In a paper to be published in the Astronomical Journal, AMNH astronomer Sebastien Lepine reports the discovery of four very young stars located within only 60 parsecs (200 light-years) of the Sun. The 12-million-year-old stars are found to be members of a group of stars known as the Beta Pictoris moving group. The 50 or so currently known members of this group are spread all over the sky, but they have this in common: they are all moving as one, drifting through the Solar Neighborhood in the same direction and at the same speed.

Young stars are often to be found in compact clusters of hundreds to thousands of objects. Stars in these clusters were all born roughly at the same time, out of one massive cloud of gas and dust. This makes them easy to find on the sky, as dense groups of stars clearly stand out from the more uniform distribution of field stars. But not all stars are all born in compact clusters. Some stars coalesce out of more diffuse cloudlets, which form loose groups of stars which quickly diffuse into the field, unable to hold on to each other as in a cluster. Young groups like these are much more challenging to find, as they can be spread out over a large volume in space. But if the group has formed only recently, all members will be moving in the same general direction, like fish in a school.

Lepine and collaborator Michal Simon, of Stony Brook University, have come up with a technique to sift through thousands or stars in catalogs of proper motion, which record the historic motions of stars on the sky. Knowing at what speed and in which direction stars in a particular moving group are going, they can search for other stars that fit the pattern, and find new members of the moving group. We proceed by elimination says Lepine, first getting rid of all stars that do not move in the direction expected for stars in the moving group. Stars that look too distant, or are moving too fast or too slow, are then taken off the list as well. Starting from a list of 80,000 stars, they narrowed down the search to thirty-four possible candidates to the Beta Pictoris moving group. These were then observed at telescopes in Arizona and Hawaii. Four of them were confirmed to be young stars. Two of the stars are known as TYC 1186-706-1 and TYC 2211-1309-1. The other two are a double star: TYC 7443-1102-1 A and TYC 7443-1102-1 B. The team suspects that the Beta Pictoris moving group possibly has dozens more members, just waiting to be discovered.

In recent years, nearby young stars have become increasingly popular with astronomers, because they are prime targets in the search for extra-solar planets. The planets in orbit around young stars are still forming, and are very hot and bright, which makes them much easier to detect against the blare of their young sun. Most star clusters are relatively far from the Sun, however. Young stars in moving groups, on the other hand, are spread out all over space, so they can be found much closer to the Sun, where they make better targets. Lepine and Simon are hoping to use their technique to find many more nearby young stars which could then be searched for planets. These young stars must be out there, somewhere, just hiding in plain sight, says Lepine. The two astronomers now hope to apply the same technique to larger catalogs and identify hundreds more nearby young stars. all we need is to pull these needles out the haystack.