A groundbreaking discovery has been made around the supermassive black hole Sagittarius A* at the center of the Milky Way galaxy. Led by German scientist Florian Peibker, a team has identified a binary star system orbiting this black hole. The discovery, named D9, was announced in a paper published today in Nature Communications.
This finding not only provides crucial insights into the extreme conditions at the center of the Milky Way, but also helps explain the long-standing mystery of why some stars move much faster than others.
WHAT IS A BINARY STAR SYSTEM?
A binary star system consists of two stars orbiting each other. Observations show that about one-third of stars in the Milky Way are part of binary or multiple star systems, with more massive stars typically found in pairs. Binary systems are key to astronomers, offering valuable clues about the stars’ motions, masses, and ages. For example, it was determined that D9 formed approximately 2.7 million years ago.
CHALLENGES OF THE DISCOVERY
The existence of binary star systems near supermassive black holes has long been predicted. However, D9 marks the first direct observation of such a system. The discovery was technically challenging, as the stars were too far away to be directly imaged. Instead, the Doppler effect in the light from the stars was measured using the European Southern Observatory’s Very Large Telescope (VLT). Regular fluctuations in the light confirmed that the stars were orbiting each other.
UNRAVELING THE MYSTERY OF HYPERVELOCITY STARS
The discovery also sheds light on the origins of hypervelocity stars, which travel through the galaxy at speeds over 1,000 kilometers per second. These stars are believed to have once been part of a binary system around a supermassive black hole, but were ejected after one star was thrown out by the black hole’s gravity.
Observations of Sagittarius A* may help verify this theory, with the D9 system offering an important step toward solving the mystery.
A GLIMPSE INTO THE HEART OF THE MILKY WAY
Sagittarius A*, located about 27,000 light-years from Earth, has a diameter of 23.5 million kilometers and resides in the brightest part of the Milky Way, near the Sagittarius constellation. Astronomers aim to further explore this region to understand the nature of black holes and galactic dynamics.
This significant discovery opens a new chapter in our understanding of the relationship between black holes and star systems.