HCO is frequently discussed in conjunction with PDRs (photo
L. E. Snyder, J. M. Hollis, and B. L. Ulich,
reported on the
Radio Detection of the Interstellar Formyl Radical
Astrophys. J. 208, L91L94 (1976).
The NRAO 11 M dish was used to detect the strongest HFS components (J = 1.5 0.5, F = 2 1) of the 101 000 transition near 86.671 GHz in emission toward sources showing carbon recombination lines: W3, W51, NGC 2024C, and K3-50. Please note that the NGC 2024 position was stated more precisely in the follwing paragraph.
J. M. Hollis and E. Churchwell
looked at the
Comparison of C+ Distributions with new Interstellar Sources of HCO Emission
Astrophys. J. 271, 170744 (1983).
The same HFS component was observed with the same instruments as above. New detections were made at a position close to Sgr B2(OH) and in DR21C.
L. E. Snyder, M. S. Schenewerk, and J. M. Hollis,
reported on the
Observations of Several new Transitions of Interstellar HCO
Astrophys. J. 298, 360368 (1985).
Observations of the 202 101 and 303 201 transitions were made. In addition,
Å Hjalmarson, M. S. Schenewerk, and L. E. Snyder,
Interstellar HCO Detection of the Missing 3 Millimeter Quartet
Astrophys. J. 298, L71L74 (1986).
H. S. Liszt, J. Pety, M. Gerin, and R. Lucas,
detected with the IRAM 30 m telescope
HCO, c-C3H and CF+: three new molecules in diffuse, translucent and “spiral-arm” clouds
Astron. Astrophys. 564, Art. No. A64 (2014).
The formyl radical is also found quite commonly toward
certain types of dark clouds, as found, e.g., by
M. Agúndez, J. Cernicharo, and M. Guélin
in the report on the
Discovery of Interstellar Ketenyl (HCCO), a Surprisingly Abundant Radical
Astron. Astrophys. 577, Art. No. L5 (2015).