Show notes for the 18th of November 2013
Hosts: Jesse, Pat, Rob B., Harrison
Title: Weird Quasars Have Extra Suck
A busy night with lots to talk about on ‘the Universe.’ Live guest, friend of the show, and all around good guy Randy Attwood joined the crew to chat about his new venture: Earthshine Astronomy and Space Science Org. This is a group that focuses on astronomy outreach in the Greater Toronto Area. York Universe host Dr. Patrick Hall was also on this evening, and chatted about his new discovery that was getting some ‘rounds on the internet. Hold onto your butts.
This week in space/astronomy history:
1. November 20, 1889 – Edwin Hubble born (died September 28, 1953). Hubble is most famous for (among other things), measuring the distance to Andromeda Galaxy confirming the Universe was bigger than the Milky Way, and his distance vs. redshift relationship (redshift increases with distance).
2. November 18, 1989 – The Cosmic Background Explorer (COBE) is launched. This was an ‘explorer’ class spacecraft (2nd tier space research missions). This satellite was launched to study the Cosmic Microwave Background Radiation (CMB). It confirmed that the CMB is a perfect blackbody, and also measured the intrinsic anisotropy (of order 1 in 100 000).
3. November 14, 1971 – Mariner 9 (aka Mars ‘71) becomes first human made object to orbit another planet (Mars), just ahead of Soviet Mars 2 (November 27, 1971) and Mars 3 (December 2, 1971). More reading on November being a significant month in the history of space exploration: ‘Reaching Mars.’
Live Guest: Randy Attwood
Bio: Randy Attwood is an astronomy and space science educator, writer and communicator. He is a resident of Mississauga and has been looking up at the night sky for over 40 years. Mr Attwood is very active in educational public outreach. He is the President of a not for profit charitable organization called The Earthshine Astronomy and Space Science Organization. Earthshine runs monthly astronomy sessions at the Riverwood Conservancy in Mississauga where members of the public are invited to come out and look at various astronomical objects through telescopes. Earthshine is making plans to obtain a medium sized planetarium and run educational programs for school and youth groups and members of the public. Ultimately, Earthshine hopes to fund and built a permanent astronomy and space science educational facility in Mississauga. He is the founder and Past-President of the Mississauga Centre of the Royal Astronomical Society of Canada. He is a Past President of the Royal Astronomical Society of Canada – Canada’s national astronomy organization. He has appeared on CTV, CBC, GLOBAL and the Discovery Channel to provide background information for space and astronomy related stories. He has covered 12 space shuttle launches and landings as a journalist and photographer. He has travelled to various places around the world to observe and photograph total eclipses of the Sun. He was recently a Senior Editor with SpaceRef – a news reference organization which covers all aspects of civil, commercial and military space as well space policy, space technology, astronomy and other space related topics. Mr Attwood is the Managing Editor of Space Quarterly – a magazine produced four times a year which covers all aspects of space exploration. www.spaceref.com and www.spaceref.ca are the two main websites. He has also written a Grade 9 astronomy unit for a text book published by McGraw-Hill Ryerson.
Asteroid 260235 was renamed Asteroid Attwood in his honour.
1. Jaw dropping new image of planet Saturn by Cassini. This brand new midnight image from NASA’s Cassini Spacecraft (currently orbiting Saturn) comes from 141 stacked wide-angled images (red, green, and blue filters). It features: all of Saturn’s rings out to the E ring (created by the geysers of Enceladus), the Earth-Moon system, Mars, Enceladus, Tethys, Mimas, and more. Note that many of these objects were brightened in post-processing in order to make seeing them easier. (Suggested Reading: NASA news article, Bad Astronomy article, follow up article on ‘amateur’ saturn image making, The Day the Earth Smiled)
2. Mars Atmosphere and Volatile Evolution (MAVEN) launched from Launch Complex 41 on a ULA Atlas V. The 5,400-pound spacecraft lifted off at 1:28 p.m. EST, the mission’s first opportunity. MAVEN’s solar arrays deployed and are producing power. MAVEN will reach Mars on Sept. 22, 2014.
MAVEN will explore the Red Planet’s upper atmosphere, ionosphere and interactions with the sun and solar wind. It will measure the escape rates for all the applicable processes that work to strip away parts of the planet’s atmosphere. The goal is to determine the role that loss of volatiles from the Mars atmosphere to space has played through time, giving insight into the history of Mars’ atmosphere and climate, liquid water, and planetary habitability.
Liquid water cannot exist pervasively on the Martian surface today due to the low atmospheric pressure and surface temperature. The amount of water needed to explain some of Mars’ features such as flow channels and minerals such as clays and hematites might have required as much as a planet-wide layer one-half a kilometer deep or more
Possible theories for the water loss include hydrodynamic outflow and ejection from massive asteroid impacts during the later heavy bombardment period (ending 4.1 billion to 3.8 billion years ago) and the leading theory that Mars lost its intrinsic magnetic field that was protecting the atmosphere from direct erosion by the impact of the solar wind.
(Suggested Reading: YU Blog: MAVEN launches to Mars)
4. Comet ISON will be at perihelion on November 28th, 2013 (T-10 days). At the time of the show, ISON-Earth distance: 0.872AU. ISON-Sun distance: 0.575AU. ISON-Tatooine distance: Far, Far Away. (Suggested reading: Universe Today article).
Major Topics Discussed:
1. Gas Falling into Black Holes, with Dr. Patrick Hall
A quasar is a disk of hot gas around a black hole at the centre of a distant galaxy. Gas clouds are attracted by the black hole’s gravity, they fall towards it and collide, and you end up with a flattened, rotating disk of gas slowly spiralling into the black hole. We call this an accretion disk.
The closer you get to the center of the accretion disk, the faster the gas particles are orbiting and colliding with each other. That means more friction, and higher temperatures. So there’s a region around the quasar at least as big as Earth’s orbit around the Sun, which is at least as hot as the surface of the Sun. (And we can see something putting out that much light across the universe.)
But an accretion disk in nature seems to resemble a blender running with the lid off. Most of the gas goes around & around (and eventually into the black hole), but some gets flung off the disk in a ‘wind.’
We see these winds silhouetted in front of the quasar, absorbing some of the quasar’s light. And because the gas is moving away from the quasar and towards us, we see a blueshift from the Doppler effect (meaning that the gas absorbs light of bluer colors than it normally would).
But what I discovered was some quasars with _redshifted_ absorption.
This could be caused by gas falling into the black holes at the centres of these quasars.
But if that’s the case, why are there so few of them? We know of 17 examples, but they are very rare: only 1 in 12,000 quasars shows redshifted absorption.
Or, this could be gas which is orbiting the black hole and slowly moving out. A wind like that will show gas moving both toward us and away from us. Here’s an analogy: imagine an ant on a spinning merry-go-round, crawling from the center to the edge. You will see the ant moving toward you about half the time and away from you about half the time. The same idea could apply to the gas in these quasars.
In either case, the gas in these quasars is moving in an unusual fashion. And these objects weren’t predicted! I found them by chance while looking for something else. Science marches on…
(Suggested Reading: York University press release, Flickr photos, Animations on Pat Hall’s Research blog, io9 article)
2. Hubble observes 6 comet-like tails from asteroid
Using the Hubble Space Telescope, astronomers have run across a very unexpected find: an asteroid with comet-like tails. Not just one, but SIX tails streaming away from the asteroid, much like comets generate tails as they plunge towards the Sun. The asteroid is designated as P/2013 P5.
The tails of dust emitting from the asteroid also appear to be very transient, as they changed dramatically over 13 days of observation. A possible explanation for the dust tails is the rotation rate of the asteroid steadily increased until it began to fly apart. The astronomers do not believe the tails are related to any impacts.
So how do you spin-up an object to this rotation speed? It may be possible using sunlight. When the Sun shines on an object in space, it heats it up. The object then re-emits some of that radiation as infrared light (heat), which imparts a (very small) momentum kick to the object. This is known as the YORP effect, and this principle may have caused the asteroid to spin-up to very high speeds, eventually enough for it to start to break apart.
This is very different from a cometary tail; those are created by volatile gasses frozen onto the icey-rocky bodies (comets) sublimating and being pushed away by the Sun as the comet gets closer to the inner solar system.
(Suggested Reading: Hubble Press Release, Bad Astronomy article, arXiv preprint)
Thanks for listening!
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