New 3D map shows interstellar gas within 1,000 light-years from the sun

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Washington, Feb 10 (ANI): A French-American team of astronomers has produced a new 3D map that shows interstellar gas situated in an area about 1,000 light-years around the Sun.

Knowledge of the interstellar medium properties, including the spatial distribution, dynamics, and the chemical and physical characteristics, allows astronomers to better understand the interplay between the evolution of stars and their exchange of matter with the ambient interstellar medium.

The local area around our Sun has been studied with many surveys at various wavelengths, but the whole picture is still far from being either complete or fully understood.

The team, led by Barry Y. Welsh and his colleagues R. Lallement and J.-L. Vergely, presents new, high spectral resolution measurements of the singly-ionized-calcium (Ca II) K line (at a wavelength of 3933 angstroms, or 393.3 nanometers) and the neutral-sodium doublet (at 5889 and 5895 angstroms).

These absorption lines have long been used to study the interstellar medium.

The Ca II K lines were first observed in 1904 by German astronomer J. Hartmann, in the spectrum of the star Delta Orionis.

This first detection of interstellar gas set the stage for the early studies of interstellar medium.

The sodium (Na I) doublet was later discovered in 1919 toward Delta Orionis and Beta Scorpii.

The Ca II K line and the Na I doublet are complementary: the first one is sensitive to partially ionized gas (Ca II atoms are missing one electron), and the second one traces cold and neutral interstellar gas.

The team combined their new data (mostly recorded at the European Southern Observatory in Chile) with previously published results.

The new paper represents a catalog of absorption measurements towards 1,857 stars located within 800 parsecs from the Sun.

Maps of the distribution of Ca II have never been made before, and they reveal that the Local Cavity contains numerous filamentary structures of partially ionized gas that appear to form in a honeycomb-like pattern of small interstellar cells. (ANI)

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