Il faudra aller un peu vers le sud et avoir un téléscope avec un miroir d'une taille d'au-moins 300 mm.
Astronomers Accidentally Discover Black Hole So Big You Can Spot It With A Backyard Telescope
( Editorial Team February 08, 2023 )
Black holes are the cosmic gluttons, consuming anything that approaches too closely, even light.Now, a team of worldwide researchers has identified a supermassive black hole that devours the mass of one Earth every second.
By observing other light objects billions of years old, the scientists determined that the newly found behemoth was the brightest and fastest-growing supermassive black hole of the previous nine billion years (that we know of).
This dazzling cosmic beast, located in the constellation Centaurus, is more than 500 times bigger than the supermassive black hole at the centre of our own galaxy.
The results, which are presently being reviewed, were published in a physics academic journal last week.
"People have been looking for these kinds of objects since the 1960s," said lead author Christopher Onken, an astronomer at the Australian National University.
"And somehow, this one seemed to have escaped all our previous efforts to find it."
While searching the Milky Way for nearby pairs of binary stars — stars that circle the same centre of mass — the team came onto the strange object.
They were using the SkyMapper telescope at Siding Spring Observatory near Coonabarabran, between the New South Wales areas of Central West and North West Slopes.
Adrian Lucy, a PhD candidate at Columbia University in New York, discovered over 200 possibilities for binary stars, but according to Dr. Onken, there was something peculiar about them.
One of them turned out to be unlike a binary system in every way.
To get a closer look at the peculiar object, the crew travelled to Cape Town's South African Astronomical Observatory's 1,9-meter telescope.
Here, they were able to examine the different wavelengths of light emitted by SMSS J114447.77-430859.3, or J1144 for short.
"You really see the detailed fingerprints of what's making up these objects," Dr Onken said.
And it did not resemble a giant star in any way.
Instead, the object featured brilliant lines showing that gas was flowing very quickly, indicating that it was propelled by a supermassive black hole.
Several of the brightest objects in the sky, quasars, are powered by supermassive black holes, which have a mass of millions or billions of Suns.
From Earth, these brilliant objects resemble stars, but their light originates from the accretion disc, a ring of gas, dust, and stars that swirls around the black hole.
As this material is pulled into the black hole's gaping mouth by its enormous gravitational attraction, it becomes very hot and produces blinding light.
"The gas is kind of funnelling down into a pancake shape, and that material then heats up through friction," Dr Onken said.
Like a ball rolling down a hill, the material accelerates as it approaches the event horizon of a black hole — the point from which not even light can escape — releasing its potential energy.
"Eventually all that stuff falls into the black hole past the event horizon, adding to the mass of the black hole as it does so."
This bright, fast-moving cloud of gas enabled Dr. Onken and his colleagues to estimate the supermassive black hole's mass at three billion Suns.
In comparison, Sagittarius A*, the supermassive black hole at the centre of our galaxy, has a mass of around 4 million Suns.
And although J1144 was fainter than previous quasars discovered in the last 60 years, it was still far more distant and brighter than other objects of the same age.
"That was very exciting because these are pretty unusual finds," Dr Onken said.
In addition, the scientists analysed J1144's brightness over the last 45 years by analysing its appearance in earlier data sets.
They discovered that the brightness of the enormous quasar remained constant throughout time, suggesting that its black hole was continually consuming gas and everything else that came its way.
Michael Cowley, an astronomer at the Queensland University of Technology, said that the supermassive black hole's size indicated that it was most likely related with a huge galaxy.
"Usually you'll find that the more massive the black hole, the more massive the galaxy is as well," said Dr Cowley, who was not involved in the study.
Keep an eye out for J114 just north-west of the Southern Cross.
This quasar's brightness is about 7,000 times brighter than all of the light in the Milky Way, making it visible from your backyard with the right telescope.
Dr. Onken recommended a telescope with a diameter of 30 to 40 centimetres and a camera capable of lengthy exposures.J1144 is situated in the sky approximately north-west of the Southern Cross, emanating from the constellation Centaurus.
"It's just right overhead at sunset at this time of year," Dr Onken said.
https://blog.shiningscience.com/2023/02 ... black.html
Une publication associée à l'article :
https://arxiv.org/abs/2206.04204
