About IMSNG

  Intense Monitoring Survey of Nearby Galaxies (IMSNG) began to understand Supernovae better, especially the progenitors of supernovae. The study aims to understand the progenitors of supernovae through observation of the early light curve.

Supernova Mechanism ("Astronomy Today" by Chaisson/McMillian)

  Our current understanding of supernovae and their theoretical model depict them in two types. In a Type-I Supernova, a white dwarf(WD) in a binary system with a companion (be it a red giant, a main-sequence star, or another WD) gains mass from the companion and triggers a thermonuclear explosion. In a Type-II Supernova, a massive star (such as a red, yellow supergiant) goes through a core collapse in its late stage of evolution. However, direct observations of the progenitor are scarce.

  By observing and measuring the early light curve of supernovae, it is possible to estimate the size of the progenitor
(Kassen 2010; Nakar & Sari 2010; Piro et al. 2010; and more). Also soon after the explosion, the stellar atmosphere of the companion star, or the atmosphere of the exploding core-collapse star is shock-heated, and emits light. This shock-heated light emission requires high frequency monitoring observation, for it lasts only hours to days.

Shock Heated Emission (Kasen 2010)

Early Light Curve (Kasen 2010)

  To observe the early light curve of supernovae, IMSNG monitors galaxies with high possibility of supernovae event. Since galaxies with higher star formation rate(SFR) are likely to host supernovae events, galaxies with high ultraviolet luminosity were chosen. Also to get a better observation of the faint shock-heated emission, the target needs to be close. Therefore the criteria for the survey were selected thus:

     • UV bright galaxies: M(NUV) < -18.4 mag
     • Close galaxies : D < 50 Mpc

  With these criteria, 60 galaxies were chosen (Gil de Paz et al. 2007; Bai et al. 2015), and the expected supernovae rate is about ~3.6 SN per year(Refer to Targets for more information).

Expected Supernova Rate

  The IMSNG survey started in 2014 and is currently ongoing with several ~1m class telescopes around the globe. The picture below illustrate the various sites of IMSNG observation(Refer to Facilities for more information).

Astronomy Program, Department of Physics and Astronomy, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea
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