Can two stars be gravitationally bound to each other across the void of space? Determining whether a pair of stars that appear close together in the sky are actually in orbit around each other — or merely close in our line of sight by coincidence — requires measuring their positions precisely, repeatedly, over many years. If the separation and angle between the two stars change in a consistent, predictable way, they are likely a true binary system. This branch of astronomy is called astrometry.
A team of five high school and college students, working through an online Double Star Science class taught by Dr. Rachel Freed and funded by the Astronomical Society of the Pacific, investigated the double star system WDS 22267+4433 ES 1346 AC. Their paper was published in the Journal of Double Star Observers.
How They Did It
The students — drawn from schools around the world — learned the full cycle of scientific research over the course of the class. They selected their target from the Washington Double Star Catalog, which maintains astrometric measurements for hundreds of thousands of double star systems going back more than a century. They scheduled remote telescope time at Las Campanas Observatory (LCO) in Chile using an online scheduling interface. They downloaded their images from LCO and analyzed them with AfterGlow software, precisely measuring the separation and position angle of the two stars. And they wrote their findings up as a formal scientific paper and submitted it for publication.
The Contribution
Every precise astrometric measurement added to the record for a double star system is a data point in a long-baseline dataset. No single measurement can prove whether two stars are gravitationally bound — that determination requires consistent measurements over years and ideally decades. By contributing a new measurement of WDS 22267+4433, the student team has added to the archive that future researchers — human and automated — will use to settle the question.