GRAVITY-MODE PERIOD SPACINGS AS A SEISMIC DIAGNOSTIC FOR A SAMPLE OF
                    <i>γ</i>
                    DORADUS STARS FROM
                    <i>KEPLER</i>
                    SPACE PHOTOMETRY AND HIGH-RESOLUTION GROUND-BASED SPECTROSCOPY

Reeth, T. Van; Tkachenko, A.; Aerts, C.; Pápics, P. I.; Triana, S. A.; Zwintz, K.; Degroote, P.; Debosscher, J.; Bloemen, S.; Schmid, V. S.; Smedt, K. De; Frémat, Y.; Fuentes, Antonio; Homan, W.; Hrudková, M.; Karjalainen, R.; Lombaert, R.; Németh, P.; Østensen, R. H.; Steene, G. C. Van de; Vos, J.; Raskin, Gert; Winckel, H. Van

doi:10.1088/0067-0049/218/2/27

Cited by 143 publications

(128 citation statements)

References 41 publications

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“…The five stars color coded in blue are bona fide γ Dor pulsators. Right: as in left panel, with overplotted the location of ≈300 γ Dor stars analyzed by Bruntt et al (2008), Catanzaro et al (2011), Fossati et al (2011), Tkachenko et al (2012, Bradley et al (2015), and Van Reeth et al (2015) and some hybrid γ Dor-δ Sct stars from Catanzaro et al (2011) and Tkachenko et al (2012). broadening of spectral lines (Aerts et al 2009). If indeed turbulent pressure fluctuations excite high-order modes, a connection with γ Dor may be present as well, which could involve finite amplitude pressure fluctuations in the HCZ.…”

Section: Discussionmentioning

confidence: 99%

“…In addition, the stars that present a non-negligible macroturbulent broadening lie predominantly along this same area of the sHR diagram. As a matter of fact, all the stars listed in Table A.1 and HD 37594 are indeed bona fide γ Dor pulsators (Díaz-Fraile et al 2014;Van Reeth et al 2015).…”

Section: The γ Dor Instability Stripmentioning

confidence: 93%

“…For all stars, we analyzed the spectral lines as described in Fossati et al (2011), and we adopted the atmospheric parameters listed in Bruntt et al (2008) for HD 167858 and in Van Reeth et al (2015) for KIC 8378079, KIC 9751996, and KIC 11754232. The results, listed in Table A.1, show that for all stars we obtained a non-negligible υ mac value.…”

Section: Macroturbulence Broadeningmentioning

confidence: 99%

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Relating turbulent pressure and macroturbulence across the HR diagram with a possible link toγDoradus stars

Grassitelli

Fossati

Langer

et al. 2015

A&A

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A significant fraction of the envelope of low-and intermediate-mass stars is unstable to convection, leading to sub-surface turbulent motion. Here, we consider and include the effects of turbulence pressure in our stellar evolution calculations. In search of an observational signature, we compare the fractional contribution of turbulent pressure to the observed macroturbulent velocities in stars at different evolutionary stages. We find a strong correlation between the two quantities, similar to what was previously found for massive OB stars. We therefore argue that turbulent pressure fluctuations of finite amplitude may excite high-order, high-angular degree stellar oscillations, which manifest themselves at the surface an additional broadening of the spectral lines, i.e., macroturbulence, across most of the HR diagram. When considering the locations in the HR diagram where we expect high-order oscillations to be excited by stochastic turbulent pressure fluctuations, we find a close match with the observational γ Doradus instability strip, which indeed contains high-order, non-radial pulsators. We suggest that turbulent pressure fluctuations on a percentual level may contribute to the γ Dor phenomenon, calling for more detailed theoretical modeling in this direction.

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Section: Discussionmentioning

confidence: 99%

Section: The γ Dor Instability Stripmentioning

confidence: 93%

Section: Macroturbulence Broadeningmentioning

confidence: 99%

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Relating turbulent pressure and macroturbulence across the HR diagram with a possible link toγDoradus stars

Grassitelli

Fossati

Langer

et al. 2015

A&A

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“…When these modes show clear multiplets, the core rotation rate can be determined. Period spacings have been detected in dozens of γ Dor stars (Van Reeth et al 2015a), but only a small number have evident rotational splittings . Some γ Dor stars also show p modes, which are sensitive to conditions at the surface.…”

Section: Introductionmentioning

confidence: 99%

Near-uniform internal rotation of the main-sequence γ Doradus pulsator KIC 7661054

Murphy

Fossati

Bedding

et al. 2016

Mon. Not. R. Astron. Soc.

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We used Kepler photometry to determine the internal rotation rate of KIC 7661054, a chemically normal γ Dor star on the main sequence at spectral type F2.5 V. The core rotation period of 27.25 ± 0.06 d is obtained from the rotational splittings of a series of dipole g modes. The surface rotation period is calculated from a spectroscopic projected rotation velocity and a stellar radius computed from models. Literature data, obtained without inclusion of macroturbulence as a line-broadening mechanism, imply that the surface rotates much more quickly than the core, while our detailed analysis suggests that the surface may rotate slightly more quickly than the core and that the rotation profile is uniform within the 1-σ uncertainties. We discuss the pitfalls associated with the determination of surface rotation rates of slow rotators from spectroscopy in the absence of asteroseismic constraints. A broad signal is observed at low frequency, which we show cannot be attributed to rotation, contrary to previous suggestions concerning the origin of such signals.

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“…Thanks to the high-precision photometric observations of space missions such as Kepler (Koch et al 2010), such period spacing patterns were recently found in some γ Doradus stars (e.g., Chapellier et al 2012;Kurtz et al 2014;Bedding et al 2015;Van Reeth et al 2015b;Keen et al 2015;Saio et al 2015). They have since been used to probe the rotation rates (e.g, Murphy et al 2016;Van Reeth et al 2016;Ouazzani et al 2017;Sowicka et al 2017;Guo et al 2017) and the nature of the mixing processes (e.g., Schmid & Aerts 2016) in the deep interior of these stars.…”

Section: Introductionmentioning

confidence: 96%

Constraining the near-core rotation of theγDoradus star 43 Cygni using BRITE-Constellation data

Zwintz

Reeth

Tkachenko

et al. 2017

A&A

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Context. Photometric time series of the γ Doradus star 43 Cyg obtained with the BRITE-Constellation nano-satellites allow us to study its pulsational properties in detail and to constrain its interior structure. Aims. We aim to find a g-mode period spacing pattern that allows us to determine the near-core rotation rate of 43 Cyg and redetermine the star's fundamental atmospheric parameters and chemical composition.Methods. We conducted a frequency analysis using the 156-days long data set obtained with the BRITE-Toronto satellite and employed a suite of MESA/GYRE models to derive the mode identification, asymptotic period spacing and near-core rotation rate. We also used high-resolution, high signal-to-noise ratio spectroscopic data obtained at the 1.2m Mercator telescope with the HER-MES spectrograph to redetermine the fundamental atmospheric parameters and chemical composition of 43 Cyg using the software Spectroscopy Made Easy (SME). Results. We detected 43 intrinsic pulsation frequencies and identified 18 of them to be part of a period spacing pattern consisting of prograde dipole modes with an asymptotic period spacing ∆Π l=1 of 2970 +700 −570 s. The near-core rotation rate was determined to be f rot = 0.56 +0.12 −0.14 d −1 . The atmosphere of 43 Cyg shows solar chemical composition at an effective temperature, T eff , of 7150 ± 150 K, a log g of 4.2 ± 0.6 dex and a projected rotational velocity, υ sin i, of 44 ± 4 km s −1 . Conclusions. The morphology of the observed period spacing patterns shows indications of the presence of a significant chemical gradient in the stellar interior.

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GRAVITY-MODE PERIOD SPACINGS AS A SEISMIC DIAGNOSTIC FOR A SAMPLE OF γ DORADUS STARS FROM KEPLER SPACE PHOTOMETRY AND HIGH-RESOLUTION GROUND-BASED SPECTROSCOPY

Cited by 143 publications

References 41 publications

Relating turbulent pressure and macroturbulence across the HR diagram with a possible link toγDoradus stars

Relating turbulent pressure and macroturbulence across the HR diagram with a possible link toγDoradus stars

Near-uniform internal rotation of the main-sequence γ Doradus pulsator KIC 7661054

Constraining the near-core rotation of theγDoradus star 43 Cygni using BRITE-Constellation data

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