Images by Date
Images by Category
Solar System
Stars
White Dwarfs
Supernovas
Neutron Stars
Black Holes
Milky Way Galaxy
Normal Galaxies
Quasars
Galaxy Clusters
Cosmology/Deep Field
Miscellaneous
Images by Interest
Space Scoop for Kids
4K JPG
Multiwavelength
Sky Map
Constellations
3D Wall
Photo Blog
Top Rated Images
Image Handouts
Desktops
High Res Prints
Fits Files
Image Tutorials
Photo Album Tutorial
False Color
Cosmic Distance
Look-Back Time
Scale & Distance
Angular Measurement
Images & Processing
AVM/Metadata
Getting Hard Copies
Image Use Policy
Web Shortcuts
Chandra Blog
RSS Feed
Chronicle
Email Newsletter
News & Noteworthy
Image Use Policy
Questions & Answers
Glossary of Terms
Download Guide
Get Adobe Reader
Sagittarius A* Animations
Click for low-resolution animation
Tour of Sagittarius A*
Quicktime MPEG With closed-captions (at YouTube)

Since NASA's Chandra X-ray Observatory was launched over 15 years ago, it has frequently turned its gaze to the center of the Milky Way galaxy. One of the reasons is that at the center of our Galaxy there is a black hole, which astronomers now estimate contains about four and a half million times the mass of the Sun. This makes this object, called Sagittarius A*, the closest supermassive black hole to us. Over the years, astronomers have learned many things about Sagittarius A* and it continues to surprise and intrigue scientists to this day. On September 13, 2013, astronomers saw a flare from Sagittarius A* that was 400 times brighter than its usual X-ray output. A little more than a year later, astronomers again used Chandra to see another flare from Sagittarius A* that was 200 times brighter than its normal state in October 2014.

What's going on with the Milky Way's biggest black hole? Astronomers have two theories about what could be causing these "megaflares" from Sagittarius A*. The first idea is that the intense gravity around the black hole ripped apart an asteroid that wandered too close. As the asteroid's debris swirled around the black hole, it would have been heated to temperatures that cause it to emit X-rays before passing over the edge of the black hole. The other proposed explanation involves the strong magnetic fields that exist around Sagittarius A*. If the magnetic field lines reconfigured themselves and reconnected, this could also create a large burst of X-rays. Scientists see flares happen regularly on the Sun and the events around Sgr A* appear to have a similar pattern in intensity levels to those. Whatever the final explanation is for these flares, scientists will continue to observe Sagittarius A* with Chandra and will undoubtedly make more fascinating discoveries about our Galaxy’s supermassive black hole.
[Runtime: 02:30]

(Credit: NASA/CXC/A. Hobart)


Click for low-resolution animation
Megaflares Shed Light On Our Black Hole
Quicktime MPEG With closed-captions (at YouTube)

Our Galaxy is shaped like a whirlpool, with long strips of cosmic gas and dust swirling around the center. And like a whirlpool, objects that float too close are dragged into the center never to be seen again.

The fate of these unfortunate objects is no mystery. Lurking in the dark at the heart of our Galaxy is gigantic, hungry monster - a supermassive black hole. Supermassive black holes are famous for their ability to swallow anything – even light! But they don't just eat; they sometimes spit too!

In late 2013, an outburst (what astronomers call 'flares') was spotted blasting from the center of our Galaxy. Like many flares, it was made up of high-energy X-rays. However, this particular outburst was 400 times brighter than the X-ray output normally seen coming from this black hole!

A little more than a year later, it let off another flare, this time it was 200 times brighter than usual.

Astronomers have two theories about what could be causing these so-called "megaflares". The first idea is that the black hole's strong gravity tore apart an asteroid that strayed too close. The debris was then heated to millions of degrees before being devoured.

The other possible explanation involves the strong magnetic fields around the black hole. If these magnetic fields wobbled somehow, it could cause a large burst of X-rays. In fact, such events are seen regularly on our own Sun, we call them solar flares.

The main part of this picture shows the area around the supermassive black hole at the center of our Galaxy, called Sagittarius A* (pronounced as "SAJ-ee-TARE-ee-us A-star"). The small box shows a close up of the black hole and the giant flare from 2013.
[Runtime: 02:42]

(Credit: NASA/CXC/April Jubett)



Return to Sagittarius A* (January 5, 2015)