Show notes for the night of July 29th, 2013
Hosts: Paul, Jesse, Jen
Title: Good As Gold!
This week in space/astronomy history:
1. July 29, 1958 – U.S congress passes legislation establishing the National Aeronautics and Space Administration (NASA).
2. July 30, 1971 – Apollo 15 lands (first vehicle driven on another body)
3. July 30 1878 – March 16 1966), Joel Stebbins born: developed photoelectric photometry. Paul)
4. August 1, 1818 – Maria Mitchell is born (Massachusetts), first american woman astronomer. Harvard prof! Found a comet 1847.
1. Planets orbiting cool stars may be much warmer and less icy than planets orbiting much hotter stars. This is due to the interaction of a star’s light with ice and snow on the planet’s surface. Stars emit different types of light. Hotter stars emit high- energy visible and ultraviolet light and cooler stars give off infrared and near infrared light. Ice absorbs much of the longer- wavelengths near infrared light emitted by cooler stars. Therefore the more light the ice absorbs the warmer the planet gets. The planet’s atmospheric greenhouse gases also absorb this near infrared light, which contributes to the warming effect. Planets orbiting cooler stars are therefore less likely to experience “Snowball States” (where the planet ices over from pole to equator).
2. Earth’s gold came from colliding neutron stars. This making it not only rare on Earth but in the entire universe as well. Unlike most elements (ie. carbon or iron) gold cannot be created within a star, it must be born in a more cataclysmic event such as a gamma-ray burst. A gamma-ray burst is a flash of high-energy light from an extremely energetic explosion. It is believed that all the gold in the cosmos might have come from gamma-ray bursts.
3. Supernova Type 2 in M74 is still brightening. Discovered by LOSS on July 25, as of today had brightened 1 full magnitude to 12.5. In a well placed observing location in the outer spiral arm of this near face on spiral, it is well placed for morning observations at this time. Likely progenitor was a 25th magnitude M red giant. Paul
4. NASA budget slashed and NO asteroid mission!
Major Topics Discussed:
1. Exoplanet observed using Xray transit method
Searching for exoplanets was originally done using the radial velocity method wherein the researchers look for a wobble of the host star. The most popular method (as a result of Kepler) used to look for exoplanets is the transit method, wherein the researchs search for a dip in light as a result of the planet passing in front of the host star.
Kepler uses optical light to search for these transits. For the first time, astronomers have observed an exoplanet transit in X-ray light. Using the Chandra X-ray telescope, astronomers from the Harvard-Smithsonian Center for Astrophysics (CfA) were able to detect the transit of HD189733b around its host star.
The interesting result is that the X-ray transit is deeper than the Optical transit. In the optical, the planet blocks about 2-3% of the star’s light; in X-rays, the planet blocks about 6-8% of the light. This means that the planet’s X-ray blocking radius is about 75% bigger than its optical blocking radius.
For this to happen, the planet’s atmosphere must be heated to about 20 000K.
Universe Today – Exoplanet in Xrays
NASA press release – NASA’s Chandra Sees Eclipsing Planet in X-rays for First Time
arXiv paper – Transit observations of the hot Jupiter HD 189733b at X-ray wavelengths
Where in the Universe?:
Last week’s answer: Stephen’s Quintet
This Weeks image: http://yorkuniverse.com/wp-content/uploads/2013/07/WITU_ep163.jpg
Thanks for listening!
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