A Wolf 359 in Sheep's Clothing: Hunting for Substellar Companions in the Fifth-closest System Using Combined High-contrast Imaging and Radial Velocity Analysis
Rachel Bowens-Rubin, Joseph M. Akana Murphy, Philip M. Hinz, Mary Anne Limbach, Andreas Seifahrt, Rocio Kiman, Maïssa Salama, Sagnick Mukherjee, Madison Brady, Aarynn L. Carter, Rebecca Jensen-Clem, Maaike van Kooten, Howard Isaacson, Molly Kosiarek, Jacob L. Bean, David C. Kasper, R. Luque, Guðmundur Stefánsson, Julian Stürmer
Abstract
Abstract Wolf 359 (CN Leo, GJ 406, Gaia DR3 3864972938605115520) is a low-mass star in the fifth-closest neighboring system (2.41 pc). Because of its relative youth and proximity, Wolf 359 offers a unique opportunity to study substellar companions around M stars using infrared high-contrast imaging and radial velocity monitoring. We present the results of Ms -band (4.67 μ m) vector vortex coronagraphic imaging using Keck-NIRC2 and add 12 Keck-HIRES and 68 MAROON-X velocities to the radial velocity baseline. Our analysis incorporates these data alongside literature radial velocities from CARMENES, the High Accuracy Radial velocity Planet Searcher, and Keck-HIRES to rule out the existence of a close ( a < 10 au) stellar or brown dwarf companion and the majority of large gas giant companions. Our survey does not refute or confirm the long-period radial velocity candidate, Wolf 359 b ( P ∼ 2900 days), but rules out the candidate's existence as a large gas giant (>4 M Jup ) assuming an age of younger than 1 Gyr. We discuss the performance of our high-contrast imaging survey to aid future observers using Keck-NIRC2 in conjunction with the vortex coronagraph in the Ms band and conclude by exploring the direct imaging capabilities with JWST to observe Jupiter- and Neptune-mass planets around Wolf 359.