EARLY SOLAR SYSTEM: A supernova gave the Sun its tilt
S. Portegies Zwart et al. Astron. Astrophys. submitted (2018).
The idea that a supernova explosion in the vicinity of the pre-Solar nebula influenced the development of our Solar System has been around for many years (for instance, in this classic paper from Cameron & Truran or this 40 year old paper from Donald Clayton). Such an occurrence is likely to have been a reality, given that the Sun is thought to have formed in a star cluster which would have contained ~1,000 stars within a ~1 pc radius. This proto-Solar cluster would have contained several massive stars that exploded as supernovae. Recently, Simon Portegies Zwart and collaborators have re-addressed this notion with complex hydrodynamical and radiative transfer models that consider the influence of both the supernova irradiation and the impact of a nuclear blast wave arriving several decades later. They find that in certain cases, where the supernova is very nearby (0.15–0.40 pc) and in the right area of the sky, the blast wave can induce a misalignment between the Sun’s equator and its disk (now the ecliptic) that matches the tilt that the Sun has in the present day. Moreover, such a blast wave could have truncated the disk at ~50 au, roughly consistent with the inner edge of the Kuiper Belt. This act of supernova violence would explain the Solar System’s unusually small disk in comparison to those found in nearby star-forming regions.
Another model with a different set of parameters results in the protoplanetary disk being heated to more than 1,200 K, consistent with the temperatures required to melt chondrules.
The models of Portegies Zwart et al. explain a number of features of our Solar System, however, a sticking point is that none of these models can introduce sufficient supernova material to explain the high abundance of the 26Al radionuclide in our present-day planetary system.
Image credit: NASA/David A. Hardy/www.astroart.org