Characterisation of an EXor outburst SPICY 97589

¹ European Southern Observatory, Casilla 19001 Santiago 19, Chile
² European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 25 April 2025
Accepted: 1 March 2026

Abstract

Context. Stellar outbursts from variable or periodic accretion are thought to be ubiquitous across young stellar populations. However, relatively few outbursting objects have been discovered to date. Here, we present the characterisation of a new EXor-type episodic accretor.

Aims. We aim to characterise the nature of the 2023 outburst of SPICY 97589(Gaia23bab) and characterise the stellar source for the first time, while exploring how an accretion outburst contributes to disk evolution.

Methods. We employ multi-waveband medium-resolution spectroscopy with UVB-VIS-NIR coverage during the peak of the 2023 outburst and the post-outburst quiescent object. The broad wavelength coverage of the dataset allows for robust measurements of the accretion rate using known line tracers. The addition of quiescent spectra provides a good estimation of stellar parameters of the central star while also informing us about the evolution of the disk during outburst phases.

Results. We find that the stellar source is a 3410 K, M3.0 type star with a luminosity of 0.41 L_⊙ and an estimated stellar mass of 0.29 M_⊙. We measure the accretion rate of SPICY 97589 to be Ṁ = 2.38 ± 0.58 × 10⁻⁷ M_⊙ yr⁻¹. This value is two orders of magnitude greater than the quiescent accretion rate. Thus, we confirm that the 2023 outburst was driven by an influx of material from the surrounding environment to the central star, an accretion outburst. The spectral fingerprint of the emission lines is also characteristic of an outbursting EXor-type source, including variable disk winds.