Padova-Asiago Supernova Group
My research activity is focused on explosive phenomena involving massive stars.
They can either be terminal supernova (SN) explosions, or non-terminal eruptions.
I am mostly interested in studying the following families of transients:
- Gap Transients. They are faint transients lying in the luminosity gap separating classical novae and under-luminous core-collapse SNe. The nature of these events (unusual bright outbursts from low to moderate mass stars, stellar mergers, major eruptions of luminous blue variables (LBVs) or even extremely faint core-collapse SNe) and the physical mechanisms triggering the outbursts are debated.
- CSM-ejecta interacting supernovae
Type IIn SNe, SN impostors and LBVs are likely connected phenomena. Thanks to the inspection of archive images, we detected stellar outbursts at the position of Type IIn SNe occurred weeks to (few) years before the SN explosions. The interaction between the material ejected by the SN and pre-existing circumstellar matter (CSM) produced by the progenitor star in recent eruptive episodes powers the light curve giving rise to a luminous SN IIn (Pastorello et al. 2013, ApJ, 765, 57; Tartaglia, Pastorello et al. 2016, MNRAS, 459, 1039; Elias-Rosa, Pastorello et al. 2016, MNRAS, 463, 3894; Pastorello et al. 2018, MNRAS, 474, 197).
Type Ibn SNe have ejecta interacting with He-rich CSM produced via eruptive mass loss occurred a short time before the SN explosion (e.g. Pastorello et al. 2008, MNRAS, 389, 113). A luminous outburst of the Wolf-Rayet progenitor was registered two years before the explosion of the Type Ibn SN 2006jc (Pastorello et al. 2007, Nature, 447, 829), and this study was followed by a series of publications on other newly discovered SNe Ibn (Pastorello et al. 2016, MNRAS, 456, 853; Maund, Pastorello et al. 2016, ApJ, 833, 128; and references therein).
- Super-luminous supernovae, with peak absolute magnitudes between -21 and -23 and a very slow spectro-photometric evolution. It is currently unclear which is the physical mechanism powering the huge luminosity of these transients, but it is evident that they do not match any of the proposed SN scenarios, i.e. core-collapse and 56Ni-powered explosion, pair--instability, pulsational pair-instability nor magnetar--powered event (Pastorello et al. 2010, ApJ, 724, L16; Inserra et al. 2013, ApJ, 770, 128; Nicholl et al., 2013, Nature, 502, 346).
- Type II-plateau supernovae (SNe IIP) , with main focus on objects in unusual environments and/or under-luminous, 56Ni-poor events (Pastorello et al 2004, MNRAS, 347, 74; Pastorello et al 2006 MNRAS, 370, 1752; Pastorello et al. 2009, MNRAS, 394, 2266; Spiro, Pastorello, et al. 2014, MNRAS, 439, 2873). In this context, I am studying correlations among physical parameters of SNe IIP, in collaboration with M. L. Pumo.
- SN 1987A-like events are a rare group of H-rich core-collapse SNe (<4% of SNe II) produced by the explosion of blue supergiant stars. So far, only a tens objects are known, showing a wide range of observed parameters, in analogy to normal SNe IIP (Pastorello et al. 2005, MNRAS, 360, 950; Taddia et al. 2012, A&A, 537, 140; Pastorello et al. 2012, A&A, 537, 141). In particular, an extremely luminous object of this class, OGLE-2014-SN-073, has been proposed to be a plausible pair-instability candidate (Terreran et al. 2017, Nature Astronomy, 1, 713).