March 10, 2010 - The Bright, Turbulent and Short Life of the Most Massive Stars - Andr�-Nicolas Chen�

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The Bright, Turbulent and Short Life of the Most Massive Stars - Dr. Andr�-Nicolas Chen�, HIA Post Doctorate with Gemini Program - presented at the March 10, 2010 monthly meeting of RASC Victoria Centre.

In spite of their rarity, the most massive stars dominate the luminosity and the dynamic of star-forming galaxies. They contribute large amounts of energy, momentum and matter to the ecology, making them crucial constituent of the universe. I will describe the stages of the life of the most massive stars, from the Main Sequence, i.e. just after their birth, to the Wolf-Rayet stage, i.e. just before their death in supernova. I will also present the theoretical and observational efforts deployed in the last decade and the biggest challenges for the next one.

Presentation (1.4Mb pdf) - please right click & "Save as..."

Biography: I have completed a PhD in Astrophysics at the Universite de Montreal under the supervision of Nicole St-Louis. My thesis about the observational determination of the rotation rate of Wolf-Rayet stars. In November 2007, I moved to Victoria and I started a postdoctoral fellowship with the Canadian Gemini Office at the Herzberg Institute of Astrophysics. I am currently looking for a second postdoctoral position. Site web d'Andr�-Nicolas Chen� -- Most Massive Star in Class By Itself

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Postscript from Andr�-Nicolas:

I had many question about what is the largest known star. Here is what I found:

It is not clear which star is the big winner.

The derived radii for VY Canis Majoris are between 1800 and 3000(!) Solar Radii (reference). Also, according to (reference), the radius of WOH G64 should be pretty much the same, i.e. ~8AU~1800 SolRad. Finally, (reference) finds something like 1200 to 1650 SolRad for VV Cephei.

There are many other stars that seem to have radii around 1500SolRad. E.g.

bullet Water in Emission in the ISO Spectrum of the Early M Supergiant Star mu Cephei
bullet -- List of Largest Stars Gets 3 New Chart Toppers

All these radii have been determined with either interferometry, asteroseismology (pulsations), eclipse with the moon, brief, many different methods that have their limits.

Betelgeuse and Antares seem to have more or less the same radius, i.e. between 800 and 1000 SolRad. Within the error bars, Betelgeuse seems to win the competition between the two stars (so far).

That's it for now!

Clear skies,


PS: I really love the RASC T-shirt. Thank you very much!


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