2019ApJ...871...39M


Query : 2019ApJ...871...39M

2019ApJ...871...39M - Astrophys. J., 871, 39-39 (2019/January-3)

Understanding the limitations of gyrochronology for old field stars.

METCALFE T.S. and EGELAND R.

Abstract (from CDS):

Nearly half a century has passed since the initial indications that stellar rotation slows while chromospheric activity weakens with a power-law dependence on age, the so-called Skumanich relations. Subsequent characterization of the mass-dependence of this behavior up to the age of the Sun led to the advent of gyrochronology, which uses the rotation rate of a star to infer its age from an empirical calibration. The efficacy of the method relies on predictable angular momentum loss from a stellar wind entrained in the large-scale magnetic field produced by global dynamo action. Recent observational evidence suggests that the global dynamo begins to shut down near the middle of a star's main-sequence lifetime, leading to a disruption in the production of large-scale magnetic field, a dramatic reduction in angular momentum loss, and a breakdown of gyrochronology relations. For solar-type stars this transition appears to occur near the age of the Sun, when rotation becomes too slow to imprint Coriolis forces on the global convective patterns, reducing the shear induced by differential rotation, and disrupting the large-scale dynamo. We use data from Barnes to reveal the signature of this transition in the observations that were originally used to validate gyrochronology. We propose that chromospheric activity may ultimately provide a more reliable age indicator for older stars, and we suggest that asteroseismology can be used to help calibrate activity-age relations for field stars beyond the middle of their main-sequence lifetimes.

Abstract Copyright: © 2019. The American Astronomical Society. All rights reserved.

Journal keyword(s): stars: activity - stars: evolution - stars: magnetic field - stars: rotation - stars: solar-type

Simbad objects: 16

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Number of rows : 16
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 HD 45067 PM* 06 25 16.5464141963 -00 56 45.178168018   6.43 5.90     F9V 180 0
2 HD 89744 PM* 10 22 10.5623067078 +41 13 46.308754730       5.4   F7V 311 1
3 HD 95735 Er* 11 03 20.1948195942 +35 58 11.576182057 10.030 8.960 7.520 5.99 4.79 M2+V 650 0
4 * 9 Com PM* 12 19 29.5259620179 +28 09 24.908355473   6.83   6.1   F8Va 191 0
5 * e Vir PM* 13 16 46.5161591991 +09 25 26.967205938   5.81   4.8   G0V 518 1
6 * tau Boo Ro* 13 47 15.74340 +17 27 24.8552 5.02 4.98 4.49 4.09 3.85 F7IV-V 914 1
7 * rho CrB PM* 16 01 02.6608052290 +33 18 12.642245533   6.01   5.0   G0+VaFe-1 598 1
8 BD+45 2796 PM* 18 56 21.2644967292 +45 30 53.232987726   9.80 9.29     G0.5IV 72 0
9 HD 176693 Ro* 18 59 08.6846510375 +48 25 23.598982331   9.34 8.83     F8V 105 0
10 TYC 3545-1033-1 * 19 04 45.6028236992 +48 21 33.385044320   11.54 11.00     F6IV 21 0
11 HD 178428 SB* 19 07 57.3202463316 +16 51 12.185570430   6.77   5.6   G4.5V 178 0
12 HD 234856 Ro* 19 17 45.8021284617 +50 28 48.273320177   9.87 9.32     F9IV-V 68 0
13 NGC 6811 OpC 19 37 17 +46 23.3   7.47 6.8     ~ 283 0
14 NGC 6819 OpC 19 41 18 +40 11.2   8.21 7.3     ~ 506 0
15 * omi Aql PM* 19 51 01.6437560393 +10 24 56.595177367   5.66   4.8   F8V 432 0
16 * 34 Peg SB* 22 26 37.3705884794 +04 23 37.605589572   6.37 5.81 5.4   F7V 142 0

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2021.09.19-07:12:49

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