72 Earth years are squeezed into one day on this dead star

The 'dead star' is positioned roughly 2,760 light-years away from Earth
An illustration shows the TMTS J0526 binary star system. — Jingchuan Yu/Beijing Planetarium
An illustration shows the TMTS J0526 binary star system. — Jingchuan Yu/Beijing Planetarium

In a remarkable discovery within a binary system, astronomers have stumbled upon a "dead star" known as a white dwarf, whirling around its blazing stellar companion so swiftly that it condenses approximately 72 Earth years into a single day.

Using the Tsinghua University-Ma Huateng Telescope for Survey (TMTS), a research team from Tsinghua University unveiled this system, christened TMTS J0526. It is positioned roughly 2,760 light-years away from Earth, as detailed by Space.

At the heart of TMTS J0526 lies a white dwarf star abundant in carbon and oxygen, boasting a mass equivalent to around 74% of the Sun's. This star orbits a scorching subdwarf star, stretching about seven times the width of Earth and weighing roughly a third of our Sun's mass. Remarkably compact, this subdwarf star is smaller in volume than Jupiter, marking one of the smallest stars ever documented.

The components of TMTS J0526 complete each orbit approximately every 20.5 minutes, setting a new record for this type of binary system, although falling short of the speed seen in HM Cancri, where two white dwarfs orbit each other every 5.4 minutes.

Despite its diminutive size, the subdwarf star appears larger and more visible than its white dwarf counterpart due to its tenuous hydrogen atmosphere. However, the gravitational influence of the white dwarf during their rapid orbital dance can distort the tiny star into an ellipsoidal shape.

Beyond its breathtakingly brief orbital period, the discovery of TMTS J0526 holds significance for shedding light on the formation process of such diminutive subdwarf stars.

When sun-sized stars exhaust their hydrogen fuel in their cores, they succumb to gravitational collapse, forming white dwarfs. The outer layers of these stars, where nuclear fusion persists, expand outward, followed by the implosion of the stellar core. This sequence transforms the stars into red giants, eventually cooling into white dwarfs enveloped by gas and dust remnants.