Star Death and Me

The Star-Stuff Continuum

I haven’t been online much lately because in mid-June I suffered an injury to my neck that required an immediate operation and the aftermath of healing has limited how long I can sit in front of a computer.  But, I’m healing well, and am resuming my blogging (or at least trying to up my frequency of blogging). There’s a lot to write about — Higgs bosons, dark galaxies, some other news coming up later this week — so I’ll have plenty to dive into.

One of the things that occurred right after that sudden surgery was a little discussion in the post-op room about the level of potassium (chemical symbol K) that was showing up in my blood tests. While I was there waking up and sipping some ice water soon after surgery, I listened to the medical folks talking about what the measurements meant. I let my mind wander a bit, thinking about potassium and how it got to be in our blood chemistry.

You’ve all heard the term “star-stuff” enough to know that the elements that make up our bodies (and the structures of all life on Earth) came from stars. To be more succinct, much of the “stuff” we have in our bodies is from the ashes of long-dead stars. The oxygen, iron, calcium, on down to traces of potassium, and many other chemical bits were created in stars that are now no longer on the scene.  The hydrogen, of course, was there from the beginning of the universe.

About 4.5 billion years ago in our neighborhood of the galaxy (give or take a few eons), there was a population of stars doing what stars have always done:  fusing elements together, starting with hydrogen, and moving through carbon, nitrogen, oxygen, and so forth.  The local Sun-like stars did this, and when they died, they blew what they created out to space.  Stars much more massive than the Sun went through similar processes — blowing mass out to space eons before the end actually came. When these stellar behemoths died in supernova explosions, it set the stage for the creation of heavier elements. The propulsive force of the explosion scattered their “stuff” out  to interstellar space. All the materials from all the different star death processes ended up in the nebula that formed the Sun, planets, and on Earth, where we evolved using all those elements (and the chemical compounds they make up) as seed material for life.

Now, it’s a long trip from the bits of potassium made inside a long-dead star to the amount of potassium that exists in your body in blood particles.  But, suffice to say, without that dead star, I wouldn’t have been laying in the post-op unit, listening to medical personnel have a little conference about my blood potassium levels (and, it turns out it was no big deal — the issue resolved itself).  That day in the OR recovery room, I was thinking about things that I knew and have known for years about star stuff and elements. But, a little blood test made it much more personal to me and that potassium reminded me once again in a very personal way that I am, indeed, star stuff.

Titanic Ocean?

Could Well Be!

This artist's concept shows a possible scenario for the internal structure of Titan, as suggested by data from NASA's Cassini spacecraft. Scientists have been trying to determine what is under Titan's organic-rich atmosphere and icy crust. Image credit: A. Tavani

The more we explore the outer solar system with probes like the Cassini spacecraft, the cooler things we discover. This week planetary scientists working with data from that spacecraft announced that there’s a good chance Saturn’s moon Titan has a layer of liquid water hidden beneath that desolate icy surface.

The discovery came from the study of tides on Titan.  This moon is squeezed and stretched as it orbits Saturn, and that is bound to cause some heating in the core.  It’s also a shape-changing process.

The scientists figured out that Titan is not a big rocky ball that would show a slight bulge on its surface as Saturn’s strong gravitational pull tugged on it.  The way they did this is quite ingenious.  They looked at Titan during its 16-day orbit of Saturn.  As it whirls around the huge planet, Titan’s shape changes and scientists could chart those changes.  Titan is not a perfectly round sphere. Instead, it’s slightly elongated like a football. As it orbits Saturn, its  long axis grows when it’s closer to Saturn. Eight days later, when Titan is farther from Saturn, it’s much less elongated and more nearly round. Cassini measured the gravitational effect of that squeeze and pull.  These measurements and the assessment of Saturn’s gravitational pull on Titan provide the best data yet of  Titan’s internal structure and what they show is that for the shape to change as much as it does, Titan likely has a an ocean layer.  It’s not necessarily a huge or deep one, but the fact that it’s there at all is one more step in learning more about Titan’s structure.

Now, I read a few stories here and there about how this supposed ocean is darn near proof that life could exist on Titan.

Not so fast.  The presence of a subsurface layer of liquid water at Titan is not necessarily an indicator for life. There are still a lot of studies to be done before scientists understand what Titan looks like in its interior, and whether or not the conditions are right for life to exist in that ocean, or perhaps at a rock-water interface deep inside.

The implications of an ocean in Titan is an exciting finding, no matter what else is discovered there. This mysterious, cloudy world is slowly yielding up its secrets, and in the process, is opening our minds about what other surprises we’re going to find in, on, or near the worlds of the outer solar system.

Exploring Science and the Cosmos

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