A 38 Million Year Old Neptune-sized Planet in the Kepler Field

March 2022 • 2022AJ....163..121B

Authors • Bouma, L. G. • Curtis, J. L. • Masuda, K. • Hillenbrand, L. A. • Stefansson, G. • Isaacson, H. • Narita, N. • Fukui, A. • Ikoma, M. • Tamura, M. • Kraus, A. L. • Furlan, E. • Gnilka, C. L. • Lester, K. V. • Howell, S. B.

Abstract • Kepler 1627A is a G8V star previously known to host a 3.8 R _⊕ planet on a 7.2 day orbit. The star was observed by the Kepler space telescope because it is nearby (d = 329 pc) and it resembles the Sun. Here, we show using Gaia kinematics, TESS stellar rotation periods, and spectroscopic lithium abundances that Kepler 1627 is a member of the ${38}_{-5}^{+6}$ Myr old δ Lyr cluster. To our knowledge, this makes Kepler 1627Ab the youngest planet with a precise age yet found by the prime Kepler mission. The Kepler photometry shows two peculiarities: the average transit profile is asymmetric, and the individual transit times might be correlated with the local light-curve slope. We discuss possible explanations for each anomaly. More importantly, the δ Lyr cluster is one of ~10³ coeval groups whose properties have been clarified by Gaia. Many other exoplanet hosts are candidate members of these clusters; their ages can be verified with the trifecta of Gaia, TESS, and ground-based spectroscopy.

Links

• PREPRINT http://arxiv.org/abs/2112.14776
• ELECTR https://doi.org/10.3847/1538-3881/ac4966
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2022AJ....163..121B
• PDF https://iopscience.iop.org/article/10.3847/1538-3881/ac4966/pdf
• DATA http://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/163/121
• DATA https://archive.gemini.edu/searchform/publication=2022AJ....163..121B
• DATA https://irsa.ipac.caltech.edu/bibdata/2022/B/2022AJ....163..121B.html