 |
| An illustration shows the the tidal disruption of an unlucky star when it meets a supermassive black hole. Photo by Robin Dienel/Carnegie Institution for Science |
NASA's Transiting Exoplanet Survey Satellite has spotted the remnants
of a star that was recently shredded by a supermassive black hole -- a
first.
Astrophysicists and cosmologists estimate supermassive black holes
are located at the center of most galaxies. When stars wander too close,
a black hole's tremendous gravitational pull can rip it apart. The
violent interaction is known as a tidal disruption event, or TDE.
Scientists can come to better understand the dynamics of black holes by studying the spectral signatures of TDEs.
The tidal disruption event ASASSN-19bt was first spotted by an
international network of telescopes called the All-Sky Automated Survey
for Supernovae. TESS was able to observe the TDE, as well, providing
complementary images of the event.
When a star is ripped apart by a supermassive black hole, it peaks in
brightness before tapering off. The NASA space telescope utilizes a
wide field-of-view and continuous viewing, allowing it to capture the
sudden spike in brightness in fine detail.
The newest images of ASASSN-19bt revealed the evolution of the shredded star in unprecedented detail.
"Only a handful of TDEs have been discovered before they reached peak
brightness and this one was found just a few days after it started to
brighten; plus, thanks to it being in what's called TESS' 'Continuous
Viewing Zone,' we have observations of it every 30 minutes going back
months -- more than ever before possible for one of these events,"
Thomas Holoien, astronomer at the Carnegie Institution for Science, said in a news release. "This makes ASASSN-19bt the new poster child for TDE research."
Scientists were able to get a comprehensive picture of the tidal
disruption event by coupling ground-based and space-based observations.
"I was actually observing at Carnegie's Las Campanas Observatory on
the night of the discovery," Holoien 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 by part of ASAS-SN's network."
By analyzing the spectral patterns -- the changes in different
frequencies of light produced by the event -- scientists can identify
the chemical composition and speed of materials being shredded by the
black hole.
The latest findings, published this week in the Astrophysical Journal, suggest TDEs are more variable than astronomers previously thought.
Scientists found ASASSN-19bt in a galaxy that is younger and more
dust-filled than the types of galaxies that typically host TDEs. The
spectral patterns also revealed a brief period of cooling and fading
prior to the buildup to the shredded star's peak brightness. Despite the
blip, the data showed ASASSN-19bt approached peak brightness
surprisingly smoothly.
"Having so much data about ASASSN-19bt will allow us to improve our
understanding of the physics at work when a star is unlucky enough to
meet a black hole," said Carnegie's Decker French.
COMMENTS