Recent analysis on more than 100,000 stars studied by the European Space Agency’s Hipparcos satellite showed that about 20 percent of them within 1,000 light years are moving in unusual trajectories. Rather than circular paths around the galactic center, they’re moving toward or away from the core. The cause: so-called ‘density waves’ that compress gas and have a hand in star formation; they also seem to be able to deflect normal stellar motions.
But don’t count on a stellar near miss to give us an easy way to go interstellar, at least not any time soon. The closest encounter with another star won’t occur for another 1.4 million years, when Gliese 710 will pass within 1 light year of the Sun (some 70,000 AU, perhaps within the Oort Cloud of cometary debris). In any case, Gliese 710 does not appear to be one of the stars affected by galactic density waves; its motion around the galactic center seems relatively normal.
Barnard’s Star is approaching us as well, at a speed of 87 miles per second. But the distances will remain daunting. In some 8,000 years, this star, the second closest to the Sun after the Alpha Centauri triple star system, will close to within four light years of the solar system, slightly closer than Centauri is right now.
The Hipparcos work will appear in the European journal Astronomy & Astrophysics. Reference: B. Famaey, A. Jorissen et al, Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data, available here (PDF warning).
ESA’s press release on the Hipparcos findings is here.
