Scientists discover extremely massive black hole

The video discusses the discovery of a massive stellar black hole, LB-1, located 15,000 light-years from Earth in the Milky Way galaxy. Professor Liu Jifeng and an international team found that LB-1 has a mass 70 times greater than the sun, challenging previous estimates of stellar black hole sizes. The discovery was made by observing stars orbiting the black hole, with LB-1's companion star having eight times the sun's mass. China's Large Sky Area Multi-Object Fiber Spectroscopic Telescope played a crucial role in the discovery, while telescopes in Spain and the US helped determine LB-1's physical parameters.

What is the mass of LB-1's companion star?

Which telescopes contributed to determining the physical parameters of LB-1?