2025-04-12 コロンビア大学
＜関連情報＞
- https://news.columbia.edu/news/close-look-planet-swallowed-star-yields-surprise
- https://webbtelescope.org/contents/news-releases/2025/news-2025-117
- https://iopscience.iop.org/article/10.3847/1538-4357/adb429
- https://tiisys.com/blog/2023/05/04/post-121228/
JWSTで惑星を消費した主系列星を明らかにする Revealing a Main-sequence Star that Consumed a Planet with JWST
Ryan M. Lau, Jacob E. Jencson, Colette Salyk, Kishalay De, Ori D. Fox, Matthew J. Hankins, Mansi M. Kasliwal, Charles D. Keyes, Morgan Macleod, Michael E. Ressler,…
The Astrophysical Journal Published: 2025 April 10
DOI:10.3847/1538-4357/adb429
Abstract
The subluminous red nova (SLRN) Zwicky Transient Facility (ZTF) SLRN-2020 is the most compelling direct detection of a planet being consumed by its host star, a scenario known as a planetary engulfment event. We present JWST spectroscopy of ZTF SLRN-2020 taken +830 days after its optical emission peak using the NIRSpec fixed-slit 3–5 μm high-resolution grating and the MIRI 5–12 μm low-resolution spectrometer. NIRSpec reveals the 12CO fundamental band (ν = 1–0) in emission at ∼4.7 μm, Brackett-α emission, and the potential detection of PH3 in emission at ∼4.3 μm. The JWST spectra are consistent with the claim that ZTF SLRN-2020 arose from a planetary engulfment event. We utilize DUSTY to model the late-time ∼1–12 μm spectral energy distribution (SED) of ZTF SLRN-2020, where the best-fit parameters indicate the presence of warm, 720+80−50 K, circumstellar dust with a total dust mass of Log (Md/M⊙)=−10.61+0.08−0.16 M⊙. We also fit a DUSTY model to archival photometry taken +320 days after the peak that suggested the presence of a cooler, Td=280−20+450 K, and more massive, Log (Md/M⊙)=−5.89+0.29−3.21, circumstellar dust component. Assuming the cool component originates from the ZTF SLRN-2020 ejecta, we interpret the warm component as fallback from the ejecta. From the late-time SED model, we measure a luminosity of L∗=0.29+0.03−0.06 L⊙ for the remnant host star, which is consistent with a ∼0.7 M⊙ K-type star that should not yet have evolved off the main sequence. If ZTF SLRN-2020 was not triggered by stellar evolution, we suggest that the planetary engulfment was due to orbital decay from tidal interactions between the planet and the host star.
