Astronomers discovered in 2019 that a star had been “spaghettified” by a black hole. A black hole 215 million light years away destroyed a sun-like star. Because it was a spectacular enough event, the University of California, Berkeley’s Astronomers were able to examine the optical light of star death and its Polarisation.
The observations made on October 8, 2019, show that the star’s majority of its material was likely to have been blown off at an extremely high rate (up to 10,000 km per second), which led to the formation of a spherical cloud. These observations, known as AT 2019qiz (from optical radiation), showed that the star’s mass was being pushed outwards by a strong wind. Astronomers have discovered that the cloud was likely spherically symmetric based on new information about the light’s Polarisation.
This was almost null when it was at its brightest, either at visible or optical wavelengths. Alex Filippenko (UC Berkeley’s lead researcher in astronomy) stated that this was the first time ever that the gas cloud surrounding a tidally spaghettified Star has been determined. These results support one theory that explains why many of the dozens of tidal disturbances observed so far have not produced high-energy radiation like X-rays. The X-rays are protected by the powerful winds that push the gas outside of the black hole. These X-rays are made from the material that was ripped off the star and dragged in the accretion disk surrounding the black hole.
Kishore Patra (a doctorate student at UC Berkeley) said that the discovery “rules out a class theoretically suggested solutions” and gives us a stronger constraint on gas around a black hole. People have already seen more wind-related evidence from these events. My opinion is that our polarisation work greatly strengthens that evidence, as sufficient wind cannot produce a spherical geometry. It is interesting to observe that not all the material in the star spiraling inwards into the black hole, but a substantial amount of it is blown off.”
Many scientists have proposed that star debris from a rupture will create an eccentric, asymmetric disk. It is expected that an eccentric disc would exhibit a high degree of polarization, which could correspond to only a small percentage of total light is polarized. This was not the case with this tidal disturbance. According to Wenbin Lu (an assistant professor of astronomy from the University of California at Berkeley), one of the most bizarre things that a supermassive dark hole can do is to pull apart a star with its strong tides.
Stellar disruption events are one method astronomers use to confirm the existence of supermassive dark holes in the center of galaxies. They also help determine their features. Astronomers still have a hard time understanding the complicated processes that result from tidal disruptions due to the high computational costs involved in statistically modeling them. On Nov. 6, the second round of measurements revealed that the light was slightly polarized, at about 1%.
This is 29 days after October’s initial sighting. It indicates that the cloud had thinned sufficiently to allow the black hole’s asymmetrical gas structure to be visible. These observations were made using the 3-meter Shane telescope located at San Jose’s Lick Observatory and the Kast spectrograph. This tool can detect the polarization of light across all wavelengths. The electrons that scatter light from the cloud create a polarized field. Light vibrates in one direction and preferentially in the other.
Patra stated that even though the accretion disk is hot enough to produce most of its light as an X-ray, the rays must still travel through a cloud. It must undergo several scatterings, and then absorptions before the light can escape this cloud. Each of these processes results in light losing a portion of its photon energies, which is why it produces ultraviolet and optical energy.
The final scatter determines the state of polarization. By observing polarisation we can then determine the geometry of the surface where the final scattering takes place. Patra says that the deathbed scenario cannot be applied to “oddballs,” relativistic jets that contain material that the black holes expel from the poles. However, it can be applied to other tidal disturbances. This study is led by Kishore Patra, a graduate student at UC Berkeley. “This observation rules in a number of theoretical solutions and gives us greater constraints on gas around black holes.”
These events have also been reported to show wind. This polarization study strengthens that evidence in that you need wind to get spherical geometry. It is interesting to see that most of the material spiraling inwards in the star does not end up in a black hole. It’s instead blown away. He stated that “Polarization research is extremely challenging and very few people are competent in using it.”
This type of tidal disruption has never occurred before. These observations were made by Lu, Filippenko, Lu, Thomas Brink, and Sergiy Vasilyev of UC Berkeley. They were also reported by Yi Yang and Sergiy Vasiliev, a doctoral student. The article was published in Monthly Notes of the Royal Astronomical Society.
Experts at UC Berkeley believe that the cloud’s top created the polarised sun. The cloud’s radius is 100 astronomical units (au), making it 100 times farther from the star than the Earth. The hot gas in the area of 30 au was emitting optical light. Spectropolarimetric measurements have been taken using AT2019qiz since 2019.
This is a tidal disturbance that occurred in a spiral galaxy within the constellation Eridanus. This method analyses polarisation across a wide range of light wavelengths. The polarized photons are balanced, which indicates a spherically-symmetric cloud of gas. This theory is supported by October’s zero-polarization. Because of their small polarization, there is a very slight imbalance in November’s measurements. Experts at UC Berkeley claim that the polarized light was produced by the cloud’s top.
This is one of the few clues that can help identify the shape of objects. The cloud’s radius is 100 astronomical units (AU), which is 100 times farther from the star than the sun. The hot gas in the area of 30 au was emitting optical light. Filippenko stated that it was impossible to determine the structure and geometry of explosions or disruption events because they are too far away. The study of polarized radiation may be able to help determine the distribution of materials, and in this case, the shape of gas (and possibly the accretion disk) around the black holes.
