Show notes for October 7th, 2013
Hosts: Paul, Jesse, Hugh
Title: Hugh and You Chasing Eclipses
Live Guest: Dr. Ralph Chou
It was a busy night on York Universe! Tonight we welcomed a new host to our show, Hugh Podmore. He is a graduate student in Space Engineering at York University. We were also delighted to interview Dr. Ralph Chou, former president of the Royal Astronomical Society of Canada Toronto Faction, and seasoned solar eclipse chaser (he has GREAT stories!). We condemned the U.S. government shutdown, celebrated NASA’s victory with MAVEN, and chatted about Ultra Compact Dwarf galaxies. Podcast and show notes below.
New Host: Hugh Podmore
York Universe welcomes a new host to the ‘airwaves:’ Hugh Podmore. Graduate student in Earth and Space Engineering. A little about Hugh:
Hugh did his undergrad at McGill university in Montreal, studying physics and computer science during this time he did some research with the science division of the Canadian Space Agency — white dwarf astroseismology to begin with, and then modelling circumstellar debris disks around white dwarf stars in his final year.
Currently Hugh works in nanosatellite development, part of the YuSEND group at York, who are building a cubesat for a mission called QB50. The cubesat, which will launch in 2015 will take in situ measurements of the thermosphere to determine its chemical composition and will act as a demonstration vehicle for nanosatellite technology developed within the ESSE department. Hugh is working on the attitude control system, as well as tinkering with the solar cells.
This week in space/astronomy history:
1. October 5, 1984 – on this date, Marc Garneau (first Canadian in space) launched aboard STS-41-G, followed by STS-77 in 1996, STS-97 in 2000. Current sitting member of Canadian Parliament for Westmount (Montreal).
2. October 9, 1604 – Kepler’s Supernova observed. Observed by Johannes Kepler on October 9th, 1604, it is the most recent naked eye supernova observed in our own galaxy. The ‘new star’ was observed in the constellation Ophiuchus. Now 409 years later, we see the supernova remnant SN-1604. The progenitor supernova would have been a type 1a (white dwarf collapse after accretion), this was solidified using data from the Chandra X-ray Observatory (see Press Release).
Live Guest Interview:
Guest: Dr. Ralph Chou
Bio: Dr. Ralph Chou has been an amateur astronomy for almost 50 years and actively involved in The Royal Astronomical Society of Canada for over 40 of them. After obtaining his BSc in Astronomy from the University of Toronto, he studied Optometry and Vision Science, and is now a Professor Emeritus of Optometry and Vision Science at the University of Waterloo. His research on occupational and environmental eye protection has been applied to ISO and Canadian Standards Association standards for sports and industrial eye protectors as well as sunglasses and solar filters. Dr. Chou has successfully observed 16 total solar eclipses. A past president of the Toronto Centre of the RASC, he actively participates in outreach and observing programmes at the Toronto Centre’s observatories and serves as Co-Chair of the David Dunlap Observatory Management Committee.
Quote of the show: Paul had asked Dr. Chou what some of his best experiences were with chasing total solar eclipses around the world. Immediately, Dr. Chou called up a memory from his trip to Iguacu Falls, Brazil in November 1994 (though noting you can be in either Brazil, Uruguay, or Paraguay at Iguacu Falls). Dr. Chou described his view of the sky at mid-eclipse (during totality):
Planets were like diamonds on dark blue velvet. -Dr. Chou
We wish we were there!
1. The United States government shuts down.
1a) LADEE Enters Lunar orbit. The newest Lunar mission, the Lunar Atmosphere and Dust Environment Explorer, aka LADEE, entered Lunar orbit on October 6, 2013 at 6:57 am EDT. The new orbiter will be analyzing the Moon’s exosphere. Among its science payload is a demonstration of an optical communication system. Unlike Radio communications, this technology uses pulses of laser light (much like fiber optics). (Suggested Reading: LADEE wiki, Lunar Atmosphere wiki, Universe Today article, York Universe episode covering LADEE launch)
1b) MAVEN granted ‘emergency exemption’ status. The next mission to Mars, an orbiter named MAVEN, was taken out of furloughed status that has put so many other NASA missions on hold. Scientists on the project were outspoken on the fact that a launch window to Mars comes around only once every couple of years. Therefore any waiting on this project (which is slated to launch between November 18, 2013 – December 7, 2013) could mean potential 2 year hiatus or even cancellation of the project. On October 3rd, 2013 (two days after the ‘government shutdown’ began), MAVEN was given an exemption, allowing the team to continue their work. (Suggested Reading: University of Colorado Press Release, Universe Today article, MAVEN wiki)
2. Draconids meteor shower peaks tonight/tomorrow (read more here).
Major Topics Discussed:
1. Evidence for the densest galaxy in nearby universe
Using a wide range of telescopes both on Earth and off, astronomers have been analyzing what seems to be the densest galaxy in the local universe, dubbed M60-UCD1.
This object is a particularly massive example of an Ultra Compact Dwarf galaxy (UCD), a type of galaxy only discovered in the last 15 years. UCDs have sizes that range from the largest globular clusters to the smallest compact elliptical galaxies (typically between 10-100 parsecs). Since discovery, the origin of these objects has been up for debate. The problem breaks down into two answers: UCDs may just be the massive end of the normal sequence of globular clusters, or UCDs are the low-mass end of individual galaxy growth (i.e., inside a normal dark matter halo). Of course, the answer could be an amalgam of the two theories, and globular clusters/compact galaxies may co-exist at some overlapping size/density regime.
Originally discovered using the Hubble Space Telescope, follow up observations (with Chandra X-ray observatory, and Keck Observatory), are hinting towards a possible answer. Perhaps most notable, the density of M60-UCD1 is about 15000x greater than the Earth’s local neighbourhood [side note: this would mean stars are approx. 25x closer to eachother. If Alpha Centauri were 25x closer to Earth, it would be approx. 11000 A.U. away. Voyager is 1/10th that distance from Earth already]. Not only is it the densest, but it is also the most luminous and most massive of all known Ultra Compact Dwarf galaxies.
Optical observations (through the Multiple Mirror Telescope in Airzona) indicate metallicity near solar, indicating an age >10 Gyr. Chandra observations indicate the presence of a super massive black hole (roughly 1E7 Msol), which may be active (or may also be an X-ray Binary).
Based on the above observations it seems unlikely that M60-UCD1 is a globular cluster. Specifically, the possible presence of a supermassive black hole, the high metallicity, and different structures inside it point toward M60-UCD1 being a tidally stripped remnant of a more massive progenitor galaxy. The astronomers also point to nearby galaxy M60 as possibly guilty of stripping M60-UCD1.
Also, recent simulations of tidal stripping of larger galaxies can produce the various sizes/densities of Ultra Compact Dwarf galaxies. (Suggested Reading: Keck Press Release, Astrophysical Journal Letter, arXiv preprint, Dwarf Galaxy wiki)
Thanks for listening!
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