Imagine what space exploration would look like if the Sun were a member of a binary system. Suppose we had another star a few hundred AU away, one that had built its own planetary system. The second star, a thousand times brighter than any other star in our night sky, would be an object of obvious interest, its planets visible to our astronomers and reachable targets for early space technology. The question of life on a planet in that star’s habitable zone would be relatively easy to resolve, and the imperative to study that world first-hand would surely drive space science.

Now we learn that a binary system some 1300 light years from Earth may be evolving in a similar direction. Located in the Orion Nebula, a region rich in star-birth, the stars are about a third the mass of the Sun, considerably cooler and redder in color. One is known to be an M2 dwarf, while the other’s spectral type hasn’t been precisely identified because of obscuration by the disk. The stars are 400 AU apart, so that a single orbit around their common center would take 4,500 years. As this news release from the University of Hawaii at Mânoa points out, that’s about the length of recorded human history.

Researchers have been able to study the pair in the extreme infrared, using the Submillimeter Array on Mauna Kea. That adds to earlier Hubble work showing the presence of one of the disks, visible only as a shadow. The Hawaii researchers have now confirmed the existence of the second. Studies of binary protostars in other regions have generally discovered protoplanetary disks (proplyds) around only the primary star, making this binary system, called 253-1536, an intriguing find.

From the just published paper on this work:

The binary proplyd 253-1536 stands out as the first example of two optically visible stars each with sufficient mass to form a Solar System. Their separation, > 440 AU in projection, is large enough that both the evolution of the disks and their prospects for planet formation can be considered independently of each other.

Remember, too, that at least twenty percent of exoplanets found thus far have been in binary star systems. We’ll learn more about how planets form around binaries — and about how the mass ratio of the stars involved contributes toward the result — as we sample more disks. A key issue considered in this paper is the effect of ionizing radiation from nearby massive stars on the viability of emerging circumstellar disks.

The paper is Mann and Williams, “Massive Protoplanetary Disks in Orion beyond the Trapezium Cluster,” in Astrophysical Journal 699 (June 15, 2009), L55-L58 (abstract).