Brianphelan

Interstellar Formaldehyde

Initial Discovery

Formaldehyde was first discovered in 1969 by L. Snyder et al. using the National Radio Astronomy Observatory. H₂CO was detected by means of the 1₁₁ - 1₁₀ ground state rotational transition at 4830 Mhz [1].

Subsequent Discoveries

Formaldehyde was the first polyatomic organic molecule detected in the interstellar medium and since its initial detection has been observed in many regions of the galaxy [2]. The isotopic ratio of [¹²C]/[¹³C] was determined to be about or less than 50% in the galactic disk [3]. Formaldehyde has been used to map out kinematic features of dark clouds located near Gould's Belt of local bright stars [4]. In 2007, the first H₂CO 6 cm maser flare was detected [7]. It was a short duration outburst in IRAS 18566 + 0408 that produced a line profile consistent with the superposition of two Gaussian components, which leads to the belief that an event outside the maser gas triggered simultaneous flares at two different locations [7]. Although this was the first maser flare detected, H₂ masers have been observed since 1974 by Downes and Wilson in NGC 7538 [8]. Unlike OH, H₂O, and CH₃OH, only five galactic star forming regions have associated formaldehyde maser emission, which has only been observed through the 1₁₀ → 1₁₁ transition [8].

References

1. Snyder, L. E., Buhl, D., Zuckerman, B., & Palmer, P. 1969, Phys. Rev. Lett., 22, 679

2. Zuckerman, B.; Buhl, D.; Palmer, P.; Snyder, L. E. 1970, Astrophysical Journal, 160, 485

3. Henkel, C.; Guesten, R.; Gardner, F. F. 1985, Astronomy and Astrophysics, 143, 148

4. Sandqvist, A.; Tomboulides, H.; Lindblad, P. O. 1988, Astronomy and Astrophysics, 205, 225

5. Woon, D. E. 2002, Astrophysical Journal, 569, 541

6. Tudorie, M. _et al_. 2006, Astronomy and Astrophysics, 453, 755

7. Araya, E. _et al_. 2007, Astrophysical Journal, 654, L95

8. Hoffman, I. M.; Goss, W. M.; Palmer, P. 2007, Astrophysical Journal, 654, 971

9. Muller, H. S. P. _et al_. 2000, Journal of Molecular Spectroscopy, 200, 143

10. S. Brunken _et al_. 2003, Physical Chemistry Chemical Physics, 5, 1515

11. W. A. Schutte _et al_. 1993, Science, 259, 1143

12. W. A. Schutte _et al_. 1993, Icarus, 104, 118