stroyan@hpfcrx.UUCP (06/19/84)
Regarding short period pulses from very large objects- Here is one mechanism that might produce short period oscillations from a very large source viewed from an arbitrary position. A large sphere of molecular particles is raised to a high energy state by some low level 'pump' mechanism. Perhaps an external radiation source or some uniform radioactive decay. A 'small' pulsating object at the center of the sphere emits photon pulses with a short period. The particles in the sphere then lase, amplifying the pulses, ***only along the photons paths of motion***. This provides a mechanism for producing very high energy pulses from a large 'engine', yet with a short period. Does anyone out there who care to say what's wrong with this picture? Mike Stroyan hpfcla!stroyan
matt@oddjob.UChicago.UUCP (Matt Crawford) (06/22/84)
We must assume that the photons do not scatter from the atoms in the lasing body. In this case, the light received by a distant observer all comes from a small patch of surface, not the entire sphere. I guess this *is* a large source with short period, but the non-scattering requirement is very unplausible. ___________________________________________________________ Matt University ARPA: crawford@anl-mcs.arpa Crawford of Chicago UUCP: ihnp4!oddjob!matt
allan@noao.UUCP (06/22/84)
I do not see any objection to your idea IN PRINCIPLE. However, most astronomical
sources of radiation are not lasers and so your idea does not then apply.
We can recognise sources which are lasing (actually they are masers) by
their brightness temperature being too high.
Perhaps it is time to clear up all this discussion about pulsation times.
Fact: There is no way that a source of radiation can vary significantly on
a time shorter than the light travel time across the source if the
source is radiating isotropically.
The conditional clause in the above sentence provides the loop hole.
In cases where the radiation is not isotropic, due to relativistic beaming,
laser action, or anything else, then it is POSSIBLE (but not certain) to get
faster variations. However, most astrophysical sources are sufficiently close
to radiating isotropically that the light travel time argument is a useful
working tool.
Peter (theories to go) Allan
Kitt Peak National Observatory
Tucson, Az
UUCP: {akgua,allegra,arizona,decvax,hao,ihnp4,lbl-csam,seismo}!noao!allan
ARPA: noao!allan@lbl-csam.arpa