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- Title
On the effective temperature of AlC molecular lines in sunspot umbral spectra.
- Authors
Sindhan, R.; Sriramachandran, P.; Shanmugavel, R.; Ramaswamy, S.
- Abstract
In the present work, a significant rotational lines of the B 4 Σ − – X 4 Σ − (0 , 0 ) band system of the AlC molecule were identified in high resolution FTS sunspot umbral spectra in the region from 22,450 to 22,600 cm−1. Among the well-resolved identified lines, the rotational temperatures have been estimated to be 4018 K for photosphere and 3722 K for a hot umbra. Hence, the estimated effective rotational temperatures provide evidence for the possible presence of the AlC molecule in a sunspot umbra. The radiative transition parameters for A 4 Π − – X 4 Σ − and B 4 Σ − – X 4 Σ − systems of the AlC molecule have been estimated for experimentally known vibrational levels using the Rydberg–Klein–Rees (RKR) potential. The Franck-Condon (FC) factor of B 4 Σ − – X 4 Σ − (0 , 0 ) band system is most intense ( q v ′ v ″ = 0.741 ). For the B 4 Σ − state, the radiative lifetime of v ′ = 0 level is found as 103.93 ns. The effective vibrational temperature of the A 4 Π − – X 4 Σ − and B 4 Σ − – X 4 Σ − band systems of the AlC molecule is 3981 K and 2706 K, respectively. Therefore, the effective vibrational temperature and radiative transition parameters help us to ascertain the possible presence of the AlC molecule in the solar atmosphere.
- Subjects
SUNSPOTS; RADIATIVE transitions; SOLAR atmosphere; TRANSITION temperature; TEMPERATURE
- Publication
Astrophysics & Space Science, 2020, Vol 365, Issue 9, pN.PAG
- ISSN
0004-640X
- Publication type
Article
- DOI
10.1007/s10509-020-03866-7