The last time a supernova was observed within the Milky Way was in 1604 by Johannes Kepler, and was only appreciated by the human eye, since optical telescopes and other measurement devices had not yet been invented. Despite a lack of hard observational data, astronomers have a theoretical framework to describe the processes that occur during a supernova, and numerical simulations are always growing more detailed and sophisticated. Still, without observation, neither theory nor numerical result can be put to the test.
While supernovae in our galaxy are relatively rare, extragalactic supernovae are not. That is because there are countless galaxies that have supernova rates similar to that of the Milky Way. But, due to their distance from Earth are not resolvable and offer little insight into the mechanisms at work during the explosion. Although astronomers haven’t observed supernovae in the Milky Way for several hundred years (read on to find out why this may be), the good news here is that astronomers are developing methods to be ready when the next one happens...
A star is formed when a large cloud of gas and dust condenses and eventually becomes so dense that it collapses into a ball of gas, where the pressure heats the matter, creating a glowing gas ball – a star is born. New research from the Niels Bohr Institute, among others, shows that a young, newly formed star in the Milky Way had such an explosive growth, that it was initially about 100 times brighter than it is now. The results are published in the scientific journal, Astrophysical Journal Letters.
Authors: Jes K. Jorgensen, Ruud Visser, Nami Sakai, Edwin A. Bergin, Christian Brinch, Daniel Harsono, Johan E. Lindberg, Ewine F. van Dishoeck, Satoshi Yamamoto, Suzanne E. Bisschop, Magnus V. Persson
The Star of Bethlehem is only known from a few verses in the Gospel of Matthew, with the Star inspiring and leading the Magi (i.e., Persian astrologers) to Jerusalem and ultimately worshipping the young Jesus Christ in Bethlehem. In the last four centuries, astronomers have put forth over a dozen greatly different naturalistic explanations, all involving astronomical events, often a bright nova, supernova, or comet. This paper will evaluate one prominent recent proposal, that the Star was a 'recurrent nova' now catalogued as DO Aquilae, and provide three refutations. In particular, (1) DO Aql is certainly not a recurrent nova, but rather an ordinary nova with a recurrence time scale of over a million years, (2) in its 1925 eruption, DO Aql certainly never got brighter than 8.5 mag, and the physics of the system proves that it could never get to the required luminosity of a supernova, and (3) the Magi were astrologers who had no recognition or interpretation for novae (or supernovae or comets) so any such event is completely irrelevant and meaningless to them.
The authors investigate the orbital decay of two black hole X-ray binaries. Combined with previous data, they were able to measure how fast the orbit is decaying and make predictions about the exact cause of this orbital decay. These systems are some of the best to look for this orbital decay because of their extreme masses compared to other systems. By obtaining spectra to create a radial velocity curve, the authors were able to add an additional O-C point with a larger baseline than before. This larger baseline is important because it allows time for small changes to build up.