[Paper Review] New Eruptive YSOs from SPICY and WISE

Carlos Contreras Peña, Muhammad Ashraf+7 more|arXiv (Cornell University)|Nov 30, 2023

Astrophysics and Star Formation Studies4 citations

TL;DR

This study identifies four new eruptive young stellar objects (YSOs) using infrared data from the SPICY and NEOWISE surveys, confirming two as bona fide FUors and one as a V1647 Ori-like outburst source. Three outbursts last over a year and remain ongoing, while one's duration is uncertain, highlighting the importance of continued monitoring to understand accretion outbursts in YSOs.

ABSTRACT

This work presents four high-amplitude variable YSOs ($\simeq$ 3 mag at near- or mid-IR wavelengths) arising from the SPICY catalog. Three outbursts show a duration that is longer than 1 year, and are still ongoing. And additional YSO brightened over the last two epochs of NEOWISE observations and the duration of the outburst is thus unclear. Analysis of the spectra of the four sources confirms them as new members of the eruptive variable class. We find two YSOs that can be firmly classified as bona fide FUors and one object that falls in the V1647 Ori-like class. Given the uncertainty in the duration of its outburst, an additional YSO can only be classified as a candidate FUor. Continued monitoring and follow-up of these particular sources is important to better understand the accretion process of YSOs.

Motivation & Objective

• To identify and characterize high-amplitude variable YSOs with significant infrared outbursts using multi-epoch infrared surveys.
• To classify newly detected outbursting YSOs within established eruptive variable subclasses, such as FUors and V1647 Ori-like objects.
• To determine the duration and evolution of outbursts in newly identified YSOs using long-baseline infrared photometry from SPICY and NEOWISE.
• To assess the accretion dynamics of YSOs by analyzing spectral and photometric properties of newly discovered eruptive sources.
• To support future monitoring campaigns by identifying the most promising candidates for studying accretion outbursts in young stars.

Proposed method

• Utilized the SPICY catalog of infrared sources to identify YSOs with high-amplitude variability in near- and mid-infrared wavelengths.
• Analyzed multi-epoch photometry from the NEOWISE survey to track the light curves of candidate YSOs over multiple years.
• Applied spectral analysis to confirm the classification of eruptive YSOs based on their emission-line features and continuum shape.
• Compared light curve morphology and amplitude (≈3 mag) to known eruptive variables like FUors and V1647 Ori to classify new sources.
• Used the duration of outbursts—defined by sustained brightening over multiple epochs—as a key criterion for classifying long-lived outbursts.
• Evaluated the uncertainty in outburst duration for one source due to limited data coverage in the final NEOWISE epochs.

Experimental results

Research questions

• RQ1 What are the light curve characteristics of newly detected high-amplitude variable YSOs in the SPICY catalog?
• RQ2 How do the outburst durations of these YSOs compare to known FUors and V1647 Ori-like objects?
• RQ3 Can spectral analysis confirm the classification of these YSOs as eruptive variables, particularly within the FUor or V1647 Ori-like subclasses?
• RQ4 What is the significance of ongoing outbursts lasting over one year in the context of YSO accretion physics?
• RQ5 How do the photometric and spectroscopic properties of the newly identified sources compare to established eruptive YSO templates?

Key findings

• Four high-amplitude variable YSOs were identified, each brightening by approximately 3 magnitudes in near- or mid-infrared wavelengths.
• Three of the four YSOs exhibit outbursts lasting over one year, with all three still ongoing at the time of observation.
• Spectral analysis confirms two sources as bona fide FUors, based on their characteristic emission-line features and continuum shape.
• One source is classified as a V1647 Ori-like object due to its spectral and photometric similarity to this outburst class.
• An additional YSO shows a brightening over the last two NEOWISE epochs, but its outburst duration remains uncertain due to limited data coverage.
• The study identifies a critical need for continued monitoring of these eruptive YSOs to better understand the accretion processes driving their outbursts.