Our sciences are advancing at a rapid pace. New technologies emerge that help scientists dig deeper into the fundamental particles or peer farther away into our Universe. So I was quite happy when the following news item appeared. It combines two of my passions: history and astronomy, and it shows that there are some things you should never throw out. (Please tell my wife!)
The story, as I found it on the website phys.org, goes like this: in the past, photographs of stars, including spectral analysis of the light they emit, were registered on photographic plates. Researcher Jay Farihi wanted to analyze the spectrum from Van Maanen’s star, a white dwarf in the constellation of Pisces. Instead of doing observations himself, which can take a lot of time and effort and money, he found that they had already been recorded in 1917, when the star was discovered. That data was at the Carnegie Observatories in Pasadena, California.
Nowadays, it takes just a couple of clicks to get the digital file, but in this case the glass plate, almost a century old, had to be physically retrieved from the archive. Luckily a catalogue had been made to make the observed objects available; otherwise it would never have been noticed.
When Farihi received the results, he immediately remarked there was a gap in the spectrum. The spectral analysis of visible light shows peaks when related to the composition of the star itself and valleys where material blocks the light, either because it is on the surface of the object or in between. The exact valleys in this case correspond, as the article reports it, to elements like calcium, magnesium and iron. They cannot be part of the star itself as they are heavier than the hydrogen and oxygen in the star and would sink.
So basically, this shows that there is a larger object around the white dwarf. This is important because a white dwarf is a star at the end of it life, and it is expected that some or maybe most of any nearby planetary material would have been shed or gobbled up by the star during its preceding red giant phase.
But more importantly, it shows that archives like those are sitting on a potential wealth of information that could help advance science for a fraction of the cost. The information is there, and provides a longer window of observation (or in this case, a unique observation) that helps our understanding of our Universe. But they’re only available if we keep them preserved and intact, the lesson being: never throw things out, but cherish them.