Show notes for the night of August 26th, 2013
Hosts: Paul, Jesse
Title: Paul’s Boomerang Nebula gets WISE
This week in space/astronomy history:
1. August 28, 1789 – William Herschel discovers Enceladus, moon of Saturn.
2. September 1, 1979 – Pioneer 11 becomes the first spacecraft to fly by Saturn (second spacecraft to fly through the asteroid belt).
3. August 30, 1871 – Happy birthday Ernest Rutherford (August 30 1871-19 October 1937). Characterised radioactivity (alpha and beta radiation) and improved our understanding of radioactive decay and the atom in general. Originally from New Zealand, Rutherford ended up at McGill University (Montreal) via the University of Manchester.
1. WISE is revived. The Wide field Infrared Survey Explorer (WISE) was originally launched into space on the 14th of December 2009; it’s primary mission was to map the entire sky in infrared approximately 8 times. WISE was placed in a polar orbit approximately 525 km high. It worked until October 2010, at which point it ran out of its oxygen coolant. However, a follow up mission called NEOWISE was started to look for Near Earth Objects. It was placed in hibernation in February of 2011. Luckily, NASA has revived the spacecraft for a new mission where it will help search for more Near Earth Objects. (Suggested Reading: NASA Press Release, NASA Mission Page, Universe Today Article).
2. The Global Exploration Roadmap. Fourteen space agencies from around the world map out the way we get to Mars via the Moon and Asteroid rendezvous over the next 15-20 years. Ambitious and fraught with challenge, it is at least some type of blueprint to our future exploration of the Solar System. (Suggested Reading: NASA Press Release).
3. Io Erupts! Volcanic eruption on Io observed with Keck (1 – 5 micron infrared). We have come a long way since the Voyager probes discovery of volcanism on Io. Now we ‘routinely’ monitor the Jovian satellite from Earth. On August 15, 2013 Inke de Pater (U of C, Berkeley) observed a titanic eruption from the Rarog Patera region of Io. Rivers of lava are likely flowing onto Io surface. (Suggested Reading: Universe Today Article, New Scientist).
4. Summary of McMaster University, York University and Ontario Science Centre exchange. [See Jesse’s post on this here]
Major Topics Discussed:
1. New pulsar near galactic centre.
Eatough (Max Planck Institute) has found PSR J1745–2900 within 3 arc seconds of our galaxy’s central black hole. Perhaps as close as 33 light years (distance determination from Sol found by the dispersion method of long and short wavelength radiation passing through line-of-sight hot, ionised gas), this pulsar may hold the key to better understanding how and at what rate our central black hole is devouring the core of the Milky Way. For the first time, we actually have observational data that measures such parameters as ambient magnetic field strength (8 milli-gauss, 1,000 x greater than mean galactic field strength), density and temperature of the central accretion disk. With modeling about to commence in earnest, new revelations about the central black hole maybe just around the corner.
NATURE – A Strong Magnetic Field around a Super Massive Black Hole
2. X-ray observations reveal old collision invisible in optical
Galaxy collisions are ubiquitous in the universe. Giant galaxies are always pulling in smaller dwarf galaxies, the process by which big galaxies form. Data from the Chandra X-ray space telescope has shown the effects of a collision of a dwarf galaxy. As a dwarf galaxy plunges into the larger galaxy, the gases of both will encounter ram pressure. This is what happens when two clouds of gas interact/impact with each other. This significantly increases the temperature of the gas; in the case of NGC 1232, the gas is as hot as 6 million degrees.
Using Chandra, scientists took a picture of NGC 1232 in the X-ray, and say a large portion of the galaxy to be glowing at this high temperature. This is most likely the result of a recent collision with a smaller dwarf galaxy. Since the collision, NGC 1232 has absorbed the entire dwarf galaxy, only the X-ray data can indicate that any collision happened. The reason the gas still holds this temperature is because the density is very low, and therefore it is very difficult for the gas to radiate away all the energy.
NASA Press Release – NGC 1232: Dwarf Galaxy caught ramming into a large spiral
National Geographic – Photo: Galaxy crash revealed first time in X-rays
3. The Boomerang Nebula, the coldest place in the Universe?
Stars live most of their lives on the main sequence, which is essentially the time they spend fusing Hydrogen. Once they leave the main sequence it is a relatively short time before they are mostly dead (i.e., black holes, neutron stars, white dwarfs, and the like). There are, however, a multitude of transitional stages a star may, or may not, go through before they officially die. The route any given star takes to death is ultimately dependent on its mass. Asymptotic Giant Branch (AGB) stars are what relatively low mass stars (1-10 solar masses or so) can become before they die. Over the course of about 1000 years, an AGB star will become a planetary nebula. The Boomerang Nebula is a class of object exactly in between an AGB star and a planetary nebula, known as a proto-planetary nebula.
The astronomers in the project were able to measure the temperature of the gas, by measuring an absorption feature in Carbon Monoxide (CO). Given the depth of absorption, and the velocity of the outflowing gas, astronomers believe the specific set of conditions have allowed the expansion to drop the temperature within the nebula to below that of the Cosmic Microwave Background Radiation, which makes the Boomerang Nebula the coldest place in the Universe (other than labs on Earth).
APOD – A Beautiful Boomerang Nebula
Astrophysical Journal Letters [PDF] – The Boomerang Nebula: The Coldest Place in the Universe?
Thanks for listening!
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