spaceSpace and Physics

The Stars Of The Omega Nebula Lack Companions


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockFeb 14 2017, 20:32 UTC

The Omega Nebula also known as M17. ESO

If you’re spending Valentine’s Day alone, know that across the vast empty universe there are stars that are just like you – and this is actually very puzzling to scientists.

According to observations, 70 percent of massive stars have a nearby companion, but in the Omega Nebula – a star-forming region 5,000 light-years away – that percentage drops to about 10. This result will be published in Astronomy & Astrophysics and it’s available online.


This is the first time such a young star-forming region has been studied for the presence of binaries. The clouds where stars are formed are dense with gas and dust, which makes it difficult for astronomers to see the newborn stars.

The team used the X-shooter spectrograph that is part of the suite of instruments on the Very Large Telescope. If the stars were in close binary, their light would change slightly. Binaries move around each other, so some of the stars would appear to move away from us while others move towards us, with a range in velocities up to many hundreds of kilometers per second. In the Omega Nebula, also known as M17, the velocity range is only about five kilometers (3 miles) per second.

This discovery suggests that these stars have formed alone or have a very distant companion, which implies that a mechanism might be at play for how massive stars, which weigh between 10 and 100 times the Sun, end up mostly in tight stellar pairs.


“If M17 has indeed no narrow binaries, these systems have to appear later in evolution," lead author Dr Hugues Sana, said in a statement. "Maybe they are only wide binaries, which later migrate towards each other."

The study of the Omega Nebula has only just begun. Out of the dozens of stars hiding in M17, researchers have studied 10, so there’s a lot more there to discover.

Co-author Maria Ramirez-Tannus added enthusiastically: “We have now observed ten of them and will study many more to understand how wide binaries change in narrow binary stars.”


Massive stars play an important role in our understanding of star formation as well as being crucial in galaxy evolution models. They also matter when it comes to gravitational waves. Binary neutron stars are gravitational wave powerhouse and they evolve from massive binaries at the end of their lives.

spaceSpace and Physics
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  • star formation,

  • massive star,

  • Omega Nebula,

  • M17