Our Nearest 15 Million Neighbors: The Field Low-Mass Stellar Luminosity and Mass Functions

TL;DR

This study uses SDSS data to measure the luminosity and mass functions of approximately 15 million low-mass stars, providing new insights into their distribution and properties in the Milky Way.

Contribution

It introduces a novel technique for measuring the luminosity function that accounts for Galactic structure and provides a detailed mass function for low-mass stars.

Findings

The mass function is well-described by a log-normal distribution.

The characteristic mass (Mo) is approximately 0.27 Msun.

The luminosity function aligns with previous studies but offers improved accuracy.

Abstract

We report on a new measurement of the luminosity function (LF) and mass function (MF) of field low-mass dwarfs using Sloan Digital Sky Survey (SDSS) photometry. The final catalog is composed of ~15 million low-mass stars (0.1 Msun < M < 0.8 Msun), spread over 8,400 square degrees. Distances to the stars are estimated using new photometric parallax relations, constructed from ugriz photometry of nearby low-mass stars with trigonometric parallaxes. The LF is measured with a novel technique, which simultaneously measures Galactic structure and the stellar LF. The resulting LF is compared to previous studies and converted to a MF. The MF is well-described by a log-normal distribution, with Mo = 0.27 Msun.