variable stars

Measurements of the brightness of supernova SN2011FE are plotted on the AAVSO website. My data points (Observer TDW) appear with boxes.

By extending the curve through next week (when I won’t be able to make any new observations), I predict that the brightness (V-filter) at 00:00 on 2011-09-14 will be 9.6.

I’ll measure it at that time and compare with my prediction.

The supernova in the Pinwheel Galaxy (M101) has now been designated “SN2011FE” (formerly “PTF11kly” which was even more difficult to remember). It continues to brighten. Comparing my measurements over the past two nights, it has brightened half a magnitude, from 12.9 to 12.4 in the past 24 hours. This is consistent with observations submitted by others to the AAVSO:

The total exposure time for the image below was 50 minutes. It shows a bit more detail of the Pinwheel Galaxy than the image taken the previous night (5 minutes).

Last Tuesday, August 23rd, a new supernova was discovered by researchers connected to the University of California, Berkeley. Designated SN2011FE, the supernova was observed exceptionally early in its process of explosion. Scientists predict that SN2011FE will grow in brightness over the next couple of weeks, possibly becoming bright enough to observe with binoculars. Located in the Pinwheel Galaxy (M101) near the handle of the Big Dipper, the “new star” is 21 million light years away, meaning that it actually exploded 21 million years before last Tuesday! Supernovas of this type (Ia) result from binary star systems that eventually evolve into a white dwarf and another star that feeds matter into the white dwarf. Suddenly, a substantial fraction of the matter undergoes nuclear fusion, causing material to be expelled at about 3% the speed of light. For a few days or weeks, the brightness of the supernova can exceed the total brightness of the galaxy in which it resides.

Last night, I captured some images of the Pinwheel Galaxy. By comparing my images with an archival DSS (Digital Sky Survey) image, I could easily see the supernova. Here is the archival image, with two comparison stars, 138 and 140 labeled:

 

 

 

 

 

 

 

 

 

 

 

Below is the photo I took last night, with the same two comparison stars identified:

 

 

 

 

 

 

 

 

 

 

 

The two comparison stars, 138 and 140 are in our own Milky Way Galaxy, probably no more that 5,000 light years away. Supernova, by contrast lies in the Pinwheel Galaxy, 21 million light years away. So even though it looks roughly comparable in brightness to 138 and 140, it is actually many millions of times brighter.

I submitted my measurements to the American Association of Variable Star observers (AAVSO), which are shared with others to produce the light curve:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

If we continue to have clear skies for a few days, I plan on checking on the supernova each night as it grows in brightness.