Abstract
Konovalenko and Sodin1 recently reported the detection of an absorption line at a frequency of 26.131 MHz towards Cassiopeia A and attributed the line to the 26.127 MHz F = 5/2 → 3/2 hyperfine transition of 14N. The difference in frequency corresponds to a radial velocity of –40 km s–1, which is compatible with the mean velocity of the Perseus arm H I absorption lines seen towards Cas A. However, to explain the strength of the line, Konovalenko and Sodin require (N/H) = 8 × 10–3 compared with the cosmic ratio of 1.2 × 10–4. An anomalous abundance of this magnitude would have substantial impact on ideas about galactic nucleosynthesis. We suggest here that the line is a 631α recombination line due to neutral atoms of heavy elements—either carbon atoms in the H I clouds or possibly heavier atoms (Mg, Ca, Fe) in hot (∼104 K) ionized gas along the line of sight to Cas A.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Konovalenko, A. A. & Sodin, L. G. Nature 283, 360–361 (1979).
Menzel, D. H. Astrophys. J. Suppl. 18, 221–246 (1969).
Greisen, E. W. Astrophys. J. 184, 363–377 (1973).
Shuter, W. L. H. & Verschuur, G. L. Mon. Not. R. astr. Soc. 127, 387–403 (1964).
Troland, T. H. & Heiles, C. Astrophys. J. 194, 43–48 (1974).
Scoville, N.Z., Irving, W.M., Wannier, P.G. & Predmore, C.R. Astrophys. J. 216, 320–328 (1977).
Shavers, P. A. Astr. Astrophys. 49, 1–16 (1976).
Ungerechts, H. & Walmsley, C. M. Astr. Astrophys. 80, 325–328 (1979).
Gee, C. S., Percival, I. C., Lodge, F. G. & Richards, D. Mon. Not. R. astr. Soc. 175, 209–215 (1976).
Watson, W. D., Western, L. R. & Christensen, R. B. Astrophys. J. (in the press).
Griem, H. R. Spectral Line Broadening by Plasmas, 260 (Academic, New York, 1974).
Shavers, P. A. Astr. Astrophys. 46, 127–130 (1976).
Brocklehurst, M. & Leeman, S. Astrophys. Lett. 9, 35–36 (1971).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Blake, D., Crutcher, R. & Watson, W. Identification of the anomalous 26.131-MHz nitrogen line observed towards Cas A. Nature 287, 707–708 (1980). https://doi.org/10.1038/287707a0
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/287707a0
This article is cited by
-
The modern radio astronomy network in Ukraine: UTR-2, URAN and GURT
Experimental Astronomy (2016)
-
Carbon recombination lines from the Galactic plane at 34.5 & 328 MHz
Journal of Astrophysics and Astronomy (2001)
-
Observation of highly excited radio recombination lines towards Cassiopeia A
Nature (1985)
-
Astronomical spectroscopy: Interstellar space contains the largest encountered atoms
Nature (1985)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.
