Interstellar reddening towards six small areas in Puppis-Vela

TL;DR

This study maps interstellar dust distribution in six small sky regions near the Gum nebula using high-quality photometry, revealing low-density interstellar medium and multiple structures including the Local Cavity wall and the Gum nebula.

Contribution

It provides detailed interstellar reddening measurements and distance estimates in the Puppis-Vela region, enhancing understanding of local interstellar structures with high-precision data.

Findings

Low interstellar dust density up to 1 kpc from the Sun.

Identification of multiple interstellar structures crossing the lines-of-sight.

Estimated distances to the Local Cavity wall (~150 pc) and Gum nebula front (~350 pc).

Abstract

We investigate the distribution of the interstellar dust towards six small volumes of the sky in the region of the Gum nebula. New high-quality four-colour uvby and H\beta\ Str\"omgren photometry obtained for 352 stars in six selected areas of Kapteyn, complemented with data obtained in a previous investigation for two of these areas, were used to estimate the colour excess and distance to these objects. The obtained colour excess versus distance diagrams, complemented with other information, when available, were analysed in order to infer the properties of the interstellar medium permeating the observed volumes. On the basis of the overall standard deviation in the photometric measurements, we estimate that colour excesses and distances are determined with an accuracy of 0.010 mag and better than 30%, respectively, for a sample of 520 stars. A comparison with 37 stars in common with the new Hipparcos catalogue attests to the high quality of the photometric distance determination. The obtained colour excess versus distance diagrams testify to the low density volume towards the observed lines-of-sight. Very few stars out to distances of 1 kpc from the Sun have colour excesses larger than E(b-y) = 0.1 mag. In spite of the low density character of the interstellar medium towards the Puppis-Vela direction, the obtained reddening as a function of the distance indicates that two or more interstellar structures are crossed towards the observed lines-of-sight. One of these structures may be associated with the very low density wall of the Local Cavity, which has a distance of 100-150 pc from the Sun. Another structure might be related to the Gum nebula, and if so, its front face would be located at about 350 pc from the Sun.