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July 2019

Reading Astronomy News: Galactic Superbubbles

By Stacy Palen

It’s that time of the semester when we are talking about galaxies, galactic structure, and supermassive black holes. Fortunately, Chandra has our back and has released a new image of a superbubble in NGC3079. The picture is sufficiently spectacular that I want to let you know about it right now!

Article: NGC: Galactic Bubbles Play Cosmic Pinball with Energetic Particles

1. Along the bottom of the composite image on the website, there are tabs that allow you to switch back and forth between the composite image, the X-ray image and the optical image.  Compare the X-ray image and the optical image. 

Answer: The X-ray image contains mostly just point sources, as well as two larger fuzzy patches. One of these fuzzy patches is shaped like a ring. The optical image, however, shows the entire galaxy, including dark lanes of dust and gas and bright light from stars and emission nebulae.

2. How big are the superbubbles, compared to the diameter of the disk of the Milky Way Galaxy?

Answer: The superbubbles have diameters of a few thousand light years. The disk of the Milky Way has a diameter of a few hundred thousand light years. So, these bubbles are about 1/100 (0.01 or 1%) the size of the Milky Way’s disk.

3. What is a cosmic ray? 

Answer: A high energy positively charged particle traveling through space. Note: they will have to click through to find this answer, if they don’t already know it! Let’s encourage that behavior!

4. Humans also accelerate particles, in particle accelerators, funny enough. How much more energy do the particles in these bubbles have than those accelerated by humans?

Answer: These particles have 100 times more energy than those in particle accelerators.

5. Run your mouse over the composite image to see it with labels on it. Why do astronomers think these superbubbles are associated with a supermassive black hole?

Answer: Because they are located together in space. 


 Photo credit:

 X-ray: NASA/CXC/University of Michigan/J-T Li et al.; Optical: NASA/STScI


Reading Astronomy News: Chasing Down the Mystery

Credit: Sloan Digital Sky Survey,


Once in a while something new happens. In the case of an article published in The Atlantic, astronomers observed an object that had properties like those of a supernova explosion, but much too fast. That led to some detective work across the electromagnetic spectrum to try to figure out what was happening!


1. What event triggered astronomers to pay attention to this particular location in space?

Answer: A bright spot appeared where none had been before.


2. How did astronomers communicate with each other that something interesting was happening?

Answer: They used The Astronomer’s Telegram, a global astronomy alert system.


3. Where did the event happen?

Answer: This event occurred in a nearby galaxy. It was detected at a telescope in Hawaii. (Note: I would use answers to this question to find out if students have sorted out what an “event” is, and the difference between an “event” and the detection of it.)


4. What about this event made it clear that this was not a “normal” supernova?

Answer: It was too bright, and also faded away too quickly. This is weird because brighter supernovae should fade away more slowly, not more quickly.


5. What is the current working hypothesis about what happened in the event?

Answer: Astronomers think this may have been the formation of a black hole or a neutron star.


6. How will astronomers test this hypothesis?

Answer: This event is over, so astronomers will have to wait for another one to occur to test their ideas against observations of that future event.