Turn Right At Orion Read Online Free PDF

I had intuitively expected, the distribution of stars was lopsided! There were more stars to the left of the Galactic Center than to the right.
    I was face to face with the Galaxy’s stellar “bar,” which resembles nothing so much as a huge tumbling peanut made up entirely of stars. Stars caught up in the gravity of the bar execute motions that are far different from the orderly circular orbits of disk stars, different even from the chaotic dashing of halo stars. These trapped stars trace out semi-repetitive shapes ranging from figure eights, to complicated cat’s cradles, to woven tubelike structures reminiscent of those “Chinese puzzles” that trap your fingers. It is amazing that these patterns can hang together, but bars are remarkably robust and are found in a good half of the spiral galaxies.
    Thanks to the bar, for once the inexorable central pull of gravity is foiled. The bar hinders the inward drift of gaseous debris. The churning gravitational forces produced by the tumbling peanut stir up the motions of any gas clouds that venture inside, driving the clouds slightly farther from the Galactic Center. That explains why I was emerging into a region of the Galaxy where the clouds were becoming sparser. But it does not explain what I saw next.

3
    A Ballet
    Suddenly I emerged into a clearing only 10 or 20 light-years from the Galactic Center and saw a cluster of stars the likes of which I had never seen before. Nearly a million stars were crammed into a volume that would have been occupied by only a few dozen stars had it been in the vicinity of the Sun. I was immediately struck by—and would lose several night’s sleep to—the many blue-white, blindingly luminous stars that were mixed in with the more common stellar varieties in every direction. These kinds of superstars, though only a few times more massive than the Sun, were so bright that they were doomed to burn themselves out in a blaze of glory, I had seen a few of them en route from the solar neighborhood, but everywhere else in the Galaxy they seemed to be quite rare. This relative rarity was not a surprise, because such stars last less than 10 million years (compared to 10 billion years for a star like the Sun) before throwing off their envelopes in violent convulsions and, if they are heavy enough—more than 8 or 10 times the mass of the Sun—exploding as supernovae. But even before they become violently unstable, they will have spent most of their lives injecting fast, hot streams of gas into their surroundings.
    Given how many massive stars there were, it came as no surprise that the whole Galactic Center was immersed in a kind of
hot bubble, similar to the superbubbles I had traversed earlier but lacking their opportunity to vent into the Galaxy’s halo. As a result, the pressure outside my craft had increased enormously, although it was still much lower than any vacuum ever produced on Earth. I had measured it when I arrived in interstellar space near the Sun: There it was 0.000000000000000001 of the mean atmospheric pressure at sea level on Earth. But in the Galactic Center it was thousands of times higher than in the Sun’s vicinity, pumped up by the combined effect of the fast winds and the added jolt of a stellar explosion every thousand years or so.
    How did these stars get here? Because they were burning up inside at such a prodigious rate, they couldn’t have been older than a few million years. Were they formed here? I looked around for likely sites of star formation, giant clouds rich in molecules, shielded from the heating and evaporative influences of hot stars and supernova blasts. But I couldn’t find any. Streamers of compressed gas stretched here and there, squeezed by the high pressure and combed out along magnetic lines of force. A few of the nearby gaseous streamers seemed dense enough to collapse under their own weights, and it’s just possible that I spotted a couple of