Abstract
Abstract We present the discoveries of KELT-25 b (TIC 65412605, TOI-626.01) and KELT-26 b (TIC 160708862, TOI-1337.01), 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 ( K, M ⋆ = M ⊙), while KELT-26 b is on a 3.34 day orbit around the V = 9.95 star HD 134004 ( = K, M ⋆ = M ⊙), 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 = R J and a 3σ upper limit on the companion’s mass of ∼64 M J. For KELT-26 b, we infer a planetary mass and radius of M P = and R P = 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.
Highlights
The field of exoplanets has grown tremendously since the first detection of a transiting exoplanet around a bright star (Charbonneau et al 2000; Henry et al 2000) two decades ago
While we measure the reflex Doppler signal from Kilodegree Extremely Little Telescope (KELT)-26 to ∼σK/K ; 30% and are able to constrain the mass of KELT-26 b, we do not obtain a definitive detection of the reflex Doppler signal from KELT-25 and are only able to provide an upper limit on the planet mass
We cross-matched existing Transiting Exoplanet Survey Satellite (TESS) objects of interest (TOIs) to the catalog of clusters presented in Kounkel & Covey (2019), and we found a match between TOI-626.01 (KELT-25) and one of the putative clusters identified in that paper as Theia 449
Summary
The field of exoplanets has grown tremendously since the first detection of a transiting exoplanet around a bright star (Charbonneau et al 2000; Henry et al 2000) two decades ago. Doppler tomographic observations can help confirm that the planet transits the target star and is not, for example, a signal from a nearby eclipsing binary, confirming the planetary nature of the occultor requires an appropriately stringent upper limit on its mass (see, e.g., Bieryla et al 2015 for a discussion of validating planets orbiting rapidly rotating stars using DT). The advantage of this technique is that it is better suited to faster stellar rotations, thereby providing an alternative way to confirm planets around hot stars. TESSs expected yield complements the discoveries made by KELT and other ground-based surveys and advances our understanding of giant planets around hot stars
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