The Kepler Cluster Study: Stellar Rotation in NGC 6811

Meibom, S.; Barnes, Sydney A.; Latham, David W.; Batalha, Natalie M.; Borucki, W. J.; Koch, David; Basri, Gibor; Walkowicz, Lucianne M.; Janes, K. A.; Jenkins, Jon M.; Cleve, Jeffrey Van; Haas, Michael R.; Bryson, Stephen T.; Dupree, A. K.; Fürész, Gábor; Szentgyorgyi, Andrew; Buchhave, Lars A.; Clarke, Bruce; Twicken, Joseph D.; Quintana, Elisa V.

doi:10.1088/2041-8205/733/1/l9

Cited by 237 publications

(242 citation statements)

References 45 publications

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“…Its rotation period of 3-4 d also matches rotation periods found for stars of this spectral type in the 1 Gyr old cluster 6811 (2-6 d) (Meibom et al 2011).…”

Section: Resultssupporting

confidence: 78%

Indications for an influence of hot Jupiters on the rotation and activity of their host stars

Poppenhaeger

Wolk

2014

A&A

124

121

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Context. The magnetic activity of planet-hosting stars is an important factor for estimating the atmospheric stability of close-in exoplanets and the age of their host stars. It has long been speculated that close-in exoplanets can influence the stellar activity level. However, testing for tidal or magnetic interaction effects in samples of planet-hosting stars is difficult because stellar activity hinders exoplanet detection, so that stellar samples with detected exoplanets show a bias toward low activity for small exoplanets. Aims. We aim to test whether exoplanets in close orbits influence the stellar rotation and magnetic activity of their host stars. Methods. We developed a novel approach to test for systematic activity-enhancements in planet-hosting stars. We use wide (several 100 AU) binary systems in which one of the stellar components is known to have an exoplanet, while the second stellar component does not have a detected planet and therefore acts as a negative control. We use the stellar coronal X-ray emission as an observational proxy for magnetic activity and analyze observations performed with Chandra and XMM-Newton. Results. We find that in two systems for which strong tidal interaction can be expected the planet-hosting primary displays a much higher magnetic activity level than the planet-free secondary. In three systems for which weaker tidal interaction can be expected the activity levels of the two stellar components agree with each other. Conclusions. Our observations indicate that the presence of Hot Jupiters may inhibit the spin-down of host stars with thick outer convective layers. Possible causes for this effect include a transfer of angular momentum from the planetary orbit to the stellar rotation through tidal interaction, or differences during the early evolution of the system, where the host star may decouple from the protoplanetary disk early because of a gap opened by the forming Hot Jupiter.

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“…Its rotation period of 3-4 d also matches rotation periods found for stars of this spectral type in the 1 Gyr old cluster 6811 (2-6 d) (Meibom et al 2011).…”

Section: Resultssupporting

confidence: 78%

Indications for an influence of hot Jupiters on the rotation and activity of their host stars

Poppenhaeger

Wolk

2014

A&A

124

121

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“…Hartman et al 2010;Agüeros et al 2011;Meibom et al 2011a;Irwin et al 2011;Affer et al 2012Affer et al , 2013Bouvier et al 2014;Gallet & Bouvier 2013;McQuillan et al 2014). These new observational results provide extremely useful guidance for the modelling of angular momentum evolution of low-mass stars (M * < 1.2 M ) from 1 Myr to 10 Gyr (e.g.…”

Section: Introductionmentioning

confidence: 77%

Improved angular momentum evolution model for solar-like stars

Gallet

Bouvier

2015

A&A

229

290

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Context. Understanding the physical processes that dictate the angular momentum evolution of solar-type stars from birth to maturity remains a challenge for stellar physics. Aims. We aim to account for the observed rotational evolution of low-mass stars over the age range from 1 Myr to 10 Gyr. Methods. We developed angular momentum evolution models for 0.5 and 0.8 M stars. The parametric models include a new wind braking law based on recent numerical simulations of magnetised stellar winds, specific dynamo and mass-loss rate prescriptions, as well as core-envelope decoupling. We compare model predictions to the distributions of rotational periods measured for low-mass stars belonging to star-forming regions and young open clusters. Furthermore, we explore the mass dependence of model parameters by comparing these new models to the solar-mass models we developed earlier.Results. Rotational evolution models are computed for slow, median, and fast rotators at each stellar mass. The models reproduce reasonably well the rotational behaviour of low-mass stars between 1 Myr and 8−10 Gyr, including pre-main sequence to zero-age main sequence spin up, prompt zero-age main sequence spin down, and early-main sequence convergence of the surface rotation rates. Fast rotators are found to have systematically shorter disk lifetimes than moderate and slow rotators, thus enabling dramatic pre-main sequence spin up. They also have shorter core-envelope coupling timescales, i.e., more uniform internal rotation. As for the mass dependence, lower mass stars require significantly longer core-envelope coupling timescales than solar-type stars, which results in strong differential rotation developing in the stellar interior on the early main sequence. Lower mass stars also require a weaker braking torque to account for their longer spin-down timescale on the early main sequence, while they ultimately converge towards lower rotational velocities than solar-type stars in the longer term because of their reduced moment of inertia. We also find evidence that the mass dependence of the wind braking efficiency may be related to a change in the magnetic topology in lower mass stars. Conclusions. We have included in parametric models the main physical processes that dictate the angular momentum evolution of low-mass stars. The models suggest that these processes are quite sensitive to both mass and instantaneous rotation rate. We have worked out and reported here the main trends of these mass and rotation dependencies, whose origin still have to be addressed through a detailed modelling of magnetised stellar winds, internal angular momentum transport processes, and protoplanetary disk dissipation mechanisms.

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“…The period-age relations are empirically calibrated with stellar systems for which independent ages and rotation periods are measured. Several calibrations are reported in the literature (Pace & Pasquini 2004;Barnes 2007;Mamajek & Hillenbrand 2008;Meibom et al 2009Meibom et al , 2011a), but they consistently struggle to find a calibration set at old ages and long rotation periods. Kepler light curves provide means to measure both the stellar age through asteroseismology, and the rotation periods through spot modulation for an old field star population, and as such represent an important contribution to the gyrochronological calibrators.…”

Section: Introductionmentioning

confidence: 99%

Rotation and magnetism ofKeplerpulsating solar-like stars

García

Ceillier

Salabert

et al. 2014

A&A

267

344

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Kepler ultra-high precision photometry of long and continuous observations provides a unique dataset in which surface rotation and variability can be studied for thousands of stars. Because many of these old field stars also have independently measured asteroseismic ages, measurements of rotation and activity are particularly interesting in the context of age-rotation-activity relations. In particular, age-rotation relations generally lack good calibrators at old ages, a problem that this Kepler sample of old-field stars is uniquely suited to address. We study the surface rotation and photometric magnetic activity of a subset of 540 solar-like stars on the mainsequence and the subgiant branch for which stellar pulsations have been measured. The rotation period was determined by comparing the results from two different analysis methods: i) the projection onto the frequency domain of the time-period analysis, and ii) the autocorrelation function of the light curves. Reliable surface rotation rates were then extracted by comparing the results from two different sets of calibrated data and from the two complementary analyses. General photometric levels of magnetic activity in this sample of stars were also extracted by using a photometric activity index, which takes into account the rotation period of the stars. We report rotation periods for 310 out of 540 targets (excluding known binaries and candidate planet-host stars); our measurements span a range of 1 to 100 days. The photometric magnetic activity levels of these stars were computed, and for 61.5% of the dwarfs, this level is similar to the range, from minimum to maximum, of the solar magnetic activity. We demonstrate that hot dwarfs, cool dwarfs, and subgiants have very different rotation-age relationships, highlighting the importance of separating out distinct populations when interpreting stellar rotation periods. Our sample of cool dwarf stars with age and metallicity data of the highest quality is consistent with gyrochronology relations reported in the literature.

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The Kepler Cluster Study: Stellar Rotation in NGC 6811

Cited by 237 publications

References 45 publications

Indications for an influence of hot Jupiters on the rotation and activity of their host stars

Indications for an influence of hot Jupiters on the rotation and activity of their host stars

Improved angular momentum evolution model for solar-like stars

Rotation and magnetism ofKeplerpulsating solar-like stars

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