Quote:
Originally Posted by CraigS
Hmm .. Thanks again, Steven … interesting ..
I was just snooping around looking for info on DRIFT and I found this one ..
Its a bit of an old article, (ScienceDaily: Dec. 9, 2008), but it is relevant to space bound CO2 detection of an exoplanet..
Hubble Telescope Finds Carbon Dioxide On An Extrasolar Planet
I guess in this case, we've got a hot glowing exoplanet radiating EM/light.
In the case of a comet, I presume it could only reflect light.
Still, I would've thought the absorption spectrum would be evident.
Clearly, the distance to the object vs resolution of the image isn't the problem (63 light-years) !
I'm still stumped !
Cheers |
That's because you are dealing with a point source. No need to mask the aperture of the detector. Also you increase the S/N ratio by simply increasing the exposure time.
Isolating a specific region in an extended object is far more challenging in particular when the spectrums of both regions may be similiar. The aperture of the detector may be no larger than a pinhole, in which case lght travelling through the telescope is diffracted at the detector.
The result is a noisy spectrum with a low S/N ratio irrespective of the exposure.
I have had a bit of experience with X-ray spectrometers. You can analyse very small particles in a matrix by using very small detector apertures going down to 0.5mm. The smaller the aperture the noisier the spectrum.
Regards
Steven