MIRIS Pa{\alpha} Galactic Plane Survey. I. Comparison with IPHAS H{\alpha} in l = 96{\deg}-116{\deg}

TL;DR

This study presents the MIRIS Pa{\alpha} Galactic Plane Survey data, compares it with IPHAS H{\alpha} maps, identifies new H II regions, and analyzes extinction features and H{\alpha} excess in the Galactic plane.

Contribution

First comparison of MIRIS Pa{\alpha} survey data with IPHAS H{\alpha} maps, identifying new H II regions and analyzing dust extinction and scattering effects.

Findings

Identified 90 H II region candidates, with 53 detected at Pa{\alpha}.

Mapped E(B-V) extinction features, revealing dust scattering effects.

Detected H{\alpha} excess regions indicating dust scattering and complex extinction.

Abstract

The Multipurpose InfraRed Imaging System (MIRIS) performed the MIRIS Pa{\alpha} Galactic Plane Survey (MIPAPS), which covers the entire Galactic plane within the latitude range of -3{\deg} < b < +3{\deg} at Pa{\alpha} (1.87 um). We present the first result of the MIPAPS data extracted from the longitude range of l = 96.5{\deg}-116.3{\deg}, and demonstrate the data quality and scientific potential of the data by comparing them with H{\alpha} maps obtained from the INT Photometric H{\alpha} Survey (IPHAS) data. We newly identify 90 H II region candidates in the WISE H II region catalog as definite H II regions by detecting the Pa{\alpha} and/or H{\alpha} recombination lines, out of which 53 H II regions are detected at Pa{\alpha}. We also report the detection of additional 29 extended and 18 point-like sources at Pa{\alpha}. We estimate the E(B-V) color excesses and the total Lyman continuum luminosities for H II regions by combining the MIPAPS Pa{\alpha} and IPHAS H{\alpha} fluxes. The E(B-V) values are found to be systematically lower than those estimated from point stars associated with H II regions. Utilizing the MIPAPS Pa{\alpha} and IPHAS H{\alpha} images, we obtain an E(B-V) map for the entire region of the H II region Sh2-131 with an angular size of ~2.5{\deg}. The E(B-V) map shows not only numerous high-extinction filamentary features but also negative E(B-V) regions, indicating H{\alpha} excess. The H{\alpha} excess and the systematic underestimation of E(B-V) are attributed to light scattered by dust.