Dr. Giorgio Valerin (INAF-Padova)
6 Novembre 2024
11:30, Aula Piazzi
Abstract:
Intermediate Luminosity Red Transients (ILRTs) are a class of objects populating the luminosity gap between classical novae and standard supernovae.
Their physical origin is still debated, with some studies associating ILRTs to non-terminal eruptions of post-main sequence stars, while other indicators favouring the terminal explosion of an electron capture supernova within a dense circumstellar medium. We present multi-wavelength photometric follow-up together with extensive optical and near-infrared spectroscopic monitoring of four ILRTs, namely NGC 300 2008OT-1, AT 2019abn, AT 2019ahd and AT 2019udc. Through the analysis of their spectral energy distribution we infer the temperature and radius of the emitting source, also revealing the presence of two blackbody components. Basic modelling of the bolometric light curves is compatible with the ejection of a few solar masses of material. Furthermore, the study of the shape and evolution of the spectral lines provides key insight into the geometry of the transients, which is articulated into two distinct emitting regions: a slow moving wind and a faster, dense circumstellar medium. Late time monitoring in the mid-infrared domain reveals the presence of steadily dimming dust, well below the luminosity of the progenitor system.
Their physical origin is still debated, with some studies associating ILRTs to non-terminal eruptions of post-main sequence stars, while other indicators favouring the terminal explosion of an electron capture supernova within a dense circumstellar medium. We present multi-wavelength photometric follow-up together with extensive optical and near-infrared spectroscopic monitoring of four ILRTs, namely NGC 300 2008OT-1, AT 2019abn, AT 2019ahd and AT 2019udc. Through the analysis of their spectral energy distribution we infer the temperature and radius of the emitting source, also revealing the presence of two blackbody components. Basic modelling of the bolometric light curves is compatible with the ejection of a few solar masses of material. Furthermore, the study of the shape and evolution of the spectral lines provides key insight into the geometry of the transients, which is articulated into two distinct emitting regions: a slow moving wind and a faster, dense circumstellar medium. Late time monitoring in the mid-infrared domain reveals the presence of steadily dimming dust, well below the luminosity of the progenitor system.
We finally discuss our findings in the context of the most debated scenarios for ILRTs: stellar eruptions or terminal explosions.