perseuscluster

Perseus Cluster: Chandra Proves Black Hole Influence is Far Reaching (The central region of a rich galaxy cluster about 250 million light years from Earth.)

from Smithsonian Institution

• 4 older comments, and then…
• Meagan Critzman said:

  Cool

• Tremendous Expert said:

  I'm wondering one thing. How comes they can see in colours, when HUBBLE or other objects used in studying these galaxies, haven't got the ability of 'seeing' the real colours. About those fantastic colours inside a gas clod, it's all about ... presumptions of how the galaxy would look like, and someone decides for what colour to give to it.

• Krista said:

  Claudiu, consider it more of a color "coding". X-rays are still "light", but of course are not within our visible spectrum. However, they still have various types of wavelengths and can then program the computer to code in a certain way. I don't know of course exactly what their decisions are in regards to this, but in general that's how it's done when you see color photographs of space that show non-visible wavelengths (thus, color "coding").

• Tremendous Expert said:

  You're right. However, I would feel really bad knowing that the scientists have altered the pictures that they've been taking from the depths of space just for the sake of making them more.. cool! I am sure science will reach new levels in the future and we will be able to make sure about the colours of the gas clouds, and so on. I'm still waiting for the science to advance, whilst being happy with the things we have now, even if not always COOL ! Bye bye ps: 'and by the way, I am not reffering in ANY way to "mcritzman" 's comment. '

• Smithsonian Institution said:

  Thank you for your interest in the Chandra Xray photos. In the Perseus image, the scientist cut the energies into the following divisions: Red 0.3-1.2 keV, Green 1.2-2 keV, Blue 2-7 keV, where keV is kiloelectron volt (keV), a unit used to describe the energy of X-rays, equal to a thousand electron volts. X-rays can’t be seen with the human eye, and don’t have any "color." Images taken by telescopes that observe at the "invisible" wavelengths are sometimes called representative or false color images. That’s because the colors used to make them are not real but are chosen to bring out important details. The color choice is typically used as a type of code in which the colors can be associated with the intensity or brightness of the radiation from different regions of the image, or with the energy of the emission. At chandra.harvard.edu/photo/false_color.html you'll find a detailed description of representative, or "false" color for invisible wavelengths such as X-rays.