Fitting procedure for estimating interstellar extinction at high galactic latitudes

Aleksandra Avdeeva,Dana Kovaleva,Oleg Malkov,Alexey Nekrasov

doi:10.1515/astro-2021-0022

Abstract

Abstract We determine the interstellar extinction in the selected high-latitude areas of the sky based on Gaia EDR3 astrometry and photometry and spectroscopic data from RAVE survey. We approximate the results with the cosecant law in each area thus deriving the parameters of the barometric formula for different lines of sight. The distribution of the parameters over the entire sky is described using spherical harmonics. As a result, we get a mathematical description of the interstellar visual extinction for different lines of sight and distances from the Sun which can be used for estimating interstellar extinction.

Highlights

We determine the interstellar extinction in the selected high-latitude areas of the sky based on Gaia EDR3 astrometry and photometry and spectroscopic data from RAVE survey
We approximate the results with the cosecant law in each area deriving the parameters of the barometric formula for different lines of sight
We get a mathematical description of the interstellar visual extinction for different lines of sight and distances from the Sun which can be used for estimating interstellar extinction

Summary

Introduction

Taking extinction into account is an essential step in almost every astronomical, and astrophysical, research. Sale et al (2014) produced a 3D map based on hierarchical Bayesian model using the IPHAS photometric data Both works mentioned above are focused only on low-latitude areas of the sky, mainly the part of the Galactic plane, which makes them unsuitable for the high-latitude estimation of the interstellar extinction. The results can be downloaded for the particular lines of sight or en bloc for all available directions It covers roughly a three quaters of the sky and has a minimum reliable distance due to saturated Pan-STARRS stars. Lallement et al (2019) used 2MASS photometry and Gaia DR2 astrometry to produce a map of interstellar dust within 3 kpc. The parameter β is the scale height, and a0 is the extinction per unit length in the Galactic plane

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Observational data and obtaining the extinction

Deriving the parameters of the cosecant law in individual areas

The results of approximation within the areas

Uncertainties

Summary and future plans