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arXiv · 2610.00062

Asteroseismic Detection of a Massive Unseen Companion to the $δ$ Scuti Star TIC 160582982

Chenglong Lv·J. Pascual-Granado·Ali Esamdin·Angela Gardini·Haozhi Wang·Jianwei Yao·Shuguo Ma
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Abstract

We present TIC 160582982, an eccentric $δ$ Scuti binary with a dynamically massive unseen companion. Six coherent high-frequency pressure modes used as pulsation clocks yield a phase-modulation orbit with $P_{\rm orb}=89.29\pm0.19$ d, $e=0.539^{+0.040}_{-0.037}$, and $a_1\sin i/c=145.6^{+3.7}_{-3.4}$ s, corresponding to $K_1=42.2^{+2.2}_{-1.8}$ km s$^{-1}$ and $f(M)=0.416^{+0.032}_{-0.028}\,M_\odot$. An independent frequency-modulation analysis of the two strongest modes gives a consistent orbital solution. Rotating MIST isochrones constrained by the atmospheric parameters and spectral energy distribution (SED) give $M_1=1.93\pm0.19\,M_\odot$ and $R_1=2.65\pm0.23\,R_\odot$. The mass function implies a formal edge-on minimum companion mass of approximately $1.80\,M_\odot$. Assuming a luminous main-sequence companion and including the non-eclipsing geometry gives $M_2=2.19^{+1.24}_{-0.34}\,M_\odot$ and $i=61.5^{+16.6}_{-19.6}$ deg. However, no clear evidence for the presence of a luminous counterpart is found, either photometrically or spectroscopically. This suggests the presence of a massive compact object, such as a neutron star or even a stellar-mass black hole, as the massive unseen binary companion. Future phase-resolved high-resolution spectroscopy will be crucial for obtaining an independent orbital constraint and clarifying the nature of the companion.

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Chenglong Lv, J. Pascual-Granado, Ali Esamdin, Angela Gardini, Haozhi Wang, Jianwei Yao, Shuguo Ma. 2026-09-04. Asteroseismic Detection of a Massive Unseen Companion to the $δ$ Scuti Star TIC 160582982. https://doi.org/10.3847/1538-4357%2Faea560

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