The Ultraviolet Extinction Map and Dust Properties at High Galactic Latitude

Abstract

Abstract Extinction in ultraviolet is much more significant than in optical or infrared, which can be very informative to precisely measure the extinction and understand the dust properties in the low-extinction areas. The high Galactic latitude sky is such an area, important for studying the extragalactic sky and the universe. Based on the stellar parameters measured by the LAMOST and GALAH spectroscopy and the ultraviolet photometry by the Galaxy Evolution Explorer (GALEX) space telescope, the extinction of 1,244,504 stars in the GALEX/near-UV band and 56,123 stars in the GALEX/far-UV band is calculated precisely. The error of color excess is 0.009, 0.128, and 0.454 mag for , , and , respectively. They delineate the GALEX/near-UV extinction map of about a third of the sky mainly at the high Galactic latitude area with an angular resolution of ∼ 0.°4. The mean color excess ratio in the entire sky area is derived to be 3.25, 2.95, and −0.37 for , , and , respectively, which is in general agreement with the previous works, and their changes with the Galactic latitude and the interstellar extinction are discussed.