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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

High-resolution spectroscopy of uranium laser-produced plasma using saturated absorption spectroscopy

High-resolution spectroscopy of laser ablation plumes or laser-produced plasmas (LPPs) is valuable for various applications, including measuring crowded spectral features, determining spectroscopic constants, characterizing plasmas, and performing isotopic analysis. However, various line broadening mechanisms in plasmas limit its use for several applications. Here, in this study, we present the use of saturated absorption spectroscopy (SAS) for Doppler-free linewidth analysis in a uranium LPP. We demonstrate that SAS is effective in obtaining Doppler-free Lamb dip profiles with linewidths on the order of ≤ 20 MHz. The effects of saturation on the Doppler-broadened absorption and Lamb dip profiles at different pressures and probe intensities are quantified, and their impact on measurements of plasma properties is discussed. Finally, we show that the linewidths of the Lamb dips can be used for quantitative estimates of pressure and natural broadening in the plasma.

Absorption spectroscopy↗
NASA NTRS1986

High resolutions spectroscopy of P/Halley

High resolution spectra of the coma of P/Halley were obtained on 25 April, 2 May, and 3 May 1986. The self-scanned Digicon detector of the 2.7 m telescope coude spectrograph was used to obtain spectra at a resolution of 0.6A. Results of the observation of the NH (A 3 Pi i yields X 3 Sigma (-)) band near 3360 A are presented. The summed NH spectrum represents the results of 190 min of integration centered on the nucleus of the comet. Eight rotational lines from the P and R branches of the band are detected. The lines from the Q branch are especially weak, and are not obviously resolved in the spectrum. The data are compared with the theoretical emission spectrum of Litvak and Kuiper (1982) and substantial discrepancies are found. These discrepancies are explained through a consideration of the relative timescales for collisions, resonance fluorescence, and radiative decays of the NH molecules in the coma.

Cochran, W. D.↗
NASA NTRS1990

High resolution spectroscopy in the microwave and far infrared

High resolution rotational spectroscopy has long been central to remote sensing techniques in atmospheric sciences and astronomy. As such, laboratory measurements must supply the required data to make direct interpretation of data for instruments which sense atmospheres using rotational spectra. Spectral measurements in the microwave and far infrared regions are also very powerful tools when combined with infrared measurements for characterizing the rotational structure of vibrational spectra. In the past decade new techniques were developed which have pushed high resolution spectroscopy into the wavelength region between 25 micrometers and 2 mm. Techniques to be described include: (1) harmonic generation of microwave sources, (2) infrared laser difference frequency generation, (3) laser sideband generation, and (4) ultrahigh resolution interferometers.

Pickett, Herbert M.↗
NASA NTRS1983

Ultraviolet high-resolution spectroscopy from the Space Telescope

The High Resolution Spectrograph is one of five scientific instruments which will be part of the Space Telescope observatory. The spectrograph was designed to take advantage of the imaging and pointing capabilities of the telescope to obtain ultraviolet spectra with spectral resolution comparable to large, ground-based coudeinstruments. Some of the results of the ground-based testing program will be described, along with applications of these properties to future science programs.

Ebbets, D. C.↗
DOE OSTI2023

Initial Fulcher band observations from high resolution spectroscopy in the MAST-U divertor

High resolution D$^*_2$ Fulcher band spectroscopy was used in the MAST-U divertors during Super-X and (shorter-legged) elongated divertor density ramps with D 2 fuelling from the mid-plane high-field side. In the Super-X case, the upper divertor showed ground state rotational temperatures of the D 2 molecules increasing from ~6000 K, starting at the detachment onset, to ~9000 K during deepening detachment. This was correlated with the movement of the Fulcher emission region towards the X-point, which is in turn correlated with the movement of the ionisation source. The increase in rotational temperature occurred throughout the divertor except near the divertor entrance, where ionisation was still the dominant process. Qualitative agreement was obtained between the lower and upper divertor. Similar rotational temperatures were obtained in the elongated divertor before the detachment onset, although the increase in rotational temperature during detachment was less clearly observed as less deep detachment was obtained. The measured vibrational distribution of the upper Fulcher state does not agree with a ground state Boltzmann distribution but shows a characteristically elevated population in the ν = 2 and ν = 3 bands in particular; which is strongly correlated to the rotational temperature.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1986

High resolution spectroscopy of six new extreme helium stars

High resolution spectra of six newly discovered extreme helium stars are presented. LSS 5121 is shown to be a spectroscopical twin of the hot extreme helium star HD 160641. A preliminary LTE analysis of LSS 3184 yielded an effective temperature of 22,000 K and a surface gravity of log g = 3.2. Four stars form a new subgroup, classified by sharp-lined He I spectra and pronounced O II spectra, and it is conjectured that these lie close to the Eddington limit. The whole group of extreme helium stars apparently is inhomogeneous with respect to luminosity to mass ratio and chemical composition.

Heber, U.↗
NASA NTRS1989

High resolution spectroscopy of the 11.3 micron emission band

High resolution spectra of the 11.3 micron emission band in M82 and NGC 7027 were obtained using the University of Texas IR echelle spectrometer on the IRTF in April 1988. The spectral resolution was 0.004 micron, with coverage from 11.0 to 11.6 microns. Spectra were measured at ten positions along a 10 min. long slit. Analysis of the data is still in progress, but initial results show no clear evidence of narrow structure within the feature. The analysis will involve comparison of the observed spectra to laboratory and predicted spectra of Polycylic Aromatic Hydrocarbons (PAHs) and Quenched Carbonaceous Composite (QCCs) to determine which may be responsible for the emission. The spectra will be examined with a goal of determining whether the emission is caused by molecular or solid state material. The data are also examined for evidence of variations in the shape and strength of the 11.3 micron feature with position on the sky. In NGC 7027 the 10 min. long slit went across the edge of the ionized nebulae, allowing comparison of emission from both ionized and neutral regions.

Achtermann, Jeff M.↗
DOE OSTI2020

Prospects for Characterizing the Haziest Sub-Neptune Exoplanets with High-resolution Spectroscopy

Observations to characterize planets larger than Earth but smaller than Neptune have led to largely inconclusive interpretations at low spectral resolution due to hazes or clouds that obscure molecular features in their spectra. However, here we show that high-resolution spectroscopy (R ∼ 25,000–100,000) enables one to probe the regions in these atmospheres above the clouds where the cores of the strongest spectral lines are formed. We present models of transmission spectra for a suite of GJ 1214b–like planets with thick photochemical hazes covering 1–5 μm at a range of resolutions relevant to current and future ground-based spectrographs. Furthermore, we compare the utility of the cross-correlation function that is typically used with a more formal likelihood-based approach, finding that only the likelihood-based method is sensitive to the presence of haze opacity. We calculate the signal-to-noise ratio (S/N) of these spectra, including telluric contamination, Required to robustly detect a host of molecules such as CO, CO{sub 2}, H{sub 2}O, and CH{sub 4} and photochemical products like HCN as a function of wavelength range and spectral resolution. Spectra in the M band require the lowest S/N{sub res} to detect multiple molecules simultaneously. CH{sub 4} is only observable for the coolest models (T {sub eff} = 412 K) and only in the L band. We quantitatively assess how these requirements compare to what is achievable with current and future instruments, demonstrating that characterization of small cool worlds with ground-based high-resolution spectroscopy is well within reach.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Detecting Atmospheric Molecules of Nontransiting Temperate Terrestrial Exoplanets Using High-resolution Spectroscopy in the Mid-infrared Domain

Motivated by the development of high-dispersion spectrographs in the mid-infrared (MIR) range, we study their application to the atmospheric characterization of nearby nontransiting temperate terrestrial planets around M-type stars. We examine the detectability of CO{sub 2}, H{sub 2}O, N{sub 2}O, and O{sub 3 }features in high-resolution planetary thermal emission spectra at 12–18 μm assuming an Earth-like profile and a simplified thermal structure. The molecular line width of such planets can be comparable to or broader than the Doppler shift due to the planetary orbital motion. Given the likely difficulty in knowing the high-resolution MIR spectrum of the host star with sufficient accuracy, we propose observing the target system at two quadrature phases and extracting the differential spectra as the planetary signal. In this case, the signals can be substantially suppressed compared with the case where the host star spectrum is perfectly known, as some parts of the spectral features do not remain in the differential spectra. Despite this self-subtraction, the CO{sub 2} and H{sub 2}O features of nearby (≲5 pc) systems with mid-/late-M host stars would be feasible with a 6.5 m class cryogenic space telescope, and orbital inclination could also be constrained for some of them. For CO{sub 2} and N{sub 2}O in a 1 bar Earth-like atmosphere, this method would be sensitive when the mixing ratio is 1–10{sup 3} ppm. The detectability of molecules except O{sub 3} is not significantly improved when the spectral resolution is higher than R≳10,000, although the constraint on the orbital inclination is improved. This study provides some benchmark cases useful for assessing the value of MIR high-resolution spectroscopy in terms of characterization of potentially habitable planets.

47 OTHER INSTRUMENTATION↗
NASA NTRS1999

High-Resolution Spectroscopy of Mars: Recent Results and Implications for Atmospheric Evolution

It is believed that Earth, Venus, and Mars were formed by the same rocky and icy planetesimals, which resembled meteorites and comets in their composition, respectively. These planets are thus expected to have initially had the same chemical and isotope composition. Scaling the mass of the terrestrial ocean by the planetary mass ratio, the expected initial H2O abundance on Mars is a layer of about 1 km thick. Scaling the abundance of CO2 on Venus, the expected initial CO2 abundance on Mars is 15 bars. Evidently, significant parts of the initial H2O and CO2 abundances have been lost. Intense meteorite impact erosion and hydrodynamic escape of hydrogen (which could drag to escape more heavy species) were dominant loss processes in the first 0.8 Byr. Later, atmospheric sputtering by O+ ions resulted in the dissociation of CO2 and massive losses of O, C, and H. Formation of carbonates also reduced CO2 to its present abundance which currently exists in the atmosphere, on the polar caps, and is absorbed by regolith. Water loss is currently due to thermal escape of H and nonthermal escape of O, both formed by photodissociation of H2O. All loss processes resulted in fractionation of the H, O, and C isotopes. Therefore, the current isotope ratios in H2O and CO2 are clues to the history of volatiles on Mars. There are three tools to study H2O and CO2 isotopes in the martian atmosphere: (i) mass spectrometry from landing probes, (ii) analyses of Mars' gases trapped in the SNC meteorites which were ejected from Mars, and (iii) high-resolution spectroscopy of the H2O andCO2 bands. Method (i) is the best but is the most expensive. Mass spectrometers to be used should be designed for high-precision isotope measurements. Method (ii) makes it possible to reach an uncertainty +/- 0.1%. However, the obtained results are affected by some uncontrolled interactions: isotope fractionations of (1) trapped gases and (2) those released in pyrolysis, (3) contribution of the impactor, isotope exchanges (4) in the terrestrial environment and (5) with the host rock during pyrolysis. Therefore, the spectroscopic data are of great interest, though their formal accuracy is lower. High-resolution spectroscopy is also a tool to study the current atmosphere of Mars by mapping of some photochemically important species and searching for some minor constituents and their variations. Additional information is contained in the original extended abstract.

Krasnopolsky, V. A.↗
NASA NTRS2014

High-Resolution Spectroscopy of the Lunar Sodium Exosphere

We have applied high-resolution Fabry-Perot spectroscopy to the study of the lunar sodium exosphere for the study of exospheric effective temperature and velocity variations. Observing from the National Solar Observatory McMath-Pierce Telescope, we used a dual-etalon Fabry-Perot spectrometer with a resolving power of 180,000 to measure line widths and Doppler shifts of the sodium D2 (5889.95 Å) emission line. Our field of view was 360 km, and measurements were made in equatorial and polar regions from 500 km to 3500 km off the limb. Data were obtained from full moon to 3 days following full moon (waning phase) in March 2009. Measured Doppler line widths within 1100 km of the sunlit east and south lunar limbs for observations between 5 and 40 deg lunar phase imply effective temperatures ranging between 3260 +/- 190 and 1000 +/- 135 K. Preliminary line center analysis indicates velocity displacements between different locations off the lunar limb ranging between 100 and 600 m/s from the lunar rest velocity with a precision of +/-20 to +/-50 m/s depending on brightness. Based on the success of these exploratory observations, an extensive program has been initiated that is expected to constrain lunar atmospheric and surface-process modeling and help quantify source and escape mechanisms.

Lunar↗
NASA NTRS2010

High-Resolution Spectroscopy of Stratospheric Ethane Following the Jupiter Impact of 2009

We report on high-resolution infrared spectroscopy of ethane (C2H6) performed at the latitude of an impact site on Jupiter discovered on 19 July 2009 by A. Wesley from a location in Murrumbateman, Australia. The observations used the NASA Goddard Space Flight Center's Heterodyne Instrument for Planetary Wind and Composition (HIPWAC) at the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. HIPWAC is a mid-infrared (9-12 microns) heterodyne spectrometer operating at the highest limit of spectral resolving power (lambda\Delta\lambda > l06), providing information on atmospheric constituent abundance and temperature through fully resolved tine shapes. Ethane is a stable trace product of methane photochemistry that is nearly uniformly mixed in Jupiter's stratosphere, providing an effective probe of that altitude region. Ethane emission line profiles near 11,74 microns in the Ug band were measured in Jupiter's stratosphere at 25 MHz (11.00083/cm) resolution. A sequence of spectra of ethane acquired over a range of longitude at the impact latitude (56S planetocentric) probes constituent abundance and temperature profile, both on and off the impact region. Near the site of the impact, ethane emission increased above levels measured well outside the impact region. Radiative transfer analysis indicates increased ethane mole fraction (30% greater). Variation in the measured continuum level and line intensities within 75deg of the impact longitude indicate the presence of an opacity source (haze) at altitudes near and above the tropopause and as high as the 10-mbar level near the impact site. The indication of possible haze opacity up to the 10-mbar level in the atmosphere is consistent with measurements made by HIPWAC's predecessor as part of the IRTF Shoemaker Levy-9 campaign in 1994.

Fast, Kelly↗
NASA NTRS2008

"Long-term Timing and High Resolution Spectroscopy of Ultracompact Candidates V407 Vul and RX J0806.3+1527"

We present new, extended X-ray timing measurements of the ultracompact binary candidates V407 Vul and RX J0806.3+1527 (J0806), as well as a summary of the first high resolution X-ray spectrum of 50806 obtained with the Chandra/LETG. The temporal baseline for both objects is about 12 years, and our measurements confirm the secular spin-up of their X-ray periods. The spin-up rate in J0806 is remarkably uniform at 3.55x10(exp -16) Hz/s, with a measurement precision of 0.2%, and we place a limit (90% confidence) on [dn/dt] < 4x10(exp -26) Hz/sq s. Interestingly, for V407 Vul we find the first evidence that the spin-up rate is slowing, with d(sup 2)n/dt(sup 2) = -2.8+/- 1x10(exp -26) Hz/sq s. This provides the first indication that torques in addition to gravitational radiation are present in V407 Vul. Further monitoring could constrain the nature of the torque, as either accretion-induced or due to unipolar induction. We also obtained the first high resolution X-ray spectrum of J0806 with an 80 ksec Chandra/LETG observation. We find evidence for emission features in the 25-50 Angstrom range, with the strongest feature centered at 27 Angstrom. The spectrum appears largely devoid of common lines of oxygen, nitrogen and neon, and we suggest the 27 Angstrom feature may be associated with heavier species, such as magnesium, silicon or sulphur. Deeper observations will be needed to fully exploit the apparently strong diagnostic potential of high resolution spectroscopy for these objects.

Strohmayer, Tod↗
NASA NTRS1988

High-resolution spectroscopy of central stars of planetary nebulae - LSS 1362

High resolution spectra of the hot sdO star LSS 1362, a central star of a planetary nebula, are analyzed by means of model atmosphere techniques. Improved NLTE model atmospheres based on the newly developed 'accelerated lambda iteration' method are used. The very high effective temperature (100000 K) derived previously from the UV energy distribution is confirmed. The surface gravity (log g = 5.3) and a normal helium abundance are derived. A mass of 0.65 solar mass and a luminosity of 10 exp 3.9 solar luminosities result from a comparison with evolutionary tracks. The distance is 1.1 kpc and the nebula has a diameter of about 0.25 pc to 0.5 pc. Weak photospheric emission lines of He II, CIV, Nv, and O v are detected. These lines are slightly blue-shifted with respect to the absorption line spectrum which is regarded as evidence for an atmospheric velocity field. It is conjectured that the observed broadening of the metal lines (25 km/s) may be caused by the velocity field rather than by rotation.

Heber, U.↗
DOE OSTI2021

Detection and Bulk Properties of the HR 8799 Planets with High-resolution Spectroscopy

Using the Keck Planet Imager and Characterizer, we obtained high-resolution (R ~ 35,000) K-band spectra of the four planets orbiting HR 8799. We clearly detected H{sub 2}O and CO in the atmospheres of HR 8799 c, d, and e, and tentatively detected a combination of CO and H{sub 2}O in b. These are the most challenging directly imaged exoplanets that have been observed at high spectral resolution to date when considering both their angular separations and flux ratios. We developed a forward-modeling framework that allows us to jointly fit the spectra of the planets and the diffracted starlight simultaneously in a likelihood-based approach and obtained posterior probabilities on their effective temperatures, surface gravities, radial velocities, and spins. We measured vsin (i) values of 10.1{sub -2.7}{sup +2.8} km s{sup -1} for HR 8799 d and 15.0{sub -2.6}{sup +2.3} km s{sup -1} for HR 8799 e, and placed an upper limit of <14 km s{sup -1} of HR 8799 c. Under two different assumptions of their obliquities, we found tentative evidence that rotation velocity is anticorrelated with companion mass, which could indicate that magnetic braking with a circumplanetary disk at early times is less efficient at spinning down lower-mass planets.

74 ATOMIC AND MOLECULAR PHYSICS↗
NASA NTRS1998

High-Resolution Spectroscopy of some very Active Southern Stars

We have obtained high-resolution echelle spectra of 18 solar-type stars that an earlier survey showed to have very high levels of Ca II H and K emission. Most of these stars belong to close binary systems, but five remain as probable single stars or well-separated binaries that are younger than the Pleiades on the basis of their lithium abundances and H.alpha emission. Three of these probable single stars also lie more than 1 mag above the main sequence in a color-magnitude diagram, and appear to have ages of 10 to 15 Myr. Two of them, HD 202917 and HD 222259, also appear to have a kinematic association with the pre-main-sequence multiple system HD 98800.

Soderblom, David R.↗
NASA NTRS1984

Ultraviolet high-resolution spectroscopy of the X-ray binary Sk 160/SMC X-1

High-resolution IUE spectra of Sk 160, the optical counterpart of the X-ray source SMC X-1, show substantial variations with orbital phase of the resonance P Cygni profiles. These variations are ascribed to the changing ionization state in the stellar wind caused by the X-rays emitted by the companion, as suggested by Hatchett and McCray and first established for the galactic X-ray binary Vela X-1. Furthermore, the profile observed during X-ray eclipse differs significantly from profiles of similar stars in the absence of X-ray ionization.

Hammerschlag-Hensberge, G.↗