Friday, January 6, 2017
Day 3 at the American Astronomical Society 229th Meeting
Greetings from Palmia Observatory
Well, we are offset again at the AAS 229th meeting, just outside Dallas in Grapevine, Tx. The weather turned really cold today, especially given my California expectations, and it actually snowed a bit. I went out briefly on the convention floor 3rd floor outside balcony and could barely stand it for only 10 seconds, which was quite long given that my IPhone weather forecast said the temperature was 22 degrees F. Brr, that was cold. Anyway, I want to provide some brief comments about some of the sessions I set in on.
The first plenary session was by the AAS George Ellery Hale prize winner, Terry Forbes, University of New Hamshire, who spoke on Magnetic Energy Release from Solar Flares. Most of the presentation was over my head and very technical with discussions of intricacies of magnetohydodynamics and transfer of energy to solar flares. The general concept was understandable but there was too many technical details. One take away point for me was that even though flares and coronal mass ejections are magnetic energy transfers, the magnetograms of the sun surface do not show any change during the ejection. The energy transfer is all in the corona. Forbes then mentioned something about T Tauri type stars. I got sidetracked at that point, since I had heard that T Tauri stars are some type of variable stars but couldn't quite remember what was so definitive about T Tauri stars.
Well, it turns out that TTauri stars are stars that are quite young and have not yet evolved enough to move onto the main sequence. They also do not generate any energy by nuclear fusion, instead they glow very bright just by the energy released by gravitational collapse. The stars internal pressure is not yet high enough to begin nuclear fusion, but the "star" can still be more luminous that it will eventually be once it moves onto the main sequence, because event thought their temperatures are similar, their radii are larger and therefore the star is more luminous. All of this because of the release of gravitational energy from the collapsing gas cloud that is becoming a full fledged star.
The second session, which I got to to a bit late and didn't get the speaker's name, was on the DARE program, which stands for Dark Ages Radio Explorer. This program is really neat in that it's goal is to probe back in time to the birth of the first stars formed after the Big Bang. The method is to monitor radio frequencies in the 40 to 120 MHz range, which corresponds to 21 cm radiation from hydrogen, which has been red shifted from microwave frequency to the radio frequency listed. The red shift corresponds to z = 35 to z = 11, at which time the first stars would be forming. This corresponds to tHe epoch between 80 and 420 million years after the Big Bang. This is pretty neat, but that frequency band, 40-120 MHz is a very noisy band with natural sources as well as manmade sources. So, the nest thing about DARE is that they propose to place a large antenna in orbit around the moon and only take data when the satellite is on the far side of the moon. The team hopes to launch in about 2022.
Another speaker, again I didn't get his name or affiliation, talked about some Lyman alpha probes. Remember that Lyman alpha radiation is radiation from hydrogen atoms when an electron drops from the 2nd energy level to the 1st energy level, and the emitted radiated is at 121.6 mm, or for you frequency buffs, 2.47 x 10^15 Hz. The Lyman alpha probes are very useful because the universe is made mostly of hydrogen and these energy emissions are quite common and once emitted and travels through the expanding universe, the radiation is red shifted. The speaker was looking for Lyman alpha radiation that had been redshifted z = 8.6 to z = 11.1. The presenter used an analogy that I found quite informative and that is that at those redshifted we are looking way back in time. His analogy concodered a calendar where Jan 1 represents the Big Bang and December 31 represents, today, or 13.8 billion years after the Big Bang. He said that the conditions represented by measurements with z = 11.1 would correspond to January 10 and z = 8.6 would correspond to only January 15. This is why measuring the red shift of observed galaxies and other objects represent looking back in time.
Neil Brandt, Penn State, winner of the AAS Bruno Rossi prize, talked about some of the results from the Chandra x-ray survey. X-ray emissions are key to understanding what happens in many regions of the universe where gas is heated to such high temperatures that the gas emits x-rays. He provided a lot of details, but I was more interested in some of observation parameters. He mentioned that Chandra deep field images can find almost 24,000 x-ray sources, like active galactic nuclei, per every square degree of the sky. That is a lot of objects, but also keep in mind that the deep sky image represent 7 million seconds of observation time, just starring at one place in the sky. He said that the dimmest object capable of being seen would only generate one count per 10 days. That is along time to what to get on photon. That is pretty neat and pretty sensitive. He also mentioned that they are starting to use the stacking of images technique used all the time by amateur astronomers. Wow, I would have thought if amateurs have been doing that for years, then the professionals would have using it for years too, but apparently not the case. Separately, I just saw a separate article about this very topic. If you are interested check out:
I also set in on a working group that is preparing for the release of the 2020 Decadal Survey. This survey prepared for the National Academey of Science will represent the state of the art in astronomy and indicate what the most significant remaining questions and areas of resaearch that are the most critical. This survey will the be reviewed and sent to government funding agencies to allocate the available funding to meet the most significant goals outlined in the Survey. It was neat to sit in on this process and see what happens as real science moves forward. One topic that came up was, interestingly enough, wa the recent Workshop on Searing for Life in Time and Space. This is the same workshop that many of our little science squad attended back on Dec 5-6 at rhe Beckman Center in Irvine. I commented about that our attendance at that workshop in my December 6 blog post.
Finally, I sat in on another session that dealt with the use of Cubesats for doing Research in astronomy. Astrophysics, planetary and earth science. These low cost satellites enable scientists to get good data, that is most easily or omlynattainable from orbit, without the cost of having NASA build a fully NASA qualified satellite mission. If you want to check out the status of Cubesat capabilities and benefits to science check out the free Narional Academies, 131 page report at: www.nap.edu/Cubesats
Ok, that is enough for this long day. I hope this gives you at a least one perspective of the meeting sessions. I' m wiped out and its time for a martini.
Until next time