There was a long gap between theoretical physicists working with black holes and whatever one should look for, so the confirmation of Cygnus X-1 caused a great deal of excitement. Now that thrill is back, with some puzzles, discovering that our first black hole is so much bigger than previously realized, in fact, it casts doubt on what we know about astronomical evolution.
The Cygnus X-1 is a powerful X-ray source that invented during a short rocket flight in 1964 to get an indication of the universe in the length of the atmospheric blocks. Ten years later, Stephen Hawking bet against his black hole status, taking 16 years to admit. Ilya Mandel, a professor at Monash University, used a very long baseline array to measure the apparent motion of the Cygnus X-1 compared to distant galaxies as the Earth’s sun shifted from one side to the other. In science, they report a parallel measurement that the Cygnus X-1 is 7,100 light-years away, well ahead of previous estimates.
“The black hole in the Cygnus X-1 system began life as a star, collapsing about 60 times the mass of the Sun and thousands of years ago,” Mandel said in a statement. “Incredibly, it orbits its companion star every five-and-a-half days at a distance of one-fifth of the distance between the Earth and the Sun – a supergiant.” Using what the new distance says about the dimensions of our system, the Cygnus X-1 has about 21 times the mass of the Sun – 40 percent more than previously thought. Although the smallest can compared to the supermassive black hole at the center of the galaxy, it easily creates the largest black hole we have ever seen in the Milky Way, resulting in the death of stars.
Black holes are the remnants of supergiant stars that turned into supernovae. Although the largest star with more than 100 solar masses can be born, their hyperactive solar wind shuts it down the most. In addition to what was lost in the actual explosion, the black holes we see with these sources range from two to 16 solar masses, so the Cygnus X-1 was already near the top of the range. Now it is an outlet.
LIGO has detected gravitational waves from 50 solar masses associated with black holes, but these probably produce very few iron-composed stars, meaning weaker solar winds and more masses behind them. The newly formed stars in the Milky Way have higher metallic content, which suggests that the winds are so strong that they leave behind so much energy. “The bigger the wind, the bigger the stars,” Mandel told IFLscience. “So the mass of the black hole can’t gain much by increasing the mass of the initial stellar.”
Theoretically, we could see the remnants of a triple star system; the black hole has become so large because it has swallowed the third star. Mandel told IFLscience that the presence of an extra star lengthens the orbit among other elements to make a sufficient difference, which usually lasts after its use. For the previous Triple Star system, it seemed very unusual to have a pair of orbits attached to the back as round, Mandel said; “The truth is that anything involving big stars is never normal.”
The most likely explanation from a peer-reviewed research paper in the Astrophysical Journal is that we are seriously considering the massive loss of such stars. Mandel told IFLscience that some theoretical experts recently argued that previous assumptions were too high and that “we now have a pretty good observational barrier to it.”