Angular momentum loss in low-mass stars

Kawaler, S. D.

doi:10.1086/166740

Cited by 549 publications

(650 citation statements)

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“…Models were developed to understand angular momentum loss from magnetised stellar winds (e.g. Weber & Davis 1967;Mestel 1968;Kawaler 1988).…”

Section: Discussionmentioning

confidence: 99%

“…Stauffer & Hartmann (1987) noted that these stars spin down very rapidly once on the main sequence. This suggested that angular momentum loss mechanisms were highly efficient (Kawaler 1988). In addition, observational data indicated that G-type stars spin down more quickly than K-type stars which rotate faster than G-type stars in the Pleiades and which have experienced spin-down by the age of the Hyades.…”

Section: Discussionmentioning

confidence: 99%

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X-ray emission regimes and rotation sequences in M 35

Gondoin

2013

A&A

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Context. Late-type stars in young open clusters show two kinds of dependence of their X-ray emission on rotation. They also tend to group into two main sub-populations that lie on narrow sequences in diagrams where their rotation periods are plotted against their (B − V) colour indices. A correlation between these two regimes of X-ray emission and the rotation sequences has been recently observed in the M 34 open cluster. Sun-like M 34 stars also show a drop of their X-ray to bolometric luminosity ratio by about one order of magnitude at a Rossby number of about 0.3. Aims. The present study looks for similar connections between X-ray activity and rotation in an other open cluster. The aim is to consolidate a model of X-ray activity evolution on the main sequence and to provide observational constraints on dynamo processes in the interiors of late-type stars. Methods. The paper compares XMM-Newton measurements of X-ray stellar emission in M 35 with X-ray luminosity distributions derived from rotation period measurements assuming either an X-ray regime transition at a critical Rossby number or a correlation between X-ray emission regimes and rotation sequences. Results. This second hypothesis could account for the low number of M 35 stars detected in X-rays. A model of X-ray activity evolution is proposed based on the correlation. One major output is that the transition from saturated to non-saturated X-ray emission occurs at Rossby numbers between about 0.13 and 0.4 for each star depending on its mass and initial period of rotation on the ZAMS. This prediction agrees with observations of stellar X-ray emission in M 34. It explains the large range of X-ray luminosities observed among Sun-like stars in young open clusters. Conclusions. I conclude that the correlation between X-ray emission regimes and rotation sequences could be a fundamental property of the early evolution of stellar magnetic activity on the main sequence. I argue that the angular momentum redistribution mechanism(s) responsible for the transition between rotation sequences could result in a changing mixture of dynamo processes occurring side by side, possibly including a turbulent dynamo at high rotation rate and an interface-type dynamo whose efficiency decreases progressively at later stage of stellar evolution when rotation dies away.

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“…Models were developed to understand angular momentum loss from magnetised stellar winds (e.g. Weber & Davis 1967;Mestel 1968;Kawaler 1988).…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

X-ray emission regimes and rotation sequences in M 35

Gondoin

2013

A&A

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“…Even extremely old systems still show signs of activity (Parsons et al 2012b), manifesting as starspots and flaring. These features allow us to constrain the configuration of the underlying magnetic field of the main-sequence star, crucial for understanding the evolution of these binaries, since the magnetic field is able to remove angular momentum from the system, driving the two stars closer together (Rappaport et al 1983;Kawaler 1988). …”

Section: Introductionmentioning

confidence: 99%

The crowded magnetosphere of the post-common-envelope binary QS Virginis

Parsons

Hill

Marsh

et al. 2016

Mon. Not. R. Astron. Soc.

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We present high speed photometry and high resolution spectroscopy of the eclipsing post common envelope binary QS Virginis (QS Vir). Our UVES spectra span multiple orbits over more than a year and reveal the presence of several large prominences passing in front of both the M star and its white dwarf companion, allowing us to triangulate their positions. Despite showing small variations on a timescale of days, they persist for more than a year and may last decades. One large prominence extends almost three stellar radii from the M star. Roche tomography reveals that the M star is heavily spotted and that these spots are longlived and in relatively fixed locations, preferentially found on the hemisphere facing the white dwarf. We also determine precise binary and physical parameters for the system. We find that the 14, 220 ± 350 K white dwarf is relatively massive, 0.782 ± 0.013M ⊙ , and has a radius of 0.01068 ± 0.00007R ⊙ , consistent with evolutionary models. The tidally distorted M star has a mass of 0.382 ± 0.006M ⊙ and a radius of 0.381 ± 0.003R ⊙ , also consistent with evolutionary models. We find that the magnesium absorption line from the white dwarf is broader than expected. This could be due to rotation (implying a spin period of only ∼700 seconds), or due to a weak (∼100kG) magnetic field, we favour the latter interpretation. Since the M star's radius is still within its Roche lobe and there is no evidence that its over-inflated we conclude that QS Vir is most likely a pre-cataclysmic binary just about to become semi-detached.

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“…recovering the purely-radial field configuration for n = 2 (Kawaler 1988). We assume that the wind decouples from the binary at r d , without further interaction with the binary components.…”

Section: Tides Coupled With Wind Brakingmentioning

confidence: 99%

The coupled effect of tides and stellar winds on the evolution of compact binaries

Repetto

Nelemans

2014

Monthly Notices of the Royal Astronomical Society

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We follow the evolution of compact binaries under the coupled effect of tides and stellar winds until the onset of Roche-lobe overflow. These binaries contain a compact object (either a black-hole, a neutron-star, or a planet) and a stellar component. We integrate the full set of tidal equations, which are based on Hut's model for tidal evolution, and we couple them with the angular momentum loss in a stellar wind. Our aim is twofold. Firstly, we wish to highlight some interesting evolutionary outcomes of the coupling. When tides are coupled with a non-massive stellar wind, one interesting outcome is that in certain types of binaries, the stellar spin tends to reach a quasi-equilibrium state, where the effect of tides and wind are counteracting each other. When tides are coupled with a massive wind, we parametrize the evolution in terms of the decoupling radius, at which the wind decouples from the star. Even for small decoupling radii this wind braking can drive systems on the main sequence to Roche-lobe overflow that otherwise would fail to do so. Our second aim is to inspect whether simple timescale considerations are a good description of the evolution of the systems. We find that simple timescale considerations, which rely on neglecting the coupling between tides and stellar winds, do not accurately represent the true evolution of compact binaries. The outcome of the coupled evolution of the rotational and orbital elements can strongly differ from simple timescale considerations, as already pointed out by Barker & Ogilvie 2009 in the case of short-period planetary systems.

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Angular momentum loss in low-mass stars

Cited by 549 publications

References 0 publications

X-ray emission regimes and rotation sequences in M 35

X-ray emission regimes and rotation sequences in M 35

The crowded magnetosphere of the post-common-envelope binary QS Virginis

The coupled effect of tides and stellar winds on the evolution of compact binaries

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