An all-sky catalogue of stellar reddening values

TL;DR

This paper compiles and analyzes a comprehensive all-sky catalogue of stellar reddening values, combining literature data and new estimates to improve understanding of interstellar extinction.

Contribution

It provides a large, curated catalogue of reddening values for nearly 98,000 stars, including new estimates based on classical photometric systems, and discusses systematic differences among sources.

Findings

Mean reddening values for 97,826 stars compiled from 157,631 measurements.

Identification of significant offsets and trends among different data sources.

Discussion of possible explanations for systematic differences.

Abstract

When observing astronomical objects, we must deal with extinction (i.e. the absorption and scattering of the emitted radiation by dust and gas between the source and the observer). Interstellar extinction depends on the location of the object and the wavelength. The different extinction laws describing these effects are difficult to estimate for a small sample of stars. Many sophisticated and automatic methods have recently been developed for estimating astrophysical parameters (age and metallicity, for example) depending on the reddening, which is usually treated as a free parameter within the corresponding estimations. However, many reddening values for stars have been published over the last few decades, most of which include observations in the ultraviolet, which are essential for a good estimation but are essentially no longer considered. We searched the literature through the end of 2022 for published independent reddening values of stellar objects based on various methods that exclude estimates from reddening maps. In addition, we present new reddening estimates based on the classical photometric indices in the Geneva, Johnson, and Stromgren-Crawford systems. These are based on well-established and reliable calibrations. After a careful identification procedure and quality assessment of the data, we calculated the mean reddening values of 157 631 individual available measurements for 97 826 objects. We find several statistically significant offsets and trends within the different references and discuss possible explanations for them.