SPICY 30021: an embedded bona fide FUor with a mid-infrared precursor
Abstract
Unstable mass accretion in young stellar objects (YSOs) often leads to observable outbursts, which play a key role in stellar mass assembly during pre-main-sequence evolution. The highest-amplitude, longest-duration events are classified as FUors. Until recently, only 50 FUor events had been confirmed. Many occur in embedded protostars, which are difficult to monitor in optical surveys. We present photometric and spectroscopic observations of SPICY 30021, an eruptive young star discovered in the mid-infrared (MIR) NEOWISE time series. We aim to construct its spectral energy distribution and characterise its eruptive nature. We compiled multi-wavelength photometric time series from NEOWISE, VVV and VVV-RENEW, and obtained photometric and spectroscopic observations during the outburst with SOAR, Magellan and VLT, including data from the ESO public survey VVVX-GalCen. We identified the outbursting source, separated it from nearby companions, and estimated the line-of-sight extinction from spectroscopic features. Stellar parameters were constrained using radial velocity, proper motions and stellar evolution models. SPICY 30021 is an optically obscured FUor with a total interstellar and circumstellar extinction of Av = 12.5 mag. Its spectrum closely resembles those of classical FUors. Multiple methods yield a distance of 1.7+_0.4 kpc. Its accretion luminosity is Lacc = 32 L_sol, moderate among FUors. Quiescent near-infrared photometry is consistent with a young 0.9 M_sol progenitor, although the mass depends on the adopted model and distance. We confirm SPICY 30021 as a bona fide FUor event. Its MIR precursor suggests an outside-in triggering mechanism.
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BibTeX
@misc{guo2026spicy,
title = {{SPICY 30021: an embedded bona fide FUor with a mid-infrared precursor}},
author = {Zhen Guo and Calum Morris and Vitor Fermiano and Carolina Lizana-Vidal and Aldo Aliaga and Javier Osses and Felipe Navarete and Philip Lucas and Roberto K. Saito and Adolfo Carvalho and Vardan Elbakyan and Carlos Contreras Peña and Koshvendra Singh and Min Fang and Philipp Weber and He Zhao and Tigran Yu. Magakian and Tigran A. Movsessian and Matias Gomez and Dante Minniti and Valentin Ivanov and Maria Gabriela Navarro and Sara Federle and Ilaria Petralia and Alonso Luna and Jesus Corral-Santana and Elisa R. Garro and Sean D. Points and Cesar Briceño and Zenghua Zhang and Radostin Kurtev and Jura Borissova and Jose G. Fernández-Trincado and Javier Alonso-García and Claudio Cáceres and Casmir O. Obasi and Daniela Galdeano and Laura Baravalle and Teresa Giannini and Zhikai Zhu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.19018},
eprint = {2610.19018},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.19018},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - SPICY 30021: an embedded bona fide FUor with a mid-infrared precursor
AU - Zhen Guo
AU - Calum Morris
AU - Vitor Fermiano
AU - Carolina Lizana-Vidal
AU - Aldo Aliaga
AU - Javier Osses
AU - Felipe Navarete
AU - Philip Lucas
AU - Roberto K. Saito
AU - Adolfo Carvalho
AU - Vardan Elbakyan
AU - Carlos Contreras Peña
AU - Koshvendra Singh
AU - Min Fang
AU - Philipp Weber
AU - He Zhao
AU - Tigran Yu. Magakian
AU - Tigran A. Movsessian
AU - Matias Gomez
AU - Dante Minniti
AU - Valentin Ivanov
AU - Maria Gabriela Navarro
AU - Sara Federle
AU - Ilaria Petralia
AU - Alonso Luna
AU - Jesus Corral-Santana
AU - Elisa R. Garro
AU - Sean D. Points
AU - Cesar Briceño
AU - Zenghua Zhang
AU - Radostin Kurtev
AU - Jura Borissova
AU - Jose G. Fernández-Trincado
AU - Javier Alonso-García
AU - Claudio Cáceres
AU - Casmir O. Obasi
AU - Daniela Galdeano
AU - Laura Baravalle
AU - Teresa Giannini
AU - Zhikai Zhu
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2610.19018
UR - https://arxiv.org/abs/2610.19018
AB - Unstable mass accretion in young stellar objects (YSOs) often leads to observable outbursts, which play a key role in stellar mass assembly during pre-main-sequence evolution. The highest-amplitude, longest-duration events are classified as FUors. Until recently, only 50 FUor events had been confirmed. Many occur in embedded protostars, which are difficult to monitor in optical surveys. We present photometric and spectroscopic observations of SPICY 30021, an eruptive young star discovered in the mid-infrared (MIR) NEOWISE time series. We aim to construct its spectral energy distribution and characterise its eruptive nature. We compiled multi-wavelength photometric time series from NEOWISE, VVV and VVV-RENEW, and obtained photometric and spectroscopic observations during the outburst with SOAR, Magellan and VLT, including data from the ESO public survey VVVX-GalCen. We identified the outbursting source, separated it from nearby companions, and estimated the line-of-sight extinction from spectroscopic features. Stellar parameters were constrained using radial velocity, proper motions and stellar evolution models. SPICY 30021 is an optically obscured FUor with a total interstellar and circumstellar extinction of Av = 12.5 mag. Its spectrum closely resembles those of classical FUors. Multiple methods yield a distance of 1.7+_0.4 kpc. Its accretion luminosity is Lacc = 32 L_sol, moderate among FUors. Quiescent near-infrared photometry is consistent with a young 0.9 M_sol progenitor, although the mass depends on the adopted model and distance. We confirm SPICY 30021 as a bona fide FUor event. Its MIR precursor suggests an outside-in triggering mechanism.
ER -