Astronomers found S0-2 Star is single and ready for big Einstein test

No companion found for famous young bright star orbiting Milky Way’s supermassive black hole.

CREDIT: S. SAKAI/A.GHEZ/W. M. KECK OBSERVATORY/ UCLA GALACTIC CENTER GROUP The orbit of S0-2 (light blue) located near the Milky Way's supermassive black hole will be used to test Einstein's Theory of General Relativity and generate potentially new gravitational models
CREDIT: S. SAKAI/A.GHEZ/W. M. KECK OBSERVATORY/ UCLA GALACTIC CENTER GROUP The orbit of S0-2 (light blue) located near the Milky Way's supermassive black hole will be used to test Einstein's Theory of General Relativity and generate potentially new gravitational models.

A study led by a UCLA scientist from Hawaii has discovered that S0-2 does not have a notable or minimum one binary that is adequately extensive to get in the way of critical measurements that astronomers require to test Einstein’s theory.

Astronomers have the “all-clear” for an aggravating test of Einstein’s Theory of General Relativity. Hitherto, it was thought that S0-2 perhaps binary, a system where two stars circle around each other. It would have complicated having such a partner for the upcoming gravity test.

This invention commenced by obtaining spectroscopic measurements of S0-2 utilizing W. M. Keck Observatory’s OH-Suppressing Infrared Imaging Spectrograph (OSIRIS) and Laser Guide Star Adaptive Optics.

This study published recently in The Astrophysical Journal.

Lead author Devin Chu of Hilo, an astronomy graduate student with UCLA’s Galactic Center Group said, “This is the first study to investigate S0-2 as a spectroscopic binary.”

“It’s incredibly rewarding. This study gives us confidence that an S0-2 binary system will not significantly affect our ability to measure gravitational redshift.”

Earlier Einstein’s Theory of General Relativity anticipates that light coming from a strong gravitational field gets stretched out, or “redshifted.” Now researchers outwait to directly gauge this episode commencing in the spring as S0-2 makes its closest approach to the supermassive black hole at the centre of our Milky Way galaxy.

This will permit the Galactic Center Group to witness the star being pulled at maximum gravitational strength, a point where any deviation to Einstein’s theory is expected to be the greatest.

Co-author Tuan Do, deputy director of the Galactic Center Group stated, “It will be the first measurement of its kind.”

“Gravity is the least well-tested of the forces of nature. Einstein’s theory has passed all other tests with flying colours so far, so if there are deviations measured, it would certainly raise lots of questions about the nature of gravity!”

Chu said, “We have been waiting 16 years for this. We are anxious to see how the star will behave under the black hole’s violent pull. Will S0-2 follow Einstein’s theory or will the star defy our current laws of physics? We will soon find out!”

Later in the study likewise they elucidate the strange emanation of S0-2 and its stellar neighbours in the S-Star Cluster. The fact that these stars exist very nearer to the supermassive black hole is unusual because they are so young, how they could’ve formed in such a hostile environment is a mystery.

Do say, “Star formation at the Galactic Center is difficult because the brute strength of tidal forces from the black hole can tear gas clouds apart before they can collapse and form stars.”

Chu said, “S0-2 is a very special and puzzling star. We don’t typically see young, hot stars like S0-2 form so close to a supermassive black hole. This means that S0-2 must have formed a different way.”

There are numerous theories that endure a possible explanation, with S0-2 being a binary as one of them.

Chu said, “We were able to put an upper limit on the mass of a companion star for S0-2.”

This new constraint assists astronomers to comprehend this unusual object.

Do say, “Stars as massive as S0-2 almost always have a binary companion. We are lucky that having no companion makes the measurements of general relativistic effects easier, but it also deepens the mystery of this star.”

The Galactic Center Group now plans to study other S-Stars orbiting the supermassive black hole, in hopes of differentiating between the varying theories that attempt to explain why S0-2 is single.