University of Warwick | 2014 Aug 08
A research team led by astronomers and astrophysicists at the University of Warwick have found that some of the Universe’s loneliest supernovae are likely created by the collisions of white dwarf stars into neutron stars. ...[attachment=0]nswd_binary.jpg[/attachment]
“Our paper examines so-called `calcium-rich' transients” says Dr Lyman. “These are luminous explosions that last on the timescales of weeks, however, they're not as bright and don't last as long as traditional supernovae, which makes them difficult to discover and study in detail”.
Previous studies had shown that calcium comprised up to half of the material thrown off in such explosions compared to only a tiny fraction in normal supernovae. This means that these curious events may actually be the dominant producers of calcium in our universe.
“One of the weirdest aspects is that they seem to explode in unusual places. For example, if you look at a galaxy, you expect any explosions to roughly be in line with the underlying light you see from that galaxy, since that is where the stars are” comments Dr Lyman. “However, a large fraction of these are exploding at huge distances from their galaxies, where the number of stellar systems is miniscule.
“What we address in the paper is whether there are any systems underneath where these transients have exploded, for example there could be very faint dwarf galaxies there, explaining the weird locations. We present observations, going just about as faint as you can go, to show there is in fact nothing at the location of these transients - so the question becomes, how did they get there?”
Calcium-rich transients observed to date can be seen tens of thousands of parsecs away from any potential host galaxy, with a third of these events at least 65 thousand light years from a potential host galaxy. ...
The progenitors of calcium-rich transients are not formed in situ - Joe Lyman et al
- arXiv.org > astro-ph > arXiv:1408.1424 > 06 Aug 2014