“Greater Astronomical” Announcement Thursday | Radio-Canada.ca

Map illustrating the location of the instruments in the EHT virtual radio telescope.

The locations where the instruments of the EHT virtual radio telescope are located.

Photo: ESO

The stars seem to be able to present humanity to the very first photograph of Sagittarius A *, the black hole located in the middle of the Milky Way, but we must not get carried away too quickly. When the celestial rumor last went, in 2019, ESO and its partners instead presented the image of the black hole in the center of the Messier 87 galaxy.

This announcement was no less historic as it was the very first photo of a black hole, one of the most mysterious objects in the universe.

The black hole at the center of the Messier 87 galaxy.

The black hole at the center of the Messier 87 galaxy.

Photo: Event Horizon Telescope

Around Sagittarius A *

Astrophysicist Olivier Hernandez, director of the Rio Tinto Alcan Planetarium, believes this time will be the right one. Maybe they will tell us they could not see it, but I would be surprised.he says with humor.

Hernandez thinks a Sagittarius A * picture is likely to look like Messier 87, but it may also come as a surprise.

Depending on the angle from which a black hole is observed, the outline may take several forms. It could have the shape of a ring, as is the case with the M87, but it could also have a slightly more bizarre shape. […] The interesting thing is to know from what angle we look at it. »

A quote from Olivier Hernandez

Therefore, if the news is confirmed, astrophysicists will have succeeded in showing silhouette of Sagittarius A *, which will confirm that the object at the center of our galaxy is actually a black hole, an area of ​​space whose gravitational field is so intense that it prevents any substance or radiation from entering. .

This silhouette corresponds to the event horizon, which marks the intangible limit of entry into the black hole. What we will see is the growth disk, that is, the gas that is heated and that begins to fall towards the black holesays the astrophysicist.

This outline of the black hole is considered to be one of the most violent places in the universe, and the point of no return, beyond which everything – that is, stars, planets, gas, dust and any kind of electromagnetic radiation, including light, would be irreversibly sucked out.


  • The Milky Way is a spiral galaxy.
  • In the center is a shiny core, called a bulge, from which spiral arms protrude, forming a huge flat disc.
  • In the center of the bulge is the Sagittarius A *, a supermassive black hole.
  • The bulb and disc are surrounded by a spherical shaped area called halo.
  • Sagittarius A * is about 4.5 million times more massive than the Sun.
  • The galaxy comprises over 100 billion stars, interstellar dust and gas.
  • Our sun is located on one of the spiral arms, about 27,000 light-years (1 AL = 9460 billion kilometers) from the center of the Milky Way.

Better estimate its mass

The very first image of Sagittarius A * will make it possible to better assess its mass. Is it as massive as the Messier 87? Do we have the same kind of monster inside our own galaxy? Probably not. It’s definitely a little less massive, but still massive enough to be interestingexplains Mr Hernandez.

Dozens of astrophysicists took part in the collective effort, which will be unveiled at 9 a.m. Thursday. You need to know that each telescope produces huge amounts of data which must then be shared.

Last December, the most detailed and sharp images to date of the region around Sagittarius A * were published on ESO. The Very Large Telescope Interferometer (VLTI) has made it possible to zoom in 20 times more than was possible before. This precision made it possible to detect a star that has never been observed before, called the S300, near the black hole.

Five orange dots on a black background.  The image shows stars orbiting very close to Sgr A * (center), the supermassive black hole in the heart of the Milky Way.

This image shows stars orbiting very close to Sgr A * (center), the supermassive black hole in the heart of the Milky Way. They were achieved with the GRAVITY instrument in late May 2021.

Photo: Milky Way-center-black hole

Sagittarius A * is not the only black hole in the Milky Way. There are dozens of stars’ black holes formed during the gravitational collapse of massive stars at the end of their lives that explode like supernovae. To date, 20 such black holes have been confirmed in our galaxy.

Leave a Comment