Spatially-resolved Stellar Population Properties of the M 51-NGC 5195 System from Multi-wavelength Photometric Data

TL;DR

This study uses multi-wavelength photometry and stellar population synthesis models to map the spatial distribution of stellar age, metallicity, dust, and mass in the interacting M 51-NGC 5195 system, revealing detailed stellar population differences.

Contribution

It provides the first detailed spatially resolved stellar population analysis of the M 51-NGC 5195 system using multi-band data and synthesis modeling.

Findings

Spiral arms in M 51 are young, metal-rich, and dusty.

Inter-arm regions contain older, metal-poor, less dusty stars.

NGC 5195 is older, with a dusty core and high stellar mass density.

Abstract

Using multi-band photometric images of M 51 and its companion NGC 5195 from ultraviolet to optical and infrared, we investigate spatially resolved stellar population properties of this interacting system with stellar population synthesis models. The observed IRX is used to constrain dust extinction. Stellar mass is also inferred from the model fitting. By fitting observed spectral energy distributions (SEDs) with synthetical ones, we derive two-dimensional distributions of stellar age, metallicity, dust extinction, and stellar mass. In M 51, two grand-designed spiral arms extending from the bulge show young age, rich metallicity, and abundant dust. The inter-arm regions are filled with older, metal-poorer, and less dusty stellar populations. Except for the spiral arm extending from M 51 into NGC 5195, the stellar population properties of NGC 5195 are quite featureless. NGC 5195 is much older than M 51, and its core is very dusty with $A_V$ up to 1.67 mag and dense in stellar mass surface density. The close encounters might drive the dust in the spiral arm of M51 into the center of NGC 5195.