A Rv map of the Milky Way revealed by LAMOST
Ruoyi Zhang, Haibo Yuan, Bingqiu Chen

TL;DR
This study maps the Rv extinction ratio across the Milky Way using LAMOST data, revealing its distribution, variability, and correlations with interstellar dust properties, which aids in understanding dust evolution and improving extinction corrections.
Contribution
It presents the first large-scale, high-resolution Rv map of the Milky Way derived from optical to mid-infrared data, highlighting spatial variations and environmental correlations.
Findings
Rv distribution peaks around 3.25 with a standard deviation of 0.25
Lower Rv values are found within molecular clouds
Relationships between Rv and dust/gas parameters vary with extinction level
Abstract
The total-to-selective extinction ratio, Rv, is a key parameter for tracing the properties of interstellar dust, as it directly determines the variation of the extinction curve with wavelength. By utilizing accurate color excess measurements from the optical to the mid-infrared range, we have derived Rv values for approximately 3 million stars from the LAMOST data release 7 (DR7) using a forward modeling technique. This extensive dataset enables us to construct a comprehensive two-dimensional Rv map of the Milky Way within the LAMOST footprint at a spatial resolution of ~27.5arcmin. Based on reliable sightlines of E(B-V) > 0.1, we find that Rv exhibits a Gaussian distribution centered around 3.25 with a standard deviation of 0.25. The spatial variability of Rv in the Galactic disk exhibits a wide range, spanning from small scales within individual molecular clouds to large scales up to…
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Taxonomy
TopicsSpectroscopy and Laser Applications · Atmospheric Ozone and Climate · Astrophysics and Star Formation Studies
