USING M DWARF SPECTRA TO MAP EXTINCTION IN THE LOCAL GALAXY

Abstract

We use spectra of more than 56,000 M dwarfs from the Sloan Digital Sky Survey\n(SDSS) to create a high-latitude extinction map of the local Galaxy. Our\ntechnique compares spectra from the stars in the SDSS Data Release 7 M dwarf\nsample in low-extinction lines of sight, as determined by Schlegel, Finkbeiner,\n& Davis, to other SDSS M dwarf spectra in order to derive improved distance\nestimates and accurate line-of-sight extinctions. Unlike most previous studies,\nwhich have used a two-color method to determine extinction, we fit extinction\ncurves to fluxes across the entire spectral range from 5700 to 9200 {\\AA} for\nevery star in our sample. Our result is an extinction map that extends from a\nfew tens of pc to approximately 2 kpc away from the sun. We also use a similar\ntechnique to create a map of R_V values within approximately 1 kpc of the sun,\nand find they are consistent with the widely accepted diffuse interstellar\nmedium value of 3.1. Using our extinction data, we derive a dust scale height\nfor the local galaxy of 119\\pm15 parsecs and find evidence for a local dust\ncavity.\n

Keywords

Affiliated Institutions

• Boston University US

Related Publications