Presentation on theme: "Supernova 1987A at 25 years. 1.Highlights of the past 25 years 2.Outstanding mysteries and surprises 3.What we can expect to learn, sooner and later TOPICS."— Presentation transcript:
Supernova 1987A at 25 years
1.Highlights of the past 25 years 2.Outstanding mysteries and surprises 3.What we can expect to learn, sooner and later TOPICS
Supernova Energy Sources Core collapse: E ~ GM 2 /R ~ 0.1 Mc 2 ~ ergs Neutrinos: t ~ 10s Radioactivity: 0.07 M [ 56 Ni 56 Co 56 Fe] ~ ergs. Light: t ~ 3 months Kinetic energy: ~ 10 M , V expansion ~ 3000 km/s ~ ergs ~ 1% core collapse. X-rays: t ~ decades - centuries.
Neutrino signal (10 53 ergs) a neutron star formed (I think!)
Optical Light (10 49 ergs): driven by radioactivity 56 Co 57 Co 44 Ti
X-rays (10 51 ergs): from kinetic energy (crash)
What we have learned: the interior
IR nebular spectrum: CO bands interior T < days; now < 300 K Strong, optically thick FIR lines of [FeII], [CoII] newly synthesized Fe must occupy ~ 50% of volume of glowing interior: “nickel bubbles” due to foaming action driven by radioactive heating Fe, Co, Ni Dust C, O, Si, S H, He
Interior Dust Formation 400 – 700 d: bolometric luminosity shifted from optical to FIR; Red sides of nebular emission lines vanished Visible glow of interior comes mostly from near side. Morphology determined largely by dust distribution. Dust obscures central object. Southern extension is in equatorial plane
What we have learned: the exterior
Crash: birth of SNR1987A Time-lapse movie of HST images
Light Curves of CS Ring Optical (HST) Radio, IR, X-ray
Motion of optical (HST) hotspots
Expansion of X-ray ring (Racusin et al) and radio shell (Ng et al)
Heating of debris by external X-rays
Hubble observations of the reverse shock: an adventure in spectroscopy
Line emission and impact ionization at reverse shock surface = v /c H* H + h H , Ly
Luminosities of H and Ly Each hydrogen atom crossing RS will produce, on average: R exc (2p)/R ion = 1 Ly R exc (H )/R ion = 0.2 H Integrated luminosity of H mass flux of H atoms across RS.
z o = v/c where v = H 0 z and H 0 = 1/t Surfaces of constant Doppler shift are planar sections of the supernova debris To observer
Doppler Mapping of H Emission from RS Surface
Resonance Scattering of Ly by Supernova Debris Source of Ly is nearly stationary emission from hotspots in circumstellar ring Model requires: Sufficient luminosity of Ly photons from hotspots to account for broad Ly ; Sufficient optical depth of SN envelope in damping wings of Ly 5000 km/s.
Ly NV 1240 CIV1550 He II 1640 H (2S 1S) continuum from hotspots
Carbon/Nitrogen Ratio Standard cosmic abundance ratio: C/N = 4.1 Narrow UV emission lines from ring C/N = 0.11 Broad UV emission lines from RS C/N = 0.05 Interpretation: nuclear burning (CNO bi-cycle) converts C, O into N. This explains decreased C/N ratio in ring. Further decrease of C/N ratio seen in RS either: (a) stratification of C/N ratio in outer envelope of progenitor; or (b) continued nucleosynthesis subsequent to ejection of ring.
The Future: what can we hope to learn? What is the compact object? What made the triple ring system? How (where) are the relativistic electrons accelerated? What is the distribution of newly-synthesized elements in the SN interior
Compact object? – not a clue! Bolometric luminosity < few hundred L < Crab pulsar The best hope: image compact FIR source with JWST (2018?)
How (where) are the relativistic electrons accelerated? Image non- thermal radio emission. ALMA will do these things: Angular resolution <0.1 arcsec Cycle 0 observations: April 2012 Mysteries
New Far Infrared Results from Herschel Telescope 250 m emission has been interpreted as continuum emission from interior dust grains (Matsuura et al 2011). This requires ~ 0.6 solar masses of dust at 18K !!??. Even if CO (2.6 m) line emission is 1% of dust emission, ALMA will see it. If so, ALMA will provide a 3-d map of the interior CO emitting region.
Simulated ALMA Cycle mm L: 10 mJY central, 10 mJy ring; R: 3 mJy central, 17 mJy ring
HST Cycle 20 (we hope!) STIS: 3-d map of interior debris + RS WFC3 + filters: 2-d images of high-velocity Ly and H
Thanks to: Bob Kirshner and SAINTS team Kevin France Claes Fransson Remy Indebetouw Sangwook Park and many others
VLT broad H profile: Fransson et al 2011 Inner debris Reverse Shock
HeII 1640: analogue of H : 1640/H = [X He /X H ][R exc /R ion (He)]/[R exc /R ion (H)] = [X He /X H ] = 0.21 ✔ But line profiles are different, because He + can be accelerated in shocked gas.