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arXiv · 2401.14470

Multi-wavelength detection of an ongoing FUOr-type outburst on a low-mass YSO

Zhen Guo·P. W. Lucas·R. G. Kurtev·J. Borissova·V. Elbakyan·C. Morris·A. Bayo·L. Smith·A. Caratti o Garatti·C. Contreras Peña·D. Minniti·J. Jose·M. Ashraf·J. Alonso-García·N. Miller·H. D. S. Muthu
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Abstract

During the pre-main-sequence evolution, Young Stellar Objects (YSOs) assemble most of their mass during the episodic accretion process. The rarely seen FUOr-type events (FUOrs) are valuable laboratories to investigate the outbursting nature of YSOs. Here, we present multi-wavelength detection of a high-amplitude eruptive source in the young open cluster VdBH 221 with an ongoing outburst, including optical to mid-infrared time series and near-infrared spectra. The initial outburst has an exceptional amplitude of $>$6.3 mag in Gaia and 4.6 mag in $K_s$, with a peak luminosity up to 16 $L_{\odot}$ and a peak mass accretion rate of 1.4 $\times$ 10$^{-5}$ $M_\odot$ yr$^{-1}$. The optical to infrared spectral energy distribution (SED) of this object is consistent with a low-mass star (0.2$M_\odot$) with a modest extinction ($A_V < 2$ mag). A 100-d delay between optical and infrared rising stages is detected, suggesting an outside-in origin of the instability. The spectroscopic features of this object reveal a self-luminous accretion disc, very similar to FU Orionis, with a low line-of-sight extinction. Most recently, there has been a gradual increase in brightness throughout the wavelength range, possibly suggesting an enhancement of the mass accretion rate.

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Zhen Guo, P. W. Lucas, R. G. Kurtev, J. Borissova, V. Elbakyan, C. Morris, A. Bayo, L. Smith, A. Caratti o Garatti, C. Contreras Peña, D. Minniti, J. Jose, M. Ashraf, J. Alonso-García, N. Miller, H. D. S. Muthu. 2024-01-25. Multi-wavelength detection of an ongoing FUOr-type outburst on a low-mass YSO. https://doi.org/10.1093/mnrasl%2Fslad201

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