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Untangling the Galaxy. IV. Empirical Constraints on Angular Momentum Evolution and Gyrochronology for Young Stars in the Field

Kounkel, Marina and Stassun, Keivan G. and Bouma, Luke G. and Covey, Kevin and Hillenbrand, Lynne A. and Curtis, Jason Lee (2022) Untangling the Galaxy. IV. Empirical Constraints on Angular Momentum Evolution and Gyrochronology for Young Stars in the Field. . (Unpublished)

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We present a catalog of ~100,000 periodic variable stars in TESS FFI data among members of widely distributed moving groups identified with Gaia in the previous papers in the series. By combining the periods from our catalog attributable to rotation with previously derived rotation periods for benchmark open clusters, we develop an empirical gyrochronology relation of angular momentum evolution that is valid for stars with ages 10-1000 Myr. Excluding stars rotating faster than 2 days, which we find are predominantly binaries, we achieve a typical age precision of ~0.2-0.3 dex and improving at older ages. Importantly, these empirical relations apply to not only FGK-type stars but also M-type stars, due to the angular momentum distribution being much smoother, simpler, continuous and monotonic as compared to the rotation period distribution. As a result, we are also able to begin tracing in fine detail the nature of angular momentum loss in low-mass stars as functions of mass and age. We characterize the stellar variability amplitudes of the cool stars as functions of mass and age, which may correlate with the starspot covering fractions. We also identify pulsating variables among the hotter stars in the catalog, including δ Scuti, γ Dor and SPB-type variables. These data represent an important step forward in being able to estimate precise ages of FGK- and M-type stars in the field, starting as early as the pre-main-sequence phase of evolution.

Item Type:Report or Paper (Discussion Paper)
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URLURL TypeDescription Paper ItemJournal Article
Kounkel, Marina0000-0002-5365-1267
Stassun, Keivan G.0000-0002-3481-9052
Bouma, Luke G.0000-0002-0514-5538
Covey, Kevin0000-0001-6914-7797
Curtis, Jason Lee0000-0002-2792-134X
Additional Information:Attribution 4.0 International (CC BY 4.0) . This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Software: TOPCAT (Taylor 2005), eleanor (Feinstein et al. 2019), GaussPy (Lindner et al. 2015, 2019)
Group:Astronomy Department
Funding AgencyGrant Number
Gaia Multilateral AgreementUNSPECIFIED
Record Number:CaltechAUTHORS:20220816-192417168
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:116313
Deposited By: George Porter
Deposited On:16 Aug 2022 22:37
Last Modified:23 Sep 2022 18:09

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