Expansion of Supernova 1993J

In this exercise, you will be presented with background information on the topic of interest, including lecture notes. After reviewing that material, you should download and print out the PDF of the problem. Finally with the problem in front of you, open up the image tool and use it to analyse the images in order to answer the questions on the PDF. Write on the printout of the problem and bring it to class.

Components

Background

SN expansion cartoon

Introduction

Massive stars are known to lose considerable amount of their mass as a result of fast moving stream of ionized gas or stellar winds before they explode. Massive stars lose mass at a rate of 10^-6 solar mass per year, which is 10^8 times the mass loss rate from a low mass star such as our Sun. Supernova explosions, the final death throes of massive stars and the most powerful explosion in nature, create an expanding bubble of hot gas that overruns the winds that had been created prior to its explosion.

The speed of the explosion is so high that the expansion rate is constant with time as this phase of the expansion is called the free expansion. The bubble of hot gas created a shell that we observe. The second phase occurs when the expanding shell of hot materials are slowed down as they get decelerated.

SN 1993J

SN 1993J

Astronomers discovered a remarkable supernova explosion on 28 March 1993. This object is known as SN 1993J (the tenth supernova detected in 1993) and is estimated to have had a mass of 15 or 30 times the mass of the sun before it exploded. The figure to the left shows the position of SN 1993J located in the spiral arm of a nearby spiral galaxy called M81. M81 like the Milky Way galaxy is known to have a spiral structure.

SN 1993J Animation

SN 1993J Animation

A monitoring program was followed after those results. New maps showed a sequence of images of SN 1993J, that was expanding with circular symmetry. The circularly symmetric images continued showing emission asymmetries. This sequence of images constituted the first "movie" of a radio supernova, and were reported as a paper in the journal Science.

PDF of Assignment

Print out the following PDF file, print out and answer using the interactive tool below.

PDF of Assignment

Interactive Measurement of Expansion

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