%ADungee, Ryan%Avan Saders, Jennifer%AGaidos, Eric%AChun, Mark%AGarcía, Rafael%AMagnier, Eugene%AMathur, Savita%ASantos, Ângela%BJournal Name: The Astrophysical Journal; Journal Volume: 938; Journal Issue: 2; Related Information: CHORUS Timestamp: 2024-01-16 12:47:01 %D2022%IDOI PREFIX: 10.3847 %JJournal Name: The Astrophysical Journal; Journal Volume: 938; Journal Issue: 2; Related Information: CHORUS Timestamp: 2024-01-16 12:47:01 %K %MOSTI ID: 10376230 %PMedium: X; Size: Article No. 118 %TA 4 Gyr M-dwarf Gyrochrone from CFHT/MegaPrime Monitoring of the Open Cluster M67 %XAbstract

We present stellar rotation periods for late K- and early M-dwarf members of the 4 Gyr old open cluster M67 as calibrators for gyrochronology and tests of stellar spin-down models. Using Gaia EDR3 astrometry for cluster membership and Pan-STARRS (PS1) photometry for binary identification, we build this set of rotation periods from a campaign of monitoring M67 with the Canada–France–Hawaii Telescope’s MegaPrime wide-field imager. We identify 1807 members of M67, of which 294 are candidate single members with significant rotation period detections. Moreover, we fit a polynomial to the period versus color-derived effective temperature sequence observed in our data. We find that the rotation of very cool dwarfs can be explained by simple solid-body spin-down between 2.7 and 4 Gyr. We compare this rotational sequence to the predictions of gyrochronological models and find that the best match is Skumanich-like spin-down,Prott0.62, applied to the sequence of Ruprecht 147. This suggests that, for spectral types K7–M0 with near-solar metallicity, once a star resumes spinning down, a simple Skumanich-like relation is sufficient to describe their rotation evolution, at least through the age of M67. Additionally, for stars in the range M1–M3, our data show that spin-down must have resumed prior to the age of M67, in conflict with the predictions of the latest spin-down models.

%0Journal Article