Color, Rotation, Age, and Chromospheric Activity Correlations in Late‐Type Main‐Sequence Stars

Cardini, D.; Cassatella, A.

doi:10.1086/519991

Cited by 48 publications

(47 citation statements)

References 34 publications

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“…Returning to Figure 3, which shows the distribution of periods for stars in our statistical sample, the lack of stars at intermediate periods is clear in the grade A and grade B rotators, as well as in the candidate periods for the "possible" detections. A similar gap has been seen in activity studies of M dwarfs (Herbst & Miller 1989;Gizis et al 2002;Cardini & Cassatella 2007;Browning et al 2010).…”

Section: The Mass-period Relationsupporting

confidence: 76%

The Rotation and Galactic Kinematics of Mid M Dwarfs in the Solar Neighborhood

Newton

Irwin

Charbonneau

et al. 2016

ApJ

266

417

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Rotation is a directly observable stellar property, and it drives magnetic field generation and activity through a magnetic dynamo. Main-sequence stars with masses below approximately 0.35  M (mid-to-late M dwarfs) are fully convective, and are expected to have a different type of dynamo mechanism than solar-type stars. Measurements of their rotation rates provide insight into these mechanisms, but few rotation periods are available for these stars at field ages. Using photometry from the MEarth Project, we measure rotation periods for 387 nearby, mid-to-late M dwarfs in the northern hemisphere, finding periods from 0.1 to 140 days. The typical rotator has stable, sinusoidal photometric modulations at a semi-amplitude of 0.5%-1%. We find no period-amplitude relation for stars below 0.25  M and an anticorrelation between period and amplitude for higher-mass M dwarfs. We highlight the existence of older, slowly rotating stars without Hα emission that nevertheless have strong photometric variability. We use parallaxes, proper motions, radial velocities, photometry, and near-infrared metallicity estimates to further characterize the population of rotators. The Galactic kinematics of our sample is consistent with the local population of G and K dwarfs, and rotators have metallicities characteristic of the solar neighborhood. We use the W space velocities and established age-velocity relations to estimate that stars with P<10 days have ages of on average <2 Gyr, and that those with P>70 days have ages of about 5 Gyr. The period distribution is dependent on mass: as the mass decreases, the slowest rotators at a given mass have longer periods, and the fastest rotators have shorter periods. We find a lack of stars with intermediate rotation periods, and the gap between the fast and slow rotators is larger for lower masses. Our data are consistent with a scenario in which these stars maintain rapid rotation for several gigayears, then spin down quickly, reaching periods of around 100 days by a typical age of 5 Gyr.

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Section: The Mass-period Relationsupporting

confidence: 76%

The Rotation and Galactic Kinematics of Mid M Dwarfs in the Solar Neighborhood

Newton

Irwin

Charbonneau

et al. 2016

ApJ

266

417

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show abstract

“…This can also be related with stellar rotational properties, as stars with strong magnetic fields can be magnetically braked, leading to slow rotation rates, whereas stars with weak magnetic fields can remain rapid rotators (e.g. Cardini & Cassatella 2007). Additionally, we observe the eMSTO in the optical CMD of clusters younger than 1.7 Gyr (NGC 419, 1783(NGC 419, ,1806(NGC 419, , 1846, while we do not observe such a feature in the ∼ 2 Gyr old NGC 1978 (see Fig.…”

Section: Discussionmentioning

confidence: 99%

Age as a major factor in the onset of multiple populations in stellar clusters

Martocchia

Cabrera-Ziri

Lardo

et al. 2017

Monthly Notices of the Royal Astronomical Society

120

139

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It is now well established that globular clusters (GCs) exhibit star-to-star light-element abundance variations (known as multiple stellar populations, MPs). Such chemical anomalies have been found in (nearly) all the ancient GCs (more than 10 Gyr old) of our Galaxy and its close companions, but so far no model for the origin of MPs is able to reproduce all the relevant observations. To gain new insights into this phenomenon, we have undertaken a photometric Hubble Space Telescope survey to study clusters with masses comparable to that of old GCs, where MPs have been identified, but with significantly younger ages. Nine clusters in the Magellanic Clouds with ages between ∼ 1.5-11 Gyr have been targeted in this survey. We confirm the presence of multiple populations in all clusters older than 6 Gyr and we add NGC 1978 to the group of clusters for which MPs have been identified. With an age of ∼ 2 Gyr, NGC 1978 is the youngest cluster known to host chemical abundance spreads found to date. We do not detect evident star-to-star variations for slightly younger massive clusters (∼ 1.7 Gyr), thus pointing towards an unexpected age dependence for the onset of multiple populations. This discovery suggests that the formation of MPs is not restricted to the early Universe and that GCs and young massive clusters share common formation and evolutionary processes.

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“…We initially compared two empirical relations, due to Aigrain et al (2004) and Cardini & Cassatella (2007), respectively. Note that in what follows we have not plotted the results for the ZAMS models, since the empirical relations are more uncertain there.…”

Section: Rotationmentioning

confidence: 99%

Challenges for asteroseismic analysis of Sun-like stars

Chaplin¹,

Houdek²,

Appourchaux

et al. 2008

A&A

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Context. Asteroseismology of Sun-like stars is undergoing rapid expansion with, for example, new data from the CoRoT mission and continuation of ground-based campaigns. There is also the exciting upcoming prospect of NASA's Kepler mission, which will allow the asteroseismic study of several hundred Sun-like targets, in some cases for periods lasting up to a few years. Aims. The seismic mode parameters are the input data needed for making inference on stars and their internal structures. In this paper we discuss the ease with which it will be possible to extract estimates of individual mode parameters, dependent on the mass, age, and visual brightness of the star. Our results are generally applicable; however, we look at mode detectability in the context of the upcoming Kepler observations. Methods. To inform our discussions we make predictions of various seismic parameters. To do this we use simple empirical scaling relations and detailed pulsation computations of the stochastic excitation and damping characteristics of the Sun-like p modes. Results. The issues related to parameter extraction on individual p modes discussed here are mode detectability, the detectability and impact of stellar activity cycles, and the ability to measure properties of rotationally split components, which is dependent on the relative importance of the rotational characteristics of the star and the damping of the stochastically excited p modes.

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Color, Rotation, Age, and Chromospheric Activity Correlations in Late‐Type Main‐Sequence Stars

Cited by 48 publications

References 34 publications

The Rotation and Galactic Kinematics of Mid M Dwarfs in the Solar Neighborhood

The Rotation and Galactic Kinematics of Mid M Dwarfs in the Solar Neighborhood

Age as a major factor in the onset of multiple populations in stellar clusters

Challenges for asteroseismic analysis of Sun-like stars

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