ON THE EVOLUTION OF ANGULAR MOMENTUM, MAGNETIC ACTIVITY AND MASS LOSS RATE OF LATE TYPE MAIN SEQUENCE STARS
-
Published:2020-04-01
Issue:1
Volume:56
Page:
-
ISSN:0185-1101
-
Container-title:Revista Mexicana de Astronomía y Astrofísica
-
language:
-
Short-container-title:RMxAA
Affiliation:
1. Instituto de Astronomı́a, Universidad Nacional Autónoma de México, México
Abstract
With the best data, I find that nearly all 0.5 to 1.2 M main sequence stars converge to a single rotational mass-dependent sequence after 750 Myr; when M > 0.8 M_, most of them converge in ≈ 120 Myr. If stars rotate as rigid bodies, most have angular momenta within clear bounds. The lower bound defines a terminal main sequence rotational isochrone, the upper one coincides with slow rotators from the Pleiades; stars from Praesepe delineate a third one. Mass dependent exponential relationships between angular momentum and age are determined. Age estimates based on the angular momentum are acceptable for stars older than 750 Myr and with M > 0.6− 0.7 M_⨀. The Rossby number indicates that the Parker dynamo may cease early on in stars with M/M_≥ 1.1. An empirical formula and a model for the torque, and a relation between rotational period and magnetic field, lead to a formula for the evolution of the mass loss rate; the present solar rate is near a minimum and was about five times larger when life on Earth started.
Publisher
Universidad Nacional Autonoma de Mexico
Subject
Space and Planetary Science,Astronomy and Astrophysics
Reference227 articles.
1. 1. Aerts, C., Mathis, S., & Rogers, T. M. 2019, A&AR, 57, 35A 2. 2. Affer, L., Micela, G., Favata, F., & Flaccomio, E. 2012, MNRAS, 424, 11 3. 3. Agüeros, M. A., Bowsher, E. C., Bochanski, J. J., et al. 2018, ApJ, 862, 33 4. 4. Agüeros, M. A., Covey, K. R., Lemonias, J. J., et al. 2011, ApJ, 740, 110 5. 5. Amard, L., Palacios, A., Charbonnel, C., Gallet, F., & Bouvier, J. 2016, A&A, 587, A105
|
|