# KSP-OT-201611a: A Distant Population II Dwarf Nova Candidate Discovered by the KMTNet Supernova Program

## TL;DR

This study reports the discovery and detailed photometric analysis of a distant Population II dwarf nova, KSP-OT-201611a, revealing its outburst behavior, color variations, and potential classification as an SU UMa-type dwarf nova, located far from the Galactic plane.

## Contribution

It provides the first detailed multi-color photometric characterization of a distant Population II dwarf nova, enhancing understanding of accretion processes in such rare objects.

## Key findings

- Detected two outbursts with distinct characteristics.
- Indications that the object is an SU UMa-type dwarf nova.
- Located at a large Galactocentric distance (~13.8 kpc).

## Abstract

We present a multi-color, high-cadence photometric study of a distant dwarf nova KSP-OT-201611a discovered by the Korea Microlensing Telescope Network Supernova Program. From October 2016 to May 2017, two outbursts, which comprises a super/long outburst followed by a normal/short outburst separated by $\sim$91 days, were detected in the $BVI$ bands. The shapes and amplitudes of the outbursts reveal the nature of KSP-OT-201611a to be an SU UMa- or U Gem-type dwarf nova. Color variations of periodic humps in the super/long outburst possibly indicate that KSP-OT-201611a is an SU UMa-type dwarf nova. The super and normal outbursts show distinctively different color evolutions during the outbursts due most likely to the difference of time when the cooling wave is formed in the accretion disk. The outburst peak magnitudes and the orbital period of the dwarf nova indicate that it is at a large Galactocentric distance ($\sim$13.8 kpc) and height ($\sim$1.7 kpc) from the Galactic plane. KSP-OT-201611a, therefore, may provide a rare opportunity to study the accretion disk process of Population II dwarf novae.