# The ASAS-SN Catalog of Variable Stars V: Variables in the Southern Hemisphere

## TL;DR

This paper presents a catalog of approximately 220,000 variable stars identified from 30.1 million light curves in the southern hemisphere, including many new discoveries, using a machine learning pipeline on ASAS-SN data.

## Contribution

The study systematically identifies and catalogs variable stars in the southern sky using a novel machine learning approach, expanding the known variable star population.

## Key findings

- Identified ~220,000 variable stars, including ~88,300 new ones.
- Discovered ~48,000 red pulsating variables and ~23,000 eclipsing binaries.
- Provided publicly accessible light curves and star characteristics.

## Abstract

The All-Sky Automated Survey for Supernovae (ASAS-SN) provides long baseline (${\sim}4$ yrs) light curves for sources brighter than V$\lesssim17$ mag across the whole sky. As part of our effort to characterize the variability of all the stellar sources visible in ASAS-SN, we have produced ${\sim}30.1$ million V-band light curves for sources in the southern hemisphere using the APASS DR9 catalog as our input source list. We have systematically searched these sources for variability using a pipeline based on random forest classifiers. We have identified ${\sim} 220,000$ variables, including ${\sim} 88,300$ new discoveries. In particular, we have discovered ${\sim}48,000$ red pulsating variables, ${\sim}23,000$ eclipsing binaries, ${\sim}2,200$ $\delta$-Scuti variables and ${\sim}10,200$ rotational variables. The light curves and characteristics of the variables are all available through the ASAS-SN variable stars database (https://asas-sn.osu.edu/variables). The pre-computed ASAS-SN V-band light curves for all the ${\sim}30.1$ million sources are available through the ASAS-SN photometry database (https://asas-sn.osu.edu/photometry). This effort will be extended to provide ASAS-SN light curves for sources in the northern hemisphere and for V$\lesssim17$ mag sources across the whole sky that are not included in APASS DR9.