Greetings from Palmia Observatory
Well, we are still trying to get some measurements of the position of Mercury to show its retrograde motion, but the clouds are not helping.
I happened to notice that Venus was bright and shiny, just after sunset, but when I brought the camera and flimsy tripod outside, the darn clouds had risen up and blocked any chance. Every now and again, Venus would pop out, but mostly it just stayed hidden behind the clouds. Even without the clouds, it is going to be hard to photograph the position of Mercury which is even lower on the horizon and the sky is also so bright at that time.
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| Venus, until the clouds came in at sunset, DSLR, 75mm, 2 sec (Source: Palmia Observatory) |
So, we will have to keep updating our observing plan and hope to still catch Mercury and make some retrograde measurements. In addition to that, is anybody excited about the upcoming annular solar eclipse? The eclipse path is visible in parts of Canada and the eastern US.
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| Path of June 10 annular solar eclipse (Source: Space.com) |
Travelling to Canada right now is still complicated by COVID restrictions and locations in the US that are close to airports don't have the best eclipse viewing opportunities. I looked at airfares and they ranged from about $300 to $500. But the eclipse is visible just after sunrise and the sun and moon will be very close to the horizon. I checked the location in Pittsburgh, where I remember flying into many times and thought I could more easily find a viewing spot there, but it would just be a partial eclipse, not an annular eclipse. Check out the Go Sky Watch screenshot below for 6:10 am ET. The sun would be just about 3 - 4 degrees above the horizon. Hmm, it just seems to iffy to travel to see this event; so no I am not going!
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| Go Sky Watch screenshot for sunrise eclipse in Pittsburgh, PA (Source: Palmia Observatory) |
In other astrophysics news, the Dark Energy Survey (DES) just released their 3-year data and analysis package. If you want a user friendly review of some of the findings, check out Dr. Becky's podcast on the release. The DES measured the positions of 226 million galaxies to get better estimates of relative amounts of ordinary matter, dark matter and dark energy that make up the universe. Check out her YouTube video at: https://www.youtube.com/watch?v=IHMFDxLcMYs
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| Dark Energy Survey releases 3-year data (Source: @ Dr. Becky) |
Dr. Becky provided the references for 30 of the recently released DES papers that are all free online. She also described some the latest findings. I will share some of those comments on the measurements of astrophysical terms, "w" and "S8."
"W" is a dimensionless number that is the ration of pressure divided by energy density. Hmm, can w be dimensionless when we divide pressure by energy density? Yes, it can because after dimensional analysis, all the terms just cancel out.
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| New updated DES values for w (Source: @ Dr Becky) |
We see that previous estimates of w included values of -1.02, -1.08, then -1.006, and now w = -0.98. Whew, at least now w is greater than minus 1. Remember that for universes with w less than -1, a possibility of what is call "the big rip" can occur and in that universe the space will expand so fast that first galaxies will be destroyed and finally even atoms will be ripped apart.
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| DES latest estimate to pin down value for w = -0.98 (Source: @Dr Becky) |
So, w = -1 is sort of a special boundary value. Depending on whether it is less than or greater than -1 has been used to define three aspects of dark energy. For w exactly equal to -1, this condition is just the same as a universe with the old cosmological constant. The big rip is associated with "phantom energy." Quintessence is associated with a special form of a cosmological constant, but one which can change over time.
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| The critical value for w is w = -1 (Source: @ Dr Becky) |
Now, I had to go back and review what the definition of w was and how it fit into the equation of state. For these details, it was easy to just pick up a copy of Barbara Ryden's "Introduction to Cosmology." and look it up. Check out how w fits into the equation of state and the Friedmann equation in this screenshot from the textbook. Chapter 4 and 5 of the textbook goes into all the other gory details.
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| This is where w shows up in the equation of state (Source: Barbara Ryden, "Intro to Cosmology") |
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| S8 results from DES show smoother universe (Source: @ Dr Becky) |
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| DES show smoother universe with S8 = 0.772 (Source: @ Dr Becky) |
Finally after reviewing some of the DES data and puzzling over w and S8, it was time for some relaxation and a brew or two. We went to one of our favorite tap houses for dinner and sampled a martini or two and and had some healthy food. By chance, we saw that they were offering an Icelandic beer. So, we just had to sample one as part of us doing our homework for the upcoming trip to Iceland. Yum, yum; the Einstok Icelandic White Ale was pretty tasty. Hmm, I sure do like doing this kind of homework!
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| Doing our homework by sampling Icelandic at local tap house White Ale (Source: Einstok) |
Until next time, here from our burrow, stay safe, as we recover more of our freedom,
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