.…”

Section: Modelmentioning

confidence: 99%

“…Evolutionary models were calculated using Modules for Experiments in Stellar Evolution (MESA; Paxton et al 2013) with the same settings as in Kurtz et al (2014): i.e., the heavy element abundance, Z = 0.003, was scaled by the solar mixture of Asplund et al (2009); the radiative OPAL opacity tables (Iglesias & Rogers 1996) were used; and mixing length was set equal to 1.7 Hp, where Hp is the pressure scale height. Atomic diffusion was activated in the code to erase noise in the Brunt-Väisälä frequency.…”

Section: Modelmentioning

confidence: 99%

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Spectroscopic and asteroseismic analysis of the remarkable main-sequence A star KIC 11145123

Takada-Hidai

Kurtz

Shibahashi

et al. 2017

Monthly Notices of the Royal Astronomical Society

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A spectroscopic analysis was carried out to clarify the properties of KIC 11145123 -the first main-sequence star with a determination of core-to-surface rotation -based on spectra observed with the High Dispersion Spectrograph (HDS) of the Subaru telescope. The atmospheric parameters (T eff = 7600 K, log g = 4.2, ξ = 3.1 km s −1 and [Fe/H] = −0.71 dex), the radial and rotation velocities, and elemental abundances were obtained by analysing line strengths and fitting line profiles, which were calculated with a 1D LTE model atmosphere. The main properties of KIC 11145123 are: (1) A low [Fe/H] = −0.71 ± 0.11 dex and a high radial velocity of −135.4 ± 0.2 km s −1 . These are remarkable among late-A stars. Our best asteroseismic models with this low [Fe/H] have slightly high helium abundance and low masses of 1.4 M ⊙ . All of these results strongly suggest that KIC 11145123 is a Population II blue straggler; (2) The projected rotation velocity confirms the asteroseismically predicted slow rotation of the star; (3) Comparisons of abundance patterns between KIC 11145123 and Am, Ap, and blue stragglers show that KIC 11145123 is neither an Am star nor an Ap star, but has abundances consistent with a blue straggler. We conclude that the remarkably long 100-d rotation period of this star is a consequence of it being a blue straggler, but both pathways for the formation of blue stragglers -merger and mass loss in a binary system -pose difficulties for our understanding of the exceedingly slow rotation. In particular, we show that there is no evidence of any secondary companion star, and we put stringent limits on the possible mass of any such purported companion through the phase modulation (PM) technique.

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Section: Investigating Line Broadening and The Rotational Velocitymentioning

confidence: 55%

Section: Rotation Velocitymentioning

confidence: 93%

Section: Modelmentioning

confidence: 99%

Section: Modelmentioning

confidence: 99%

See 2 more Smart Citations

Spectroscopic and asteroseismic analysis of the remarkable main-sequence A star KIC 11145123

Takada-Hidai

Kurtz

Shibahashi

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…Typical values for the surface rotation periods of A stars are short (about 1 day; see, e.g., Zorec & Royer 2012). Moreover, asteroseismic observations of slowly rotating A stars suggest that these stars are nearly rigidly rotating (Kurtz et al 2014 Brun et al (2005) show dynamo action with magnetic fields reaching a considerable fraction of equipartition (B ≈ 10 4 -10 5 G). Note also that the generation of equipartition and even superequipartition magnetic fields with peak strengths above 1 megagauss (MG) has been shown in MHD simulations of core convection in massive B-type stars (Augustson et al 2016).…”

Section: Operation Of Main-sequence Dynamomentioning

confidence: 99%

Asteroseismic Signatures of Evolving Internal Stellar Magnetic Fields

Cantiello

Fuller

Bildsten

2016

ApJ

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Recent asteroseismic analyses indicate the presence of strong (B  10 5 G) magnetic fields in the cores of many red giant stars. Here, we examine the implications of these results for the evolution of stellar magnetic fields, and we make predictions for future observations. Those stars with suppressed dipole modes indicative of strong core fields should exhibit moderate but detectable quadrupole mode suppression. The long magnetic diffusion times within stellar cores ensure that dynamo-generated fields are confined to mass coordinates within the main-sequence (MS) convective core, and the observed sharp increase in dipole mode suppression rates above 1.5 M e is likely explained by the larger convective core masses and faster rotation of these more massive stars. In clump stars, core fields of ∼10 5 G can suppress dipole modes, whose visibility should be equal to or less than the visibility of suppressed modes in ascending red giants. High dipole mode suppression rates in low-mass (M  2 M e ) clump stars would indicate that magnetic fields generated during the MS can withstand subsequent convective phases and survive into the compact remnant phase. Finally, we discuss implications for observed magnetic fields in white dwarfs and neutron stars, as well as the effects of magnetic fields in various types of pulsating stars.

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The age and interior rotation of stars from asteroseismology

Aerts

2015

Astron Nachr

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We provide a status report on the determination of stellar ages from asteroseismology for stars of various masses and evolutionary stages. The ability to deduce the ages of stars with a relative precision of typically 10 to 20 % is a unique opportunity for stellar evolution and also of great value for both galactic and exoplanet studies. Further, a major uncalibrated ingredient that makes stellar evolution models uncertain, is the stellar interior rotation frequency Ω(r) and its evolution during stellar life. We summarize the recent achievements in the derivation of Ω(r) for different types stars, offering stringent observational constraints on theoretical models. Core-to-envelope rotation rates during the red-giant stage are far lower than theoretical predictions, pointing towards the need to include new physical ingredients that allow strong and efficient coupling between the core and the envelope in the models of low-mass stars in the evolutionary phase prior to core helium burning. Stars are subject to efficient mixing phenomena, even at low rotation rates. Young massive stars with seismically determined interior rotation frequency reveal low core-to-envelope rotation values. Asteroseismology: the new route for stellar physicsContemporary stellar structure and evolution theory still has several open questions, the answers having vast implications for exoplanetary, supernova, and (extra)galactic science. One major uncalibrated quantity is the rotation frequency in the stellar interior throughout stellar life. Also the level of chemical mixing inside stars is hard to judge from surface abundance measurements. While models of stars not too different from the Sun in terms of mass, rotation, and evolutionary stage are well scalable from the solar model, this is far less so for stars with appreciably different properties such as high mass, rapid rotation, strong wind, evolved status, etc.A recent driver to improve stellar physics is the availability of long-duration high-cadence quasi-uninterrupted white-light space photometry with a precision of μmag as- ) satellites. This offered the opportunity to confront stellar models with asteroseismic data. This is done by computing the predicted spectrum of normal oscillation modes from theoretical models, by considering small perturbations to the equations of stellar structure, usually in the approximation of a spherically symmetric star. Normal modes are either pressure (p-)modes or gravity (g-)modes, depending Corresponding author: Conny.Aerts@ster.kuleuven.be on whether the pressure force, respectively buoyancy, is the dominant restoring force. Pressure modes probe the stellar envelope while g-modes tune the inner part of star. Such seismic diagnostics are far more suitable to probe stellar interiors compared to measurements of surface quantities. Figure 1 shows part of a typical Kepler light curve for a newly discovered g-mode pulsator, as well as the frequency spectrum based on the entire light curve in the range of maximum amplitude. An extensive description of t...

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Asteroseismic measurement of surface-to-core rotation in a main-sequence A star, KIC 11145123

Cited by 228 publications

References 30 publications

Spectroscopic and asteroseismic analysis of the remarkable main-sequence A star KIC 11145123

Spectroscopic and asteroseismic analysis of the remarkable main-sequence A star KIC 11145123

Asteroseismic Signatures of Evolving Internal Stellar Magnetic Fields

The age and interior rotation of stars from asteroseismology

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