Radio stars of the SKA

TL;DR

The paper evaluates SKA's potential to detect various stellar radio sources in the Milky Way, highlighting its capability to observe faint objects like OB stars, Be stars, M dwarf flares, and Ultra Compact HII regions with high sensitivity.

Contribution

This study models the SKA's sensitivity requirements and detection capabilities for different stellar radio sources in the Milky Way, providing guidance for future surveys.

Findings

SKA will detect all Ultra Compact HII regions.

At 10 nJy sensitivity, SKA can detect 1500 Be stars and 50 OB stars per square degree.

Flares from 4500 M dwarfs per square degree can be detected at this sensitivity.

Abstract

Radio emission from stars can be used, e.g., to study ionized winds or stellar flares. The radio emission is faint and studies have been limited to few objects. The Square Kilometer Array (SKA) will bring a survey ability to the topic of radio stars. In this paper we investigate what the SKA can detect, and what sensitivity will be required for deep surveys of the stellar Milky Way. We focus on the radio emission from OB stars, Be stars, flares from M dwarfs, and Ultra Compact HII regions. The stellar distribution in the Milky Way is simulated using the Besancon model, and various relations are used to predict their radio flux. We find that the full SKA will easily detect all UltraCompact HII regions. At the limit of 10 nJy at 5 GHz, the SKA can detect 1500 Be stars and 50 OB stars per square degree, out to several kpc. It can also detect flares from 4500 M dwarfs per square degree. At 100 nJy the numbers become about 8 times smaller. SKA surveys of the Galactic plane should be designed for high sensitivity. Deep imaging should consider the significant number of faint flares in the field, even outside the plane of the Milky Way.