High-resolution spectroscopy and spectropolarimetry of the total lunar eclipse January 2019
| Autor: | Michael Weber, M. Mallonn, I. V. Ilyin, Arto Järvinen, Felix Mackebrandt, Klaus G. Strassmeier, E. Keles, J. M. Hill |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
010504 meteorology & atmospheric sciences
Infrared FOS: Physical sciences Astrophysics 01 natural sciences Spectral line Impact crater 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Spectral resolution Spectroscopy 010303 astronomy & astrophysics Instrumentation and Methods for Astrophysics (astro-ph.IM) Solar and Stellar Astrophysics (astro-ph.SR) 0105 earth and related environmental sciences Physics Earth and Planetary Astrophysics (astro-ph.EP) Lunar eclipse Astrophysics::Instrumentation and Methods for Astrophysics Astronomy and Astrophysics Light curve Atmosphere of Earth Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science Physics::Space Physics Astrophysics::Earth and Planetary Astrophysics Astrophysics - Instrumentation and Methods for Astrophysics Astrophysics - Earth and Planetary Astrophysics |
| Popis: | Observations of the Earthshine off the Moon allow for the unique opportunity to measure the large-scale Earth atmosphere. Another opportunity is realized during a total lunar eclipse which, if seen from the Moon, is like a transit of the Earth in front of the Sun. We thus aim at transmission spectroscopy of an Earth transit by tracing the solar spectrum during the total lunar eclipse of January 21, 2019. Time series spectra of the Tycho crater were taken with the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in its polarimetric mode in Stokes IQUV at a spectral resolution of 130000 (0.06 \AA). In particular, the spectra cover the red parts of the optical spectrum between 7419-9067 \AA . The spectrograph's exposure meter was used to obtain a light curve of the lunar eclipse. The brightness of the Moon dimmed by 10.75 mag during umbral eclipse. We found both branches of the O$_2$ A-band almost completely saturated as well as a strong increase of H$_2$O absorption during totality. The deep penumbral spectra show significant excess absorption from the NaI 5890 \AA doublet, the CaII infrared triplet around 8600 \AA, and the KI line at 7699 \AA in addition to several hyper-fine-structure lines of MnI and even from BaII. The detections of the latter two elements are likely due to an untypical solar center-to-limb effect rather than Earth's atmosphere. The absorption in CaII and KI remained visible throughout umbral eclipse. A small continuum polarization of the O$_2$ A-band of 0.12\% during umbral eclipse was detected at 6.3$\sigma$. No line polarization of the O$_2$ A-band, or any other spectral-line feature, is detected outside nor inside eclipse. It places an upper limit of $\approx$0.2\% on the degree of line polarization during transmission through Earth's atmosphere and magnetosphere. Comment: Accepted for publication in Astronomy & Astrophysics |
| Databáze: | OpenAIRE |
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