Well, it is finally time to make our way to the 235th American Astronomical Society (AAS) meeting in Honolulu. So after making our way to the meeting we can summarize some of the technical sessions.
First though, we could see a beautiful sunset as our plane took off from John Wayne Airport.
|Leaving SNA at sundown (Source: Palmia Observatory)|
Once airborne, we get instant verification of what we mean by city lights pollution. Hmm, no wonder we have to drive away from the city to get a little darker nighttime skies.
Normally, we don't think of photographing Alpha Centauri because it is too far below the horizon for us viewers in the continental US. But as we can see in this screenshot, the star is just above the horizon.
|Hey, we are much further south and have a chance of seeing Alpha Centauri (Source: Palmia Observatory)|
It's the first day of the AAS meeting for us and it is about a 15 minute walk from the hotel to the convention center. There have been several previous days of workshops but this year I elected not to attend any of those pre-meetings. I recognized a couple of other AAVSO members and said high to them as we got to the conference center. Here we see Resident Astronomer Peggy ready for the first plenary session on "Black Holes Snacking on Stars."
|Resident Astronomer Peggy ready for the first plenary session at AAS 235th meeting (Source: Palmia Observatory)|
The 235th AAS meeting is brought to order by AAS President, Megan Donahue, Michigan State University. If I remember correctly there was something over 3000 astronomers and at least one physicist wannabe present. The AAS encourages the non-professional astronomers to attend and offers a discounted conference fee for those attendees.
|The 235th AAS Meeting is kicked off by AAS President Megan Donahue, MSU (Source: Palmia Observatory)|
The first plenary session was presented by Suvi Gezari, U. of Maryland. Dr. Suvi's interest has been in tracking how black holes accrete more material and stars in order to become even larger black holes. She described how the accretion process will result in emission of x-rays and other radiation as material falls into the black hole. A star can be destroyed by tidal forces if it comes too close to a black hole. This material will be heated to high temperatures and its progress can be tracked. But often it happens that if the black hole is big enough that there is no emissions and the star can be swallowed whole. Remember that the radius of a black hole's event horizon goes up linearly with the mass of the black hole, but that the tidal forces that can rip a star apart go up as the inverse cube of the radius from the black hole. So, for very large black holes, they can swallow a star whole before the tidal forces get large enough to tear the star apart. In these cases, no visible or x-ray radiation will be present and no evidence of the snacking will be left behind.
|Suvi Gezari, U. of Maryland, presents plenary session on Black Holes Snacking on Stars (Source: Palmia Observatory)|
So Suvi's task is to identify how many accretions events occur and follow black hole accretion events before they become too big for any evidence of snacking to be emitted. But, many other signals can be falsely interpreted as snacking events. Supernovas can be misinterpreted as snacking events. You can see in the following screen shot of one of her slides that many false signals have to be eliminated in order to identify true tidal disruption events (TDE). When a true TDE is identified then the alert can go out to other observatories to begin a follow up observation plan of the event. Pretty neat, thanks for that Suvi!
|New electronic posters along with old paper posters in the AAS exhibit hall (Source: Palmia Observatory)|
One of the posters that caught my attention was one that described how the rotation rates of various stars can be made by measuring their brightness with photometric techniques. Hmm, how do you tell the difference between just a regular variable star and some star that has some feature, like some sunspots, or star spots to be fair, that can be observed and found to be rotating? Likewise, if rotation of stars can be determined by analysis of light curves, then how do we know that a variable star is just a rotating star itself?
So, I asked UCI student, Rae Holcomb, how she was able to differentiate between a variable star and any associated rotation. She said that yes, it was true, that these two effects occur and you have to be able to differentiate between them. Her approach, described on the poster, includes the analysis needed to resolved the differences and then estimate the star's rotation rate, independently of its normal variable brightness. The two astrophysical processes are not correlated so the lightcurve can be separated into both of the components. Hmm, I see the photo of the poster is not really clear enough to examine the method used. Anyway, it was very interesting to find out that it could be done. Thanks for that discussion and good luck going forward, Rae!
|Rae Holcomb, UCI, at her poster tells how stellar rotation can be extracted from light curves (Source: Palmia Observatory)|
Finally, after wondering around on the exhibit hall floor, sampling coffee and chocolate treats at various of the booths of vendors displays, I bumped into some old acquaintances from my dalliance with trying to design and build a cubesat. We all met as part of a Meetup.com group, started by Visionary Physicist, Dr. Don. Randy and Sean left that group and went on to found SpaceFab. You can check out the vision and other details of this new company at www.spacefab.us!
SpaceFab's initial goal was to launch small cubesats, but now they say launch costs have come down enough so that instead of launching a cubesat, they can launch the larger satellite, shown between them in the photo below, for about the same cost. Hmm, keep going and good luck, Sean and Randy!
|Meeting up with Sean and Randy of SpaceFab.us on the 235th AAS Exhibit Floor (Source: Palmia Observatory)|
Finally, it was time to play a little hooky and check out of the AAS meeting and enjoy the Hawaiian sunset. Yes, it's January, but the sun is strong, the temperature in the high 70's, and even when it rains, which it seems to do quite often, it is over before you can usually get out your umbrella.
|Sunset from the bar along Waikiki Beach (Source: Palmia Observatory)|
So, after the sun went down and the beach crowds thinned out, it was time to walk along the beach and play keep away from the surf. Venus was bright enough to show through the clouds but that was the only visible object in the sky in that direction.
|Warm ocean waters along Waikiki Beach (Source: Palmia Observatory)|
Until next time, Aloha!