- Title
- An Absolute Mass, Precise Age, and Hints of Planetary Winds for WASP-121A and b from a JWST NIRSpec Phase Curve
- Creator
- Sing, David K.; Evans-Soma, Thomas M.; Rustamkulov, Zafar; Lothringer, Joshua D.; Mayne, Nathan J.; Schlaufman, Kevin C.
- Relation
- The Astronomical Journal Vol. 168, Issue 6, no. 231
- Publisher Link
- http://dx.doi.org/10.3847/1538-3881/ad7fe7
- Publisher
- Institute of Physics (IOP)
- Resource Type
- journal article
- Date
- 2024
- Description
- We have conducted a planetary radial velocity measurement of the ultrahot Jupiter WASP-121b using JWST NIRSpec phase curve data. Our analysis reveals the Doppler shift of the planetary spectral lines across the full orbit, which shifts considerably across the detector (∼10 pixels). Using cross-correlation techniques, we have determined an overall planetary velocity amplitude of Kp = 215.7 ± 1.1 km s−1, which is in good agreement with the expected value. We have also calculated the dynamical mass for both components of the system by treating it as an eclipsing double-line spectroscopic binary, with WASP-121A having a mass of M⋆ = 1.330 ± 0.019 M⊙, while WASP-121b has a mass of Mp = 1.170 ± 0.043 MJup. These dynamical measurements are ∼3× more precise than previous estimates and do not rely on any stellar modeling assumptions that have a ∼5% systematic floor mass uncertainty. Additionally, we used stellar evolution modeling constrained with a stellar density and parallax measurement to determine a precise age for the system, found to be 1.11 ± 0.14 Gyr. Finally, we observed potential velocity differences between the two NIRSpec detectors, with NRS1 lower by 5.5 ± 2.2 km s−1. We suggest that differences can arise from day/night asymmetries in the thermal emission, which can lead to a sensitivity bias favoring the illuminated side of the planet, with planetary rotation and winds both acting to lower a measured KP. The planet's rotation can account for 1 km s−1 of the observed velocity difference, with 4.5 ± 2.2 km s−1 potentially attributable to vertical differences in wind speeds.
- Subject
- planetary winds; orbit; mass; measurements
- Identifier
- http://hdl.handle.net/1959.13/1516695
- Identifier
- uon:57011
- Identifier
- ISSN:0004-6256
- Rights
- "© 2024. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence (http://creativecommons.org/licenses/by/4.0/). Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI."
- Language
- eng
- Full Text
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