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This content will become publicly available on December 11, 2026

Title: Surprise Nondetection of Upsilon Andromedae b with MIRC-X and MYSTIC at the CHARA Array
Abstract Ground-based long baseline interferometry is a powerful tool for characterizing exoplanets that are too close to their host star to be imaged with single-dish telescopes. The CHARA Array can resolve companions down to 0.5 mas, allowing us in principle to directly measure the near-infrared spectra of nontransiting “hot Jupiter” exoplanets. We present data taken with the Michigan InfraRed Combiner-Exeter (MIRC-X) and MYSTIC instruments at the CHARA Array on the hot Jupiter Upsilon Andromedae b. By resolving the star–planet system, we attempt to directly detect the flux from the planet. We describe our self-calibration methods for modeling systematics in the closure phase data, which allows us to reach subdegree precision. Through combining multiple nights of data across two MIRC-X runs in 2019 and 2021, we achieved a very tentative detection of Ups And b in theHband at a planet/star contrast of 2–3 × 10−4. Unfortunately, we cannot confirm this detection with 2021 MYSTIC data in theKband, or in a 2023 joint MIRC-X and MYSTIC data set. We run updated global circulation models and create post-processed spectra for this planet, and report the resulting model spectra inH- andKbands as a function of orbital phase. We then run planetary injection tests to exploreH/K-band contrast limits, and find that we can confidently recover planets down to a planet/star contrast of 1–2 × 10−4. We show that we are probing contrasts fainter than predicted by the model, making our nondetection surprising. We discuss prospects for the future in using this method to characterize companions with interferometry.  more » « less
Award ID(s):
2407956 2034336
PAR ID:
10659329
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
American Astronomical Society; IOP
Date Published:
Journal Name:
The Astronomical Journal
Volume:
171
Issue:
1
ISSN:
0004-6256
Page Range / eLocation ID:
30
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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