Seismic constraints on the radial dependence of the internal rotation profiles of six Kepler subgiants and young red giants
By S. Deheuvels, G. Dougan, M. Goupil, T. Appourchaux, O. Benomar, H. Bruntt, T. Campante, Luca Casagrande, Tugdual Ceillier, G. Davies and 18 more. 2014
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Context. We still do not understand which physical mechanisms are responsible for the transport of angular momentum inside stars. The recent detection of mixed modes that contain the clear signature of rotation in the spectra of Kepler subgiants and red giants gives us the opportunity to make progress on this question.Aims. Our aim is to probe the radial dependence of the rotation profiles for a sample of Kepler targets. For this purpose, subgiants and early red giants are particularly interesting targets because their rotational splittings are more sensitive to the rotation outside the deeper core than is the case for their more evolved counterparts.Methods. We first extracted the rotational splittings and frequencies of the modes for six young Kepler red giants. We then performed a seismic modeling of these stars using the evolutionary codes Cesam2k and astec. By using the observed splittings and the rotational kernels of the optimal models, we inverted the internal rotation profiles of the six stars.Results. We obtain estimates of the core rotation rates for these stars, and upper limits to the rotation in their convective envelope. We show that the rotation contrast between the core and the envelope increases during the subgiant branch. Our results also suggest that the core of subgiants spins up with time, while their envelope spins down. For two of the stars, we show that a discontinuous rotation profile with a deep discontinuity reproduces the observed splittings significantly better than a smooth rotation profile. Interestingly, the depths that are found to be most probable for the discontinuities roughly coincide with the location of the H-burning shell, which separates the layers that contract from those that expand.Conclusions. We characterized the differential rotation pattern of six young giants with a range of metallicities, and with both radiative and convective cores on the main sequence. This will bring observational constraints to the scenarios of angular momentum transport in stars. Moreover, if the existence of sharp gradients in the rotation profiles of young red giants is confirmed, it is expected to help in distinguishing between the physical processes that could transport angular momentum in the subgiant and red giant branches.
Subfields: Astronomy and Astrophysics, Instrumentation
View Paper: https://www.semanticscholar.org/paper/f74400264b8ef095b3a0fa05bd3dfc45dfc1bdb4
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Citations in the corpus
- Rotation and magnetism of Kepler pulsating solar-like stars : Towards asteroseismically calibrated age-rotation relations (2014, background): “…al. 2013), but indications of the rotation profile from the external outer convection zone to the inner radiative core using inversion techniques (Deheuvels et al. 2012, 2014; Beck et al. 2014), as is also commonly done for the Sun (e.g. Thompson et al. 2003; García et al. 2008b; Mathur et al.…”
- Asteroseismology of 16,000 Kepler Red Giants: Global Oscillation Parameters, Masses, and Radii (2018, background): “…et al. 2016; Elsworth et al. 2017; Hon et al. 2017), measurement of internal rotation (Beck et al. 2012; Deheuvels et al. 2012; Mosser et al. 2012b; Deheuvels et al. 2014) and possible detection of magnetic fields in radiative cores (Fuller et al. 2015; Stello et al. 2016; Mosser et al. 2017).”
- Slowing the spins of stellar cores (2019, background): “…et al. 2014; Benomar et al. 2015; Saio et al. 2015; Van Reeth et al. 2018), sub-giant/red giant branch (RGB) (Beck et al. 2012; Mosser et al. 2012; Deheuvels et al. 2014; Triana et al. 2017; Gehan et al. 2018), red clump (Mosser et al. 2012; Deheuvels et al. 2015), and finally in WD remnants…”
- PLATO as it is: a legacy mission for Galactic archaeology (2017, unknown): “These objects are key to constraining transport processes of chemicals and the distribution (and evolution) of angular momentum inside stars (e.g., see Deheuvels et al. 2014).”
- Mixed modes in red giants: a window on stellar evolution (2014, background): “Determining ΔΠ1 allows us to probe the core, to monitor its rotation (Beck et al. 2012; Mosser et al. 2012a; Deheuvels et al. 2012, 2014), and to investigate how angular Article published by EDP Sciences L5, page 1 of 5 momentum is transferred between the stellar core and the envelope (Cantiello et…”
- Revised Stellar Properties of Kepler Targets for the Q1-17 (DR25) Transit Detection Run (2016, background): “…discoveries, such as the asteroseismic measurement of the internal rotation (Beck et al. 2012; Deheuvels et al. 2012; Mosser et al. 2012; Deheuvels et al. 2014) and magnetic fields (Fuller et al. 2015; Stello et al. 2016) of subgiants and red giants, the detection of surface rotation…”
- ANGULAR MOMENTUM TRANSPORT WITHIN EVOLVED LOW-MASS STARS (2014, methodology): “In the era of space asteroseismology, the Kepler satellite enabled the measurement of the core rotation in many red giant branch (RGB) stars using the splitting of mixed modes (Beck et al. 2012; Deheuvels et al. 2012; Mosser et al. 2012b; Deheuvels et al. 2014).”
- Determining stellar macroturbulence using asteroseismic rotational velocities from Kepler (2014, background): “For this to be true, we select only stars that do not show evidence of modes of mixed character that show greater sensitivity to the deep stellar interior (see Deheuvels et al. (2012) and Deheuvels et al. (2014) for more details on mixed modes in the context of rotation).”