And my post was erased incredible hats off to censorship..

What I find incredible is how many occasional commenters whose comments go into moderation or disappear for some other reason then comment to whine about censorship. If Phil really censored comments, what makes any of you think he’d allow a comment commenting about censorship through moderation?

In fact, there is only one reason why Phil will delete a post, and that is if the comment is outright offensive i.e. not family-friendly. Kids read this blog too.

You only have to look at some of the insane stuff that people post (for example, in threads about AGW) to realise that, if Phil wanted to censor comments, he would certainly censor those comments.

If your comment failed to appear, maybe it got lost in the intertubes somewhere, or maybe you failed to enter an email address (I’ve done this, when using a computer different from the one I normally use to visit, losing sometimes 15 or 20 minutes’ worth of typing through having forgotten to fill in that field).

Thanks for the great writeup, Phil!

@23 Zack: Did it have a link in it? Any posts with links are automatically subject to moderation.

And, like babies will, these stars eject material from both ends: called bipolar outflow, twin beams of material (typically called “jets”) are screaming out of these newborns at several hundred kilometers per second in opposite directions.

Wait, what?

How many babies have you encountered with “bipolar outflow” measured at several hundred km/s???

Well, not really. Unlike a supernova, which is a transition from star to neutron star/black hole/nothing in a matter of hours or minutes, star birth happens relatively slowly. The proto-star slowly contracts – the gravitational potential energy of the star-stuff is converted to heat, and this heat keeps the contraction from proceeding too quickly. These proto-stars can actually shine more brightly from the heat of formation then the young actively fusing star that it becomes. Inside the star, processes can take quite awhile to normalize. For instance, you have convective and non-convective layers forming as the core heats up. And even once fusion is ignited in the core, it can take many thousands of years for the fusion energy to actually make it to the surface.
In a nutshell, it takes a very long time (by human standards) for protostars to become stars, long enough that there isn’t a tremendous amount of change in any “birthing” star in a human lifetime*. I think a better metaphor then birth might be growth from a baby to an adult

*This is what I understand to be true, but I may be totally wrong. Take with a grain of salt

I’d also add that very bright objects, like Venus, (or Jupiter, now fairly close to opposition and pretty bright) often appear to “blink” more because of atmospheric scintillation, and that the human eye will often see a bright point source as “moving” (one reason why so many UFO sightings turn out to be Venus). I’d bet on Venus if it was just after sundown, Jupiter if it was later at night.

The human eye, in a dark desert, is only able to perceive about 3000 stars, so the short answer would be,,no. Stellar nebula are way to far away and dim to be seen w/o assistance.

If what you saw was “blinking” and appeared to move, it was most likely either a high altitude aircraft or a satellite,,,

Gary 7

In fact many of the stars in Sh2-239 are binaries.

I’ll go one step further here and note that most of the stars in the universe are binaries.

Although I may be mistaken on this I think the figure is that about 70 % of all stars have stellar companions. High mass stars in particular tend to be in multiple star systems with this being somewhat less common for red dwarfs although many low mass stars do also have companion stars eg. UV Ceti, Kruger 60 and SCR 1845-6357 with its brown dwarf companion. (Click on my name for link for the latter.)

I love looking at pretty astronomical pictures as much as the next person, but what gets to me is that these are far, far more than just snapshots of the cosmos. These are telling us stories; complicated, wonderful, deep stories of the complexity and history of the Universe, which in turn will certainly yield insight into the birth and evolution of our own Sun and planets. By looking out, we look in, and find that the farther we voyage, the closer to home we get.

Very well said and seconded by me, BA. Thanks – great article here as usual.

I’ll add one other thing to this : Nothing puts one’ s life and all the mundanities of, well everything, into perspective and nothings expands the mind and imagination quite as much as astronomy and looking up into the sky, wondering and learning in my view.

My only worry in that respect is that a certain director is no longer distracted by the Transformer franchise and will use it for the plot of his next science fiction blockbuster.

We obviously don’t live in the center of a nebula, so I always wondered that. Must be a yellow dwarf thing, being s smaller and later generation star?

Then that leads to the question, how hard is it for a later generation star to form in a nebula being ripped apart from earlier stars.

Any day now it will quit it’s day job and go buy a Porsche.

Joke aside, few people make the material come alive like you do BA.

This is my absolute favorite aspect of astronomy.

Also, as has been said, your image links are linking to error pages.

ennebulenation error. Page not found.

He Who Really Wanted To Ennebulenate Too.

Ejecta at both ends is the best short description I’ve ever heard of what babies do,,,

Gary 7

I see a marketing opportunity here for infant wear. “I’m a baby star. I eject material from both ends.”

But, has anyone ever seen a stellar “birth”, where a new star appears where previously there wasn’t one? (Okay, I suspect that the actual ignition is hidden behind lots of dust. But at some point, the star will blow away enough dust for us to see it.)