文章基本信息

标题：High-resolution spectroscopy and spectropolarimetry of the total lunar eclipse January 2019 ★ ★★
本地全文：下载
作者：K. G. Strassmeier ; I. Ilyin ; E. Keles 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2020
卷号：635
页码：1-19
DOI：10.1051/0004-6361/201936091
语种：English
出版社：EDP Sciences
摘要：Context.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.Aims.We thus aim at transmission spectroscopy of an Earth transit by tracing the solar spectrum during the total lunar eclipse of January 21, 2019.Methods.Time series spectra of theTychocrater were taken with the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope in its polarimetric mode in StokesIQUVat a spectral resolution of 130 000 (0.06 Å). In particular, the spectra cover the red parts of the optical spectrum between 7419–9067 Å. The spectrograph’s exposure meter was used to obtain a light curve of the lunar eclipse.Results.The brightness of the Moon dimmed by 10.m75 during umbral eclipse. We found both branches of the O2A-band almost completely saturated as well as a strong increase of H2O absorption during totality. A pseudo O2emission feature remained at a wavelength of 7618 Å, but it is actually only a residual from different P-branch and R-branch absorptions. It nevertheless traces the eclipse. The deep penumbral spectra show significant excess absorption from the Na I5890-Å doublet, the Ca IIinfrared triplet around 8600 Å, and the K Iline at 7699 Å in addition to several hyper-fine-structure lines of Mn Iand even from Ba II. 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 Ca IIand K Iremained visible throughout umbral eclipse. Our radial velocities trace a wavelength dependent Rossiter-McLaughlin effect of the Earth eclipsing the Sun as seen from theTychocrater and thereby confirm earlier observations. A small continuum polarization of the O2A-band of 0.12% during umbral eclipse was detected at 6.3σ. No line polarization of the O2A-band, or any other spectral-line feature, is detected outside nor inside eclipse. It places an upper limit of ≈0.2% on the degree of line polarization during transmission through Earth’s atmosphere and magnetosphere.
关键词：Key wordsensolar-terrestrial relationsSun: atmosphereEarthMooneclipsespolarization