2016/06/27 by Stefan Kraus, Alessio Caratti o Garatti, A. Caratti o Garatti +9 · 27 citations
Chemistry · Physics and Astronomy · #Accretion (finance) #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Brightness #Light curve #Molecular Spectroscopy and Structure #Physics #Stars #astro-ph.SR
paper · pdf · doi:10.1093/mnrasl/slw126
published in Monthly Notices of the Royal Astronomical Society Letters 462(1), L61-L65 (Oxford University Press) · 5 pages, 2 figures, accepted at MNRAS Letters
openalex publication_date 2016/06/27 · arxiv created 2016/07/11 · arxiv updated 2016/07/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract During their formation phase, stars gain most of their mass in violent episodic accretion events, such as observed in FU Orionis (FUor) and EXor stars. V346 Normae is a well-studied FUor that underwent a strong outburst beginning around 1980. Here, we report on photometric and spectroscopic observations, which show that the visual/near-infrared brightness has decreased dramatically between the 1990s and 2010 (ΔR ≈ 10.9 mag, ΔJ ≈ 7.8 mag and ΔK ≈ 5.8 mag). The spectral properties of this fading event cannot be explained by variable extinction alone, but indicate a drop in accretion rate by two to three orders of magnitude. This is the first time that a member of the FUor class has been observed to switch to a very low accretion phase. Remarkably, in the last few years (2011–2015) V346 Nor has brightened again at all near-infrared wavelengths, indicating the onset of a new outburst event. The observed behaviour might be consistent with the clustered luminosity bursts that have been predicted by recent gravitational instability and fragmentation models for the early stages of protostellar evolution. Given V346 Nor's unique characteristics (concerning outburst duration, repetition frequency and spectroscopic diagnostics), our results also highlight the need to revisit the FUor/EXor classification scheme.