First real evidence for an extrasolar plantary system was obtained almost 100 years ago

Recognition of the First Observational Evidence of an Extrasolar Planetary System

Quote :

With 20-20 hindsight, it is now possible to say that the first observational indication - by any means - of the existence of an extrasolar planetary system came almost a century ago when van Maanen discovered and noted the spectrum of the nearest single white dwarf to Earth.

Of historical interest only, but it's more evidence that awareness of specific extrasolar planetary systems could have been gained significantly earlier than actually happened.

Probably first planetary system discovered on this images from 1917
http://astronomynow.com/2016/04/13/first-ever-evidence-of-exoplanetary-system-found-on-1917-photograph/

Since it's hidden in the article, this is the relevant paper.

Circumstellar Debris and Pollution at White Dwarf Stars

Quote :

Circumstellar disks of planetary debris are now known or suspected to closely orbit hundreds of white dwarf stars. To date, both data and theory support disks that are entirely contained within the preceding giant stellar radii, and hence must have been produced during the white dwarf phase. This picture is strengthened by the signature of material falling onto the pristine stellar surfaces; disks are always detected together with atmospheric heavy elements. The physical link between this debris and the white dwarf host abundances enables unique insight into the bulk chemistry of extrasolar planetary systems via their remnants. This review summarizes the body of evidence supporting dynamically active planetary systems at a large fraction of all white dwarfs, the remnants of first generation, main-sequence planetary systems, and hence provide insight into initial conditions as well as long-term dynamics and evolution.

It's a long read, but it's a good overview of a quickly developing subfield.

Saying this is a "discovery of a planetary system" is definitely misleading, though. The article frames it correctly, it's the first evidence of the existence of extrasolar planets. Hindsight is 20/20; At the time, Van Maanen's star had just been discovered, and white dwarfs had not even been named, much less explained. Who could have known that a metal absorption line implicated accretion by some bizarre new type of star?

It is only with a century's knowledge that we can look back and see the remains of planets that once circled that old stellar core.

Also of note is this arXiv paper from 2014, which was linked by Mongo in this thread.

I knew I had heard of this before. Thanks for finding that. I've merged the threads.