A nearby just-named black hole that we discovered earlier this year has just been demolished. After re-analyzing the data, separate teams of scientists concluded that the system in question named HR6819 did not contain black holes.
Instead, they have discovered that it is possible. There are two stars with a few unusual binary orbits that make it difficult to interpret.
The HR6819, located about 1,120 light-years away, has been a bit of a puzzle for a while. Initially, it was thought to be a B-spectral type single star.
This is a hot, blue-and-white star on the main sequence, with a strong hydrogen emission line in its spectrum, interpreted as evidence of a discharge of permeable gas emitted by a star, as it has an equator of about 200 kilometers per second. Rotates at speed.
In the 1980s, astronomers noticed that the object also seemed to exhibit the light signature of another type of B-type star, the B3 III star. In 2003 this meant that HR6819 was not one, but two stars, although they could not be resolved individually.
Further analysis revealed that the B3 Three Star, entering approximately 6 solar masses, has an orbit of about 40 days – but the B Star, also estimated to have about 6 solar masses, was found to be motionless. If two stars are made of the same mass binary, they must orbit the mutual center of gravity, one star not revolving around the other.
After careful calculations, a team of astronomers concluded that the B3 III star could orbit a second, third object that could not be seen. A black hole
But, as other astronomers argue, that is far from the only possibility. What if we miscalculated the mass of stars?
“The presence of the B-star component in the spectrum of HR6819 suggests another interpretation of the system,” Georgia State University astronomers Douglas Geez and Lucian Wang wrote in their paper.
“It is possible that the component of the B3 III stars is actually a low mass, strapped down star that is still relatively young and bright. In this case, the B star will become an ally in a 40-day binary rather than a black hole.”
In other words, a very low-mass B3 II star will orbit around a B star. If this were the case, the orbital motion could be detected in the hydrogen gas around the star – it would move almost indistinctly as it was pulled by a small star. Geez and Wang were looking for this.
They carefully studied the hydrogen emissions in the spectrum of the system, and found that the hydrogen disks around the B stars actually showed a 40-day periodicity in the shape of both the Doppler shift and the emission line. This is consistent with the orbit of the B3 II star – the same would be expected if the system were unequal-mass binary.
“This suggests,” they wrote, “that HR6819 is a binary system consisting largely of a B-star and a low-mass ally that snatches the former mass donor star into a mass transfer binary.”
In other words, the B star cut the entire material from the star of B3 II, leaving it very small. There, the team noted, recent evidence suggests that many B Stars are a product of this process. According to their calculations, the B star would be about 6 solar masses, which were found earlier; But the B3 III star will be between 0.4 and 0.8 solar masses.
But it becomes more interesting. Jiaz and Wang were not the only researchers to explore the idea. In the second paper, a team of astronomers led by Julia Bodensteiner of KU Leuven in Belgium independently examined the B-star’s hydrogen emissions, and analyzed the orbit of the system. She and her colleagues came to almost the same conclusion.
“We estimate a spectroscopic mass of 0.4 [solar masses] And 6 [solar masses] For primary and secondary, “they wrote in their paper.” This suggests that the primary may be a striped star rather than a B-type giant. Evolutionary modeling suggests that a potential progenitor system would be a tight B + B binary system that experienced Rs serv tight mass transfer … In the framework of this interpretation, HR 6819 does not have BH. “
And, in the third paper, currently in print, astronomers Karim al-Bedri and Elliott Quartet of UC Berkeley also independently analyzed the system’s spectra, obtaining 0.47 and 6.7 solar masses for the B3 III and B Stars, respectively.
“We argue that the B-star is an inflated, recently stripped helium star with a mass of solar .solar solar mass that is currently contracting to be a hot subdwarf,” al-Bedri and Katar એટ wrote.
“The orbital motion of the B-star adheres to the need for a black hole to explain the motion of the B-star. The strip-star model reproduces the observed brightness of the system, while the normal star with the temperature and gravity of the B-star will be 10 times brighter.”
Therefore, the future looks bleak for the interpretation of black holes, although it has not yet stabilized. Future observations can help resolve any delayed questions. But, Guys and Lang argue, the binary system could be more interesting than a black hole.
“The bright and low-mass mate in the HR6819 system may present a rare and important case in which the mate has recently completed a mass transition and has yet to cool the evolutionary white dwarf,” they wrote.
So, anyway, we haven’t heard the last one from HR6819 yet.
Giz and Lang’s research was published Astrophysical Journal Letters. Bodensteiner Et al.The research was published Astronomy and Astrophysics. The papers of Al-Bedri and Cata Airt have been submitted to him Monthly instructions of the Royal Astronomical Society And available at Archive.
.
