Please refer to my post “Deconstructing the Wow!”, Space/Science, 26 June ’13).

Due to the configuration of the antenna which detected the Wow signal, the exact location of its point of origin on the celestial sphere cannot be determined unambiguously. Searching for a possible transmitting star must therefore demand a certain amount of speculation. A look at the POSS plates shows thousands of stars in the area, it is in the Sagitarrius Milky Way, not too far from the galactic center. Its a crowded neighborhood.

The 1950 Coordinate Right Ascension error box of the signal position ranges from about 19h 22m 25s to 19h 25m 17s, Declination is known more precisely: – 27d 03′ (+/- 20′). There are literally thousands of stars in that box, but are there any stars near earth within those coordinates?

As it turns out, the Gliese Catalog of Nearby Stars lists one candidate at RA 19h 26m 47s, Dec – 27d 05′.4. Not exactly inside the box, but pretty close: a distance of roughly 1.5m (23′ of arc) in RA and 2′ of arc in Dec from one corner. The full moon is 2 m of time, or 30′ of arc in diameter. It’s worth folllowing up.

The suspect is Wo 9657, (Wo is Dr Wooley’s catalog) a double star system located 155 light years away according to Gliese, but about another hundred ly further away according to more recent estimates. We’ll go with the Gliese number for the time being, the latter isn’t necessarily more accurate, the new satellite data is very good, but this is a double star, and this could have confused the automated systems that determined the new parallax. The older numbers have been scrutinized critically for much longer.

The two stars that make up the system, A and B, are of apparent magnitudes 5.52 and 8.69 respectively (depending on where you look them up!). The brighter of the pair, a K giant, is just visible to the naked eye. The B component is 22 times fainter. Using the 155 ly distance figure, the A component is intrinsically twelve times brighter than our Sun. The B component is a K subdwarf 2/3 the luminosity of our Sun, not too different from our own star. People could live there.

Of course, having a giant star for a neighbor could be problematic. The catalogs tell us A and B are separated by about 6″ of arc (a good amateur scope could resolve this pair). Over the last century and a half, we have actually watched one rotate about the other by a few degrees, so I don’t know right off whether this separation is increasing or decreasing. I don’t know if we have precise orbital elements (size, period, shape and orientation to our line of sight) for this system, but we can assume that is at least as close as the two stars get in real space (as opposed to the perspective view). At a distance of 155 ly (47.5 pc), one arcsecond corresponds to 47.5 AU, further than the distance from the sun to Pluto.

For example, if the orbital plane is perpendicular to the line of sight, the two stars will be at least 6″ (from our perspective) apart all the time. If the plane is 90 degrees off, the two stars will appear to merge periodcally, but they are actually always at least 6″ apart in real space. The system dimensions are such that the B component is far enough from its giant neighbor for life to be.possible. Unless the orbit is highly eccentric, the visible angular separation of the pair is a good measure of the minimum distance at periastron (closest approach). Of course, it could always be greater. If Wo 9657 is further away than we think, both stars will be brighter, but both will also be farther apart.

I don’t think its very likely this star is the origin of the Wow signal, but I don’t think it can be ruled out either.