Well, here we are trying to adapt to our shelter in place guidelines and still continue on our physicist wannabe journey. Luckily more and more meetings are being rescheduled for online viewing.
Our local OCA general meeting has now completed its first online meeting where we heard a presentation by Dr. Laura Danly, who works now at Griffith Observatory, but conducted the meeting from her home.
|March 13 OCA meeting, conducted April 10, as online virtual meeting (Source: Laura Danly, Griffith Observatory)|
Laura discussed the Apollo mission to the moon, including the upcoming 50th anniversary of Apollo 13. She also described the ongoing planning in NASA and elsewhere about the how and why of returning to the Moon or maybe just concentrating more on going to Mars. Thanks for that Dr. Laura!
I was a little disappointed though because we were not able to view any of the smiling faces of our friends and associates who viewed the discussion online. The meeting organizers have to weight privacy and other concerns so they elect not to enable viewing the audience, so we have to seek out everyone's smiling face elsewhere!
The other good virtual news is that the American Physical Society (APS) April Meeting, which originally was going to be held live in Washington, DC, is now scheduled to be conducted at the same scheduled time but now online. So next week we all can sign up for the event and my understanding is that it will probably be available for free. Yeah, even though both Resident Astronomer Peggy and I had planned to go DC, not having to travel and still be able to attend seems like a pretty good alternative. Sadly, we will miss meeting up there with Searching for Gravity Waves, Dr. Gary. Darn!, it'l have to next time, Gary!
|Hooray, the APS April Meeting is going Virtual (Source: www.aps.org)|
While most of the NASA sponsored space work is in quarantine mode, SpaceX in Texas at Boca Chica facilities still is operating pretty much around the clock getting the next Starship serial number #4 ready. In the meantime, SpaceX released a six page "Starship Users Guide", so you can follow up on the many uses they see for the Starship. Go Elon!
|Starship Users Guide (6 pages) now available (Source: SpaceX)|
In this weeks Nature Briefing email, two articles caught my attention. First up is some more results from the Event Horizon Telescope (EHT) collaboration, who have now released their study of the block hole in 3C279. They also said that while the observatories have now been shut down, they have collected enough data on the black hole at the center of the Milky Way, Sgr A*, that they continue to analyze that during their non-observing time and hope to release those results shortly. This Sgr A* study is what I am waiting to hear all about!
In the referenced article by Jonathan Amos at the BBC, you can see some of the higher resolution images of the black hole powered jet in 3C279. This quasar is very distant, something like 5 billion lightyears and very dim, but the EHT can achieve higher resolution than other telescopes.
|Nature Briefing of April 9 illustrates new paper on EHT study of 3C279 (Source: J. Amos, BBC)|
If you don't remember where all the telescopes of the EHT are located, here is a convenient graphic showing their locations. To get higher resolution, you need a bigger aperture, in this case about as big as the Earth.
|Location of observatories making up the EHT (Source: J. Amos, BBC, April 7, 2020)|
If you want more of the technical details of the 3C279 study you can check out the paper from April 7, 2020, in the latest issue of Astronomy and Astrophysics. Here is the title page and the list of authors who make up the EHT collaboration. Luckily they don't have to all be in the same physical location to continue working together.
|List of authors for EHT study of 3C279 (Source: J. Kim, et al, Astronomy and Astrophysics, April 7, 2020)|
Another article from the current issue of Nature Briefing had a discussion of the number of viral vaccines currently in the development cycle. Wow, a lot of work is going on in many different commercial and government laboratories. This is really amazing especially when you consider that the viral genome was just sequenced back in January.
|Pipeline of COVID-19 vaccine candidates (Source: T. Thanh Le, et al, Nature Reviews, April 9, 2020)|
So, it was good to see that many vaccine development projects are in the pipeline. It turns out that the online lecture series by Professor Vincent Racaniello is also just covering vaccines in his recent video released April 11 on Youtube entitled, "Virology Lectures 2020 #19: Vaccines." Check it out if you want to hear the latest as delivered to online medical students. It is always a bit over my head but Professor Vincent always does a good job of making clear presentations.
There is a separate topic associated with the COVID-19 pandemic that is of some interest to this scientist wannabe and that is "what determines how long viruses can live on different material surfaces?" You can see in the following screenshot from WebMD that the virus can survive from a few hours to a few days depending on the material. Now we know that viruses are not really alive, but the question really applies to how long they can remain intact and still capable of causing infection. But why is it, for example, why it can survive on most metals for 5 days, but for only 4 hours on another metal, copper?
We know that the capsid protective coat of most viruses is a icosohedral, 20-sided structure made of of say 20 identical molecules, held together by ionic bonds, not covalent bonds, so the disruption energy is quite small. I'm curious how these survival times come about. I estimated the kinetic energy of air molecules and then compared it to estimates of capsid bond energy, which was about a billion times bigger than individual air molecule. It seems to be so material dependent that it is not just due to say air molecules bumping into the capsids. If you have an explanation, please let us know.
|What physical properties establish these virus particle survival times? (Source: WebMD)|
Ok, let' return to see what is going on in the current Coursera course, The Evolving Universe, conducted by Caltech Professor George Djorgovski. I found the discussion about how astronomers used radio astronomy and the hydrogen 21 cm emission line to trace out the structure of the Milky Way. They found that there is enough neutral hydrogen atoms that their location and amounts could be used to map out the structure. Also the Doppler shift describes the motion of the hydrogen atoms. It was not quite clear to me, however, how the astronomers could tell the difference between close by hydrogen and far off hydrogen. Consider, for example, any of the lines from the Earth, and ask how you know the distance to the various arms etc. Measuring distance is hard and I missed the explanation about how that was done in this radio astronomical study. It had to do with assuming that a random collection of stars would have something like a uniform average brightness and if you compared different groups of stars then the difference between group averages would correspond more to effects of distance. So, you need to gather lots of star data to be able to estimate distance. More exciting lectures on the evolving universe, so be sure to sign up if you haven't done so!
|Professor Djorgovski explains how hydrogen 21 cm identified the structure of the Milky Way (Source: www.coursera.org)|
Finally, in the outside world, that is outside of our burrows, the need and value of masks continues to evolve. What started off as an official argument that they would not be that effective and not encouraged by the CDC, we now are in the position that it is illegal to go outside in some California cities without wearing a mask. It seems obvious masks will limit the transfer or reception of large droplets expelled from others and breathed in by others. More study will help resolve this issue, but for me in the meantime I concentrated on how to limit or prevent folks from touching their face with their hands.
Here is my personally tested and approved method. Just try doing this several times per day and the virus will be the least of your worries. You can't touch your face. Just use your favorite beverage. Mine, here, happens to be wine and lemon drop martinis.
|Resident Astronomer shows approved method of keeping your hands off of your face! (Source: Palmia Observatory)|
Until next time, here from our burrow, stay sane, stay safe,