An astronomer has already caught evidence of a planetary system beyond the sun back in 1917 – but without knowing it, according to new research.
The 100-year-old proof of exoplanets is an image on an astronomical glass plate belonging to the Carnegie Observatories’ collections, a specimen observing a white dwarf or the remaining core of a star that has died and shed its gases.
“The unexpected realization that this 1917 plate from our archive contains the earliest recorded evidence of a polluted white dwarf system is just incredible,” says John Mulchaey, the observatories’ director.
Mulchaey adds that the fact that renowned astronomer Walter Adams made the discovery “enhances the excitement.” A former director at Carnegie-owned Mount Wilson Observatory, Adams made the 1917 plate, with its sleeves indicating that the star looked quite warmer than the solar system’s own sun.
But there was more to the plate as noticed by the new review’s author, Jay Fahiri of University College London in the United Kingdom. He previously contacted Mulchaey to look for a plate that contains a spectrum of van Maanen’s star, a white dwarf discovered by Dutch-American astronomer Adrian van Maanen in the same year the plate was created.
The spectrum Adams recorded of van Maanen’s star’s chemical fingerprint revealed heavier elements supposedly not present then. Calcium, magnesium, and iron should have already vanished into the star’s interior because of their weight.
These heavier elements serve as proof of a great deal of debris in the planetary system that continues to fall into the star, forming what are called “polluted white dwarfs.” These systems, which feature massive rings of rocky planetary matter polluting the star’s atmosphere with debris, have only been known in the past 12 years.
They shocked astronomers, who have long believed that white dwarfs, since they are so old, should not have any remaining planetary material around them at the point – a phenomenon common among young stellar systems.
Planets, too, have not been seen orbiting van Maanen’s star or stars similar to it, which only deepens the mystery. For Fahiri, however, it is only a matter of time, as the process would not take place unless there are planets present.
"The mechanism that creates the rings of planetary debris, and the deposition onto the stellar atmosphere, requires the gravitational influence of full-fledged planets,” he explains.
The findings were discussed in the journal New Astronomy Reviews.
The hunt for exoplanets or planetary bodies beyond the solar system continues. NASA recently announced it will build a $10 million instrument to detect and search for them. The highly sophisticated project has been dubbed the NASA-NSF Exoplanet Observational Research program (NN-EXPLORE).
This new planet detection project will leverage Doppler Spectroscopy and detect exoplanets through measuring a star’s wobbling, which occurs if a planet orbits them thanks to the gravitational forces at work. The magnitude of the wobble, too, will determine the size of the planet.
