Interstellar H3+

Enigma of H3 + in Diffuse Interstellar Clouds

1. INTRODUCTION H 3 + is of fundamental importance to interstellar chemistry both because it is a hydrogenic species (and >90% of all nuclei in the universe are hydrogen nuclei; see Figure 1) and because it serves as the universal protonator, initiating a chain of ion-neutral reactions that is responsible for the formation of most interstellar molecules. The chemistry of H 3 + in dense (molecul...

H3 in Diffuse Interstellar Clouds: a Tracer for the Cosmic-ray Ionization Rate

Using high-resolution infrared spectroscopywe have surveyed twenty sight lines for H3 absorption. H þ 3 is detected in eight diffuse cloud sight lines with column densities varying from 0:6 ; 10 to 3:9 ; 10 cm . This brings to 14 the total number of diffuse cloud sight lines where H3 has been detected. These detections are mostly along sight lines concentrated in the Galactic plane but are well...

Reactions Involving the Nuclear Spin Modifications of H3 and H2; Implications for the Interstellar Medium

Nuclear Spin Dependence in Reactions of H3 in the Laboratory and the Interstellar Medium By

Hydrogen is the most abundant element in the universe. For this reason, the chemistry of the interstellar medium is largely dominated by the interaction of hydrogenic neutrals and ions. The hydrogen molecule, H2, and the simplest polyatomic ion, H3 , each exist in one of two forms identified as ortho or para, which are defined by their total nuclear spins. These spin modifications have differen...

Interstellar Holography

The dynamic spectrum of a radio pulsar is an in-line digital hologram of the ionised interstellar medium. It has previously been demonstrated that such holograms permit image reconstruction, in the sense that one can determine an approximation to the complex electric field values as a function of Doppler-shift and delay, but to date the quality of the reconstructions has been poor. Here we repo...