We show that a typical star is unlikely to migrate from its galacto-centric radius of birth by more than about 5% over its lifetime. Radial migration, or a secular change in a star’s angular momentum, is caused by stochastic scattering by spiral waves and by dense gas complexes. The expected change in angular momentum is related to the radial action acquired by the star from these processes and...

We use ultraviolet spectra of Capella from the Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer satellites to study interstellar absorption lines from the Local Interstellar Cloud (LIC). Measurements of these lines are used to empirically determine the ionization states of carbon, nitrogen, and silicon in the LIC, for comparison with the predictions of theoretical photoionizati...

Context. The 12C/13C isotope ratio in the interstellar medium (ISM), and its evolution with time, is an important tracer of stellar yields. Spatial variations of this ratio can be used to study mixing in the ISM. Aims. We want to determine this ratio and its spatial variations in the local ISM from CH absorption lines in the optical towards early-type stars. The aim is to determine the average ...

Over the course of its motion through the Galaxy, our solar system has encountered many interstellar environments of varying characteristics. Interstellar medium (ISM) density variations spanning seven orders of magnitude are commonly seen throughout the general Galactic environment, and a sufficiently dense cloud within this range has the potential to dramatically alter the structure of the he...

The isotope ratio Rb/Rb places constraints on models of the nucleosynthesis of heavy elements, but there is no precise determination of the ratio for material beyond the solar system. We report the first measurement of the interstellar Rb isotope ratio. Our measurement of the Rb i line at 7800 for the diffuse gas toward r Oph A yields Å a value of (1 j) that differs significantly from the meteo...

Measurements using the Far Ultraviolet Spectroscopic Explorer (FUSE) show that the gas-phase D/H ratio in the solar neighborhood is highly variable and suggest that the elemental abundance of deuterium in the Galactic disk may be higher than previously thought. We investigate in this Letter the possible consequences of such an enhanced D/H ratio on the deuterium fractionation in singly and mult...

The isotope ratio, Rb/Rb, places constraints on models of the nucleosynthesis of heavy elements, but there is no precise determination of the ratio for material beyond the Solar System. We report the first measurement of the interstellar Rb isotope ratio. Our measurement of the Rb I line at 7800 Å for the diffuse gas toward ρ Oph A yields a value of 1.21 ± 0.30 (1-σ) that differs significantly ...

The Sun's outer atmosphere, or corona, is heated to millions of degrees, considerably hotter than its surface or photosphere. Explanations for this enigma typically invoke the deposition in the corona of nonthermal energy generated by magnetoconvection. However, the coronal heating mechanism remains unknown. We used observations from the Solar Dynamics Observatory and the Hinode solar physics m...