The open cluster M67 offers a unique opportunity to measure rotation periods for solar-age stars across a range of masses, potentially filling a critical gap in the understanding of angular momentum loss in older main sequence stars. However, alternative explanations, e.g., a temporary reduction in the magnetic braking torque, cannot yet be ruled out. Empirically tuning a core$-$envelope coupling model with open cluster data can account for most of the apparent stalling effect. To accurately age-date low-mass stars in the field, gyrochronology formulae must be modified to account for this stalling timescale. We calculate the time at which stars resume spinning down, and find that 0.55 M$_\odot$ stars remain stalled for at least 1.3 Gyr. This sequence also intersects the $Kepler$ intermediate period gap, demonstrating that this gap was not created by a lull in star formation. The slowly rotating sequence for this joint sample appears relatively flat (22 $\pm$ 2 days) compared to sequences for younger clusters. Recent measurements of rotation periods ($P_\text$ data for the approximately coeval cluster NGC 6819 (30 stars with $M_\star > 0.85$ M$_\odot$), our new measurements more than double the number of $\approx$2.5 Gyr benchmark rotators and extend this sample down to $\approx$0.55 M$_\odot$. Empirically tuning a core–envelope coupling model with open cluster data can account for most of the apparent stalling effect. We calculate the time at which stars resume spinning down and find that 0.55 M_⊙ stars remain stalled for at least 1.3 Gyr. This sequence also intersects the Kepler intermediate-period gap, demonstrating that this gap was not created by a lull in star formation. The slowly rotating sequence for this joint sample appears relatively flat (22 ± 2 days) compared to sequences for younger clusters. Combined with the Kepler P_(rot) data for the approximately coeval cluster NGC 6819 (30 stars with M_★ > 0.85 M_⊙, our new measurements more than double the number of ≈2.5 Gyr benchmark rotators and extend this sample down to ≈0.55 M_⊙. To determine when stalled stars resume spinning down, we use data from the K2 mission and the Palomar Transient Factory to measure P_(rot) for 58 dwarf members of the 2.7 Gyr old cluster Ruprecht 147, 39 of which satisfy our criteria designed to remove short-period or near-equal-mass binaries. These data also show that the duration of this epoch of stalled spin-down increases toward lower masses. Recent measurements of rotation periods 〈P_(rot)〉 in the benchmark open clusters Praesepe (670 Myr), NGC 6811 (1 Gyr), and NGC 752 (1.4 Gyr) demonstrate that, after converging onto a tight sequence of slowly rotating stars in mass–period space, stars temporarily stop spinning down. We also present an introduction to our implementation of image subtraction photometry and the open source IRIS pipeline, alongside an overview of the data products, systematics, and catalog statistics. The catalog is available as a high-level science product on MAST, with both raw photometric data for each quarter and corrected light curves for all available quarters for each star. The IRIS catalog includes light curves for 9,150 stars, and contains a wealth of new data: 8,427 of these stars were not targeted at all by Kepler, and we have increased the number of available quarters of long cadence data for 382 stars. Using image subtraction photometry, we have produced light curves for every object in the Kepler Input Catalog that falls on the superstamps. #SUPERSTAMPS DOWNLOAD PLUS#The four-year Kepler mission collected long cadence images of the open clusters NGC 6791 and NGC 6819, known as "superstamps." Each superstamp region is a 200-pixel square that captures thousands of cluster members, plus foreground and background stars, of which only the brightest were targeted for long or short cadence photometry during the Kepler mission.
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