NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
A Solar-Pumped Fluorescence Model for Line-By-Line Emission Intensities in the B-X, A-X, and X-X Band Systems of 12C14NWe present a new quantitative model for detailed solar-pumped fluorescent emission of the main isotopologue of CN. The derived fluorescence efficiencies permit estimation and interpretation of ro-vibrational infrared line intensities of CN in exospheres exposed to solar (or stellar) radiation. Our g-factors are applicable to astronomical observations of CN extending from infrared to optical wavelengths, and we compare them with previous calculations in the literature. The new model enables extraction of rotational temperature, column abundance, and production rate from astronomical observations of CN in the inner coma of comets. Our model accounts for excitation and de-excitation of rotational levels in the ground vibrational state by collisions, solar excitation to the A(sup 2)Pi(sub I) and B(sup 2)Sum(sup +) electronically excited states followed by cascade to ro-vibrational levels of X(sup 2)Sum(sup +), and direct solar infrared pumping of ro-vibrational levels in the X(sup 2)Sum(sup +) state. The model uses advanced solar spectra acquired at high spectral resolution at the relevant infrared and optical wavelengths and considers the heliocentric radial velocity of the comet (the Swings effect) when assessing the exciting solar flux for a given transition. We present model predictions for the variation of fluorescence rates with rotational temperature and heliocentric radial velocity. Furthermore, we test our fluorescence model by comparing predicted and measured line-by-line intensities for X(sup 2)Sum(sup +) (1-0) in comet C/2014 Q2 (Lovejoy), thereby identifying multiple emission lines observed at IR wavelengths.
Document ID
20170002256
Document Type
Reprint (Version printed in journal)
Authors
Paganini, L. (Catholic Univ. of America Washington, DC, United States)
Mumma, M. J. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
March 14, 2017
Publication Date
August 31, 2016
Publication Information
Publication: The Astrophysical Journal: Supplement Series
Volume: 226
Issue: 1
Subject Category
Astrophysics
Report/Patent Number
GSFC-E-DAA-TN39971
Funding Number(s)
CONTRACT_GRANT: NNX13AD84A
Distribution Limits
Public
Copyright
Other
Keywords
Emission