scholarly journals HIGH-SPECTRAL-RESOLUTION INFRARED ABSORPTION AND EMISSION SIGNATURES AS OBSERVED AGAINST THERMAL BACKGROUND SOURCES FOR SELECTED MOLECULAR SPECIES

1999 ◽  
Author(s):  
S SCHMIDT
Keyword(s):  
Infrared Absorption ◽  
Spectral Resolution ◽  
Molecular Species ◽  
High Spectral Resolution ◽  
Absorption And Emission ◽  
Thermal Background

Star And Planet’s Characterisation Through High Spectral Resolution

2020 ◽  
Author(s):  
Maria Chiara Maimone ◽  
Andrea Chiavassa ◽  
Jeremy Leconte ◽  
Matteo Brogi
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
Molecular Species ◽  
Climate Model ◽  
Global Climate Model ◽  
Spectral Lines ◽  
High Spectral Resolution ◽  
High Resolution Spectroscopy ◽  
Stellar Disk ◽  
Precise Knowledge

<p>The study of exoplanets atmospheres is one of the most intriguing challenges in exoplanet field nowadays and the High Resolution Spectroscopy (HRS) has recently emerged as one of the leading methods for detecting atomic and molecular species in their atmospheres. In terms of numbers, if we define the resolution power R,<span class="Apple-converted-space">  </span>where λ is the wavelength and Δλ is the spectral resolution:</p> <p><span class="Apple-converted-space">     R= λ/Δλ</span></p> <p>then, “High Resolution Spectroscopy” means R > 50 000.</p> <p>Nevertheless extraordinary results have been achieved (Birkby, 2018), High Resolution Spectroscopy alone is not enough. 1D models of the host star have been coupled to HRS observations, but they do not reproduce the complexity of stellar convection mechanism (Chiavassa & Brogi, 2019). On the contrary,<span class="Apple-converted-space">  </span>3D Radiative Hydrodynamical simulations (3D RHS) take it into account intrinsically, allowing us to correctly reproduce asymmetric and blue-shifted spectral lines due to the granulation pattern of the stellar disk, which is a very important source of uncertainties at this resolution level (Chiavassa et al. 2017).</p> <p>However, numerical simulations have been computed independently for star and planet so far, while the acquired spectra are an entanglement of both the signals. In particular, some molecular species (e.g, CO) form in the same region of the spectrum, thus planetary and stellar spectral lines are completely mixed and overlapped.<span class="Apple-converted-space"> </span></p> <p>Therefore, a next step forward is needed: computing stellar and planetary models <em>together.</em></p> <p>With our work, we aim at upgrading the already-in-place 3D radiative transfer code Optim3D (Chiavassa et al. 2009) —largely used for stellar purposes so far — to taking into account also the exoplanetary contribution.<span class="Apple-converted-space"> </span>We propose to use simultaneously 3D RHS, performed for stars, and the innovative Global Climate Model (GCM), drawn up for exoplanets, in order to generate unprecedented precise synthetic spectra. As a springboard to test the code, we are carrying out the analysis of CO and H2O molecules on the well-know benchmark HD189733. Indeed, to disentangle those star’s and its companion’s signals due to the same molecules is one of the most challenging problems. In the end, we will be able to compute a complete dynamic characterisation: on one side, a precise knowledge of the stellar dynamic (i.e. convection-related surface structures) would allow to extract unequivocally the planetary signal; on the other one, a well-modelled dynamic of the planet (i.e. depth, shape, and position of spectral lines) would provide us with considerable information about the planetary atmospheric circulation.</p>

scholarly journals High-Resolution Infrared Far-IR Spectroscopy from SOFIA, 2005-2025

2005 ◽  
Vol 13 ◽  
pp. 818-821
Author(s):  
J. A. Davidson ◽  
E. F. Erickson
Keyword(s):  
High Resolution ◽  
Ir Spectroscopy ◽  
Wavelength Range ◽  
Spectral Resolution ◽  
Lower Stratosphere ◽  
Infrared Astronomy ◽  
High Spectral Resolution ◽  
Science Program ◽  
Absorption And Emission ◽  
Operational Lifetime

NASA and the DLR are developing SOFIA, the Stratospheric Observatory for Infrared Astronomy: a 2.5 m telescope in a Boeing 747SP aircraft. By flying in the lower stratosphere, SOFIA will allow astronomical measurements covering the wavelength range from 0.3 μm to 1.6 mm, with an emphasis on the spectral regions inaccessible from the ground, particularly the 6-8 μm and 30-300 μm regions. SOFIA will see “first light” in 2004; the science program will start in 2005. An operational lifetime of 20 years is planned.SOFIA will support a diverse and evolving complement of state-of-theart science instruments. Its spectrometers will have resolutions ranging from ~ 108 down to ~ 100, as needed to measure absorption and emission from astrophysically significant atoms, ions, molecules, aerosols, and solids. This paper describes the spectrometers being developed to fly on SOFIA soon after first light, and summarizes some of the high-spectral resolution investigations expected.

scholarly journals IRC +10216 as a spectroscopic laboratory: improved rotational constants for SiC2, its isotopologues, and Si2C

2018 ◽  
Vol 618 ◽  
pp. A4 ◽  
Author(s):  
J. Cernicharo ◽  
M. Guélin ◽  
M. Agúndez ◽  
J. R. Pardo ◽  
S. Massalkhi ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Molecular Species ◽  
Signal To Noise Ratio ◽  
Laboratory Data ◽  
High Spectral Resolution ◽  
Circumstellar Envelope ◽  
Centrifugal Distortion ◽  
Rotational Constants ◽  
Good Signal ◽  
Centrifugal Distortion Constants

This work presents a detailed analysis of the laboratory and astrophysical spectral data available for 28SiC2, 29SiC2, 30SiC2, Si13CC, and Si2C. New data on the rotational lines of these species between 70 and 350 GHz have been obtained with high spectral resolution (195 kHz) with the IRAM 30 m telescope in the direction of the circumstellar envelope IRC +10216. Frequency measurements can reach an accuracy of 50 kHz for features observed with a good signal to noise ratio. From the observed astrophysical lines and the available laboratory data new rotational and centrifugal distortion constants have been derived for all the isotopologues of SiC2, allowing us to predict their spectrum with an estimated accuracy better than 50 kHz below 500 GHz and around 50–100 kHz for the strong lines above 500 GHz. Improved rotational and centrifugal distortion constants have also been obtained for disilicon carbide, Si2C. This work shows that observations of IRC +10216 taken with the IRAM 30 m telescope, with a spectral resolution of 195 kHz, can be used for any molecular species detected in this source to derive, or improve, its rotational constants. Hence, IRC +10216 in addition to be one the richest sources in molecular species in the sky, can also be used as a spectroscopy laboratory in the millimetre and submillimetre domains.

scholarly journals A coma-free super-high resolution optical spectrometer using 44 high dispersion sub-gratings

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hua-Tian Tu ◽  
An-Qing Jiang ◽  
Jian-Ke Chen ◽  
Wei-Jie Lu ◽  
Kai-Yan Zang ◽  
...  
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
Wavelength Region ◽  
Ultra Violet ◽  
High Spectral Resolution ◽  
Visible Range ◽  
High Dispersion ◽  
Charge Coupled Device ◽  
Wide Range ◽  
High Resolution Spectrometer

AbstractUnlike the single grating Czerny–Turner configuration spectrometers, a super-high spectral resolution optical spectrometer with zero coma aberration is first experimentally demonstrated by using a compound integrated diffraction grating module consisting of 44 high dispersion sub-gratings and a two-dimensional backside-illuminated charge-coupled device array photodetector. The demonstrated super-high resolution spectrometer gives 0.005 nm (5 pm) spectral resolution in ultra-violet range and 0.01 nm spectral resolution in the visible range, as well as a uniform efficiency of diffraction in a broad 200 nm to 1000 nm wavelength region. Our new zero-off-axis spectrometer configuration has the unique merit that enables it to be used for a wide range of spectral sensing and measurement applications.

scholarly journals Hyperspectral Data Simulation (Sentinel-2 to AVIRIS-NG) for Improved Wildfire Fuel Mapping, Boreal Alaska

2021 ◽  
Vol 13 (9) ◽  
pp. 1693
Author(s):  
Anushree Badola ◽  
Santosh K. Panda ◽  
Dar A. Roberts ◽  
Christine F. Waigl ◽  
Uma S. Bhatt ◽  
...  
Keyword(s):  
Land Cover ◽  
Spectral Resolution ◽  
Hyperspectral Image ◽  
Spectral Response ◽  
Spectral Characteristics ◽  
Hyperspectral Data ◽  
Spectral Unmixing ◽  
High Spectral Resolution ◽  
Fuel Mapping ◽  
Sentinel 2

Alaska has witnessed a significant increase in wildfire events in recent decades that have been linked to drier and warmer summers. Forest fuel maps play a vital role in wildfire management and risk assessment. Freely available multispectral datasets are widely used for land use and land cover mapping, but they have limited utility for fuel mapping due to their coarse spectral resolution. Hyperspectral datasets have a high spectral resolution, ideal for detailed fuel mapping, but they are limited and expensive to acquire. This study simulates hyperspectral data from Sentinel-2 multispectral data using the spectral response function of the Airborne Visible/Infrared Imaging Spectrometer-Next Generation (AVIRIS-NG) sensor, and normalized ground spectra of gravel, birch, and spruce. We used the Uniform Pattern Decomposition Method (UPDM) for spectral unmixing, which is a sensor-independent method, where each pixel is expressed as the linear sum of standard reference spectra. The simulated hyperspectral data have spectral characteristics of AVIRIS-NG and the reflectance properties of Sentinel-2 data. We validated the simulated spectra by visually and statistically comparing it with real AVIRIS-NG data. We observed a high correlation between the spectra of tree classes collected from AVIRIS-NG and simulated hyperspectral data. Upon performing species level classification, we achieved a classification accuracy of 89% for the simulated hyperspectral data, which is better than the accuracy of Sentinel-2 data (77.8%). We generated a fuel map from the simulated hyperspectral image using the Random Forest classifier. Our study demonstrated that low-cost and high-quality hyperspectral data can be generated from Sentinel-2 data using UPDM for improved land cover and vegetation mapping in the boreal forest.

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