Free Turn Right At Orion by Mitchell Begelman Page A

typical headline. As though eager to avert panic, venerable TV newsreaders relayed the opinion of astronomers that “this is some kind of star that’s in some terribly weird kind of trouble.” Like everyone else, we cobbled together the rumors and fragmentary observational reports that had come in since the first announcement and began work on our own theories, in order not to miss out on a possible “scoop.”
    Rocinante signaled an abrupt heads-up from my nostalgic reverie. I was already heading into the environs of SS 433. There was no doubt that matter was being powerfully expelled from this system. Tens of light-years away from the destination itself, I encountered the vanguard of its effects on the surrounding regions. Like the bubbles around luminous stars that I had seen at various locations en route to the Galactic Center, SS 433 had inflated a hot cavity around itself, but with a difference. This cavity, instead of being spherical, sported a pair of highly elongated protrusions. The jets were pumping their energies and momenta in two diametrically opposed directions, boring into the interstellar matter like the high-pressure water jets sometimes used to excavate mine shafts. Like those pulsing water streams, the jets plashed vigorously against the working surface and, having spent only a fraction of their force, ricocheted into the main cavity, broadening it as an afterthought. I felt a minor jolt as I crossed the sharp boundary from undisturbed interstellar space into the pressurized cavity. As it happened, my route took me across the path of one of the jets, which was by this point much more diffuse and spread out than when it had left its source; nevertheless, there was no mistaking its impulse. With difficulty, I made out the pale, multicolor luminescence it left in its wake (here X-ray bright, there a mixed pinkish and ultraviolet glow from disturbed hydrogen).
    The scene was grand, but there were no surprises here. I recalled the pictures I had seen of W50, the SS 433 cavity with “ears,” long before my visit. Identification, of the ears with the impacts
of the jets had been one of the comforting verifications that had tied the whole picture so neatly together. But that had come well after the first flush of discovery. I thought back to the observation that had triggered the initial excitement, inspiring my colleagues’ hushed words about “abnormal Doppler shifts” and the like. I will not insult the quality of your liberal arts education with yet another disquisition on how the Doppler effect works. My style manual indicates emphatically that a discussion of the Doppler effect, or at least a description of its manifestations and uses, should appear in the first chapter of any astronomical memoir. I am perhaps treading dangerously close to new stylistic territory by not having informed you before Chapter 7 that I intend to dispense with this formality. If the mere squeal of an approaching train whistle or groan of a receding police siren does not elicit the expected Pavlovian response (thoughts of distorted ripples on a lake; mental images of line drawings in physics textbooks, with Pepto-Bismol-pink backgrounds), you may wish to consult Chapter 1 of any number of available works.
    What I will describe is the dramatic (and unexpected) role that the Doppler effect played in the discovery of SS 433’s true nature. The designation itself connotes nothing extraordinary. The intention of the cataloguers (Messrs. Stephenson and Sanduleak) had been to record stars that were unusual only in their production of intense spectral “lines,” blips of extra emission at certain very precise colors. These lines are the products of electrons dropping between equally precise orbits in their respective atoms. For these lines to appear with intensity requires special but not exceptional conditions, and the available colors themselves are the well-documented properties of the