Engineering topics

Goldhaber, D. M.

Publications and source records attributed to Goldhaber, D. M..

4 records

NASA NTRS1988

Neutral atomic carbon in dense molecular clouds

The 370 micron 3P2-3P1 fine-structure line of neutral carbon was detected in seven sources: OMC 1, NGC 2024, S140, W3, DR 21, M17, and W51. Simultaneous analysis of J = 2-1 data and available observations of the J = 1-0 line make it possible to deduce optical depths and excitation temperatures for these lines. These data indicate that both C I lines are likely to be optically thin, and that the ratio of C I to CO column densities in these clouds is typically about 0.1.

Zmuidzinas, J.↗

NASA NTRS1987

New lines of ethylene and a search for methylene in IRC + 10216

Seven new lines in the 10 micron nu7 band of C2H4 have been detected in the highly obscured carbon star IRC + 10216. The line intensities cannot be well described by a single rotational temperature, in contrast to the lines of CH4 and SiH4 previously observed in this source. There are at least three interpretations: the line intensities are variable on a time scale of months and years, C2H4 lines are formed over a region less homogeneous than that of CH4 and SiH4, or ethylene is somewhat nonthermally excited. Regardless, the line intensities indicate an average rotational temperature of 100 K and a column density of about 4 x 10 to the 15th/sq cm, which is approximately 2 x 10 to the -5th times the CO abundance. A search was also made for infrared transitions of CH2, the methylene radical. No lines were detected, but the observational limits are compared with the abundance and radial distribution for CH2 predicted by a model invoking the photodissociation of CH4.

Goldhaber, D. M.↗

NASA NTRS1986

Observations of neutral atomic carbon at 809 GHz

The 3P2-3P1 line at 809 GHz has been observed in four dense molecular clouds: M17, W51, W3, and DR 21(OH). The results indicate excitation temperatures of 30-60 K and optical depths of one or less. This implies that the roughly 10 to the 18th/sq cm lower limit to the C I abundance derived from 492-GHz observations is probably the actual abundance, which gives C I/CO of about 0.1 in dense molecular clouds.

Zmuidzinas, J.↗

NASA NTRS1984

Silane in IRC +10216

Silane has been detected in the gas surrounding IRC +10216. Thirteen absorption lines in the nu-4 band around 917/cm were observed at 0.2 km/s resolution. A lower limit to the radial column density is 2 x 10 to the 15th/sq cm, and the relative strengths of the transitions indicate an average rotational temperature of 173 K.

Goldhaber, D. M.↗