Sagittarius A* (short for “Sagittarius A-Star”) is a brilliant and compact astronomical radio source located at the Milky Way’s Galactic Center. It’s at the Sagittarius-Scorpius border, around 5.6 degrees south of the ecliptic, and visually close to the Butterfly Cluster (M6) and Shaula. A supermassive black hole, akin to huge structures at the centers of most, if not all, spiral and elliptical galaxies, can be found in Sagittarius A*.
Observations of numerous stars around Sagittarius A*, particularly star S2, were utilized to calculate the object’s mass and radius upper bounds. Astronomers have determined that Sagittarius A* is the Milky Way’s center supermassive black hole based on mass and increasingly accurate radius limitations. Its mass is currently estimated to be somewhat more than 4 million solar masses.
The Nobel Prize in Physics was awarded to Reinhard Genzel and Andrea Ghez in 2020 for discovering that Sgr A* is a supermassive compact object for which a black hole is the only currently known explanation.
In This Article...
What is Sagittarius A * made of?
From the perspective of the Earth, Sgr A West appears to be a three-arm spiral. It’s also known as the “Minispiral” because of this. The Minispiral’s appearance and nickname are deceiving, as its three-dimensional structure is not that of a spiral. It is made up of multiple dust and gas clouds that circle and fall at speeds of up to 1,000 kilometers per second onto Sagittarius A*. These clouds have an ionized surface layer. The population of big stars (about one hundred OB stars have been detected so far) that likewise inhabit the core parsec is the source of ionisation.
The Circumnuclear Disk, which surrounds Sgr A West, is a vast, clumpy torus of colder molecular gas (CND). The form and kinematics of Sgr A West’s Northern Arm cloud indicate that it was once a clump in the CND that dropped due to some perturbation, maybe the supernova explosion that caused Sgr A East. The Northern Arm appears as a bright North–South emission ridge, although it extends far to the East and can be seen as a dim extended source.
The ionized inner surface of the CND is interpreted as the Western Arc (outside the field of view of the figure displayed on the right). Although they do not share the same orbital plane as the Northern Arm, the Eastern Arm and the Bar appear to be two more huge clouds. They are thought to be worth around 20 solar masses each.
Many tiny cloudlets and holes inside the giant clouds may be observed on top of these massive scale formations (of the order of a few light-years in size). The Minicavity, which is regarded as a bubble blown inside the Northern Arm by the stellar wind of a massive star that has yet to be found, is the most visible of these perturbations.
How was Sagittarius A * discovered?
Balick and Brown used the then-new 35km baseline interferometer between Green Bank and a distant station near Huntersville, WV, to find the point-like radio source at the center of the Galaxy, informally known as Sgr A*, in February 1974. The radio source’s exceedingly odd features have been thoroughly explored, but the tale behind its discovery is equally fascinating. The strange geometry of the generated aperture first masked the interpretation of the signal as a single point source, despite the fact that the signal was strong (0.5 Jy) and the peak measured surface brightness was relatively high (107K). Furthermore, two parties competed unwittingly for the detection observations, each using quite different scientific rationales. The other group, which included Downes and Goss, correctly predicted the discovery’s astronomical significance but were unable to travel from Europe to Green Bank in time for their observations in the fall of 1973.
How fast is Sagittarius A * spinning?
Using the durations of QPOs corresponding to K, we can now calculate the spin parameter of black holes. Sgr A*, for example, has a period of 31.4 minutes, while Galactic X-ray sources have periods of lower HF-QPOs. The frequency of single peak HF-QPOs is denoted by the letter K. The estimated mass of a supermassive black hole in Sgr A* is taken from recent studies to constrain the consequent spin parameter (
Is Sagittarius A The biggest black hole?
The list of (normal) gravitational suspects starts with black holes that are just the size of protons but have the mass of a large mountain. The comparison then ascends through black holes the size of the one that keeps V723 Mon in orbit, a star 24 times the mass of the Sun. However, as the narrator of the channel points out, that black hole is barely 17.2 kilometers (approximately 10 miles) across.
The comparison then progresses to black holes with hundreds of times the mass of the Sun. These appear to be enormous until the film progresses to black holes millions of times larger than the Sun. Sagittarius A*, the supermassive black hole at the center of the Milky Way Galaxy, is one of these monsters, although having a radius just 17 times that of the Sun.
The film concludes with an examination of ultramassive black holes, which follow the supermassive black holes. That is, after all, a technical term. Ultramassive black holes are “perhaps the largest single bodies that will ever exist,” putting all other black holes to shame. The mass of these huge physical manifestations is billions of times that of the Sun. They have the capacity to house several solar systems. With the very end of the video, Ton 618, the greatest ultramassive black hole, appears, which, at 66 billion times the mass of the Sun, will have a significant impact on how we daydream about the cosmos in the future.
Will Earth be sucked into Sagittarius A?
Earth is moving closer to the galaxy’s center, according to a new map of the Milky Way galaxy. This also brings it closer to Sagittarius A*, the supermassive black hole at the center of the Milky Way. The good news is that we’re not going any closer to the black hole, and we’re not in any danger of being sucked in right now.
Is Sagittarius A The closest black hole to Earth?
The Unicorn is a rare little black hole with a mass of around three times that of the sun. Sagittarius A, the supermassive black hole at the heart of the Milky Way, is estimated to have a mass of around 4 million times that of the sun. It’s not just one of the tiniest black holes ever seen, but it’s also the closest one we know of, at only 1,500 light years distant.
The black hole was virtually hidden in plain sight in the shadow of partner red giant star V723 Mon, which is a known variable star, indicating that its brightness varies.
Because such an abyss would have to be so extremely small, a neighboring black hole as a possible explanation for the star’s variations has previously been disregarded.
“Rather than ignoring the potential that it could be a black hole, Tharindu looked at this thing that so many other people had looked at and thought, ‘Well, what if it could be a black hole?'” remarked Ohio State astronomy professor Kris Stanek.