A Simple Calculation in Service of Constraining the Rate of FU Orionis Outburst Events from Photometric Monitoring Surveys

TL;DR

This paper provides a simple calculation method to estimate the rate of FU Orionis outburst events from photometric surveys, aiding understanding of their frequency and role in stellar evolution.

Contribution

It introduces a straightforward approach to constrain FU Ori outburst rates using survey data, addressing the lack of robust observational constraints.

Findings

Provides a framework for estimating outburst rates from survey data

Guides parameter choices in time domain survey analyses

Highlights the rarity and diversity of FU Ori objects

Abstract

An enigmatic and rare type of young stellar object is the FU Orionis class. The members are interpreted as "outbursting," that is, currently in a state of enhanced accretion by several orders of magnitude relative to the more modest disk-to-star accretion rates measured in typical T Tauri stars. They are key to our understanding of the history of stellar mass assembly and pre-main sequence evolution, as well as critical to consider in the chemical and physical evolution of the circumstellar environment -- where planets form. A common supposition is that *all* T Tauri stars undergo repeated such outbursts, more frequently in their earlier evolutionary stages when the disks are more massive, so as to build up the requisite amount of stellar mass on the required time scale. However, the actual data supporting this traditional picture of episodically enhanced disk accretion are limited, and the observational properties of the known sample of FU Ori objects quite diverse. To improve our understanding of these rare objects, we outline the logic for meaningfully constraining the rate of FU Ori outbursts and present numbers to guide parameter choices in the analysis of time domain surveys.