Search NASA⌕ Search

SEARCH · Search NASA

Results for “far-infrared”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Sub-Kelvin temperatures in space

It is pointed out that the use of temperatures below 1 K in space would provide a significant improvement in several areas of research. The sensitivity of bolometers, for instance, can be improvead by as much as a factor of 50, if the operating temperature is lowered from 1.5 K to 0.3 K. A decrease in temperature to 0.1 K can provide even an improvement up to three orders of magnitude. Detectors based on the utilization of such improvements could be employed for far-infrared (100-1000 microns) photometry and spectroscopy in the low-background conditions of space. The study of critical phenomena in He-3/He-4 mixtures is also of interest, taking into account investigations at the tricritical point (0.87 K), which represents the junction of a first-order and a second-order transition. Tests in space are needed because gravity-related effects make adequate tests on earth impossible. He-3 refrigeration can be used to attain temperatures below 1 K. Adiabatic demagnetization can produuce temperatures below 0.3 K.

Kittel, P.↗
NASA NTRS1983

Three holes bound to a double acceptor - Be(+) in germanium

A double acceptor binding three holes has been observed for the first time with photoconductive far-infrared spectroscopy in beryllium-doped germanium single crystals. This new center, Be(+), has a hole binding energy of about 5 meV and is only present when free holes are generated by ionization of either neutral shallow acceptors or neutral Be double acceptors. The Be(+) center thermally ionizes above 4 K. It disappears at a uniaxial stress higher than about a billion dyn/sq cm parallel to (111) as a result of the lifting of the valence-band degeneracy.

Haller, E. E.↗
NASA NTRS1984

Studies of low-mass star formation with the large deployable reflector

Estimates are made of the far-infrared and submillimeter continuum and line emission from regions of low mass star formation. The intensity of this emission is compared with the sensitivity of the large deployable reflector (LDR), a large space telescope designed for this wavelength range. The proposed LDR is designed to probe the temperature, density, chemical structure, and the velocity field of the collapsing envelopes of these protostars. The LDR is also designed to study the accretion shocks on the cores and circumstellar disks of low-mass protostars, and to detect shock waves driven by protostellar winds.

Hollenbach, D. J.↗
NASA NTRS1983

High-resolution infrared spectroscopy of planetary atmospheres

Various techniques for high-resolution infrared spectroscopy of planetary atmospheres are reviewed. Resolving powers of a million are now possible at 1-5 microns with Fourier transform spectrometers and at 10 microns with heterodyne spectrometers. The extension of high-resolution spectroscopy to the far-infrared is currently under development. The role of ground-based high-resolution spectroscopy compared to observations by spacecraft is discussed.

Tokunaga, A. T.↗
NASA NTRS1983

Images in the rocket ultraviolet - The starburst in the nucleus of M83

Ultraviolet images of the SAB(s)c I-II galaxy M83 (NGC 5236) obtained with a rocketborne telescope in broad bandpasses centered at 1540 A and 2360 A show a bright resolved nuclear source which accounts for approximately 20 percent of the flux of the galaxy in both bandpasses. Low-resolution International Ultraviolet Explorer spectra of this source reveal an energy distribution similar to that of the starburst nucleus of NGC 7714. Strong blueshifted absorption lines can be interpreted as evidence for a nuclear wind powered by supernovae. Observations from UV, X-ray, optical, and far-infrared bandpasses are consistent with a starburst approximately one-sixth as strong as that in M82. A scaling of the M82 models of Rieke et al. (1980) predicts that the nucleus of M83 contains 10 to the 6th - 3 x 10 to the 7th solar masses in young stars and has a supernova rate of approximately 0.01 per yr.

Bohlin, R. C.↗
NASA NTRS1984

Early results from the Infrared Astronomical Satellite

The discoveries made with the Infrared Astronomical Satellite (IRAS) are reviewed. Findings on large-scale extended infrared emission associated with the solar system and the Galaxy and medium-scale extended infrared emission associated with zodiacal dust bands and infrared cirrus clouds are described. Comets have been found to be much dustier than previously thought. Solid material orbits Vega and other stars, and emission from cool interstellar material has been traced throughout the Galaxy up to the poles. Stars in the process of formation have been detected. The far-infrared sky away from the galactic plane has been found to be dominated by spiral galaxies, some of which emit more than 50 percent and as much as 98 percent of their energy in the infrared.

Neugebauer, G.↗
NASA NTRS1984

Observations of comet IRAS-Araki-Alcock 1983d

Observations of comet IRAS-Araki-Alcock 1983d in the infrared region from 12 to 100 microns are reported. The dominant feature seen in the infrared is an extensive dust tail not reported in visual observations. A dust production rate of 200 kg/s is deduced. The far-infrared spectrum suggests that the radius of a mean grain decreases from 30 to 5 microns along the tail.

Walker, R. G.↗
NASA NTRS1984

The formation of massive stars along the W5 ionization front

Far-infrared, near-infrared, millimeter-wave, and optical data are presented for two of the large molecular clouds which border the W5 (IC 1848) giant H II region. These data are combined to identify three B0-B2 zero-age main-sequence stars which are forming in these clouds and to study the density distribution and kinematic structure of their surrounding molecular gas. This investigation into the environment in which massive stars have formed in these clouds, when considered alongside similar studies of the W5A/S201 molecular cloud, leads to the conclusion that the expanding W5 H II region has played an important role in initiating the formation of these massive stars.

Wilking, B. A.↗
NASA NTRS1984

The proper motion of Herbig-Haro Objects. IV - RNO 40 and 43

Proper motions and spectra of the Herbig-Haro Objects RNO 40 and 43 have been obtained. The proper-motion vectors point away from far-infrared sources. The spectra were used to infer shock velocities. These shock velocities agree with the tangential motion in the case of RNO 40, but are smaller than the tangential motion in the case of RNO 43. RNO 43 appears to be associated with an entire family of comoving knots.

Jones, B. F.↗
NASA NTRS1984

The IRAS galaxy 0421+040P06: An active spiral (?) galaxy with extended radio lobes

The infrared bright galaxy 0421+040P06 detected by IRAS at 25 and 60 microns was studied at optical, infrared, and radio wavelength. It is a luminous galaxy with apparent spiral structure emitting 4 x 10 to the 37th power from far-infrared to optical wavelengths. Optical spectroscopy reveals a Seyfert 2 emission line spectrum, making 0421+040P06 the first active galaxy selected from an unbiased infrared survey of galaxies. The fact that this galaxy shows a flatter energy distribution with more 25 micron emission than other galaxies in the infrared sample may be related to the presence of an intense active nucleus. The radio observations reveal the presence of a non-thermal source that, at 6 cm, shows a prominent double lobed structure 20 to 30 kpc in size extending beyond the optical confines of the galaxy. The radio source is three to ten times larger than structures previously seen in spiral galaxies.

Beichman, C. A.↗
NASA NTRS1984

Star Formation in Globules

The low mass star formation process was studied by application of submillimeter and supplementing far-infrared continuum observations by molecular line observations to the discovery and analysis of compact cores in molecular clouds with low luminosity. These dense regions are likely to be the sites where a cloud has recently collapsed or is still collapsing to form a star. Observations show that nonisotropic effects must play an important role in star formation. Four low luminosity sources embedded in the clouds L1551, B335, L1455 and L723 are presented. All these sources exhibit collimated bipolar molecular outflows of varying strengths. Data on the outflows are combined with determinations of mass, luminosity and temperature of the dust in the dense cores surrounding these embedded energy sources, to infer the evolutionary stage of the object. The possible role of the cores in channeling or generating the outflow is examined.

Davidson, J. A.↗
NASA NTRS1984

Circumstellar Dust Disks Around Young Stars

Kuiper Airborne Observatory observations of several resolved far-infrared structures that are likely to represent disks formed during the process of the collapse of a cloud to form a star are discussed. An infrared radiation nebula, star HH57, and SVS13 were studied. Forty seven and 95 micron maps of far infrared radiation are given.

Cohen, M.↗
NASA NTRS1984

A 150 Micron Heterodyne Spectrometer for Airborne Astronomy

The advantages of heterodyne detection for high resolution spectroscopy were long known to radio astronomers. Heterodyne spectroscopy was productive at submillimeter wavelengths, but its extension to shorter submillimeter and far-infrared (FIR) wavelengths was hampered by inadequate mixers and local oscillators. A significant advance in FIR receiver technology was demonstrated using an optically-pumped FIR laser and a Schottky-diode mixer. Any similar spectrometer intended for airborne observations at shorter wavelengths must be compatible with the more restrictive aircraft environment. The effectiveness of the design of a FIR heterodyne spectrometer was verified in ground-based observations with a prototype version. The airborne successor is even more compact, and has a much broader spectral coverage. Flight tests are scheduled for the new instrument.

Betz, A.↗
NASA NTRS1984

The H flux peak and the hydrogen abundance in N type carbon stars

For galactic N and late R type irregularly variable carbon stars, a comparison is made of airborne infrared spectrophotometry to spectral flux distributions derived from model atmospheres. Although the agreement is good in several respects, the H(-) emission peak at 1.6 microns, so prominent in the models, is significantly weakened in the stellar spectrophotometry. It seems unlikely that molecular bands in the stars can completely obliterate this peak. A plausible explanation is that hydrogen is deficient in these stars, most probably from an episode of mass loss. The resultant cold shells surrounding these stars should be amenable to observation by IRAS, or other far-infrared observatories.

Goebel, J. H.↗
NASA NTRS1984

Submillimeter wavelength survey of the galactic plane from l = -5 deg to l = +62 deg - Structure and energetics of the inner disk

Observational results are presented from a new large-scale survey of the first quadrant of the galactic plane at wavelengths of 150, 250, and 300 microns, with a 10 x 10 arcmin beam. The emission detected in the survey arises from compact sources, most of which are identified with known peaks of 5 GHz or CO emission, or both, and from an underlying diffuse background with a typical angular width of about 0.9 deg (FWHM) which accounts for most of the emission. A total of 80 prominent discrete sources are identified and characterized, of which about half have not previously been reported at far-infrared wavelengths. The total infrared luminosity within the solar circle is about 1 to 2 x 10 to the 10th solar luminosity, and is probably emitted by dust that resides in molecular clouds.

Hauser, M. G.↗
NASA NTRS1984

On the nature of the material surrounding Vega

Observations of Vega at 193 microns indicate that the far-infrared emission from the circumstellar material discovered by IRAS (Aumann et al. 1984) may decline more rapidly than a Planck spectrum at wavelengths greater than 100 microns. This suggests that the emitting particles may be smaller than the millimeter-sized objects proposed by Aumann et al. (1984). Small grains would be driven from the stellar system by radiation pressure, or their orbits would decay as a result of Poynting -Robertson drag. In order to maintain a state of dynamic equilibrium, a continuous supply of new particles would be required. It is hypothesized that the small grains are ejected by sublimation of volatile material from larger comet-like bodies in a partially coalesced preplanetary disk. A reservoir containing less than a few hundred earth masses could sustain the source over the lifetime of the star.

Harper, D. A.↗
NASA NTRS1983

Analysis of 12-700 micron reflectance spectra of three optical black samples

Normal incidence, specular reflectance spectra of three samples of optical black coatings have been measured in 10 filter passbands at effective wavelengths between 12 and 700 microns. Strong absorption, due to amorphous silicate material in the coatings, is found in the 15-50 micron region of each spectrum. Reflecting-layer model calculations are fitted by a nonlinear least-squares routine to the spectra at wavelengths beyond the absorption band to determine far-infrared optical parameters. It is found that, with a similar wavelength dependence, the absorption coefficient of a new black coating (ECP 2200) made by the Minnesota Mining and Manufacturing Company (3M) is less than 1/10 that of the discontinued coating, 3M Black Velvet Nextel. It is also shown that the extinction effect of a very rough substrate is negligible compared with the effects of increased upper surface roughness and coating thickness attendant upon fully covering a very rough substrate.

Smith, S. M.↗
NASA NTRS1983

Use of Space Station for Earth and Planetary Exploration

The Earth and Planetary Exploration program attempts to develop an understanding of the earth as a planet by utilizing the capability of instruments in space to explore the earth. Studies of the solar system are conducted to gain an understanding of its origin and evolution. The facilities for planetary observations will be greatly extended by making use of a Space Station. Special demands related to the appropriate utilization of a Space Station observatory are discussed, taking into account the employment of ultraviolet spectroscopy for the study of planetary atmospheres and comets, advantages provided by infrared spectroscopy, far-infrared and submillimeter spectroscopy and radiometery, and the search for other planetary systems. The capabilities provided by the Space Station for an investigation of earth resources are explored. Attention is given to vegetation research and observations, land cover dynamics, hydrologic cycle research, geological research, suitable instruments, and a study of crustal dynamics.

Piotrowski, W. L.↗