Journal ArticleThree K2 Campaigns Yield Rotation Periods for 1013 Stars in PraesepeRampalli, Rayna; Agüeros, Marcel A; Curtis, Jason L; Douglas, Stephanie T; Núñez, Alejandro; Cargile, Phillip A; Covey, Kevin R; Gosnell, Natalie M; Kraus, Adam L; Law, Nicholas M; Mann, Andrew W<title>Abstract</title> <p>We use three campaigns of K2 observations to complete the census of rotation in low-mass members of the benchmark, ≈670 Myr old open cluster Praesepe. We measure new rotation periods (<italic>P</italic>_rot) for 220 ≲1.3 <italic>M</italic>_⊙ Praesepe members and recovery periods for 97% (793/812) of the stars with a<italic>P</italic>_rot in the literature. Of the 19 stars for which we do not recover a <italic>P</italic>_rot, 17 were not observed by K2. As K2’s three Praesepe campaigns took place over the course of 3 yr, we test the stability of our measured <italic>P</italic>_rot for stars observed in more than one campaign. We measure <italic>P</italic>_rot consistent to within 10% for >95% of the 331 likely single stars with ≥2 high-quality observations; the median difference in <italic>P</italic>_rot is 0.3%, with a standard deviation of 2%. Nearly all of the exceptions are stars with discrepant <italic>P</italic>_rot measurements in Campaign 18, K2’s last, which was significantly shorter than the earlier two (≈50 days rather than ≈75 days). This suggests that, despite the evident morphological evolution we observe in the light curves of 38% of the stars, <italic>P</italic>_rot measurements for low-mass stars in Praesepe are stable on timescales of several years. A <italic>P</italic>_rot can therefore be taken to be representative even if measured only once.</p>American Astronomical Society/IOP2021-11-0110555976The Astrophysical Journal92121670004-637Xhttps://doi.org/10.3847/1538-4357/ac0c1e2009840National Science Foundation