The Distance to the Stars

Abstract

Abstract The vastness of a clear night sky evokes for most people curiosity about the distance to the stars. There are two primary methods for estimating stellar distances – parallax and luminosity. In this study, we present a new analysis revealing a noteworthy discrepancy between these two methods. Due to the accuracy of GAIA, parallaxes can directly be converted into distances. In contrast, luminosity distances require – apart from the determination of apparent and absolute brightness of a star – the reddening value that allows a correction for interstellar extinction. Using 47 stars with non-peculiar reddening curves from the high-quality sample1 we find here that the luminosity distance overestimates the parallactic distance for most (79%) of these stars. This puzzling discrepancy can only be removed when incorporating a new population of large dust grains – so-called dark dust – with our model2 that respects contemporary constraints of the interstellar dust3 and is updated to scope for the first time with the absolute reddening. The model provides a visual extinction which unifies the conflicting distances. Another far-reaching consequence of the flat absorption and scattering properties of dark dust is that it broadens the light curves4 of SNIa, which serve as a measure of the quantity of dark energy5.