Revealing a Main-sequence Star that Consumed a Planet with JWST

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 pe...

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Main Authors: 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, Sam Rose
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Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adb429
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author 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
Sam Rose
author_facet 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
Sam Rose
author_sort Ryan M. Lau
collection DOAJ
description 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 μ m high-resolution grating and the MIRI 5–12 μ m low-resolution spectrometer. NIRSpec reveals the ^12 CO fundamental band ( ν  = 1–0) in emission at ∼4.7 μ m, Brackett- α emission, and the potential detection of PH _3 in emission at ∼4.3 μ m. 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 μ m spectral energy distribution (SED) of ZTF SLRN-2020, where the best-fit parameters indicate the presence of warm, $72{0}_{-50}^{+80}$ K, circumstellar dust with a total dust mass of Log $\left(\tfrac{{M}_{{\rm{d}}}}{{M}_{\odot }}\right)=-10.6{1}_{-0.16}^{+0.08}$ M _⊙ . We also fit a DUSTY model to archival photometry taken +320 days after the peak that suggested the presence of a cooler, ${T}_{{\rm{d}}}=28{0}_{-20}^{+450}$ K, and more massive, Log $\left(\tfrac{{M}_{{\rm{d}}}}{{M}_{\odot }}\right)=-5.8{9}_{-3.21}^{+0.29}$ , 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 ${L}_{* }=0.2{9}_{-0.06}^{+0.03}$ 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.
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spelling doaj-art-efdc021557274d66b069216965b8fd7d2025-08-20T02:11:34ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198328710.3847/1538-4357/adb429Revealing a Main-sequence Star that Consumed a Planet with JWSTRyan M. Lau0https://orcid.org/0000-0003-0778-0321Jacob E. Jencson1https://orcid.org/0000-0001-5754-4007Colette Salyk2https://orcid.org/0000-0003-3682-6632Kishalay De3https://orcid.org/0000-0002-8989-0542Ori D. Fox4https://orcid.org/0000-0003-2238-1572Matthew J. Hankins5https://orcid.org/0000-0001-9315-8437Mansi M. Kasliwal6https://orcid.org/0000-0002-5619-4938Charles D. Keyes7https://orcid.org/0000-0002-4834-369XMorgan Macleod8https://orcid.org/0000-0002-1417-8024Michael E. Ressler9https://orcid.org/0000-0001-5644-8830Sam Rose10https://orcid.org/0000-0003-4725-4481NSF NOIRLab , 950 N. Cherry Ave., Tucson, AZ 85719, USA ; ryan.lau@noirlab.eduIPAC , Mail Code 100-22, Caltech, 1200 E. California Blvd. Pasadena, CA 91125, USADepartment of Physics and Astronomy , Vassar College, 124 Raymond Ave., Poughkeepsie, NY 12604, USAMIT-Kavli Institute for Astrophysics and Space Research , 77 Massachusetts Ave., Cambridge, MA 02139, USASpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USAArkansas Tech University , 215 West O Street, Russellville, AR 72801, USADivision of Physics, Mathematics, and Astronomy, California Institute of Technology , Pasadena, CA 91125, USASpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USACenter for Astrophysics—Harvard & Smithsonian 60 Garden Street , MS-16, Cambridge, MA 02138, USAJet Propulsion Laboratory, California Institute of Technology , MS 169-327, 4800 Oak Grove Drive, Pasadena, CA 91109, USADivision of Physics, Mathematics, and Astronomy, California Institute of Technology , Pasadena, CA 91125, USAThe 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 μ m high-resolution grating and the MIRI 5–12 μ m low-resolution spectrometer. NIRSpec reveals the ^12 CO fundamental band ( ν  = 1–0) in emission at ∼4.7 μ m, Brackett- α emission, and the potential detection of PH _3 in emission at ∼4.3 μ m. 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 μ m spectral energy distribution (SED) of ZTF SLRN-2020, where the best-fit parameters indicate the presence of warm, $72{0}_{-50}^{+80}$ K, circumstellar dust with a total dust mass of Log $\left(\tfrac{{M}_{{\rm{d}}}}{{M}_{\odot }}\right)=-10.6{1}_{-0.16}^{+0.08}$ M _⊙ . We also fit a DUSTY model to archival photometry taken +320 days after the peak that suggested the presence of a cooler, ${T}_{{\rm{d}}}=28{0}_{-20}^{+450}$ K, and more massive, Log $\left(\tfrac{{M}_{{\rm{d}}}}{{M}_{\odot }}\right)=-5.8{9}_{-3.21}^{+0.29}$ , 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 ${L}_{* }=0.2{9}_{-0.06}^{+0.03}$ 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.https://doi.org/10.3847/1538-4357/adb429Star-planet interactionsPlanetary system evolutionStellar mergers
spellingShingle 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
Sam Rose
Revealing a Main-sequence Star that Consumed a Planet with JWST
The Astrophysical Journal
Star-planet interactions
Planetary system evolution
Stellar mergers
title Revealing a Main-sequence Star that Consumed a Planet with JWST
title_full Revealing a Main-sequence Star that Consumed a Planet with JWST
title_fullStr Revealing a Main-sequence Star that Consumed a Planet with JWST
title_full_unstemmed Revealing a Main-sequence Star that Consumed a Planet with JWST
title_short Revealing a Main-sequence Star that Consumed a Planet with JWST
title_sort revealing a main sequence star that consumed a planet with jwst
topic Star-planet interactions
Planetary system evolution
Stellar mergers
url https://doi.org/10.3847/1538-4357/adb429
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