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Wynn-Williams, C. G.

Publications and source records attributed to Wynn-Williams, C. G..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Luminous infrared galaxies - Sizes at 10-32 microns

We have made estimates of the sizes of 19 infrared galaxies drawn from the highest luminosity galaxies detected by the IRAS survey. The techniques we used were to make multiaperture photometric measurements on the ground-based IR Telescope Facility and to compare these flux densities with the much broader beam measurements obtained by the IRAS survey. Our primary result is that most, but not all, of the galaxies in our sample are extended at 10-25 microns, with characteristic radii of a few hundred parsecs. This result directly supports the widely held assumption that the bulk of the infrared luminosity in these galaxies comes from a central starburst region rather than from the whole disk of the galaxy or from a compact nucleus. The compact nature of Arp 220 is confirmed by direct scans with a 2.9 arcsec aperture at 32 microns.

Wynn-Williams, C. G.↗
NASA NTRS1992

Infrared emission and mass loss from evolved stars in elliptical galaxies

Small aperture 10.2-micron measurements of normal elliptical galaxies show that for almost all of these galaxies the 12-micron emission seen by IRAS is extended on the scale of the galaxy. NGC 1052 and NGC 3998 are exceptions to this; much of their 10-12-micron emission comes from the inner regions of the galaxies and may be associated with their active nuclei, as is the case for many radio galaxies. The distribution of the IR light and the IR colors of elliptical galaxies suggest that the most plausible source of the 12-micron emission is photospheric and circumstellear emission from cool evolved red giant stars. The 12-micron emission is well in excess of that expected from photospheric emission alone; about 40 percent of it probably comes from circumstellar dust.

Knapp, G. R.↗
NASA NTRS1990

Infrared studies of elliptical galaxies. II - A radio-selected sample

An IR survey of radio galaxies in the Bologna B2 catalog is reported. It is found that 40 percent of the sample has IR luminosities of at least one billion solar luminosities, as opposed to about 8 pecent of normal ellipticals. The galaxies are inhomogeneous in their IR properties. The most IR-luminous galaxies are those listed as peculiar by Zwicky. Statistically, these galaxies are strikingly different from Seyfert galaxies in their IR properties in that they show much more radio emission in comparison with their IR emission than do Seyferts, even when the emission from the extended radio lobes has been discounted.

Impey, C. D.↗
NASA NTRS1988

The properties and environment of the giant, infrared-luminous galaxy IRAS 09104 + 4109

IRAS 09104 + 4109 is the most luminous object yet discovered by means of the IRAS survey. It is identified with a cD galaxy having a strong emission-line spectrum at a redshift of 0.442 and emits 6 x 10 to the 12th solar luminosities/sq h, 99 percent of which emerges at infrared wavelengths. One component of a double radio source is coincident with the center of the galaxy. The high luminosity of this source may be related to an interaction with one or more members of the rich cluster in which it lies. There is a secondary peak in the emission-line image of the galaxy. Emission lines from both regions are broad but narrower than those characteristic of the only other objects known to have such high luminosities, such as Seyfert 1's and QSOs. It is suggested that the strong infrared excess of IRAS 09104 + 4109 is produced by dust obscuring a broad line region.

Kleinmann, S. G.↗
NASA NTRS1987

Star formation in normal galaxies

The ways in which recent infrared observations, particularly by the Infrared Astronomy Satellite (IRAS), have influenced ideas about star formation in normal galaxies, are discussed.

Wynn-Williams, C. G.↗
NASA NTRS1987

VLA observations of a sample of galaxies with high far-infrared luminosities

Preliminary results are presented from a radio survey of galaxies detected by the IRAS minisurvey. It was found that the main difference between galaxies selected in the far infrared and those selected in the optical is that the former have higher radio luminosities and that the radio emission is more centrally concentrated. There is some evidence that the strong central radio sources in the galaxies selected in the infrared are due to star formation, the star formation rate divided by the volume in which the star formation is occuring is 100 to 1000 times greater in the galaxies selected in the infrared than in the disks of normal galaxies.

Eagles, S. A.↗
NASA NTRS1987

Ground-based 1- to 32-microns observations of ARP 220: Evidence for a dust-embedded AGN?

New observations of the 10 and 20 micron size of the emission region in Arp 220 are presented. Also given are ground based photometry from 1 to 32 micron including measurements of the strength of the silicate feature at 10 micron. The results show that the 20 micron size of Arp is smaller than 1.5 arcsec (500 pc); comparison of IRAS and ground based observations show that IRAS 12 micron flux measured with a large arcmin beam is the same as that seen from the ground with a 3 arcsec aperture. At 10 micron a deep silicate absorption feature is seen that corresponds to a visual extinction of about 50 mag. These results suggest that a very significant portion of the 10 to the 12th power L sub 0 infrared luminosity from Arp 220 comes from a region less than or of the order of 500 pc in diameter. When these results are combined with recent measurement of a broad Brackett alpha line by DePoy and an unresolved 2.2 micron source by Neugebauer, Matthews and Scoville, a very attractive possibility for the primary luminosity source Arp 220 is a dust embedded compact Seyfert type nucleus.

Becklin, E. E.↗
NASA NTRS1986

The 2 micron spectrum of NGC 6240 - Evidence for more than a starburst

The exceptionally luminous interacting galaxy NGC 6240 has been studied with infrared spectroscopy and photometry. Emission lines of molecular hydrogen and the Paschen-alpha line of ionized hydrogen have been detected. Broad-band 10 micron and 20 micron emission has also been observed. Combined with previous optical spectroscopy and results from IRAS, the observations show that NGC 6240 cannot be explained along the lines of a superstarburst of massive stars such as seen in M82. It may be more easily understood in terms of an active nucleus similar to Seyfert galaxies.

Depoy, D. L.↗
NASA NTRS1985

The infrared size of IRc2/KL and its structure on an arcsecond scale

Small-aperture diffraction-limited scans of IRc2/KL at 7.8 and 12.5 microns are discussed. These scans, which were made at several position angles, spatially resolve the region within a 250 AU radius of this source, which is thought to be a newly formed luminous star undergoing heavy mass loss. IRc2 is found to have a pronounced elongation. The shape and orientation of this extended structure is similar to that seen on a larger scale in low-excitation molecular transitions, and is very similar to the distribution of H2O 'shell' masers. The size of the object may be reconciled with its dereddened blackbody temperature and total luminosity of 0.00001 solar luminosities (which is appropriate to OMC1) by the presence of small-scale structure. The observations thus support the idea that IRc2 is the primary luminosity source for OMC1. New astrometric measurements indicate that the 12.5 microns peak of IRc2 is coincident with the positions of the two bright SiO masers to within 0.3 arcsec.

Lester, D. F.↗
NASA NTRS1985

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.↗
NASA NTRS1985

Multiaperture infrared photometry of the nuclei of spiral galaxies

Results of a multiaperture, 2.2- and 10-micron photometric survey of the nuclei of 25 nearby, low-inclination spiral galaxies are presented. The 10-micron nuclear luminosities, attributed to thermal reradiation by dust in regions of active star formation, and 10-micron/2.2-micron nuclear flux ratios, are examined as a function of the slope of 2.2-micron growth curve. No correlation is seen, suggesting that the contribution of young, red giants and supergiants to the near-infrared light of spiral nuclei is small. These results indicate that the 2.2-micron light of galaxies in the present sample is not radically altered by starbursts.

Cizdziel, P. J.↗
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

A luminous 3 kiloparsec infrared disk in NGC 1068

A 10 micron map of the Seyfert galaxy NGC 1068 and airborne measurements of its angular extent in the far-infrared are presented. It is shown that the infrared emission originates primarily from two physically distinct regions; approximately half of the total infrared luminosity of 3 x 10 to the 11th solar luminosities is associated with the Seyfert nucleus and half with a 3 kpc (35 arc sec) diameter disk surrounding it. It is argued that the disk component of infrared emission originates from an extended but heavily obscured burst of star formation which resembles those seen in some non-Seyfert galaxies. This high-luminosity disk is distinguished more by its large size than by its high surface brightness. On the basis of current evidence it cannot be concluded that the high disk luminosity in NGC 1068 is causally related to its Seyfert activity.

Telesco, C. M.↗
NASA NTRS1984

The Kleinmann-Low nebula - An infrared cavity

High resolution 20-30 micron IR continuum emission observations of the Orion-KL region, combined with the recent 3.8-micron polarization results of Werner et al. (1983), yield a self-consistent model of the central 30 arcsec of the nebula. In this model, the geometry of the KL nebula is that of a clumpy cavity rather than that of a number of isolated objects. The cavity is centered on IRc2, which is confirmed to be the source of nearly all the region's luminosity. The model which best fits all the IR and radio data implies that the other peaks in th KL nebula are irregularities in the material at the edge and surrounding the cavity, rather than individual self-luminous sources.

Becklin, E. E.↗
NASA NTRS1982

The infrared emission from the elliptical galaxy NGC 1052

Multi-aperture IR photometry of the elliptical galaxy NGC 1052 shows that its IR excess is confined to a region smaller than 2 arc sec (300 pc) in diameter coincident with the visible nucleus. It is suggested that the emission in the 5-20 micron range arises from dust heated by the nonthermal source seen at other wavelengths.

Becklin, E. E.↗
NASA NTRS1981

The albedo and diameter of 1862 Apollo

Infrared thermal emission measurements are reported of 1862 Apollo, which is the type example of an earth-crossing asteroid. A geometric albedo of 0.21 plus or minus 0.02 is derived which is within the albedo range of the S class of asteroids. The effective diameter was observed to vary with rotation from 1.2 plus or minus 0.1 to 1.5 plus or minus 0.1 km.

Lebofsky, L. A.↗
NASA NTRS1981

The multiple infrared source GL 437

Infrared and radio continuum observations of the multiple infrared source GL 437 show that it consists of a compact H II region plus two objects which are probably early B stars undergoing rapid mass loss. The group of sources appears to be a multiple system of young stars that have recently emerged from the near side of a molecular cloud. Emission in the unidentified 3.3 micron feature is associated with, but more extended than, the emission from the compact H II region; it probably arises from hot dust grains at the interface between the H II region and the molecular cloud.

Wynn-Williams, C. G.↗