Showing papers by "Daniel Y. Gezari published in 1994"
01 Jan 1994
TL;DR: In this paper, a 20.0 µm image of the core of the Sgr A West complex was used to detect the presence of a 20 µm point source in a region of weak emission on the edge of the extended ridge known as the "east-west bar".
Abstract: We have made 20.0 µm imaging array observations of the core of the Sgr A West complex in an attempt to detect emission from Sgr A*. An improved upper limit at 20 µm further constrains models for the emission mechanism and structure of Sgr A* (e.g. Zylka et al. 1992). Simple visual inspection of the 20 µm array image shows no indication of any 20 µm point source at the position of Sgr A*. In this case establishing an upper limit is complicated by the fact that Sgr A* is not located in blank sky, but lies in a region of weak emission on the edge of the extended ridge known as the “east-west bar” where the 20.0 µm image brightness is 1.2 Jy arcsec-2 (4 times the 1σ noise level). An additional concern is that if Sgr A* lies behind the ridge along the line-of-sight, extinction by dust in the intervening ridge could introduce an additional small correction factor.
5 citations
01 Jan 1994
TL;DR: In this article, the authors investigated the luminosity of the BN/KL infrared complex, using array images at nine wavelengths between 4.8 and 20μm, and found a much lower luminosity for IRc2 than the generally accepted value.
Abstract: We have reconsidered the energetics of the BN/KL infrared complex, using array images at nine wavelengths between 4.8 and 20μm, and find a much lower luminosity for IRc2 than the generally accepted value. The new observations resolve 1arcsec structure throughout the region, including several new compact sources within a few arcsec of IRc2 and significant details imaged in the 9.7μm silicate feature. Together with other recent work, the results suggest that luminous stars associated with three compact HII regions found within BN/KL, rather than IRc2, may be the more significant luminosity sources for the complex.
2 citations
01 Jan 1994
TL;DR: In this article, the authors investigated the luminosity of the BN/KL infrared complex, using array images at nine wavelengths between 4.8 and 20JLm, and found a much lower luminosity for IRc2 than the generally accepted value.
Abstract: We have reconsidered the energetics of the BN /KL infrared complex, using array images at nine wavelengths between 4.8 and 20JLm, and find a much lower luminosity for IRc2 than the generally accepted value. The new observations resolve larcsec structure throughout the region, including several new compact sources within a few arcsec of ffic2 and significant details imaged in the 9.7JLm silicate feature. Together with other recent work, the results suggest that luminous stars associated with three compact HII regions found within BN/KL, rather than ffic2, may be the more significant luminosity sources for the complex.
1 citations
01 Jan 1994
TL;DR: In this paper, a mid-infrared array camera system was designed for high-background 5-18 μm general astronomical imaging observations and the electronic and optical design of the camera, its photometric characteristics, examples of observational results, and the requirements for imaging in both high-and low-background solar applications are discussed.
Abstract: The anticipated requirements and operating conditions are considered for using a mid-infrared array camera in broad-and narrow-band solar imaging observations. The array camera system was designed for high-background 5–18 μm general astronomical imaging observations. The electronic and optical design of the camera, its photometric characteristics, examples of observational results, and the requirements for imaging in both high-and low-background solar applications are discussed.
TL;DR: In this article, the luminosity of the BN/KL infrared complex was investigated using array images at nine wavelengths between 4.8 and 20 μm, and it was shown that luminous stars associated with three compact HII regions, rather than IRc2, may be the more significant luminosity sources for the complex.
Abstract: We have reconsidered the energetics of the BN/KL infrared complex, using array images at nine wavelengths between 4.8 and 20 μm, and find a much lower luminosity for IRc2 than the generally accepted value. The new observations resolve larcsec structure throughout the region, including several new compact sources within a few arcsec of IRc2 and significant details imaged in the 9.7 μm silicate feature. Together with other recent work, the results suggest that luminous stars associated with three compact HII regions found within BN/KL, rather than IRc2, may be the more significant luminosity sources for the complex.
01 Jan 1994
TL;DR: The Atlas of Mid-Infrared Astronomical Sources (Atlas) as discussed by the authors is a collection of images collected by the Infrared Array Camera astronomy applications program at NASA/Goddard Space Flight Center.
Abstract: Array camera images of bright 5 – 20µm astronomical objects sources are being assembled into an Atlas of Mid-Infrared Astronomical Sources. The Atlas has been conceived as a means of making available, in a timely manner, the observational results of our Infrared Array Camera astronomy applications program at NASA/Goddard Space Flight Center. This first release of images consists primarily of bright, extended galactic sources, but also includes solar system and extragalactic objects. The data are presented in both image and contour map formats. An appendix contains a partial survey of Solar System objects. Examples of the Atlas image data are given in Figure 1 and Color Plates 1 – 4.