MBM 12 and MBM 16 distances

TL;DR

This study introduces a photometric method using SDSS data to determine distances and extinctions of molecular clouds MBM 12 and MBM 16 with about 20-26% precision, confirming their distances at approximately 160 and 100 parsecs.

Contribution

The paper presents a novel photometric approach to estimate distances and extinctions of molecular clouds using SDSS color indices, with specific application to MBM 12 and MBM 16.

Findings

Distances to MBM 12 and MBM 16 are approximately 160 pc and 100 pc.

The method achieves 20-26% accuracy in stellar distance estimates.

Extinction estimates are accurate within 0.2 mag for most stars.

Abstract

Among the multitude of intrinsic SDSS index vs. index diagrams the $(g-r) \ vs. \ (r-i)$ diagram is characterized by showing only minor $(g-r)$ variation for the M dwarfs. The $(g-r) \ vs. \ (r-i)$ reddening vector has a slope almost identical to the slope of the main sequence earlier than $\approx$M2, meaning that dwarfs later than $\sim$M2 are not contaminated by reddened dwarfs of earlier type. Chemical composition, stellar activity and evolution have only minor effects on the location of the M2$-$M7 dwarfs in the $(g-r) \ vs. \ (r-i)$ diagram implying that reddening may be isolated in a rather unique way. From $r$, $M_{r,(r-i)_0}$ and $E_{g-r}$ we may construct distance vs. $A_r$ diagrams. This purely photometric method is applied on SDSS DR8 data in the MBM 12 region. We derive individual stellar distances with a precision $\approx20-26$%. For extinctions in the $r-band$ the estimate is better than 0.2 mag for $\approx 67%$ and between 0.3 and 0.4 for the remaining $\approx 33%$. The extinction discontinuities noticed in the distance vs. $A_r$ diagrams suggest that MBM 12 is at $\approx$160 pc and MBM 16 at a somewhat smaller distance $\approx$100 pc. The distance for which $\Delta (A_r)/\sigma (\Delta(A_r))$ = 3, where $\Delta (A_r)$ refers to $\bar{A_{r, on}}-\bar{A_{r, off}}$, may possibly be used as an indicator for the cloud distance as well: For MBM 12 and 16 these distance estimates equal 160 and 100 pc, respectively