title: X-ray illumination of the ejecta of supernova 1987A.
abstract: When a massive star explodes as a supernova, substantial amounts of radioactive elements--primarily (56)Ni, (57)Ni and (44)Ti--are produced. After the initial flash of light from shock heating, the fading light emitted by the supernova is due to the decay of these elements. However, after decades, the energy powering a supernova remnant comes from the shock interaction between the ejecta and the surrounding medium. The transition to this phase has hitherto not been observed: supernovae occur too infrequently in the Milky Way to provide a young example, and extragalactic supernovae are generally too faint and too small. Here we report observations that show this transition in the supernova SN 1987A in the Large Magellanic Cloud. From 1994 to 2001, the ejecta faded owing to radioactive decay of (44)Ti as predicted. Then the flux started to increase, more than doubling by the end of 2009. We show that this increase is the result of heat deposited by X-rays produced as the ejecta interacts with the surrounding material. In time, the X-rays will penetrate farther into the ejecta, enabling us to analyse the structure and chemistry of the vanished star.
authors.affiliation: Department of Astronomy, The Oskar Klein Centre, Stockholm University, 106 91 Stockholm, Sweden. josefin.larsson@astro.su.se
authors.forename: J
authors.initials: J
authors.lastname: Larsson
authors.forename: C
authors.initials: C
authors.lastname: Fransson
authors.forename: G
authors.initials: G
authors.lastname: Ostlin
authors.forename: P
authors.initials: P
authors.lastname: Gröningsson
authors.forename: A
authors.initials: A
authors.lastname: Jerkstrand
authors.forename: C
authors.initials: C
authors.lastname: Kozma
authors.forename: J
authors.initials: J
authors.lastname: Sollerman
authors.forename: P
authors.initials: P
authors.lastname: Challis
authors.forename: R P
authors.initials: RP
authors.lastname: Kirshner
authors.forename: R A
authors.initials: RA
authors.lastname: Chevalier
authors.forename: K
authors.initials: K
authors.lastname: Heng
authors.forename: R
authors.initials: R
authors.lastname: McCray
authors.forename: N B
authors.initials: NB
authors.lastname: Suntzeff
authors.forename: P
authors.initials: P
authors.lastname: Bouchet
authors.forename: A
authors.initials: A
authors.lastname: Crotts
authors.forename: J
authors.initials: J
authors.lastname: Danziger
authors.forename: E
authors.initials: E
authors.lastname: Dwek
authors.forename: K
authors.initials: K
authors.lastname: France
authors.forename: P M
authors.initials: PM
authors.lastname: Garnavich
authors.forename: S S
authors.initials: SS
authors.lastname: Lawrence
authors.forename: B
authors.initials: B
authors.lastname: Leibundgut
authors.forename: P
authors.initials: P
authors.lastname: Lundqvist
authors.forename: N
authors.initials: N
authors.lastname: Panagia
authors.forename: C S J
authors.initials: CS
authors.lastname: Pun
authors.forename: N
authors.initials: N
authors.lastname: Smith
authors.forename: G
authors.initials: G
authors.lastname: Sonneborn
authors.forename: L
authors.initials: L
authors.lastname: Wang
authors.forename: J C
authors.initials: JC
authors.lastname: Wheeler