11 papers
Stellar Activity Cycles Grow Longer and Weaker Before Disappearing
Travis S. Metcalfe
In 2007, Erika Bohm-Vitense published a provocative figure suggesting that the solar rotation period and activity cycle made the Sun an outlier compared to the trends observed for…
Characterizing six seismic solar analogs observed by Kepler, K2, and HERMES
R. A. GarcÃa, S. Mathur, G. T. Hookway +31
Solar analogs, stars that closely match the fundamental properties of the Sun, provide key benchmarks for testing stellar structure and evolution across different ages and activity…
Spectropolarimetric Constraints on the Maunder Minimum Analog HD 166620: Evidence for Weakened Magnetic Braking
Federica Chiti, Jennifer L. van Saders, Oleg Kochukhov +1
We present the first spectropolarimetric time-series analysis of the Maunder Minimum analog HD 166620, using 12 nights of data from CFHT/SPIRou and a single epoch from CFHT/ESPaDOn…
Anti-Solar Differential Rotation May Have Revived Magnetic Braking in the Subgiant 31 Aquilae
Travis S. Metcalfe, Jennifer L. van Saders, Thomas R. Ayres +16
Recent observations have shown that sufficiently slow rotation disrupts the organization of large-scale magnetic field in older main-sequence stars, leading to weakened magnetic br…
A Test of Substellar Evolutionary Models with High-Precision Ages from Asteroseismology and Gyrochronology for the Benchmark System HR 7672AB
Yaguang Li, Michael C. Liu, Trent J. Dupuy +35
We present high-precision measurements for HR~7672AB, composed of a Sun-like (G0V) star and an L~dwarf companion. Three nights of precise (70 cm/s) radial velocity (RV) asteroseism…
HST Observations of HD 166620 and Tau Ceti: First UV Spectra of a Magnetic Grand Minimum Star and the Extent of Tau Ceti's Astrosphere
Brian E. Wood, Hans-Reinhard Mueller, Dean Hartshorn +2
We present new Hubble Space Telescope (HST) UV spectra of the K2 V star HD 166620, the first star clearly recognized to be in a "magnetic grand minimum" state analogous to the Sun'…