A forest of emission lines observed by Sunrise III/SUSI above the solar limb

J. S. Castellanos Durán; F. A. Iglesias; S. K. Solanki; A. Lagg; I. Milic; H. N. Smitha; D. Vukadinović; T. L. Riethmüller; A. Gandorfer; A. Feller; J. Blanco Rodríguez; D. Orozco Suárez; Y. Katsukawa; J. Hölken; J. C. del Toro Iniesta; S. Rao; M. Sánchez Toledo; K. Singh; P. Bernasconi; T. Berkefeld; A. Alvarez-Herrero; M. Kubo; V. Martínez Pillet; B. Grauf; M. Carpenter; A. Bell; H. Strecker; A. L. Siu-Tapia; P. Santamarina Guerrero; Y. Kawabata; T. Matsumoto; R. T. Ishikawa; E. Harnes; T. Oba

arXiv · 2610.04121

A forest of emission lines observed by Sunrise III/SUSI above the solar limb

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Abstract

We present off-limb spectroscopy using low-straylight data from the Sunrise Spectropolarimeter and Imager (SUSI) onboard the Sunrise III stratospheric solar observatory. A spatial scan with SUSI's slit almost parallel to the local limb reached from within the solar disc to 6.5 Mm off-limb. The wavelength range spanned from 407.6 to 410.25 nm. We detected a total of 174 spectral lines in emission off-limb, a 2.5-fold increase over previous reports. Surprisingly, 122 of these lines begin to appear in emission already on the disc, although close to the limb. In addition, one-fifth of relatively prominent emission lines are due to rare-earth and heavy elements and molecules, where the absorption lines of these transitions are typically weak on-disc.

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J. S. Castellanos Durán, F. A. Iglesias, S. K. Solanki, A. Lagg, I. Milic, H. N. Smitha, D. Vukadinović, T. L. Riethmüller, A. Gandorfer, A. Feller, J. Blanco Rodríguez, D. Orozco Suárez, Y. Katsukawa, J. Hölken, J. C. del Toro Iniesta, S. Rao, M. Sánchez Toledo, K. Singh, P. Bernasconi, T. Berkefeld, A. Alvarez-Herrero, M. Kubo, V. Martínez Pillet, B. Grauf, M. Carpenter, A. Bell, H. Strecker, A. L. Siu-Tapia, P. Santamarina Guerrero, Y. Kawabata, T. Matsumoto, R. T. Ishikawa, E. Harnes, T. Oba. 2026-10-02. A forest of emission lines observed by Sunrise III/SUSI above the solar limb. https://arxiv.org/abs/2610.04121

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