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Campbell, M. F.

Publications and source records attributed to Campbell, M. F..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Models of far-IR sources at W3-IRS4 and W3-IRS5

Far-IR continuum maps made with the KAO of W3 at 47 and 95 micrometers show peaks identified with the mid-IR sources IRS4 and IRS5 and extended emission identified with the radio source W3A. We have taken the steepest radial scan profiles from the peaks at IRS4 and IRS5 to represent the objects as spherical clouds. Spherically symmetric models were created in an attempt to match the observed profiles. Radiative transfer dust cloud models heated by central protostars or stars do not match extended emission in the 47 micrometers scan profile for any assumed density distribution for either source. However, both sources can be approximately fit by power law density profiles and ad hoc temperature profiles which are much less steep than those by the single source radiative transfer models. One possible physical explanation for the shallow temperature gradients suggested by the data is heating by a distribution of luminosity sources.

Campbell, M. F.↗
NASA NTRS1990

Multiwavelength observations of two B-star nurseries - DR 15 and DR 20

New observations of DR 15 and 20 are reported as part of a study of compact H II regions in the Cyg X region. The radio and FIR data for these objects, when combined with (C-12)O maps, IRAS imagery, and optical photographs, provide new insights into the structure of this complex region and the nature of the star-formation process there. The observations show that DR 15 may consist of one or two B0 ZAMS stars whose H I regions have formed a low-density cavity within a molecular cloud. DR 20 appears to be a young OB cluster. The cluster is dominated by an O5.5 ZAMS star and also contains an approximately 3500-yr-old B0 star appearing as a compact H II region, along with weak FIR sources that may be B0-star candidates.

Odenwald, S. F.↗
NASA NTRS1989

The compact far infrared emission from the young stellar object IRAS 16293-2422

High resolution far IR observations at 50 and 100 microns were made of the young stellar object (YSO), IRAS 16293-2422. The observations are part of a systematic high resolution study of nearby YSO's. The purpose is to obtain resolution in the far IR comparable to that at other wavelengths. Until recently, the high resolution that has been available in the far IR has been from either IRAS (angular resolution of approx 4 min) or the KAO using standard FIR photometry (approx 35 sec). With scanning techniques, it is possible to obtain 10 sec resolution on bright sources. Such a resolution is necessary to better determine the physical conditions of the YSO, and to compare with model of star formation. In order to better constrain the models for the source, the YSO was observed at both 50 and 100 microns on several flights in 1988 April from the KAO. Estimates are presented of the size both along the major and minor axis of the disk, as well as estimates of the dust temperature and 100 micron opacity for the YSO.

Butner, Harold M.↗
NASA NTRS1989

High spatial resolution far-infrared scans of W3(OH)

The strong far-infrared continuum source associated with the OH maser-ultracompact H II region W3(OH) was observed from the Kuiper Airborne Observatory in order to determine its size at 50 and 100 microns. Maximum entropy deconvolutions of the slit scans made in orthogonal directions across the source show it to be approximately circular with FWHM sizes of 8 arcsec and 13 arcsec at 50 and 100 microns, respectively. For these sizes, W3(OH) is optically thick in the far-infrared. A spherically symmetric, dusty molecular cloud model is developed to fit the data.

Campbell, M. F.↗
NASA NTRS1985

Far-infrared and submillimeter survey of the galactic center and nearby galactic plane

Maps are presented with 12-arcmin resolution of the Galactic Center and adjacent galactic plane, from l(Pc) = 359 deg to l(Pc) = 5 deg. The data were obtained with the Steward Observatory's cryogenically-cooled, balloon-borne telescope. The data are from channels filtered for a bandpass of 70 to 110 microns and for a longpass of wavelength greater than 80 microns. For the typical effective temperature of 25 K of a galactic H II region at this spatial resolution, the effective wavelengths of the channels are 93 microns and 145 microns. Continuous emission is mapped along the galactic plane in both wavelengths. There are two contrasts between the immediate vicinity of SgrA l(Pc) smaller than 1 deg, and the galactic plane in general. Firstly, for l(Pi) greater than 1 deg the galactic plane narrows dramatically at 93 microns, while retaining its width at 145 microns. Secondly, the individual sources at l(Pc) (which are associated with H II regions) have greater peak brightness in the 145-micron channel than the 93-micron channel, while SgrA has approximately equal peak brightness in each. The maps demonstrate the importance of submillimeter wavelengths to galactic surveys.

Campbell, M. F.↗
NASA NTRS1984

Far-infrared and submillimeter survey of the galactic plane from l = 11.5 deg to l = 17.5 deg

Medium resolution (11 min) maps of the galactic plane are presented from l = 11.5 deg to l = 17.5 deg at wavelengths of 93 microns, 154 microns, and 190 microns. The maps are interpreted in terms of the temperature and spatial structure of diffuse far-infrared/submillimeter sources associated with evolved H II regions and a continuous ridge of galactic emission. The emission regions are found to be more extended at the longer wavelengths which implies that there must be a range of dust temperatures in the sources. The properties of the galactic ridge are similar to those of the sources.

Campbell, M. F.↗
NASA NTRS1984

Far-infrared sources in the vicinity of the supernova remnant W28

The W28 supernova remnant molecular cloud complex has been surveyed in the 40-250 micron spectral range with a three-sigma sensitivity of 100-165 Jy per beam. Only two sources have been found. One, located near the center of the SNR, has a luminosity of 54,000 solar luminosities and can be identified with the thermal radio source G6.6-0.1. The energizing source is probably an O-type ZAMS star. The second source, which is near the boundary of the SNR at a sharp gradient of OH absorption, has a luminosity of 6000 solar luminosities and has no radio counterpart. It is best explained as a B1 ZAMS star or a pre-main sequence object presumably formed from the impact of an expanding SNR with a molecular cloud. No far-IR emission is observed at the position of the CO molecular cloud, which seems to have been impacted by the SNR.

Odenwald, S. F.↗
NASA NTRS1982

Far-infrared sources in Cygnus X - An extended emission complex at DR 21 and unresolved sources at S106 and ON 2

A new map of 90 micron emission with 15 arcmin resolution is presented of a complex of sources approximately centered on DR 21. The emission is primarily from diffuse sources. Comparison of the 90 micron map with maps at 20 microns and 2.7 GHz leads to a model for diffuse sources in which there are at least two components of interstellar dust, one at 40 K and one at 165 K, responsible for the 90 micron and 20 micron emission respectively. Both components and the ionized gas must be mixed together; dust in an outer neutral shell is relatively unimportant for these sources. The diffuse sources have small infrared excesses and weak temperature gradients. Unresolved, probably compact, sources were observed at S106 and ON 2 and are briefly discussed.

Campbell, M. F.↗
NASA NTRS1981

An extended far-infrared emission complex at IC 1318b and IC 1318c

A map of extended 90 micron emission with 15 arcmin resolution is presented for sources centered on IC 1318b and c. A strong correlation is found between far-infrared emission and radio continuum emission, although a comparison of far-infrared and CO molecular line maps shows no similarity. Extended far-infrared sources have inferred gas densities, which implies that far-infrared emitting dust is mixed with the ionized gas. Far-infrared emission from dust is also observed in the nonthermal radio source DR 4 which is part of a supernova remnant, and the data are compatible with a core-halo model for the compact source DR 7.

Campbell, M. F.↗
NASA NTRS1980

The large-scale far-infrared structure of W3 and W4

The large-scale structure of the giant H II region complex W3/W4 has been mapped in two wavelength bands covering 60 to 120 microns at an angular resolution of 12 arc min. The only region of strong emission observed lies along a molecular ridge at an ionization/shock front in the sources. This structure supports the idea that a new generation of stars formed after neutral material ahead of the front became gravitationally unstable. These embedded stars are dominating the energetics of the molecular/infrared cloud, although the visible OCl 352 cluster in neighboring IC 1805 may supply much of the heating flux to the fainter regions. A simple model relating the far-infrared and CO emission is presented.

Thronson, H. A., Jr.↗
NASA NTRS1980

Far-infrared survey of Cygnus X

Results of a new far-infrared survey of Cygnus X conducted with 12-arcmin resolution are presented. Forty-nine sources were observed, 39 of them for the first time. Associations are made with sources from mid-infrared, radio continuum, and CO radio line surveys.

Campbell, M. F.↗
NASA NTRS1979

Infrared observations of NGC 2071/IRS/ and AFGL 490 - Two low-luminosity young stars

Infrared observations are presented of two compact sources associated with molecular clouds. Photometry from 2 to 200 microns of the source associated with an OH maser in NGC 2071, OH 205.1-14.1, shows a steep increase in flux from 2 to 50 microns. Scans at several wavelengths fail to resolve the source. Photometry at 50-200 microns of the other object, GL 490, when combined with earlier 2-20-micron spectrophotometry, shows an infrared energy distribution that is much broader than that of the NGC 2071 source. Both sources are interpreted as young, possibly pre-main-sequence objects with differences in energy distributions due principally to differences in the distribution of circumstellar matter.

Harvey, P. M.↗
NASA NTRS1979

Far-infrared observations of the Carina I and II H II regions

Far-infrared (35-175 microns) mapping and photometry are presented of the Carina I and II H II regions in the Carina Nebula (NGC 3372). The far-infrared source associated with Carina I has a half-power width of 2.7 arcmin and has no compact high-surface-brightness condensations, unlike many northern H II regions such as W51 or W49. The peak emission region is offset from the radio continuum peak in the direction of a dust lane to the west. It is proposed that the H II regions and far-IR source are both powered by the O-star cluster Tr 14 about 4 arcmin to the east. The H II region then represents an ionization front at the boundary of the dense cloud west of Tr 14, and the far-infrared emission is due to thermal radiation from the heated dust in the dark cloud. A similar model may also be applicable to the Carina II region.

Harvey, P. M.↗
NASA NTRS1979

A cryogenically-cooled, balloon-borne far infrared survey telescope

The design and performance of the Arizona cryogenically-cooled, balloon-borne, multiband far infrared survey telescope are described. The 40 cm Cassegrain telescope is completely contained in a liquid helium dewar. The focal plane array consists of Fabry optics and four detectors which each have a 12 arc minute field of view. Both photoconductive and bolometer detectors are utilized at effective wavelengths of 20, 80, 100 and 150 microns. In 1977 the telescope was used to make multicolor large scale maps of 70 square degrees in the Cygnus X region and the W3 region.

Campbell, M. F.↗
NASA NTRS1978

Star formation in the NGC 7129 region - A CO molecular-line and far-infrared continuum study

Results are presented for a joint radio/IR study of the region around NGC 7129, a reflection nebula seen against a large dark cloud. The results reported include high-angular-resolution (C-12)O and (C-13)O line measurements, high-angular-resolution observations in the range from 35 to 200 microns, and observations at 10 to 20 microns of selected objects in the nebula. Important constraints are placed on the total stellar luminosities, dust densities and temperatures, and heating and cooling processes occurring in the nebula. Specifically, it is found that: (1) the (C-13)O and dust column densities increase significantly from west to east across the nebula; (2) the (C-13)O column density in the vicinity of the two brightest visible stars decreases relative to the column density north and south of those stars; (3) kinetic temperature increases along the whole boundary of the nebulosity; and (4) the strongest far-IR source in NGC 7129 is coincident with the pre-main-sequence star LkH-alpha 234.

Bechis, K. P.↗
NASA NTRS1978

Strong far-infrared emission from a compact source in sharpless 140

High-spatial-resolution observations of S140 are presented at wavelengths from 35 to 175 microns. A single strong far-infrared source has been found coincident with a compact near-infrared and H2O maser source and the center of a molecular cloud. The far-infrared spectrum suggests either significant absorption in the 20-micron region or a two-temperature dust structure. The infrared luminosity of approximately 20,000 suns is comparable to that of a late O or early B star, although no radio continuum flux has been seen from this object. The source is quite likely a dust-embedded protostar.

Harvey, P. M.↗