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

The study reports TIC 160582982, an eccentric delta Scuti binary whose companion is dynamically massive but unseen. The team used six coherent high-frequency pressure modes as pulsation clocks, analyzing phase modulation to measure the orbit. An independent frequency-modulation analysis of the two strongest modes produced a consistent orbital solution.

The phase-modulation orbit has P_orb = 89.29 ± 0.19 d, e = 0.539 +0.040 -0.037, and a1 sin i / c = 145.6 +3.7 -3.4 s, corresponding to K1 = 42.2 +2.2 -1.8 km/s and f(M) = 0.416 +0.032 -0.028 M_sun. Rotating MIST isochrones constrained by atmospheric parameters and the spectral energy distribution give M1 = 1.93 ± 0.19 M_sun and R1 = 2.65 ± 0.23 R_sun. The mass function implies a formal edge-on minimum companion mass of approximately 1.80 M_sun. Assuming a luminous main-sequence companion and including the non-eclipsing geometry yields M2 = 2.19 +1.24 -0.34 M_sun and i = 61.5 +16.6 -19.6 deg.

However, no clear evidence for a luminous counterpart is found, either photometrically or spectroscopically. This suggests the massive unseen companion may be a compact object such as a neutron star or even a stellar-mass black hole. Future phase-resolved high-resolution spectroscopy will be crucial for obtaining an independent orbital constraint and clarifying the companion's nature.