The Optical-infrared Extinction Curve and Its Variation in the Milky Way

Schlafly, E.F.; Meisner, A.M.; Stutz, A.M.; Kainulainen, J.; Peek, J.E.G.; Tchernyshyov, K.; Rix, H.-W.; Finkbeiner, D.P.; Covey, K.R.; Green, G.M.; Bell, E.F.; Burgett, W.S.; Chambers, K.C.; Draper, P.W.; Flewelling, H.; Hodapp, K.W.; Kaiser, N.; Magnier, E.A.; Martin, N.F.; Metcalfe, N.; Wainscoat, R.J.; Waters, C.

Abstract

The dust extinction curve is a critical component of many observational programs and an important diagnostic of the physics of the interstellar medium. Here we present new measurements of the dust extinction curve and its variation toward tens of thousands of stars, a hundred-fold larger sample than in existing detailed studies. We use data from the APOGEE spectroscopic survey in combination with ten-band photometry from Pan-STARRS1, the Two Micron All-Sky Survey, and Wide-field Infrared Survey Explorer. We find that the extinction curve in the optical through infrared is well characterized by a one-parameter family of curves described by R(V). The extinction curve is more uniform than suggested in past works, with $\sigma (R(V))=0.18$, and with less than one percent of sight lines having $R(V)\gt 4$. Our data and analysis have revealed two new aspects of Galactic extinction: first, we find significant, wide-area variations in R(V) throughout the Galactic plane. These variations are on scales much larger than individual molecular clouds, indicating that R(V) variations must trace much more than just grain growth in dense molecular environments. Indeed, we find no correlation between R(V) and dust column density up to $E(B-V)\approx 2$. Second, we discover a strong relationship between R(V) and the far-infrared dust emissivity.

Citation

Schlafly, E., Meisner, A., Stutz, A., Kainulainen, J., Peek, J., Tchernyshyov, K., …Waters, C. (2016). The Optical-infrared Extinction Curve and Its Variation in the Milky Way. Astrophysical Journal, 821(2), Article 78. https://doi.org/10.3847/0004-637x/821/2/78

• Journal Article Type: Article
• Acceptance Date: Mar 4, 2016
• Online Publication Date: Apr 12, 2016
• Publication Date: Apr 12, 2016
• Deposit Date: Aug 18, 2016
• Publicly Available Date: Aug 23, 2016
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 821
• Issue: 2
• Article Number: 78
• DOI: https://doi.org/10.3847/0004-637x/821/2/78
• Publisher URL: https:/doi.org/10.3847/0004-637X/821/2/78