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Science  11 Feb 2000:
Vol. 287, Issue 5455, pp. 973
DOI: 10.1126/science.287.5455.973h

In “Spectroscopic detection of molecular hydrogen frozen in interstellar ices” published by Science 15 October 1993 (Reports, p. 400), we reported the detection of solid molecular hydrogen (H2) in the interstellar medium of the ρ Ophiuchus dark cloud. Our report was based on our measurement of a broad absorption feature centered at 2.42 micrometers toward the obscured infrared source WL5; we attributed the feature to a combination of solid methanol (CH3OH) and solid H2. Recently, we obtained a lower resolution spectrum of WL5, which included the same spectral region as our 1993 spectrum but covered a broader range of wavelengths. In it are a number of bands of carbon monoxide (CO), which probably arise in the photosphere of WL5 or possibly in a hot and dense circumstellar disk. It is clear that the spectral feature which we attributed to solid hydrogen and methanol corresponds to the 6-4 band of CO, because both the 5-3 and 7-5 bands of CO, which lie adjacent to the 6-4 band, are present at comparable strengths. Although this does not preclude the presence of frozen H2, most or all of the absorption we reported is due to CO and thus we retract our claimed detection of solid H2 and solid CH3OH. We thank J. P. Emerson and T. C. Teixeira for calling this possibility to our attention.

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