Asteroseismology of Ruprecht 147 Mikkel N. Lund1∗, Jason L. Curtis2, Allyson Bieryla3, Luca Casagrande4, David W. Latham3, Karsten F. Brogaard1, Andrea Miglio5,6, Sarbani Basu7, J. M. Joel Ong7,8, Aldo M. Serenelli9,10, et al. Introduction Ruprecht 147 (NGC 6774) is the nearest old open cluster, located at a distance of approximately 300 pc and with an age of around 2.5 Gyr. Initially discovered by Ruprecht in 1966, the cluster remained largely unnoticed for decades until it was “re-discovered” by Curtis et al. in 2013. Since then, it has been the focus of several studies, particularly on the calibration of gyrochronology (e.g., Curtis et al., 2020). During Campaign 7 of the K2 mission (Howell et al., 2014), many known members of Ruprecht 147 were targeted for ∼1-min cadence observations. Additionally, the central part of the cluster was observed with a superstamp at a 30-minute cadence (Figure 1). In this study (Lund et al., in prep.), we are performing a detailed asteroseismic analysis of Ruprecht 147, aiming to establish it as one of the best asteroseismically constrained open clusters available. Fig. 1: Left: Sky plot containing part of Ruprecht 147. Circular and triangular markers indicate targets from Curtis et al. (2013); Red and gold markers indicate targets observed during K2 C7 for which pixel stamps were defined by the mission. Seismic signals were detected for the gold ones. Right: K2 superstamp superstamp with targets given as in the left panel. Methods All data from K2 were processed using the K2P2 pipeline (Lund et al., 2015). The power density spectra for all targets were searched for asteroseismic excess power, and global asteroseismic parameters were measured for stars with identified excess power. Individual mode frequencies were extracted for a subset of these stars using peak-bagging techniques (following Lund et al., 2017; Davies et al., 2015). Spectroscopic observations for the asteroseismic targets were obtained using the Magellan Inamori Kyocera Echelle (MIKE) and the Tilling- hast Reflector Echelle Spectrograph (TRES). A smaller subset of tar- gets was observed using the UVES and GIRAFFE spectrographs on the FLAMES instrument at VLT. Additionally, effective temperatures were measured using the infrared flux method (IRFM; Casagrande et al., 2020). 1Stellar Astrophysics Centre, Aarhus University, DK (∗mikkelnl@phys.au.dk) | 2Department of Astronomy, Columbia University, USA | 3Center for Astrophysics, Harvard- Smithsonian, USA | 4Research School of Astronomy and Astrophysics, Mount Stromlo Observatory, The Australian National University, AUS | 5INAF - Osservatorio di As- trofisica e Scienza dello Spazio, Bologna, ITA | 6Department of Physics and Astronomy, Università di Bologna, Bologna, ITA | 7Department of Astronomy, Yale University, USA | 8Institute for Astronomy, University of Hawai‘i, Honolulu, USA | 9Institute of Space Sciences (ICE, CSIC) Campus UAB, ESP | 10Institut d’Estudis Espacials de Catalunya (IEEC), Barcelona, ESP Results We have extracted asteroseismic parameters for a total of 33 members of Ruprecht 147. What sets Ruprecht 147 apart from other clusters studied using asteroseismology is that oscillations can be analyzed for stars ranging from the main-sequence (MS) to the red giant branch (RGB), as shown in Fig. 2. Importantly, several of the asteroseismic stars reside near the cluster turn-off, where isochrones are most distin- guishable. 10 20 30 40 50 60 EPIC 219437560 400 600 800 10 20 30 40 EPIC 219630458 600 800 1000 1200 10 20 Power density (ppm2 /µHz) EPIC 219495504 600 800 1000 Frequency (µHz) 10 20 EPIC 219684426 600 800 1000 1200 0 400 800 1200 1600 Frequency (µHz) 10 20 EPIC 219609927 0.0 0.2 0.4 0.6 0.8 1.0 Frequency mod ∆ν (∆ν) 800 1000 1200 1400 1600 0 10 20 30 40 Frequency spacing (µHz) PS ⊗PS 0 10 20 30 40 50 Frequency spacing (µHz) PS ⊗PS 0 10 20 30 40 50 Frequency spacing (µHz) PS ⊗PS 0 10 20 30 40 50 60 Frequency spacing (µHz) PS ⊗PS 0 10 20 30 40 50 60 70 Frequency s