Production of N2 Vegard-Kaplan and Lyman-Birge-Hopfield emissions on Pluto

TL;DR

This paper models and predicts the UV emission intensities of nitrogen and carbon molecules in Pluto's atmosphere under various solar conditions, aiding future observations by the New Horizons mission.

Contribution

It introduces a comprehensive model for N$_2$ and CO emissions in Pluto's dayglow, providing specific intensity predictions for upcoming spacecraft observations.

Findings

Predicted N$_2$ Vegard-Kaplan and LBH band intensities for different solar conditions.

Estimated limb and overhead emission intensities for Pluto's atmosphere during NH flyby.

Calculated CO Fourth Positive band emissions relevant for observational planning.

Abstract

We have developed a model to calculate the emission intensities of various vibrational transitions of N$_2$ triplet band and Lyman-Birge-Hopfield (LBH) band emissions in the dayglow of Pluto for solar minimum, moderate, and maximum conditions. The calculated overhead intensities of Vegard-Kaplan ($ A^3\Sigma_u^+ - X^1\Sigma^+_g $), First Positive ($ B^3\Pi_g - A^3\Sigma^+_u $), Second Positive ($ C^3\Pi_u - B^3\Pi_g $), Wu-Benesch ($W^3\Delta_u - B^3\Pi_g$), Reverse First Positive, and LBH ($a^1\Pi_g$-- $X^1\Sigma^+_g$) bands of N$_2$ are 17 (74), 14.8 (64), 2.4 (10.8), 2.9 (12.7), 2.9 (12.5), and 2.3 (10) R, respectively, for solar minimum (maximum) condition. We have predicted the overhead and limb intensities of VK (150-190 nm) and LBH (120-190 nm) bands of N$_2$ on Pluto for the New Horizons (NH) flyby condition that can be observed by Alice: the ultraviolet imaging spectrograph also know as P-Alice. The predicted limb intensities of VK and LBH bands peak at radial distance of $ \sim$2000 km with the value of about 5 (13) and 9.5 (22) R for solar zenith angle 60$ ^\circ $ (0$ ^\circ $), respectively. We have also calculated overhead and limp intensities of few prominent transition of CO Fourth Positive bands for NH flyby condition.