Show notes for Episode 189, March 17th 2014
Hosts: Paul, Julie, Hugh
Title: Julie: YorkUniverse`s Expansion!
Introducing Julie Tome: words from Julie about her background from York U to Science North to the OSC and the ROM.
This week in space/astronomy history:
1. March 16, 1750 Birth of Caroline Herschel, sister of William Herschel and astronomer in her own right. She discovered several comets including the periodic comet 35P/Herschel-Rigollet. She received many awards for her contributions to science.
2. March 13, 1781 William Herschel discovered Uranus. Uranus came from Greek mythology and the God of the Sky (Ouranos). Observed constantly in earlier times (eg Flamsteed catalogued Uranus in 1690 as 34 Tauri), Herschel tried naming the new planet (thought to be a comet initially) Georgium Sidus (after King George III) but following Bode’s suggestion, Uranius became the aame of choice universally from 1850.
3. Vanguard 1 launched March 17 1958 (56 years in space!). First solar powered satellite (4th launched) and oldest satellite to still be in orbit. Last contact in May 1964. 1.5 kg in mass, 16.5 cm diameter sphere, the primary mission was to collect geodetic data (Earth shape) and to measure atmospheric drag (eccentric orbit of 133 minutes).
1. Big announcement from Harvard-Smithsonian centre for astrophysics, BICEP2 found B-mode polarization in the CMB which is a smoking gun for gravitational waves caused by the rapid inflation of the universe immediately following the big bang. The major point of it is that this is the first ever direct observation of gravitational waves: B-mode fluctuations (polarized light that swirls and curls around itself) are predicted to result from gravitational waves caused by rapid inflation of the universe, and BICEP2 (Background Imaging of Cosmic Extragalactic Polarization) has for the first time detected those exact B-mode fluctuations. The challenge in identifying these fluctuations is that they are incredibly faint, and that your data may be skewed by E-mode fluctuations that have been distorted by gravitational lensing to look like B-mode fluctuations. The takeaway message is this: if the observations are confirmed then gravitational waves predicted by inflation have been discovered, which in turn lends immense credibility to the theory of inflation, explains why spacetime is flat and implies that our universe is in fact infinite and always will be infinite. The next question: what drove inflation? Suggested reading: Space.com article High level summary from Bad Astronomer http://bicepkeck.org/
2. New Hypergiant star 1300x Sun diameter. The stats for the star are impressive indeed: dubbed HR 5171 A, the binary system weighs in at a combined 39 solar masses, has a radius of over 1,300 times that of our Sun, and is a million times as luminous. Located 3,600 parsecs or over 11,700 light years distant, the star is 50% larger than the famous red giant Betelgeuse. Binary star (about 10 AU apart) but surfaces only 2.9 AU! 1300 day orbital period for this contact eclipsing binary. Amateurs and professional astronomers combined to unravel this system dating back over 60 years.
Read more: http://www.universetoday.com/110205/astronomers-identify-the-largest-yellow-hypergiant-star-known/#ixzz2wGoaPuna (Suggested Reading: Universe Today article, ESO Press Release, arXiv preprint)
3. Contest via NASA to find potentially harmful NEO. NASA and Planetary Resources (the asteroid miners!) have conspired with topcoder.com a crowd sourced algorithm development platform, to identify potentially harmful asteroids from data sets consisting of 4 images seperated by about 10 minutes each. The winning algorithm will be able to correctly identify errors and artifacts in the data and will receive $35,000 in prize money, so if you think you have what it takes then head on over to topcoder and give it a shot! (Suggested Reading: IFLS article, Contest Details)
4. Mars Reconnaissance Orbiter went into safe mode March 9 after an unexpected switch from one main computer to another. NASA scientists are working on the problem and hope to have the spacecraft back online in a few days. This happens somewhat regularly, this is the 5th time in MRO’s lifetime, the last time was November 2011. MRO is the link between Opportunity and Curiosity rovers and Earth. Mars Odyssey can handle the science operations while MRO is being repaired.
(Suggested Reading: Space.com article) Curiosity Rover tweeted March 13 that MRO is back online. (Suggested Reading: JPL press release)
5. The IAU has released a statement against the practice of organizations letting members of the public name features on Mars (and other places) for a fee. The statement is not explicit about which organization they are criticizing but the target would appear to be Uwingu. The Uwingu team “consists of nationally and internationally accomplished scientists, educators, NASA vets, and business people, who are passionate about astronomy, space exploration, and space education.” It uses its naming projects to raise money to fund science and education. (Suggested reading Space.com article, Uwingu web site)
6. Yutu Rover: The little jade rabbit that could survives its third lunar night, to enter its fourth lunar day! Given that it was designed to be a 3 month mission that means that as of March 14th the little Jade bunny has met its mission design requirements. Its instruments are for the most part still working, although it’s not able to maneuver its solar panels nor is it able to move around on the surface, but I’m happy to hear that it has survived! As an interesting side note, it’s always interesting to me the sense of personal and emotional attachment you end up feeling towards these little rovers as we follow along with their lonely journeys across other worlds (perhaps its the effect of watching WALL-E too many times!).
7. COSMOS episode last night: Episode 2. The big element to me last night was the discussion and explanation of Natural and Artificial Selection. I thought this was done very well. Agreed, I also particularly liked the segment on how our eyes aren’t well adapted to life on land, we often forget that evolution is a bit of a one way street (hence, compound eyes!). We could possibly talk about Titan?
8. Arecibo observatory is back in action following a 6.4 magnitude Earthquake on January 13th this year that damaged one of the cables which moves the hanging detector around the area above the dish. I for one am glad to hear this not only because the Arecibo observatory has historically and presumably will continue to produce some great science (first evidence for neutron stars in 69, first binary pulsar in 74, first millisecond pulsar in 82, first extra solar planet in 94), but I am also glad to hear this because I think the Arecibo observatory is just one of the coolest telescopes out there. Our viewers will recognize it as the large 300m concrete dish in Puerto Rico that is used for radio astronomy and was featured in the films Goldeneye and Contact (along with many others I’m sure). The cable that was damaged was one of 18 cables that holds up the 900 ton focal platform, and interestingly this cable was already known to be a structural weak point: during the original construction of the facility one of the cables that was delivered was too short, so it was spliced together with another section of cable in order to span the appropriate distance–this structural weakpoint was exposed when the earthquake caused the cable to break.
Major Topics Discussed:
Topic: Where stars transition to Brown Dwarfs on the HR diagram
The Hertzsprung-Russell (HR) diagram Main Sequence (MS) has a lower temperature limit. New observations by Dieterich & Henry suggest that the lower temperature limit of the MS (core hydrogen burning) appears to be around 2075K. They examined 62 objects with spectral types M6V to L4, determining their temperatures and distances (and thus their luminosities) to plot the lower end of the MS.
When stars reach the MS they are in thermal equilibrium (hydrostatic equilibrium having been established by coire H fusion). Brown Dwarfs however never reach such a stage as they are continually cooling. Low mass, cool stars on the MS can be potentially very old whereas the Brown Dwarfs are relatively young. Further, lower mass stars have lower radii whereas higher mass Brown Dwarfs have smaller radii (as they are held up by electron degeneracy rather than radiation pressure).
Suggested Reading: NOAO newsletter
Thanks for listening!
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