December 5, 2025 – Kennedy Space Center, Florida

In a discovery that blends cosmic violence with unexpected harmony, scientists using NASA’s Transiting Exoplanet Survey Satellite (TESS) have announced the detection of a star literally ‘singing’ to its companion—a stellar-mass black hole. The system, designated ASM-2025b, reveals a red giant star locked in a tight, 17-day orbital dance with its invisible destroyer. The star’s rhythmic, seismic vibrations, its internal ‘song,’ are being powerfully modulated by the black hole’s immense gravity, creating a celestial feedback loop that astronomers have compared to a one-sided operatic performance where the singer’s voice is twisted by an unseen, gravitational maestro. This marks the first time asteroseismology—the study of stellar oscillations—has been successfully applied to a star in the direct, relentless grasp of a black hole, opening an entirely new window into the physics of these extreme systems.

The discovery was not instantaneous but the result of meticulous analysis of over three years of TESS data. TESS, designed primarily to hunt for exoplanets by detecting the faint dimming of starlight, is also an exquisite tool for stellar astrophysics. Its sensitive cameras can pick up minute changes in a star’s brightness. In the case of the red giant in ASM-2025b, researchers led by Dr. Aris Thorne of Caltech noticed a complex, repeating pattern superimposed on the predictable dip caused by the black hole’s transit. The pattern was not the clean signature of a planetary transit, but a series of precise, periodic flickers indicative of the star’s own natural resonant oscillations. These are global standing waves, akin to seismic waves on Earth, that cause the star’s surface to rhythmically pulse and change brightness. “At first, we thought it was instrumental noise or perhaps starspot activity, but the frequencies were too clean, too mathematical,” explained Dr. Thorne during the press briefing at NASA’s Kennedy Space Center. *“They matched the theoretical models for g-mode oscillations in a low-mass red giant almost perfectly. The ‘aha’ moment came when we realized these oscillations were not static; their amplitudes and phases were being systematically altered in sync with the 17-day orbital period. The black hole was conducting the star’s orchestra.”*

The ‘song’ arises from the star’s own internal thermonuclear processes, but its transmission is catastrophically altered by its monstrous partner. The key mechanism is tidal forcing. As the star travels along its elliptical orbit, the black hole’s gravity exerts immense and varying tidal forces, stretching and squeezing the star dramatically. This constant gravitational kneading does not create the oscillations but powerfully amplifies specific resonant frequencies and suppresses others. Furthermore, the team discovered evidence of what they term “gravitational Doppler shifting” of the stellar waves. As the star moves toward and away from us in its orbit, the frequency of its light is shifted—the standard Doppler effect. But the team’s analysis shows the internal seismic waves themselves are being relativistically shifted and scattered as they propagate through the star’s distorted gravity well, a phenomenon never before observed. Dr. Elena Vásquez, an asteroseismologist from the University of Cambridge and co-author of the study, stated, “It’s as if the star is ringing like a bell, but the bell is made of flexible rubber and is being violently shaken back and forth. The sound it produces isn’t pure; it’s warped, containing harmonics and overtones that tell us not just about the bell’s material, but about the force doing the shaking. We are hearing the spacetime around the black hole imprinted on the star’s song.”

The implications of this discovery are profound for multiple fields of astrophysics. Firstly, it provides a novel and precise method for measuring the properties of the black hole itself. By modeling how the oscillations are perturbed, the team has calculated the black hole’s mass with unprecedented accuracy for such a system: 8.7 solar masses. They have also constrained its spin, finding it to be a moderate 0.45 (on a scale of 0 to 1). “Traditionally, we weigh black holes in binaries by looking at the motion of their companion star or, if we’re lucky, X-ray emissions from an accretion disk,” noted Dr. Kenji Tanaka of JAXA, another collaborator. “This star gives us a third, completely independent scale. And because the oscillations probe the star’s entire interior, we get a holistic view of the gravitational environment. It’s a fundamentally new form of measurement.” Secondly, the star itself serves as a unique laboratory for studying stellar evolution under extreme duress. The tidal forces are likely accelerating the star’s evolution, stripping its outer layers and influencing its internal chemical mixing. This provides a real-time preview of the final stages of a star’s life before it is completely consumed or torn apart in a tidal disruption event.

Perhaps the most philosophically striking implication is the validation of general relativity in a new regime. The subtle shifts in the oscillation modes align perfectly with Einstein’s predictions for how a massive, compact object warps the space-time in its immediate vicinity. The star’s pulsations are, in effect, tracing the geometry of the black hole’s gravitational vortex. “This isn’t just about a star and a black hole,” mused Dr. Thorne. “It’s about dialogue. The star, through its innate vibrations, is sending out a signal. The black hole, through the curvature of space, is modifying that signal. We are eavesdropping on a conversation written in the language of gravity and plasma physics. It’s a conversation that will ultimately end in silence, but for now, it’s teaching us volumes.”

Looking ahead, the team has secured time on the James Webb Space Telescope and the Chandra X-ray Observatory to perform multi-wavelength follow-up observations. JWST will scrutinize the star’s atmosphere for signs of mass loss being driven by the black hole, while Chandra will search for the faint X-ray signature of ambient material being heated as it spirals toward the event horizon—material potentially stolen from the singing star. ASM-2025b is now a prime target for a new era of “multi-messenger stellar astrophysics,” where conventional light, stellar oscillations, and eventually, perhaps, gravitational waves, are combined to tell a complete story.

The discovery, to be published in the journal Nature next week, underscores the continued, revolutionary output of the TESS mission, which has far exceeded its original exoplanet-hunting mandate. It reminds us that the cosmos is filled with not just silent vistas, but dynamic processes and violent interactions that can, with the right tools and patience, be perceived as a form of music.