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Constraints on Magn...
Constraints on Magnetic Braking from the G8 Dwarf Stars 61 UMa and tau Cet
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- Metcalfe, Travis S. (författare)
- White Dwarf Res Corp, 9020 Brumm Trail, Golden, CO 80403 USA.
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- Strassmeier, Klaus G. (författare)
- Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany.
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- Ilyin, Ilya V. (författare)
- Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany.
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- van Saders, Jennifer L. (författare)
- Univ Hawaii, Inst Astron, 2680 Woodlawn Dr, Honolulu, HI 96822 USA.
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- Ayres, Thomas R. (författare)
- Univ Colorado, Ctr Astrophys & Space Astron, 389 UCB, Boulder, CO 80309 USA.
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- Finley, Adam J. (författare)
- Univ Paris Saclay, Dept Astrophys, AIM, F-91191 Gif Sur Yvette, France.;Univ Paris, CEA, CNRS, F-91191 Gif Sur Yvette, France.
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- Kochukhov, Oleg (författare)
- Uppsala universitet,Observationell astrofysik
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- Petit, Pascal (författare)
- Univ Toulouse, CNRS, CNES, 14 Ave Edouard Belin, F-31400 Toulouse, France.
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- See, Victor (författare)
- European Space Agcy ESA, European Space Res & Technol Ctr ESTEC, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands.
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- Stassun, Keivan G. (författare)
- Vanderbilt Univ, Dept Phys & Astron, 6301 Stevenson Ctr Lane, Nashville, TN 37235 USA.
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- Jeffers, Sandra V. (författare)
- Max Planck Inst Sonnensystemforsch, Justus Von Liebig weg 3, D-37077 Gottingen, Germany.
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- Marsden, Stephen C. (författare)
- Univ Southern Queensland, Ctr Astrophys, Toowoomba, Qld 4350, Australia.
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- Morin, Julien (författare)
- Univ Montpellier, Ctr Natl Rech Sci CNRS, Pl Eugene Bataillon, F-34095 Montpellier, France.
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- Vidotto, Aline A. (författare)
- Leiden Univ, Leiden Observ, POB 9513, NL-2300 RA Leiden, Netherlands.
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White Dwarf Res Corp, 9020 Brumm Trail, Golden, CO 80403 USA Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany. (creator_code:org_t)
- Institute of Physics (IOP), 2023
- 2023
- Engelska.
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Ingår i: Astrophysical Journal Letters. - : Institute of Physics (IOP). - 2041-8205 .- 2041-8213. ; 948:1
- Relaterad länk:
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https://doi.org/10.3...
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https://uu.diva-port... (primary) (Raw object)
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https://urn.kb.se/re...
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https://doi.org/10.3...
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Abstract
Ämnesord
Stäng
- During the first half of their main-sequence lifetimes, stars rapidly lose angular momentum to their magnetized winds, a process known as magnetic braking. Recent observations suggest a substantial decrease in the magnetic braking efficiency when stars reach a critical value of the Rossby number, the stellar rotation period normalized by the convective overturn timescale. Cooler stars have deeper convection zones with longer overturn times, reaching this critical Rossby number at slower rotation rates. The nature and timing of the transition to weakened magnetic braking have previously been constrained by several solar analogs and two slightly hotter stars. In this Letter, we derive the first direct constraints from stars cooler than the Sun. We present new spectropolarimetry of the old G8 dwarf tau Cet from the Large Binocular Telescope, and we reanalyze a published Zeeman Doppler image of the younger G8 star 61 UMa, yielding the large-scale magnetic field strengths and morphologies. We estimate mass-loss rates using archival X-ray observations and inferences from Ly alpha measurements, and we adopt other stellar properties from asteroseismology and spectral energy distribution fitting. The resulting calculations of the wind braking torque demonstrate that the rate of angular momentum loss drops by a factor of 300 between the ages of these two stars (1.4-9 Gyr), well above theoretical expectations. We summarize the available data to help constrain the value of the critical Rossby number, and we identify a new signature of the long-period detection edge in recent measurements from the Kepler mission.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
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Metcalfe, Travis ...
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Strassmeier, Kla ...
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Ilyin, Ilya V.
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van Saders, Jenn ...
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Ayres, Thomas R.
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Finley, Adam J.
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visa fler...
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Kochukhov, Oleg
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Petit, Pascal
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See, Victor
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Stassun, Keivan ...
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Jeffers, Sandra ...
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Marsden, Stephen ...
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Morin, Julien
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Vidotto, Aline A ...
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