Show notes for September 16, 2013
Hosts: Ryan, Jesse, Paul
Title: Voyager’s Lithium Battery; Keeps Going and Going…
Tonight we celebrated the news that Voyager 1 has officially broken through the heliopause and is now bathing in the radiation from interstellar space. This is a huge moment for human exploration into nature. Jesse summarizes the work on a recent Gamma Ray Burst, Paul talks of Lithium in stars, and Ryan delivers on his promise to tell us about Odyssey. Show notes and podcast below. Thanks for listening.
This week in space/astronomy history:
1. September 17, 1789 – William Herschel discovers Mimas, another of Saturn’s moons. It is the smallest body in the solar system that is round due to self-gravitation. Not just a death star… (haha)
2. September 16, 1848 – Hyperion, moon of Saturn, discovered by William Bond, George Bond, William Lassell. Hyperion is famous for its sponge-like appearance, and is the ONLY moon in the solar system to have a chaotic axial spin.
3. September 17, 1857 – Konstantin Eduardovich Tsiolkovsky is born (died September 19, 1935). He was a Russian rocket scientist and pioneer of astronautic theory. Was the first person to coin the term ‘space elevator’ .
4. September 21, 2003 – The Galileo Mission ends with the spacecraft being deorbited into Jupiter.
1. Voyager 1 left the heliopause! The Voyager 1 probe was launched in September 1977, and has now been operating for 36 years; it is at a current distance of 125 Astronomical Units (A.U.) with a light travel round trip of approx 34 hours. Countless discoveries are credited to Voyager 1 (including: discoveries of moons of Jupiter, Io’s volcanism, Uranus’ interesting magnetic field, etc.). The Voyager team has now announced the the probe has left the heliopause, indicating it is now in interstellar space; however, it hasn’t left the solar system yet! (Suggested Reading: NASA press release 1, NASA press release 2, Universe Today article, NASA fact sheet, Science Magazine article, @NASAVoyager).
2. The Autumnal Equinox. Equinox occurs on September 22, 2013 16:44 EDT. (Suggested Reading: Wikipedia Article ‘Equinox’).
3. Gemini’s Planet Imager arrives at the observatory. The Gemini Observatory is a twin 8.1 meter diameter optical telescope, with one telescope located atop Mauna Kea in Hawaii, and the other located on Cerro Pachon in the Chilean Andes. It is controlled by an international consortium, of which Canada is a 16% partner. The newest instrument of Gemini South, the Gemini Planet Imager (GPI), arrived at the telescope and is in preparations for installation. GPI will be used to image extrasolar planets around nearby stars. It is expected to be fully operational by observing semester 2014A. (Suggested Reading: Gemini press release, Instrument Homepage).
4. Opportunity rover arrives at Solander point in Endeavour Crater, begins science operations. The rover, although sitting in the shadow of the larger and newer cousin Curiosity, has discovered a new gem of scientific discovery. Sneaking in a shallow part of the base of the crater, nearly missing an apacalyptic crash with a boulder, and manoevering through a field of several others, Opportunity has found a small escarpment like cliff with many interesting geological features. (Suggested Reading: The Planetary Society article).
5. Curiosity arrives at ‘Darwin’ feature on Waypoint 1 (Suggested Reading: Universe Today article).
Major Topics Discussed:
1. Gamma Ray Burst 12.7 billion light years away
Gemini observations were taken just 13 hours after the discovery of the Gamma Ray Burst (GRB), named GRB130606A. It was discovered in June of 2013, by the Swift Burst Alert Telescope. The research team were able to get both Gemini and MMT spectroscopy, which was as good resolution as spectra taken for quasars of equal distance. The GRB is located at a distance of z=5.9, or roughly 12.7 billion light years away.
Gamma Ray Bursts and quasars are both very important probes of the high-redshift universe, probing the time known as the ‘Dark Ages.’ This was a period of time where the universe was mostly neutral. The way in which the universe became re-ionized is still an on-going discussion. Important data from GRBs will help push this discussion forward. Even more important than quasars, as quasars may have some practical and inherent biases in their data.
(Suggested Reading: Gemini Press Release – Gamma-Ray Burst Illuminates Galaxy in the Dark Ages, arXiv preprint – GRB130606A probe of early universe)
2. Sun-like stars lose lithium with age.
Based upon the evidence of lithium abundance from primitive meteorites, the Sun should have considerably more lithium than it actually possesses. This absence has proven difficult to explain. In a recent article in Astrophysical Journal Letters it appears that the loss of lithium correlates with the age of the star itself. Munroe et al (Brazil) have studied only 3 Sun-like stars using the VLA and have found that their age and lithium abundances correlate in the sense that the older the star, the less lithium it possesses.
Lithium is destroyed at temperatures in excess of 2.5 million K suggesting that lithium must sink to very deep levels in the star, well below the conventional depth of the convective zone. It would seem that much more mixing between the hotter and deeper radiative region of the star and the convective envelope is occurring. Is there a connection between the lithium abundance and exoplanets around these stars? Stay tuned! Reference: T. R. Monroe et al. “High Precision Abundances of the Old Solar Twin HIP 102152: Insights on Li Depletion from the Oldest Sun.” Astrophysical Journal Letters, September 10, 2013.
Thanks for listening!
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