BAN #444: Getting better, Globular takes science full circle

Personal Stuff

Yeah, but not too personal

Health update: Every day, a little better. I noticed the other day that I’m no longer winded climbing the stairs! That’s cool. My legs are tired doing that, though, which means I’m losing muscle tone. I can probably start getting back on the exercise bike in a week (well, late next week after I get back from Arkansas to give a couple of talks). That’ll be nice, though it will also means I need to cut back on the gobs of food I’ve been eating to keep my strength up. Compromises.

Last week I also finally got through my prescription of these freaking horse pills:

That’s one dose of sucralfate, which coats the stomach lining and helps the ulcers heal. Now, I have pretty big hands, so that pill is huge. If it were a millimeter wider it would be impossible to swallow, and as it was it was always a struggle. It’s not coated and starts to dissolve as soon as I put it in my mouth, so blarg. At least it wasn’t bitter. But four times a day I took that awful thing. I’m glad that’s done.

I still get chills sometimes, but I’m still probably below my target hemoglobin levels. I’m not napping as much, though, so clearly I’m on the mend. Yay!

Pic o’ the Letter

A cool or lovely or mind-bending astronomical image/video with a short description so you can grok it

One of the basic principles of science is that it learns.

It’s baked into the process. The whole idea is to observe something, come up with some idea to explain it, then test that idea. Maybe it’s more observations, or a lab experiment, but you want to know if that idea is right or wrong. If the observations don’t support the idea, then your choice is to either modify it to explain the new observations or ditch it. Usually it’s the former, but sometimes the weight of evidence gets so overwhelming the latter is the right way to go.

That can lead to some funny circumstances.

Y’all know I love me some globular clusters. For one thing they’re beautiful and a joy to see in the eyepiece of a telescope; quite a few are bright enough to see in a small ‘scope pretty much any time of year and they are always a delight.

They’re also interesting scientifically. Hundreds of thousands, sometimes even millions of stars all in a small ball maybe a couple of dozen light-years across, all interacting and zipping past each other all the time, they make wonderful laboratories for testing hypotheses.

For a long time we thought they were all pretty much the same. The stars in them are very old, 11 or 12 billion years old, and all formed at the same time out of the same stuff. In an experiment you like to have as many things equal as possible so that some weird difference doesn’t throw you off. And here Nature provides that for us!

Except not so much. Not so long ago astronomers started seeing anomalies in globulars. Some stars appeared to have slightly different elements in them, indicating that maybe they didn’t all form from the same stuff. We started seeing stars of different ages in globulars too, some populations of them a billion or two years younger than the rest. It started to become clear that globulars weren’t so simple.

We now think that many of the biggest and most diverse are actually the leftover cores of small galaxies eaten by bigger ones. Omega Centauri is the biggest and brightest in the sky — it can be seen by eye from southern locations! — and is maybe the best example of this. Others abound.

Eventually the paradigm shifted. Globulars were old, but not all the same age, and even the stars in them weren’t the same age. That’s so common in globulars that this is now the accepted paradigm.

So it was with much amusement that I saw this image from Hubble of the globular Ruprecht 106, a gorgeous one about 40,000 light-years away, a fair distance:

Pretty! When I see something like this I always first check the ESA Hubble site to find the filters used to make the image, incase something is weird about them. In this case blue is blue and red is red, and green is made by cleverly combining the red and blue images, so it’s close to natural color. In other words the red stars really are red and the blue ones blue.

I also go to the Hubble Space Telescope section of the Mikulski Archive for Space Telescopes, or MAST, where you can search on objects observed and find out more about the proposal pitched by the scientists to observe them.

It turns out that in 2017 Hubble observed Ruprecht 106 to examine the stars in it for a very funny reason: Previous observations of the globular indicated all the stars in it are chemically similar and the same age. That was so weird to the astronomers that they wanted to confirm it and see what else they could learn about it.

Do you see? They wanted observe it because unlike every other globular it appears to have one, old population of stars in it.

And we’ve come full circle, at least in this one case. We used to assume they were all like that, then we found out nope, and now when we do see one like that it’s considered “exceptional”. That’s actually the word they used in the Hubble proposal!

I find that pretty amusing. Knowledge advances, and after a while we find old ideas quaint… and then when something is found that actually adheres to that old idea, everyone pounces on it as being amazing!

Et alia

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