2025/04/09 by Ryan M. Lau, J. Jencson, Jacob E. Jencson +13 · 2 voices · 10 citations
Physics and Astronomy · #Astrobiology #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Exoplanet #Main sequence #Physics #Planet #Sequence (biology) #Star (game theory) #Stars #Stellar, planetary, and galactic studies #astro-ph.EP #astro-ph.SR
paper · pdf · open access · doi:10.3847/1538-4357/adb429
published in The Astrophysical Journal 983(2), 87 (IOP Publishing)
arxiv published 2025/04/09 · arxiv updated 2025/04/09 · openalex publication_date 2025/04/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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 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, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>72</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>50</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>80</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> K, circumstellar dust with a total dust mass of Log <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mfenced close=")" open="("> <mml:mstyle displaystyle="false"> <mml:mfrac> <mml:msub> <mml:mi>M</mml:mi> <mml:mi mathvariant="normal">d</mml:mi> </mml:msub> <mml:msub> <mml:mi>M</mml:mi> <mml:mo>⊙</mml:mo> </mml:msub> </mml:mfrac> </mml:mstyle> </mml:mfenced> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:mn>10.6</mml:mn> <mml:msubsup> <mml:mn>1</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.16</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.08</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> M ⊙ . We also fit a DUSTY model to archival photometry taken +320 days after the peak that suggested the presence of a cooler, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>T</mml:mi> <mml:mi mathvariant="normal">d</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>28</mml:mn> <mml:msubsup> <mml:mn>0</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>20</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>450</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> K, and more massive, Log <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mfenced close=")" open="("> <mml:mstyle displaystyle="false"> <mml:mfrac> <mml:msub> <mml:mi>M</mml:mi> <mml:mi mathvariant="normal">d</mml:mi> </mml:msub> <mml:msub> <mml:mi>M</mml:mi> <mml:mo>⊙</mml:mo> </mml:msub> </mml:mfrac> </mml:mstyle> </mml:mfenced> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:mn>5.8</mml:mn> <mml:msubsup> <mml:mn>9</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3.21</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.29</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> , 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>L</mml:mi> <mml:mo>*</mml:mo> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>0.2</mml:mn> <mml:msubsup> <mml:mn>9</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.06</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.03</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> 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.