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Breaking up is Easy to Do — With Ultraviolet

This is one of those stories that seems almost impossible at first glance: making water in space? No way! Wouldn’t it all freeze out there?

Well, yeah… but you can get water vapor if you happen to have really hot stars near a nebula that is rich with molecules of hydrogen gas (H2), carbon monoxide (CO) and silicon monoxide (SiO). Those hot stars emit loads of ultraviolet radiation, which is energetic enough to break the oxygen molecules free. Once they are, they readily will bond with the hydrogen gas molecules to form water. Add in a heat source (like the nearby dying star and the heat from other stellar neighbors) and you get water vapor.

The star IRC+10216 -- where astronomers are studying a cloud of water vapor surrounding the star.

Of course, the water needs to have a stable environment to exist in, like a warm envelope of gas and dust. Such a curcumstellar envelope is where the European Space Agency’s Herschel spacecraft has made a significant discovery. It observed a cloud surrounding the dying star IRC+10216 and studied its steamy vapor cloud. This stellar sauna has been known to exist since astronomers first saw evidence for the vapor in 2001.

At first, astronomers thought that maybe the dying carbon star was heating up nearby cometary bodies and creating the water vapor. They even suspected that dwarf planets may have also been melted to make the cloud. However, those ideas needed to be proved, and for that, astronomers needed a telescope with instruments that could peer through the cloud of dust and steam surrounding the star.

Herschel can do the job because it has infrared capability, which allows it to see where optical telescopes cannot due to the thickness (opacity) of the cloud that surrounds the star. Some observations had already revealed clumpy structure in the dusty envelope around IRC+10216. And, there was that water vapor in the areas of the cloud around the clumps.

So, astronomers trained Herschel’s infrared “eyes” to the cloud and measured the temperature of the water vapor. It ranged from -200 degrees Celsius to 800 degrees Celsius. That’s quite warm, which means that the water vapor is being formed quite close to the star — closer, in fact, than comets could exist.

This is an interesting result and means that other carbon stars could also have the same type of water vapor cloud around them, provided there are sources of ultraviolet radiation nearby. So, the next step is for astronomers to look at some of those carbon stars with Herschel and see what they can find. Stay tuned!

But Not Goodbye

Last week an old friend and colleague, Jack Horkheimer, passed away. To most of the world, Jack was known as the Star Gazer (formerly the Star Hustler), for his little five-minute astronomy video short shows that aired on PBS for years and years. For many of us in the planetarium profession, Jack was a long-time colleague and director of the Miami Space Transit Planetarium. I’d known Jack since the early 1980s, when we met at a planetarium conference in Memphis, Tennessee. I remember we sat at a coffee shop, a bunch of us, swapping tall tales and telling jokes, and Jack had some of the funniest stories to tell about giving shows at his planetarium. I didn’t see Jack again until 1986, when we were all at a Voyager 2 flyby press event at JPL. He’d been popular as the Star Hustler for some years by then and he was at JPL to gather fodder for his shows and talks. I remember going out to a bar with Jack and another couple of his friends during that busy week, and again, we swapped tall tales and jokes.

The Jack Horkheimer I knew as a planetarian was quite a guy — maybe not always as swaggering as his Star Hustler (later renamed “Star Gazer”) persona, but always personable and friendly. He was a thoughtful guy, ready to help folks out when they needed it, and always up for sharing astronomy with anybody. His ideas about astronomy being for everybody inspired a number of us as we sought our own paths to sharing astronomy with the public. He was a public fixture and a planetarian to the core.

It was with great sadness that I heard of Jack’s death. He had moved to Miami many years ago, as he put it, to die from a respiratory ailment he’d had. The climate must have agreed with him, because he not only didn’t die — he thrived. In the end, his ailment took him away, but not before he brought astronomy to a wide audience. The world is poorer for his loss, but you know what? We’re all richer for having had him there all those years to point out the stars and bring the skies to everyone with his engaging Star Gazer series. RIP, Jack — and we’re all looking up!

The Spacewriter's Ramblings

UV FTW!

Breaking up is Easy to Do — With Ultraviolet

Say Goodnight, Jack

But Not Goodbye

Exploring Science and the Cosmos