New Radio Observations of Supernova 1978K Stuart Ryder International Telescopes Support Office Australian Astronomical Observatory

NGC 1313 SN 1978K Image credit: T.A. Rector/University of Alaska Anchorage, T. Abbott and NOAO/AURA/NSF

My favourite supernova Supernova 1978K in NGC 1313 (4.6 Mpc). Nearest “middle age” supernova after SN 1987A. Only discovered in 1991 from ATCA radio, ROSAT X-ray, unusual 2.3m optical spectrum. Type IIn = narrow emission lines on broad base  dense circumstellar medium. Luminous Blue Variable progenitor? Extremely radio luminous.

Radio properties of SNe Romero-Cañizales et al. 2014

ATCA radio spectrum 2014 SN 1978K @ 94 GHz ~300× brighter than SN 1987A. Turnover at low freq. due to free-free absorption by intervening H II region / circumstellar nebula.

Next stop: ALMA Awarded 4.6h (Priority B) in Cycle 3 for Bands 3, 4, 6, 7 (90–340 GHz). Characterise SED – upturn from cold dust emission?

Watching a supernova expand SN 1987A with ATCA

Australian Long Baseline Array ASKAP ATCA Mopra Ceduna Parkes Hobart

SN 1978K VLBI March 2015 Free expansion at 10,000 km s-1 for 37 years  0".04 LBA resolution @ 8.4 GHz = 0".003 SN remnant diameter < 0.005" (0.11 pc) Past average expansion velocity < 1,500 km s-1

Deceleration of SN 1978K For R ~ t0.78, current expansion velocity ~ 1,000 km s-1 (cf. 1,600 – 6,300 km s-1 in SN 1987A) Kuncarayakti et al. (2016) optical spectroscopy  Ṁ ~ 0.01 M yr-1 MCSM ~ 1 M

Recap Not all core-collapse supernovae are like SN 1987A! ATCA’s 1–100 GHz coverage → measure SN 1978K’s cold dust mass with ALMA. SN 1978K has been significantly decelerated by its dense circumstellar medium, and has slowed to ~1,000 km s-1 after 37 years.

Job opportunity Joint Macquarie University / International Telescopes Support Office Lecturer in Astronomy. 3 year fixed-term. Applications close 14 August 2016. See July 2016 AAS Job Register (http://jobregister.aas.org/job_view?JobID=54405). Applications from female and minority candidates are strongly encouraged. Questions? Contact me or Mark Wardle.