Engineering topics

Longmore, A. J.

Publications and source records attributed to Longmore, A. J..

4 records

NASA NTRS1990

Subarcsecond resolution observations of the central parsec of the Galaxy at 2.2 microns

Four separate lunar occultations of the Galactic center in the infrared K-band have been observed, and the results are used to estimate the size of the sources and to derive photometry. It is found that IRS 16NE, 16NW, and IRS 29 are smaller than about 510 AU and IRS 16SW-W and C are smaller than 85 AU. All sources brighter than K = 10 mag in the central pc are smaller than 510 AU and therefore seem to be stars. IRS 7 is smaller than about 100 AU. IRS 1W and 13, resolved into pairs of stars, are probably the exciting stars for these H II regions. The shape of the differential luminosity function of the stars in the central sq pc is similar to that of stars in the central 150 sq pc. There is a steady increase in star density toward the central few arcsec of the Galaxy.

Simon, M.↗

NASA NTRS1990

Discovery of five pre-main-sequence binaries in Taurus

The progress of an infrared K band lunar occultation search for binaries among premain-sequence stars is reported. From the fall of 1986 to the fall of 1989, 13 objects have been observed, all in the Taurus star-forming region. Five new binaries have been discovered: DF Tau, DI Tau, FS Tau (Haro 6-5) A, FV Tau (Haro 6-8), and FW Tau, with projected separations ranging from 0.01 to 0.57 arcsec. Including results reported previously, a total of 31 objects, 21 in Taurus and 10 in Ophiuchus, have been surveyed and nine double systems have been found. The detected binary frequency (0.29) seems consistent with that of the solar-type main-sequence field stars.

Chen, W. P.↗

NASA NTRS1984

Continuum emission from the nucleus of NGC 1275

Submillimeter and multi-aperture near-infrared observations of NGC 1275 are presented. The luminosity of the extended stellar component within the near-infrared apertures has been determined, and consequently also the 1.25-3.5 micron energy distribution of the unresolved nucleus. The 1 micron-30 cm energy distribution is reviewed. It is argued that the most likely origin for the 100 micron-30 cm radiation is synchrotron emission, with this nonthermal component also contributing significant flux at 10 microns. No observations are yet available which make it possible to distinguish unequivocally between a thermal (dust) and synchrotron emission mechanism in the 1-10 micron region, but the evidence marginally favors a nonthermal origin.

Longmore, A. J.↗

NASA NTRS1974

Infrared emission by dust in NGC 1068 and three planetary nebulae

Photometric observations of NGC 1068, NGC 7027, IC 418, and BD + 30.3639 deg between 5 and 27 microns are reported. The observations are explained as thermal radiation from a form of dust that shows spectral features, but which has not yet been identified, and resembles that in the carbon-rich RV Tauri star AC Her. Arguments are deduced for its being a condensate from a carbon- and nitrogen-rich gas in an excited environment.

Jameson, R. F.↗