A Short episode: Sept 24 2012

Show Notes: September 25, 2012 (GMT)

**Technical Difficulties tonight**

Unfortunately, our show was cut short today due to technical difficulties with the Astronomy.FM computer servers. The people at AFM are hard at work in order to bring the systems back up and running smoothly. Sorry to all who tuned in, we’ll see you next week!

Below are the notes we wrote before the show went on-air! Gives you an idea of what we were going to chat about.

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Title: A Short episode
: Jesse, Paul, Ryan

This Week in History (TWIH):
27 September 2007 – DAWN was launched
20 September 1966 – USA surveyor 2 impacts moon (not on purpose)
26 September 1848 – William Bond discovers Hyperion – the first non-round moon!
22 September 1791 – Faraday’s Bday

Selected Stories:

1. Autumunal Equinox – 10:49 am EDT  in the Toronto area.

2. Shuttle Endeavour makes its final flight.

3. The Milky Way’s not-so-small reservoir of gas!

‘missing baryon problem’–> we think we know how much baryonic matter is out there. This is done by measuring deuterium(?) and the CMBR. Absorption a high redshifts seems to account or the total needed. But at low redshift we cannot account for all baryons (by a factor of 2).

Models predict that in the early universe, gas in the universe was colder, so it absorbed at wavelengths that are easy for us to observe now. As the universe evolved and galaxies grew, the gaseous content around the galaxies became shock heated into highly ionized states. In order to see their effects near by we need X-ray telescopes.

Mass of MW = 1.0-1.5 E12 solar masses

> 300 000 ly across = 100 kpc (distance to Andromeda is 0.7 Mpc)
going by Chen & Tinker, this is somewhat underestimating the size of this gaseous halo. (it should be between 100 < s < 150 kpc (but stll cool!)

found oxygen ions in the vicinity were ‘selectively absorbing’ some of the x-rays of distant objects. that gives temp.

temperature ~ 100 000 deg kelvin (we estimate temperatures lower)

heat means something different in space

3. James Webb Space Telescope mirrors beginning to come together

4. Observing Tip: Venus and alpha Leo pair up