Category Archives: starbirth

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.

Galaxies Going Whump in the Night

Create Realms of Starbirth Light

Galaxy collisions fascinate me. And, they intrigue a growing number of astronomers who look at them with an eye toward understanding the processes at work when two or more of these cosmic behemoths interact with each other. One of my favorite galactic traffic-jam sites is Stephan’s Quintet, a visual grouping of five galaxies. Four of them are an actual compact group of galaxies in a sort of gravitational grouping. The additional galaxy appears in images of the group but it really lies much closer to us than the others and is not actually part of the group.  Here’s a recent image of it, and below that is a schematic diagram naming the pieces and parts of this galactic mingling.

https://i0.wp.com/www.naoj.org/Pressrelease/2011/08/18/fig1.jpg?resize=474%2C228
Composite tricolor images of Stephan's Quintet. Courtesy Subaru Observatory, NAOJ.
A diagram of the member galaxies of Stephan's Quintet. NGC7320 is a closer galaxy and has a recession velocity of 0. The remaining four are a group of more distant galaxies 300 million light years away. The researchers believe that the merging of NGC7318A/B and NGC7319's crashing into them are responsible for the active star formation regions in the H? emitting region around NGC7318A/B.

Among the processes that get kick-started into motion when galaxies collide is star formation. The gravitational interactions create shock waves and compress the gases in the various galaxies together, and that in turn starts a wave of star formation. Astronomers often refer to this activity as “starburst activity”.

Take a look at any given galaxy interaction with starburst activity, and the bluish-colored blobs of light you see are more than likely the sites of starburst clumps.

The folks at Subaru Telescope in Hawai’i have released a three-dimensional view of Stephan’s Quintet. The observers used special narrowband filters on the telescope’s Suprime-Cam instrument that let very specific wavelengths of light emitted by ionized hydrogen (what they call hydrogen-alpha or H?). Think of H? as light that is emitted by hydrogen that is being heated by some process—like starbirth. Its presence traces the existence of star formation.

In addition to star-forming activity, the images created using the Subaru data help astronomers pinpoint more accurate distances to the galaxies. The contrasting images show that NGC7320 (the galaxy at the lower left) is closer than the other four  galaxies. It is about 50 million light-years away while the other four galaxies are about 300 million light-years away. This explains the intriguing arrangement of the galaxies in Stephan’s Quintet. And, it helps astronomers track the process of star formation during the collisions, and can also give them a clue of what to look for in other galaxy interactions where hot young stars will eventually be one of the by-products of the galactic traffic jam.