Interstellar HDCO: Upper limit and significance as an indicator of interstellar molecule reactions

Journal Article · Wed Oct 01 04:00:00 EDT 1975 · Astrophys. J., v. 201, no. 1, pp. 102-111

DOI:https://doi.org/10.1086/153864· OSTI ID:4099008

Watson, W D; Crutcher, R M; Dickel, J R

Upper limits to the strength of the HDCO (1$sub 11$-1$sub 10$) transition at 5346 MHz are obtained from observations of Cas A, Cloud 4, NGC 2264, DR 21, Orion B, and Sgr B2. The observations are interpreted to yield an upper limit to the abundance ratio HDCO/H$sub 2$CO that is most likely)about 1/ 170. We show that likely pure gas-phase processes (those employing CH$sub 3$+O and CH$sub 3$$sup +$+O) which have been proposed to form interstellar formaldehyde must also produce an enhanced HDCO/H$sub 2$CO ratio. Our observations indicate that the required enhancement probably does not occur. Formaldehyde is observed widely throughout the Galaxy and apparently requires a more complicated formation process than the simplest molecules. If gas reactions to produce formaldehyde cannot be found, it seems unlikely that the more complex interstellar molecules are produced purely by gas-phase reactions under the low temperature-density conditions where they are observed. (AIP)

• Research Organization: Departments of Physics and Astronomy, University of Illinois
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-018171
• OSTI ID: 4099008
• Journal Information: Astrophys. J., v. 201, no. 1, pp. 102-111, Journal Name: Astrophys. J., v. 201, no. 1, pp. 102-111; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

*INTERSTELLAR SPACE-- MOLECULES
640105* --Physics Research--Astrophysics & Cosmology-- Galaxies
CARBON COMPOUNDS
DEUTERIUM COMPOUNDS
HYDROGEN COMPOUNDS
MILKY WAY
N56500* --Physics (Astrophysics & Cosmology)--Galaxies
OXYGEN COMPOUNDS
RADIOWAVE RADIATION