Discovery of New Coronal Lines at 2.843 and 2.853 μm

Samra, Jenna; Judge, P. G.; DeLuca, E. E.; Hannigan, James W.

doi:10.3847/2041-8213/aab434

Cited by 20 publications

(30 citation statements)

References 34 publications

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“…Note-Wavelength estimates and standard errors are reported for each of the four coronal slit positions. The Fe IX line was only seen in position 3 (Samra et al 2018;Samra et al 2019).…”

Section: Dark Subtractionmentioning

confidence: 96%

“…Prior measurement campaigns have confirmed the existence of Si X at 1.431 µm (Penn & Kuhn 1994;Kuhn et al 1996), S XI at 1.921 µm (Olsen et al 1971;Kastner 1993), Mg VIII at 3.028 µm (Münch et al 1967;Olsen et al 1971), and Si IX at 3.935 µm (Kuhn et al 1999;Judge et al 2002). AIR-Spec made the first detection of Fe IX at 2.853 µm (Samra et al 2018). Through coordinated observations with the Extreme Ultraviolet Imaging Spectrometer (EIS, Culhane et al 2007), the AIR-Spec measurements provided insight into line excitation processes and coronal temperature and density Madsen et al (2019).…”

Section: The August 21 2017 Eclipse Datamentioning

confidence: 97%

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The Airborne Infrared Spectrometer: Development, Characterization, and the 21 August 2017 Eclipse Observation

Samra,

Marquez,

Cheimets

et al. 2021

Preprint

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On August 21, 2017, the Airborne Infrared Spectrometer (AIR-Spec) observed the total solar eclipse at an altitude of 14 km from aboard the NSF/NCAR Gulfstream V research aircraft. The instrument successfully observed the five coronal emission lines that it was designed to measure: Si X 1.431 µm, S XI 1.921 µm, Fe IX 2.853 µm, Mg VIII 3.028 µm, and Si IX 3.935 µm. Characterizing these magnetically sensitive emission lines is an important first step in designing future instruments to monitor the coronal magnetic field, which drives space weather events as well as coronal heating, structure, and dynamics. The AIR-Spec instrument includes an image stabilization system, feed telescope, grating spectrometer, and slit-jaw imager. This paper details the instrument design, optical alignment method, image processing, and data calibration approach. The eclipse observations are described and the available data are summarized.

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“…Note-Wavelength estimates and standard errors are reported for each of the four coronal slit positions. The Fe IX line was only seen in position 3 (Samra et al 2018;Samra et al 2019).…”

Section: Dark Subtractionmentioning

confidence: 96%

Section: The August 21 2017 Eclipse Datamentioning

confidence: 97%

The Airborne Infrared Spectrometer: Development, Characterization, and the 21 August 2017 Eclipse Observation

Samra,

Marquez,

Cheimets

et al. 2021

Preprint

Self Cite

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“…The authors found that the architecture and modernity of the instruments were still inadequate to detect coronal lines from low-altitude sites due to various sensitivities such as atmospheric absorption and background. The Airborne Infrared Spectrometer (AIR-Spec) was constructed with the goal of studying several magnetically sensitive coronal lines, assessing their validity to pursue as future spectro-polarimetric observations (Samra et al 2018). The combination of the moderate-resolution FTS and AIR-Spec spectra therefore clearly revealed for the first time the effects of telluric extinction on the IR coronal emission lines.…”

Section: Introductionmentioning

confidence: 99%

“…Mg VIII ∼3028nm, are detectable in ground observations is still debatable. Theoretical intensity calculations and older observational runs are reserved (Münch 1966;Olsen et al 1971;Judge 1998), but a definitive ruling has not been reached, as discussed by Judge et al (2001) and Samra et al (2018). For this reason, we limited our coronal line selection to encompass only the more reliable Fe XIII, Si X, and Si IX ions.…”

Section: Introductionmentioning

confidence: 99%

A spectroscopic survey of infrared 1-4μm spectra in regions of prominent solar coronal emission lines of Fe XIII, Si X, and Si IX

Ali,

Paraschiv,

Reardon

et al. 2022

Preprint

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The infrared solar spectrum contains a wealth of physical data about the Sun and is being explored using modern detectors and technology with new ground-based solar telescopes. One such instrument will be the ground-based Cryogenic Near-IR Spectro-Polarimeter of the Daniel K. Inouye Solar Telescope that will be capable of sensitive imaging of the faint infrared solar coronal spectra with full Stokes I, Q, U, and V polarization states. Highly ionized magnetic dipole emission lines have been observed in galaxies and the solar corona. Quantifying the accuracy of spectral inversion procedures requires a precise spectroscopic calibration of observations. A careful interpretation of the spectra around prominent magnetic dipole lines is essential for deriving physical parameters, and particularly, for quantifying the off-limb solar coronal observations from DKIST. In this work, we aim to provide an analysis of the spectral regions around the infrared coronal emission lines of Fe XIII 1074.68 nm, Fe XIII 1079.79 nm, Si X 1430.10 nm, and Si IX 3934.34 nm, aligning with the goal of identifying solar photospheric and telluric lines that will help facilitate production of reliable inversions and data products from four sets of solar coronal observations. The outputs will be integrated in the processing pipeline to produce Level-2 science-ready data that will be made available to DKIST observers.

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“…AIR-Spec was commissioned during the 2017 eclipse, when it observed five emission lines between 1.4 and 4 µm (Table 1). The 2.853 µm Fe IX line was detected for the first time (Samra et al 2018), and coordinated observations with the Hinode Extreme Ultraviolet Imaging Spectrometer (EIS, Culhane et al 2007) were used to characterize plasma temperature and density (Madsen et al 2019).…”

mentioning

confidence: 99%

New Observations of the IR Emission Corona from the July 2, 2019 Eclipse Flight of the Airborne Infrared Spectrometer

Samra,

Madsen,

Cheimets

et al. 2021

Preprint

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The Airborne Infrared Spectrometer (AIR-Spec) was commissioned during the 2017 total solar eclipse, when it observed five infrared coronal emission lines from the Gulfstream V High-performance Instrumented Airborne Platform for Environmental Research (GV HIAPER), a research jet owned by the National Science Foundation (NSF) and operated by the National Center for Atmospheric Research (NCAR). The second AIR-Spec research flight took place during the July 2, 2019 total solar eclipse across the south Pacific. The 2019 eclipse flight resulted in seven minutes of observations, during which the instrument measured all four of its target emission lines: S XI 1.393 µm, Si X 1.431 µm, S XI 1.921 µm, and Fe IX 2.853 µm. The 1.393 µm line, half of a density-sensitive S XI line pair, was detected for the first time. The 2017 AIR-Spec detection of Fe IX was confirmed and the first observations were made of the Fe IX intensity as a function of solar radius. Observations of S XI and Si X were used to estimate the temperature and density above the east and west limbs, the subject of a future paper. Atmospheric absorption was significant in the 2019 data, and atmospheric modeling was required to extract accurate line intensities. Telluric absorption features were used to calibrate the wavelength mapping, instrumental broadening, and throughput of the instrument. AIR-Spec underwent significant upgrades in preparation for the 2019 eclipse flight. The thermal background was reduced by a factor of 30, providing a 5.5x improvement in signal-to-noise ratio, and the pointing stability was improved by a factor of five to <10 arcsec RMS after image co-alignment. In addition, two imaging artifacts were identified and resolved, making the 2019 data easier to interpret and improving the spectral resolution by up to 50%. INTRODUCTIONInfrared (IR) solar coronal emission lines (Judge 1998; Del Zanna & DeLuca 2018) are currently of significant interest due to their advantages for coronal magnetic field measurements and coronal plasma characterization at large solar radii. These magnetic dipole transitions encode the magnetic field through both the "weak-field" Zeeman effect and the "strong field limit" of the Hanle effect (Casini & Judge 1999;Lin & Casini 2000;Judge et al. 2001). Unlike their ultraviolet (UV) and X-ray counterparts, visible and IR lines are excited in part by resonant scattering of photospheric radiation and fall off in intensity more gradually with radius (Judge 1998;Habbal et al. 2011). Near and mid-IR lines are particularly promising because they balance Zeeman sensitivity, which increases as λ 2 , with line intensity, which generally decreases with wavelength (Judge et al. 2001). This wavelength region also optimizes the instrumental tradeoff between thermal emission, which increases nearly exponentially with wavelength, and Rayleigh scattering, which decreases as λ 4 (Judge et al. 2001).Thanks to recent advances in IR detectors, new instruments and observatories are beginning to open a window into the IR corona. The Coronal...

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Discovery of New Coronal Lines at 2.843 and 2.853 μm

Cited by 20 publications

References 34 publications

The Airborne Infrared Spectrometer: Development, Characterization, and the 21 August 2017 Eclipse Observation

The Airborne Infrared Spectrometer: Development, Characterization, and the 21 August 2017 Eclipse Observation

A spectroscopic survey of infrared 1-4μm spectra in regions of prominent solar coronal emission lines of Fe XIII, Si X, and Si IX

New Observations of the IR Emission Corona from the July 2, 2019 Eclipse Flight of the Airborne Infrared Spectrometer

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