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A Color-locus Method for Mapping R V Using Ensembles of Stars

Lee, Albert; Green, Gregory M.; Schlafly, Edward F.; Finkbeiner, Douglas P.; Burgett, William; Chambers, Ken; Flewelling, Heather; Hodapp, Klaus; Kaiser, Nick; Kudritzki, Rolf-Peter; Magnier, Eugene; Metcalfe, Nigel; Wainscoat, Richard; Waters, Christopher

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Albert Lee

Gregory M. Green

Edward F. Schlafly

Douglas P. Finkbeiner

William Burgett

Ken Chambers

Heather Flewelling

Klaus Hodapp

Nick Kaiser

Rolf-Peter Kudritzki

Eugene Magnier

Richard Wainscoat

Christopher Waters


We present a simple but effective technique for measuring angular variation in R V across the sky. We divide stars from the Pan-STARRS1 catalog into Healpix pixels and determine the posterior distribution of reddening and R V for each pixel using two independent Monte Carlo methods. We find the two methods to be self-consistent in the limits where they are expected to perform similarly. We also find some agreement with high-precision photometric studies of R V in Perseus and Ophiuchus, as well as with a map of reddening near the Galactic plane based on stellar spectra from APOGEE. While current studies of R V are mostly limited to isolated clouds, we have developed a systematic method for comparing R V values for the majority of observable dust. This is a proof of concept for a more rigorous Galactic reddening map.


Lee, A., Green, G. M., Schlafly, E. F., Finkbeiner, D. P., Burgett, W., Chambers, K., …Waters, C. (2018). A Color-locus Method for Mapping R V Using Ensembles of Stars. Astrophysical Journal, 854(2), Article 79.

Journal Article Type Article
Acceptance Date Jan 18, 2018
Online Publication Date Feb 15, 2018
Publication Date Feb 15, 2018
Deposit Date Mar 8, 2018
Publicly Available Date Mar 8, 2018
Journal Astrophysical Journal
Print ISSN 0004-637X
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 854
Issue 2
Article Number 79


Published Journal Article (4.5 Mb)

Copyright Statement
© 2018. The American Astronomical Society. All rights reserved.

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