Evidence of an exoplanetary system was recorded in 1917
While the search for exoplanets hasonly comparatively recently picked up steam, a chance re-examination of an oldastronomical glass plate has shown that the very first evidence of anexoplanetary system was actually recorded almost 100 years ago. Thedata on the plate doesn't outright confirm exoplanets in the system,but astronomers are confident that it's only a matter of time before their existence in such systems is confirmed.
While modern astronomers use digitaltools to image stars, that hasn't always been the case. Turn theclock back a century, and stargazers were using glass photographicplates to record stellar spectra, showing a spread of all of thecomponent colors of the light from the distant objects. Thatinformation can be used to ascertain a lot of information about a star, including its chemical composition.
The new discovery was made whenUniversity College London's Jay Farhi contacted the Carnegie Institute of Science looking fora plate in its archive that showed a star discovered byDutch-American astronomer Adriaan van Maanen in 1917, known as van Maanen's star.
The plate was made by formerObservatories Director Walter Adams at Mount Wilson Obseravtory, atthe time part of the Carnegie Institute. Back then, not much out ofthe ordinary was noticed about the distant object, with an attachednote commenting only that the star appeared to be a little warmer than ourown Sun.
However, examining the plate usingmodern technology revealed much more, confirming the presence ofabsorption lines on the spectrum, which are essentially gaps in thedata where the light coming from the star was absorbed by a substancethat it passed through.
Studying these lines tells us about thechemical makeup of the obscuring object, in this case highlightingthe presence of heavier elements such as calcium, magnesium and iron.These elements would usually have long since sunk into the interiorof the star due to their weight.
Research over the last 12 years hasshown that the presence of such elements indicates the existence of atype of planetary system incorporating huge rings of rocky planetaryremnant material around the star. These are known as "pollutedwhite dwarfs," and while actual planets are yet to be detected insuch a system, astronomers believe that it's only a matter of timeuntil the discovery in made.
"The mechanism that creates the ringsof planetary debris, and the deposition onto the stellar atmosphere,requires the gravitational influence of full-fledged planets," saidFarihi. "The process couldn't occur unless there were planetsthere."
The chance discovery is an astonishingone, and considering that there are some 250,000 plates sitting inthe Carnegie archive, it's likely that there's plenty moreinformation stored away that we could only fully appreciate with thebenefits of modern technology.
Source: Carnegie Institute