About SN 1987A Astronomers were greeted in February 23, 1987 with a relatively nearby supernova. A star in the Large Magellanic Cloud (LMC) erupted. Such an event has not taken place in the Milky Way for almost 400 years, so they are rare events for a galaxy (most estimate an average of one supernova per galaxy per 100 years, so our Milky Way is long overdue). Since the LMC is so close to us, astronomers were able to witness the event and make some detailed observations. The discovery of Supernova 1987A was a great opportunity for detailed observation of the dynamics of a supernova. This supernova was unusual in that it did not rise abruptly to its maximum brightness, but paused briefly before increasing its luminosity by another factor of ten. It increased for about 85 days and then began a gradual decline which was more characteristic of other observed supernovae. Another unique feature about this supernova is that the star which exploded had been observed and named Sk-69202. It was a blue supergiant presumed to have a mass of about 20 solar masses. Almost coincident with the observation of the supernova, a burst of neutrinos were observed on the Earth, providing further information for modeling supernovae and providing another test for the mass of the neutrino. Before you begin, there are a few key points to helping you complete this lab. 1) Astronomers study these supernova events for information that: a) helps them understand the evolution of stars b) helps them understand the origin of elements c) helps them understand the distance to far away objects in space 2) There are two main classes of supernova events (Type | and Type 1), and both are critical to answering the first two levels of understanding listed above. However, there is a distinct difference between the way the two classes of stars explode. The light curve of a Type | event is different in form and magnitude of brightening from that of a Type Il event. As you can see from the comparative graph below, the curve of a Type | event is higher in terms of absolute brightness and steadily dims over time. The Type Il event does not get as bright and dims more slowly over time. -19 109 -17 o f % Type la a,