When Million-Degree Gas Is Safe

Last week, we put out a press release on an elliptical galaxy known as NGC 4649. Using Chandra data, a group of astronomers measured the temperature of the hot gas around the galaxy to come up with an independent way to measure the size of the gigantic black hole at the center. You can read more about the details in the press release.

Chandra Image of NGC 4649

But what do we actually mean when we talk about hot gas? In other words, if you were in a spaceship and flew through this gas, what would happen? Instant death by vaporization? A warm and tingling breeze?

The answer is that you wouldn’t notice it at all. As those motivational gurus who teach you to walk on coals know, the key to not burning your feet is the rate of heat transfer. In the halos of hot gas around galaxies, the gas is so rarified that the heat transfer to a spaceship would be practically nil. Chandra can detect the X-rays from these halos because they are tens of thousands of light years across. So, get your spaceship fueled up and get out there.

-Megan Watzke, CXC