We work very hard with this show, and with our sister shows Astronomy Cast and Visión Cósmica, to talk about astronomical research that is grounded in observations. While we do cover a lot of computer models and theory papers, they generally are simulations that are confirmed by observations. Sometimes though, we have to recognize that the things our models reveal occur so fast that we might never manage to catch an event in real-time, and we accept what model after model shows as being true because everything makes sense and there are no contradicting observations. 

Consider star formation. Stars form in dense clusters where everything is in motion. Computer simulations and basic reasoning have long said that these environments, like busy city streets with broken traffic lights, should be rich in near-collisions. With stars, these near-collisions can toss about planets, trigger comets, and otherwise make a hot mess of a young star system. It all made sense; it’s just no one had ever seen it happen.

But sometimes, we all just happen to get lucky with the timing of our photos, and one of these collisions has now been observed by the Very Large Array and Atacama Large Millimeter/submillimeter Array (ALMA). This system, Z Canis Majoris, was distorted during the event, with a long arm of gas now reaching out toward the side swiping star. According to project researcher Hau-Yu Baobab Liu: These perturbers not only cause gaseous streams but may also impact the thermal history of the involved host stars, like Z Canis Majoris.

Project lead Ruobing Dong adds: Studying these types of events gives a window into the past, including what might have happened in the early development of our own Solar System, critical evidence of which is long since gone. Watching these events take place in a newly forming star system provides us with the information needed to say, ‘Ah-ha! This is what may have happened to our own Solar System long ago.’ Right now, VLA and ALMA have given us the first evidence to solve this mystery, and the next generations of these technologies will open windows on the Universe that we have yet only dreamed of.

This work is published in Nature Astronomy.

More Information

NRAO press release

“A likely flyby of binary protostar Z CMa caught in action,” Ruobing Dong et al., 2022 January 13, Nature Astronomy