Milky Way Galaxy

Data Sonification: Sounds from Around the Milky Way


Explore Solos

The center of our Milky Way galaxy is too distant for us to visit in person, but we can still explore it. Telescopes give us a chance to see what the Galactic Center looks like in different types of light. By translating the inherently digital data (in the form of ones and zeroes) captured by telescopes in space into images, astronomers create visual representations that would otherwise be invisible to us.

But what about experiencing these data with other senses like hearing? Sonification is the process that translates data into sound, and a new project brings the center of the Milky Way to listeners for the first time. The translation begins on the left side of the image and moves to the right, with the sounds representing the position and brightness of the sources. The light of objects located towards the top of the image are heard as higher pitches while the intensity of the light controls the volume. Stars and compact sources are converted to individual notes while extended clouds of gas and dust produce an evolving drone. The crescendo happens when we reach the bright region to the lower right of the image. This is where the 4-million-solar-mass supermassive black hole at the center of the Galaxy, known as Sagittarius A* (A-star), resides, and where the clouds of gas and dust are the brightest.

Users can listen to data from this region, roughly 400 light years across, either as "solos" from NASA's Chandra X-ray Observatory, Hubble Space Telescope, and Spitzer Space Telescope, or together as an ensemble in which each telescope plays a different instrument. Each image reveals different phenomena happening in this region about 26,000 light years from Earth. The Hubble image outlines energetic regions where stars are being born, while Spitzer's infrared image shows glowing clouds of dust containing complex structures. X-rays from Chandra reveal gas heated to millions of degrees from stellar explosions and outflows from Sagittarius A*.

In addition to the Galactic Center, this project has also produced sonified versions of the remains of a supernova called Cassiopeia A, or Cas A, and the "Pillars of Creation" located in Messier 16.

The Origins of Particle Ribbons in the Center of our Galaxy

X-ray & Radio Image of the Milky Way's Galactic Center
X-ray & Radio Image of the Milky Way's Galactic Center
Credit: X-Ray: NASA/CXC/UMass/D. Wang et al.; Radio: SARAO/MeerKAT

Astronomers are taking a closer look at a party brewing in the center of our Galaxy. The supermassive black hole that resides there, known as Sagittarius A*, appears to be throwing a celebration complete with flying cosmic ribbons.

However, the sheer scale of everything in space already tells us that these are no ordinary ribbons. They are actually gigantic filaments, up to 100 light years (about 588 trillion miles!) long and ⅓ of a light year thick. The filaments are produced by particles moving at relativistic speeds, meaning near the speed of light, spiraling around strong magnetic field lines in the center of the Galaxy.

A New Galactic Center Adventure in Virtual Reality


Galactic Center VR: 2 Minute Video
Credit: NASA/CXC/Pontifical Catholic Univ. of Chile /C.Russell et al.

By combining data from telescopes with supercomputer simulations and virtual reality (VR), a new visualization allows you to experience 500 years of cosmic evolution around the supermassive black hole at the center of the Milky Way.

This visualization, called "Galactic Center VR", is the latest in a series from astrophysicists, and is based on data from NASA's Chandra X-ray Observatory and other telescopes. This new installment features their NASA supercomputer simulations of material streaming toward the Milky Way's four-million-solar-mass black hole known as Sagittarius A* (Sgr A*). The visualization has been loaded into a VR environment as a novel method of exploring these simulations, and is available for free at both the Steam and Viveport VR stores.

Giant X-ray Chimneys and Selection Effects

Illustration of Chandra spacecraft

Astronomers frequently talk about selection effects, where results can be biased because of the way that the objects in a sample are selected. For example, if distant galaxies above a certain X-ray flux – the amount of observed X-rays – are selected for a survey, the most distant objects will tend to be the most luminous, in other words producing the most X-rays.

For doing Chandra publicity we also have a bias, as we are always on the lookout for results where NASA’s Chandra X-ray Observatory data play a starring role. However, there are many papers where Chandra has an important supporting role instead, and other observatories are the stars. Our colleagues at the European Space Agency (ESA) and the University of California, Los Angeles (UCLA), have put out press releases on just such a result.

A Scuba Dive, a (Failed) Ziploc Bag, and a Trip to the Center of the Galaxy

Chris Russell
Chris Russell

We welcome this guest post from Christopher Russell of the Pontifical Catholic University in Chile. Dr. Russell was the creator of the new immersive movies that allow viewers to explore the center of the Milky Way in 360 degrees. In this post, Dr. Russell provides the backstory of how he came to make these innovative movies.

I went to a Galactic Center meeting in Australia in July 2016, where I saw an Occulus Rift (a high-end virtual reality, or VR, setup) display by Chi-Kwan Chan (Univ. of Arizona). With the Rift, you plug it into your computer (so much more powerful rendering than available with a phone) and your position actually determines what is rendered. So if you walk left, right, forward, or backward, you are actually walking through the simulation and therefore seeing a different perspective. The thought of visualizing one of these Galactic Center simulations in this fashion was immediately apparent. Then we talked about 360/VR videos; what is required from the goggle side, computer specs, rendering programs, etc.

The day after the meeting, I went snorkeling, and unfortunately the Ziploc bag I put my phone in to keep it waterproof failed. Not one of my brightest ideas, I must say. But when I was looking for a new phone, the one I wanted (Galaxy s7) had two available promotions: get a free 256 GB memory card (useful, but not really fun), or the Samsung Gear VR goggles (definitely fun). I chose the latter, so now I could at least view 360-degree videos in their native format, and so would be able to view one of the Galactic Center if I could figure out how to make it.

Trying to Understand the Milky Way's Black Hole

Gabriele Ponti
Gabriele Ponti

Dr. Gabriele Ponti is the Marie Sklodowska-Curie EU Research Fellow at the Max Planck Institute for Extraterrestrial Physics in Germany. Prior to that, he was a post-doctoral fellow at the University of Southampton in the UK, after spending a year at Cambridge University’s Institute of Astronomy. Dr. Ponti earned his Ph.D. from Bologna University in Italy before moving on to the Laboratories Astro-Particule et Cosmologie in Paris. His doctoral thesis topic was studying relativistic effects in bright active galactic nuclei and he has been interested in this area since then.

As a boy, I read about the existence of black holes for the first time. I still remember the fascination of trying to grasp the physical concepts behind one of the weirdest manifestations of nature.

Black holes produce an enormous gravitational pull, as a consequence of being extremely compact: a significant amount of mass concentrated in a very small volume.

Milky Way's Black Hole Shows Signs of Increased Chatter

SgrA*
Three orbiting X-ray telescopes have been monitoring the supermassive black hole at the center of the Milky Way galaxy for the last decade and a half to observe its behavior. This long monitoring campaign has revealed some new changes in the patterns of this 4-million-solar-mass black hole known as Sagittarius A* (Sgr A*).

Magnetar Near Supermassive Black Hole Delivers Surprises

SGR 1745-2900
In 2013, astronomers announced they had discovered a magnetar exceptionally close to the supermassive black hole at the center of the Milky Way using a suite of space-borne telescopes including NASA's Chandra X-ray Observatory.

Magnetars are dense, collapsed stars (called "neutron stars") that possess enormously powerful magnetic fields. At a distance that could be as small as 0.3 light years (or about 2 trillion miles) from the 4-million-solar mass black hole in the center of our Milky Way galaxy, the magnetar is by far the closest neutron star to a supermassive black hole ever discovered and is likely in its gravitational grip.

NASA's Chandra Detects Record-Breaking Outburst from Milky Way's Black Hole

Sagittarius A*

On September 14, 2013, astronomers caught the largest X-ray flare ever detected from the supermassive black hole at the center of the Milky Way, known as Sagittarius A* (Sgr A*). This event, which was captured by NASA's Chandra X-ray Observatory, was 400 times brighter than the usual X-ray output from Sgr A*, as described in our press release. The main portion of this graphic shows the area around Sgr A* in a Chandra image where low, medium, and high-energy X-rays are red, green, and blue respectively. The inset box contains an X-ray movie of the region close to Sgr A* and shows the giant flare, along with much steadier X-ray emission from a nearby magnetar, to the lower left. A magnetar is a neutron star with a strong magnetic field. A little more than a year later, astronomers saw another flare from Sgr A* that was 200 times brighter than its normal state in October 2014.

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