View Single Post
  #18  
Old 20-10-2010, 03:33 PM
bojan's Avatar
bojan
amateur

bojan is online now
 
Join Date: Jul 2006
Location: Mt Waverley, VIC
Posts: 7,112
Quote:
Originally Posted by sjastro View Post
It has nothing to do with the period of the pulses. It's the distance travelled by each individual pulse through a medium. Think of the pulse as a cone shape. The diameter of the cone represents the light echo. The longer the cone, the greater the distance travelled in the medium, the larger the light echo. The fact that there is a small period between each pulse is immaterial, the first pulse emitted forms the outer edge of the light echo. Each successive pulse will lead to a "filled in" light echo.
We don't observe such beasts.
Of course I do understand the concept..
I just tried to point out there is no way to distinguish between the train of pulses from one single long brightening (like in this example you gave us earlier - V838 Monocerotis. It could have been flashing very fast during the outburst, but the effect we have now would have been the same).

Quote:
Originally Posted by sjastro View Post
How can this be. The thickness of the disk is very small even after taking into account diffraction effects on the beam. As an observer in the plane of the disk, the best we can hope to see is a small illuminated region on either side of the pulsar, and that is not possible given it is well beyond the resolution of our telescopes.
Well, I do agree the intensity of such illuminated ring would be small.
That's why I sad:
Quote:
Originally Posted by bojan View Post
... I still think we would be able to see (in principle) an illuminated ring (or fragments of it).....

Last edited by bojan; 20-10-2010 at 04:05 PM.
Reply With Quote