‘Cataclysmic’ celestial couple went wrong – stars eat their mates

WASHINGTON: Unlike the lone Sun, about half of the stars in our Milky Way galaxy have long-term relationships with other stars, orbiting each other in celestial marriages called binary star systems.

Researchers this week explained that one of those marriages didn’t work out. This is the fastest orbital period known for a rare class of binary stars, with the two pairs orbiting each other every 51 minutes of her. In the drama, a star is eating a companion.

The two stars are located about 3,000 light-years from Earth and towards the constellation Hercules. A light year is the distance that light travels in one year, 5.9 trillion miles (9.5 trillion km).

The system belongs to the class of binary stars known as cataclysmic variables, in which Sun-like stars orbit near the hot, compact cores of what are essentially burnt-out stars called white dwarfs. I’m here. Variable means that their combined brightness changes over time when viewed from Earth. Cataclysms refer to the fact that this luminosity changes dramatically, sometimes by a factor of 10,000 or more.

Over millions of years, the distance between these two stars has shrunk until it is closer than the distance between the Moon and Earth.

“Imagine the moon crossing the sky 10 times in one night,” says Kevin Barge, an astrophysicist at the Massachusetts Institute of Technology.

Just because they’re close doesn’t mean they get along with each other. White dwarfs relentlessly siphon matter from their partners.

This larger star is about the same temperature as the Sun, but has been shrunk to about 10% the diameter of the Sun, making it about the size of Jupiter, the largest planet in the Solar System. White dwarfs have about 56% the mass of the Sun, but are denser and about 1.5 times the diameter of Earth.

“This is an old pair of stars, one of the two migrating and becoming a white dwarf when the star dies of old age, but then this remnant started eating its mate,” Burdge said. increase.

“Basically, they were tied together in binary orbits for eight billion years. And now, just before a second star finishes its stellar life cycle, it can become a white dwarf the way stars normally do.” There is a possibility – called a red giant by evolving into a kind of star – the remaining white dwarf remnant of the first star interrupted the end of its companion’s life cycle and slowly began to consume it.

The researchers used data from the Palomar Observatory in California and telescopes in Hawaii and the Canary Islands.

Most stars are composed primarily of hydrogen, with small amounts of helium and other elements. The larger of his two stars in this binary, already aging, is unusually rich in helium. This is because the companion star not only absorbed hydrogen from its outer layers, but the slow fusion process enriched the core with this element. Convert hydrogen atoms into helium in a thermonuclear kettle.

The periodic brightening and fading of this binary system is due to the gravitational pull of the white dwarf physically deforming the large star into a teardrop shape instead of a spherical shape.

There are over 1,000 known cataclysmic variables, but only 12 have an orbital period of less than 75 minutes. His 51 minutes on this binary system is fast, but not a record when compared to other classes of binaries. The fastest known orbital of any binary star is just 5 minutes and 21 seconds, with two white dwarfs orbiting each other.

“There’s a lot of wild things going on in space,” Burge said.