The image shows Gaia spectra of Gaia16aeg - the first exciting supernova discovered by Gaia in 2016. This supernova was first discovered independently by the ASAS-SN survey (as ASASSN-15lv) in mid 2015, and classified as a Type IIb supernova, at a relatively close distance of around 60 million parsecs (Mpc). Type IIb supernovae arise from the core-collapse of a massive star which has retained only a thin layer of its hydrogen envelope.
The Gaia spectra, measured through its decline in brightness (see Gaia16aeg light curve), become dominated by strong emission lines from Calcium, Oxygen and Iron. These elements have been ejected from inside the core of the star, or synthesized in the explosion. The spectra shown below provide a diagnostic of the mass of the star that exploded.
This sequence of spectra charts the evolution of Gaia16aeg as it transitions towards a nebular spectrum. Over a five month period, the continuum fades while strong emission lines of Calcium (including the Ca NIR triplet), Oxygen and Iron are seen to emerge in the red spectrum. The spectra were measured with Gaia's own Blue and Red Prism Photometers (BP/RP). These spectra are uncalibrated, with the Y-axis showing normalised counts, and the X-axis showing channel number (i.e. no attempt is made to measure wavelength). The gap between channels 50-70 is the gap between the BP and RP photometers as imaged on the detectors.
See Gaia sees exploding stars next door for more information.
Page last updated: 17 March 2016