Washington, DC ̵
The observation was reported in by the Astrophysical Journal by a team of astronomers led by Carnegie Thomas Holoen, who is a founding member of the international network of telescopes that made the discovery – Ohio State University, based at All-Sky University Automated Supernova Survey (ASAS-SN).
Tide-breaking events or TDEs occur when the star approaches too closely to supermassive black hole objects with huge gravitational pull, which are thought to lie at the center of most large galaxies. Black Hole forces overcome the star's gravity and tear it apart. Part of its material is thrown into space and the rest falls back into the black hole, forming a hot, bright gas disc as it is consumed.
By observing the light emitted during this process, which increases to peak brightness and then diminishes, astronomers can better understand the physics of the black hole and the forces driving these phenomena.
TESS has been able to provide additional observations to this newly discovered TDE, called ASASSN-19bt, which shows its evolution with unprecedented detail, the extremely wide field of view and continuous coverage of the spacecraft make it a great tool for detecting and monitoring TDE.
'Only a handful of TDEs were detected before reaching maximum brightness and this one was detected only a few days after that began to illuminate; plus, because it is in the TESS Continuous Watch Area, we have been monitoring this every 30 minutes or so months – more than ever before for one of these events, "Holoen said. "This makes ASASSN-19bt the new poster child for TDE research posters."
As the detection team quickly elicited follow-up observations of ASASSN-19bt from both space and terrestrial telescopes, they were able to capture a very complete picture of TDE.
"I was actually watching at Carnegie Observatory Las Campani on the night of the discovery," Holoen added. "So I was able to take spectra with our du Pont and Magellan telescopes less than a day after the event was first seen in South Africa from part of the ASAS-SN network."
Spectra separates light from the celestial an object or event at its component wavelengths, such as the prism of a window that makes an arc as sunlight passes through it. This may reveal information about the speed and chemical composition of the chewing star material.
The team – which also included Decker French of Carnegie, Thomas Connor, Nidia Morrell, Andrew Newman and Gwen Rudie, as well as Carnegie- Princeton associate Rachel Beaton – was able to track the evolution of TDE 42 days before its peak brightness, tracing it back from the night the event was opened. The data they report in their paper continues 37 days after the peak, but they have taken much more observations in the coming months.
"It was once thought that all TDEs would look the same. But it turns out that astronomers just need the ability to make more detailed observations of them, "says Patrick Vallee, of Ohio, who is the second author of the article. "Recent sky exploration projects such as ASAS-SN have revealed new TDE features that we have not seen before – although we do not yet have enough information to tell if these deviations are common. We still have a lot to learn about how they work, which is why capturing one at such an early stage and making fine TESS observations was crucial. "
It turns out that ASASSN-19bt is unusual in several ways.  Its host galaxy is younger and more dusty than previously observed for other TDE events. Second, he felt a short chill and fade before his temperature evened out and his radiance continued to develop toward his peak.
However, overall, the brightness increase when ASASSN-19bt approached its peak was extremely smooth with very little variation – something not known about TDE before TESS data allowed researchers to see it with such detail. This information will improve the ability of astronomers to identify TDEs and distinguish them from other celestial events that have much more chopper light emission.
"Having so much data on ASASSN-19bt will allow us to improve our understanding of physics at work when a star is not lucky enough to meet a black hole," said French.
###  This work was supported by the National Science Foundation, PJV is supported by the National Science Foundation, the Danish National Research Foundation, the Institute for Advanced Studies at Radcliffe Harvard University, the Hubble Scholarship, the Simons Foundation Scholarship, the IBM Scholarship at all
TESS mission funding is provided by NASA Science Mission Directorate
ASAS-SN is supported by the Gordon and Betty Moore Foundation, NSF, Mt. Cuba Astronomical Foundation, Center for the Astronomical Foundation Cosmology and Astroparticle Physics at Ohio State University, Center for Astronomy at the Chinese Academy of Sciences (CASSACA), Villum Foundation and George Skestos. with six research departments in USA. Since its inception in 1902, the Carnegie Institution has been a leading force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials, global ecology, and Earth and planet sciences.
Reference: "The discovery and early evolution of ASASSN-19bt, the first TDE discovered by TESS" by Thomas W.-P. Holoien, Patrick J. Vallely, Katie Auchettl, KZ Stanek, Christopher S. Kochanek, K. Decker French, Jose L. Prieto, Benjamin J. Shappee, Jonathan S. Brown, Michael M. Fausnaugh, Subo Dong, Todd A. Thompson , Subhash Bose, Jack MM Neustadt, P. Cacella, J. Brimacombe, Malhar R. Kendurkar, Rachael L. Beaton, Konstantina Boutsia, Laura Chomiuk, Thomas Connor, Nidia Morrell, Andrew B. Newman, Gwen C. Rudie, Laura Shishkovksy and Jay Strader, September 26, 2019, Astrophysical Journal .
DOI: 10.3847 / 1538-4357 / ab3c66
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