Detection of H+3 in interstellar space

THE H+3 ion is widely believed to play an important role in interstellar chemistry, by initiating the chains of reactions that lead to the production of many of the complex molecular species observed in the interstellar medium1–5. The presence of H+3 in the interstellar medium was first suggested6 in 1961, and its infrared spectrum was measured7 in the laboratory in 1980. But attempts8–11 to detect it in interstellar space have hitherto proved unsuccessful. Here we report the detection of H+3 absorption in the spectra of two molecular clouds. Although the present results do not permit an accurate determination of the H+3 abundances, these ions appear nevertheless to be present in sufficient quantities to drive much of the chemistry in molecular clouds. It should soon be possible to obtain more accurate measurements, and thus better quantify the role of ion–neutral reactions in the chemical evolution of molecular clouds.

[1]  William D. Watson,et al.  The Rate of Formation of Interstellar Molecules by Ion-Molecule Reactions , 1973 .

[2]  J. Black,et al.  Molecule formation in the interstellar gas , 1976 .

[3]  M. Allen,et al.  Hot and cold gas toward young stellar objects , 1990 .

[4]  J. Greenberg,et al.  Discovery of solid formaldehyde toward the protostar GL 2136 : Observations and laboratory simulation , 1996 .

[5]  Edward B. Jenkins,et al.  Ultraviolet studies of the interstellar gas , 1975 .

[6]  J. Tennyson,et al.  What astronomy has learned from observations of , 1994 .

[7]  J. Tennyson,et al.  Detection of H3(+) from Uranus , 1993 .

[8]  A. Sternberg,et al.  The Abundance of H 3 + Ions in Dense Interstellar Clouds , 1987 .

[9]  J. Tennyson,et al.  Identification of features due to H3 + in the infrared spectrum of supernova 1987A , 1992, Nature.

[10]  J. Maillard.  Recent results in astronomical Fourier transform spectroscopy. , 1995 .

[11]  Takeshi Oka,et al.  Detection of H3(+) infrared emission lines in Saturn , 1993 .

[12]  T. Oka.  A search for interstellar H+3 , 1981, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[13]  E. W. McDaniel,et al.  On the Possible Occurence of H 3 ^{+} in Interstellar Space. , 1961 .

[14]  Eric Herbst,et al.  The formation and depletion of molecules in dense interstellar clouds , 1973 .

[15]  T. Geballe,et al.  An infrared spectroscopic search for the molecular ion H3( , 1989 .

[16]  J. H. Waite,et al.  Detection of H3+ on Jupiter , 1989, Nature.

[17]  W. D. Watson.  Interstellar molecule reactions , 1976 .

[18]  V. Anicich,et al.  A survey of bimolecular ion-molecule reactions for use in modeling the chemistry of planetary atmospheres, cometary comae, and interstellar clouds , 1986 .

[19]  A. Tielens,et al.  Interstellar solid CO: polar and nonpolar interstellar ices. , 1991, The Astrophysical journal.

[20]  E. Herbst,et al.  Fractional abundances of molecules in dense interstellar clouds: A compendium of recent model results. , 1996 .

[21]  T. Amano.  Is the dissociative recombination of H3+ really slow? A new spectroscopic measurement of the rate constant , 1988 .

[22]  Takeshi Oka,et al.  Observation of the infrared spectrum of H 3 , 1980 .

[23]  Hiroko Suzuki,et al.  Molecular Evolution in Interstellar Clouds. I : Ion Chemistry in Dense Clouds , 1979 .

[24]  J. Black,et al.  Interstellar absorption lines toward NGC 2264 and AFGL 2591 - Abundances of H2, H3(+), and CO , 1990 .