Powerful tidal waves collide with a massive star | Urania

It is the first star to pulsate with pulsating changes in brightness and refraction of surface waves, and provides a unique source of information about the evolution of massive binary star systems.

The star system has intrigued researchers because it is the most dramatic “heartbeat star” in history. The new models revealed that on this star, tidal waves break frequently, the first time such a star system has been observed.

Heartbeat stars are stars in close pairs that change their brightness periodically, similar to the rhythm of a heartbeat on an electrocardiogram. These stars revolve around each other in elongated, elliptical orbits. As they get closer together, the gravitational pull between the stars creates tides, just like the Moon creates ocean tides on Earth. These tides stretch and distort the shape of the stars, changing the amount of light that reaches us when their alternately wide or narrow sides point toward Earth.

A new study explains why the brightness fluctuations in an extremely pulsar system are about 200 times greater than those of typical pulsars. The reason for this is the huge waves that roll over the larger star, due to the approach of its smaller companion. Studies have shown that these tidal waves reach such enormous heights and speeds that they disintegrate much like ocean waves when they crash into the surface of a larger star.

Called the stellar pulse system by astronomers, this system provides unprecedented insights into the interaction between massive stars.

Each collision of the star’s high tidal waves releases enough energy to smash our entire planet several hundred times over – said a qualified doctor in the field of theoretical astrophysics at the Center for Astrophysics | Harvard and Smithsonian (CfA) and author of the new study published In Nature Astronomy, describing results. These are really big waves.

However, according to Professor Abraham (Avi) Loeb, a MacLeod advisor, director of the Institute for Theory and Computation at CfA and co-author of the paper: The waves breaking in the stars are as beautiful as those on the shores of our oceans.

Stars that pulsate in the rhythm of a pulsating heart were first observed when Kepler Space Telescopewho was looking for egzoplanetI discovered their defining characteristics, which are usually subtle fluctuations in brightness.

However, the extreme heart-beating star is not subtle. The largest star in this system is approximately 35 times the mass of the Sun, and together with the smaller companion star, is officially designated MACHO 80.7443.1718. This name has nothing to do with stellar power, but is caused by the system’s brightness changes being first recorded by MACHO project In the 90s he was engaged in research dark matter w our galaxy.

The brightness of most heartbeat stars varies by only 0.1%, but MACHO 80.7443.1718 has caught astronomers’ attention for its very dramatic brightness fluctuations of up to 20%. We know of no other star that shows such rapid changes in brightness MacLeod said.

To solve this mystery, MacLeod created the computer model MACHO 80.7443.1718, which took into account the gravitational interaction between the two stars. His model depicted the way this gravity generates giant tsunamis in an even larger star. These tidal waves reach the radius of this giant star, which corresponds to an altitude of about 4.3 million km.

Simulations show that massive waves start out looking smooth and orderly, like ocean waves, and then fluctuate and break apart. As beachgoers know, the violently crashing ocean waves release marine fog and create bubbles, leaving a “big frothy mess” where once there was a wave of calm, MacLeod said.

The MacLeod model shows that the tremendous energy released as MACHO 80.7443.1718 breaks waves has two effects. First, it causes the surface of the star to spin faster and faster, and second, it ejects the star gas outward, creating a spinning, glowing stellar atmosphere.

About once a month, the two stars pass each other, and a new wave sweeps across the surface of the pulsar. This disturbance caused the massive star MACHO 80.7443.1718 to bulge 50% more at the equator than at the poles. With each successive wave, more matter is thrown outward, as it happens Rolled pizza dough with pieces of cheese and sauce MacLeod said. The astronomer noted that the distinct glow in the atmosphere was a key indication that waves were breaking off the surface of the star.

While MACHO 80.7443.1718 is an unusual system, it is unlikely to be unique. Of the nearly 1,000 pulsars detected so far, about 20 show large variations in brightness similar to those in the system simulated by MacLeod and Loeb. This pulsar may be the first in a growing class of astronomical objects MacLeod said. We’re already planning to search for more stars of this type to find the glowing atmospheres created by their fracturing waves.

All things considered, MacLeod said, we’re lucky to be able to catch the star at this point: We are witnessing a brief, transformative moment in the star’s long life. By observing the massive waves rolling across the star’s surface, astronomers hope to understand how close interactions shape the evolution of stellar pairs.

Details:
Agnes Nowak

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Source: CfA

Pictured: An artist’s impression of a system in which a smaller star induces surface waves in a more massive companion. Source: Melissa Weiss, CfA