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The Tess space telescope observed a star engulfed in a black hole

Image: This figure shows tidal disruption, which occurs when a star passes too close to a black hole and is torn apart and turned into a stream of gas. Some of the gas eventually settles into a structure around the black hole called an accretion disk. Image: NASA's Goddard Space Flight Center
Image: This figure shows tidal disruption, which occurs when a star passes too close to a black hole and is torn apart and turned into a stream of gas. Some of the gas eventually settles into a structure around the black hole called an accretion disk. Figure: NASA's Goddard Space Flight Center

The 'Tess' space telescope (TESS-Transiting Exoplanet Survey Satellite) observed a black hole engulfing and disintegrating a star that approached it due to tidal forces (stronger attraction of the part of the star close to the black hole compared to the more distant part). To search for planets, record the event Follow-up observations by the Swift space telescope and other facilities have allowed scientists to discover more details from the moments leading up to the star's destruction event.

"The 'TESS' data allow us to see exactly when this devastating event, known as ASASSN-19bt, began to brighten, as we have never been able to do before," said Thomas Holowan, a fellow at the Carnegie Observatory in Pasadena, California. "We detected the tidal disturbance with the help of the automatic ground-based sky survey for the detection of supernovae (asas-SN), we were able to run follow-up observations at many wavelengths in the first days. This early data will be very helpful for modeling the physics of these eruptions.
A paper describing the findings, led by Holoane, was published on September 27 in the Astrophysical Journal.

ASAS-SN, a global network of 20 robotic telescopes based at Ohio State University (OSU) in Columbus, discovered the event on January 29, 2019. Holohein was working at the observatory when he received the alert from the project's telescope in South Africa. Holohein quickly mobilized the project's two telescopes in Las Campanes, requesting follow-up observations from NASA's Swift space telescope and the European Space Agency's Newton-Xmm space telescope, as well as ground-based telescopes from other networks.

Tess, on the other hand, did not need to be called into action because he looked at the same area of ​​the sky and watched specific segments for 27 days at a time. A long observation that allows 'Tess' to observe passing events and periodic changes in the light of a star in order to locate planets around it.

ASAS-SN began spending a lot of time observing the Tess segments of the sky when the satellite began scientific operations in July 2018. Astronomers expect that Tess will be able to capture the earliest light from short-lived stellar eruptions, including supernovae and tidal disturbances. 'Tess' first observed ASASSN-19bt on January 21. More than a week before the event was bright enough to allow ASAS-SN to detect it. However, the satellite transmits data to Earth only once every two weeks, and after each transmission the data must be processed at NASA's Ames Research Center in California. Therefore, the initial TESS data on tidal disturbance was not available until March 13. This is why obtaining early observations of these events depends on the coordination of ground observation-based surveys such as ASAS-SN.

Fortunately, the disturbance occurred in Tess' continuous southern viewing area, which was always in line of sight with one of the satellite's four cameras. ('Tess' later moved to the northern sky at the end of July). Had the event occurred over several segments, Holwan and his colleagues may not have been able to identify it.

The early observations of 'Tess' allow us to see light very close to the black hole, much closer than we have been able to see so far." said Patrick Vallely, co-author of the paper from Ohio State University. "They also show us that ASASSN-19bt's brightness increase was very smooth, which helps us say that the event was a gravitational disturbance and not some other type of outburst, like supernovae."
Holwan's team used ultraviolet data from Swift's first observations to determine that the temperature dropped by 50% from 40 to 20 degrees Celsius within a few days. "This is the first time that this early drop in temperature has been seen before the tidal disturbance, although several theories predicted it," Holoane said.

Astronomers think the supermassive black hole that created the ASASSN-19bt phenomenon had a mass of about 6 million times the mass of the Sun. It is in the center of a galaxy called 2Masx J07001137-6602251 which is about 375 million light years away in the constellation Volans. The destroyed star may have been similar in size to our sun.

Tidal disturbances are very rare events, occurring once every 10,000 to 100,000 years in a galaxy the size of our Milky Way. A supernova by comparison happens once every hundred years. In all, astronomers have spotted just 40 tidal disturbances so far, and scientists predicted Tess would see only one or two every two years during its initial mission.

"The very ability of Tess to observe ASASSN-19bt at such an early stage, and in a continuous viewing area where we could observe it for a long time, is really quite extraordinary," said Boyd, Tess project scientist at NASA's Goddard Center. . "Future collaborations with ground-based observatories around the world and in space will help us learn even more about the various eruptions that lit up the universe."

More of the topic in Hayadan:

5 תגובות

  1. The time of occurrence depends on the viewing distance. It is possible that the star has already been engulfed a long time ago and we are only seeing the phenomenon now

  2. No they tell about stars at great distances from us and they don't say anything about the pollution either

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