KELT-25 b and KELT-26 b: A Hot Jupiter and a Substellar Companion Transiting Young A Stars Observed by TESS

We present the discoveries of KELT-25 b (TIC 65412605, TOI-626.01) and KELT-26 b (TIC 160708862, TOI1337.01), two transiting companions orbiting relatively bright, early A stars. The transit signals were initially detected by the KELT survey and subsequently confirmed by Transiting Exoplanet Survey Satellite (TESS) photometry. KELT-25 b is on a 4.40 day orbit around the V = 9.66 star CD-24 5016 (T-eff = 8280(-180)(+440) K, M-star = 2.18(-0.11)(+0.12) M-circle dot), while KELT-26 b is on a 3.34 day orbit around the V = 9.95 star HD 134004 (T-eff = 8640(-240)(+500) K, M-circle dot = 1.93(-0.16)(+0.14) M-circle dot), which is likely an Am star. We have confirmed the substellar nature of both companions through detailed characterization of each system using ground-based and TESS photometry, radial velocity measurements, Doppler tomography, and high-resolution imaging. For KELT-25, we determine a companion radius of R-P = 1.64(-0.043)(+0.039) R-J and a 3 sigma upper limit on the companion's mass of similar to 64 M-J. For KELT-26 b, we infer a planetary mass and radius of M-P = 1.41(-0.51)(+0.43) M-J and R-P = 1.94(-0.058)(+0.060) R-J. From Doppler tomographic observations, we find KELT-26 b to reside in a highly misaligned orbit. This conclusion is weakly corroborated by a subtle asymmetry in the transit light curve from the TESS data. KELT-25 b appears to be in a well-aligned, prograde orbit, and the system is likely a member of the cluster Theia 449.