The melody was a musical theme of unknown origin encountered in 3189 by Michael Burnham of the USS Discovery.
Following the recovery of the Tal symbiont's memories on Trill, Burnham first encountered the melody when it was being played on a cello by Adira Tal, at the time channeling Tal's former host and Adira's deceased boyfriend, Gray. (DIS: "Forget Me Not")
Aboard the USS Tikhov, Burnham noticed the deceased wife of Dr. Attis humming the melody in an actively playing log, recorded prior to the coronal mass ejection that disabled the Tikhov and killed his family, commenting on her familiarity with the melody to Nhan and Hugh Culber and her confusion as to how the mother knew the melody.
Upon returning to Federation Headquarters, Burnham asked Lieutenant Willa to investigate the melody. Willa later returned to Burnham with no new information, but stated that most people know some variation of the melody, including Willa herself. Burnham expressed her skepticism to Willa about multiple people, across multiple sectors, during a time when dilithium-based warp travel was severely limited, all knowing the same melody. Her skepticism was promptly dismissed by Willa as "some things just get into the ether." (DIS: "Die Trying")
When the origination of "The Burn" was discovered, it turned out that a ship lost in the Verubin Nebula was transmitting a distress signal. This signal was distorted by magnetic interference caused by the nebula's unstable electromagnetic fields and became the basis for the melody. (DIS: "The Sanctuary")