On temperature determinations from nonresolved spectra

Area of Science:

• Astrophysics
• Spectroscopy
• Photographic Spectroscopy

Background:

• Low-intensity astronomical sources often yield film spectrograms with large, overlapping spectral lines (nonresolved case).
• Accurate interpretation of densitometer scans from these photographic spectra is crucial for determining source temperatures.
• Existing methods may be affected by the characteristics of spectral line images and the densitometer's line spread function.

Purpose of the Study:

• To investigate the impact of combined line spread functions and image sizes on densitometer scan outputs for nonresolved film spectra.
• To apply these findings to the determination of spectroscopic temperatures for the CN violet system.
• To identify optimal spectral regions for accurate temperature measurements from photographic spectra.

Main Methods:

• Simulating densitometer scans of nonresolved film spectra using various assumed line spread functions and image sizes.
• Analyzing the resulting scan data to quantify the effects of these parameters.
• Applying the analysis to spectroscopic temperature determination of the CN violet system.

Main Results:

• Different line spread functions and image sizes significantly alter densitometer scan outputs for nonresolved spectra.
• The presence of prominent band heads introduces substantial distortions in the spectral line profiles.
• Spectroscopic temperature determinations are demonstrably affected by these instrumental and spectral features.

Conclusions:

• Accurate spectroscopic temperature determination from nonresolved film spectra necessitates accounting for line spread function effects.
• Densitometry should be performed in spectral regions with minimized line spread function influence, typically away from band heads.
• This research highlights critical considerations for analyzing photographic spectra of low-intensity sources.