Rotation periods of open-cluster stars, 3

Prosser, Charles F.; Shetrone, Matthew; Marilli, E.; Catalano, S.; Williams, S. D.; Backman, D. E.; Laaksonen, Bentley D.; Adige, Vikram; Marschall, Laurence A.; Stauffer, J. R.

doi:10.1086/133541

Cited by 67 publications

(79 citation statements)

References 15 publications

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“…However, as Lamm et al note, the latter tracks give systematically smaller ages compared to others; since we use BCAH98 models instead, we adopt the larger ages provided by (2009) in lumping them into a single population with an adopted mean age of 650 Myr. Rotation and photometric data for Praesepe are from , Scholz et al (2011), and Delorme et al (2011), and for Hyades from Radick et al (1987), Prosser et al (1995), and Delorme et al (2011). The Delorme et al survey makes up the bulk of the data.…”

Section: Rotation and Activity Data And Stellar Mass Determinationmentioning

confidence: 99%

Radius-Dependent Angular Momentum Evolution in Low-Mass Stars. I

Reiners

Mohanty

2012

ApJ

195

263

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Angular momentum evolution in low-mass stars is determined by initial conditions during star formation, stellar structure evolution, and the behavior of stellar magnetic fields. Here we show that the empirical picture of angular momentum evolution arises naturally if rotation is related to magnetic field strength instead of to magnetic flux and formulate a corrected braking law based on this. Angular momentum evolution then becomes a strong function of stellar radius, explaining the main trends observed in open clusters and field stars at a few Gyr: the steep transition in rotation at the boundary to full convection arises primarily from the large change in radius across this boundary and does not require changes in dynamo mode or field topology. Additionally, the data suggest transient core-envelope decoupling among solar-type stars and field saturation at longer periods in very low mass stars. For solar-type stars, our model is also in good agreement with the empirical Skumanich law. Finally, in further support of the theory, we show that the predicted age at which low-mass stars spin down from the saturated to unsaturated field regimes in our model corresponds remarkably well to the observed lifetime of magnetic activity in these stars.

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Section: Rotation and Activity Data And Stellar Mass Determinationmentioning

confidence: 99%

Radius-Dependent Angular Momentum Evolution in Low-Mass Stars. I

Reiners

Mohanty

2012

ApJ

195

263

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“…14). Chromospheric age shows an enhancement of the star formation rate in the last 2 Gyr, then the Prosser et al (1995), whereas data from the Hyades are from Radick et al (1987). Three gyrochrones (at the ages of the Pleiades, Hyades, and the Sun) have been overplotted for a comparison.…”

Section: Age From Stellar Rotation: Gyrochronologymentioning

confidence: 99%

A spectroscopy study of nearby late-type stars, possible members of stellar kinematic groups

Maldonado¹,

Martínez-Arnáiz

Eiroa³

et al. 2010

A&A

109

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Context. Nearby late-type stars are excellent targets for seeking young objects in stellar associations and moving groups. The origin of these structures is still misunderstood, and lists of moving group members often change with time and also from author to author. Most members of these groups have been identified by means of kinematic criteria, leading to an important contamination of previous lists by old field stars. Aims. We attempt to identify unambiguous moving group members among a sample of nearby-late type stars by studying their kinematics, lithium abundance, chromospheric activity, and other age-related properties. Methods. High-resolution echelle spectra (R ∼ 57 000) of a sample of nearby late-type stars are used to derive accurate radial velocities that are combined with the precise Hipparcos parallaxes and proper motions to compute galactic-spatial velocity components. Stars are classified as possible members of the classical moving groups according to their kinematics. The spectra are also used to study several age-related properties for young late-type stars, i.e., the equivalent width of the lithium Li i 6707.8 Å line or the R HK index. Additional information like X-ray fluxes from the ROSAT All-Sky Survey or the presence of debris discs is also taken into account. The different age estimators are compared and the moving group membership of the kinematically selected candidates are discussed. Results. From a total list of 405 nearby stars, 102 have been classified as moving group candidates according to their kinematics. i.e., only ∼25.2% of the sample. The number reduces when age estimates are considered, and only 26 moving group candidates (25.5% of the 102 candidates) have ages in agreement with the star having the same age as an MG member.

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“…4. Colour-period data are taken from the recent study of M 35 by Meibom et al (2009), and for the Hyades, from Radick et al (1987) and Prosser et al (1995b). This side-by-side comparison shows that the ∼135 Myr-old M 35 cluster has two distinct sequences of rotating stars indicated by the solid and dashed line in the figure, while the older Hyades cluster has only one.…”

Section: The Photometric Period Distribution In M 34mentioning

confidence: 99%

New rotation periods in the open cluster NGC 1039 (M 34), and a derivation of its gyrochronology age

James

Barnes

Meibom

et al. 2010

A&A

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Aims. Employing photometric rotation periods for solar-type stars in NGC 1039 [M 34], a young, nearby open cluster, we use its mass-dependent rotation period distribution to derive the cluster's age in a distance independent way, i.e., the so-called gyrochronology method. Methods. We present an analysis of 55 new rotation periods, using light curves derived from differential photometry, for solar type stars in the open cluster NGC 1039 [M 34]. We also exploit the results of a recently-completed, standardized, homogeneous BV Ic CCD survey of the cluster, performed by the Indiana Group of the WIYN open cluster survey, in order to establish photometric cluster membership and assign B − V colours to each photometric variable. We describe a methodology for establishing the gyrochronology age for an ensemble of solar-type stars. Empirical relations between rotation period, photometric colour and stellar age (gyrochronology) are used to determine the age of M 34. Based on its position in a colour-period diagram, each M 34 member is designated as being either a solid-body rotator (interface or I-star), a differentially rotating star (convective or C-star) or an object which is in some transitory state in between the two (gap or g-star). Fitting the period and photometric colour of each I-sequence star in the cluster, we derive the cluster's mean gyrochronology age. Results. Of the photometric variable stars in the cluster field, for which we derive a period, 47 out of 55 of them lie along the loci of the cluster main sequence in V/B − V and V/V − I space. We are further able to confirm kinematic membership of the cluster for half of the periodic variables [21/55], employing results from an on-going radial velocity survey of the cluster. For each cluster member identified as an I-sequence object in the colour-period diagram, we derive its individual gyrochronology age, where the mean gyro age of M 34 is found to be 193 ± 9 Myr. Conclusions. Using differential photometry, members of a young open cluster can be easily identified in a colour−magnitude diagram from their periodic photometric variability alone. Such periodicity can be used to establish a period-colour distribution for the cluster, which for M 34, we have used to derive its gyrochronology age of 193 ± 9 Myr. Formally, our gyro age of M 34 is consistent (within the errors) with that derived using several distance-dependent, photometric isochrone methods (250 ± 67 Myr).

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Rotation periods of open-cluster stars, 3

Cited by 67 publications

References 15 publications

Radius-Dependent Angular Momentum Evolution in Low-Mass Stars. I

Radius-Dependent Angular Momentum Evolution in Low-Mass Stars. I

A spectroscopy study of nearby late-type stars, possible members of stellar kinematic groups

New rotation periods in the open cluster NGC 1039 (M 34), and a derivation of its gyrochronology age

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