SN 1987A: The Formation & Evolution of Dust in a Supernova Explosion A Joint GTO Program with MIRI-EC and Meixner’s US MIRI Science Time

SN1987A in the LMC SN1987A was detected with dust 1 year after explosion ( Moseley et al. 1989; Bouchet et al. 1991; Wooden et al. 1993).

The central stellar ejecta of SN 1987A is surrounded by a ring of progenitor gas and dust that is being shocked by the blast wave of the explosion.

Dust formation in SN ejecta (HERITAGE; Meixner et al. 2010) Matsuura et al. 2011

Herschel detected ~0.5 Msun of dust Matsuura et al. 2015

ALMA resolved the cold dust. It is located in the ejecta. Indebetouw et al. 2014

Day 8720 Mdust,ejecta = 10-4 – 10-3 Mʘ 80<T<100K Bouchet et al. 2011

We want to understand how massive stars explode, how their ejecta forms dust and molecules and how the blast wave from the explosion affects their surroundings. We want to understand how massive stars age and explode, how their ejecta form dust and molecules and how the blast wave from their violent explosion affects their surroundings. JWST MIRI imaging, MRS spectroscopy and NIRSpec IFU spectroscopy will provide key emission line diagnostics and dust feature and continuum measurements of SN 1987A. The central stellar ejecta of SN 1987A is surrounded by a ring of progenitor gas and dust that is being shocked by the blast wave of the explosion. A large quantity (0.4-0.7 M) of dust in the stellar ejecta has an unknown composition and our MIRI observations may provide the first constraints through the imaging and MRS spectroscopy. Both the MRS and NIRSpec IFU spectroscopy will measure key shocked line diagnostics that will constrain the shock physics as well as the elemental abundances in both the ring and the stellar ejecta. MIRI filter imaging at F560W, F1000W, F1800W and F2550W, together with MRS IFU and NIRSpec IFU imaging spectroscopy of the ring and ejecta will be obtained to measure the line and continuum. The goals are a) to study the evolution of the interaction of the blast wave with the 2 arcsec diameter equatorial ring and beyond; b) to determine the nature of the ring’s hot dust component discovered by Spitzer; c) to search for and confirm mid-IR emission from the 0.5 M of ejecta dust that was discovered at far-IR wavelengths by Herschel; d) to study the evolution of the dust and molecules in the ejecta; e) to look for a remnant neutron star. We anticipate running the MIRI imager simultaneously with the MRS. We will take all these measurements back-to-back in time to ensure the measurements are from the same epoch of this time evolving object. We want to understand how massive stars age and explode, how their ejecta form dust and molecules and how the blast wave from their violent explosion affects their surroundings. The central stellar ejecta of SN 1987A is surrounded by a ring of progenitor gas and dust that is being shocked by the blast wave of the explosion. A large quantity (0.4-0.7 M) of dust in the stellar ejecta has an unknown composition and our MIRI observations may provide the first constraints through the imaging and MRS spectroscopy. Both the MRS and NIRSpec IFU spectroscopy will measure key shocked line diagnostics that will constrain the shock physics as well as the elemental abundances in both the ring and the stellar ejecta.

What can JWST do for us? Exquisite resolution in the infrared (0.6-28 microns) — Accurately resolve both the ring and ejecta. Sensitivity — detect faint emission from ejecta & the warm dust emission from the circumstellar ring. Medium and high resolution IFU imaging spectroscopy — provides line & continuum measurements of the gas & dust which is interacting with the expanding shock wave. We want to understand how massive stars age and explode, how their ejecta form dust and molecules and how the blast wave from their violent explosion affects their surroundings. JWST MIRI imaging, MRS spectroscopy and NIRSpec IFU spectroscopy will provide key emission line diagnostics and dust feature and continuum measurements of SN 1987A. The central stellar ejecta of SN 1987A is surrounded by a ring of progenitor gas and dust that is being shocked by the blast wave of the explosion. A large quantity (0.4-0.7 M) of dust in the stellar ejecta has an unknown composition and our MIRI observations may provide the first constraints through the imaging and MRS spectroscopy. Both the MRS and NIRSpec IFU spectroscopy will measure key shocked line diagnostics that will constrain the shock physics as well as the elemental abundances in both the ring and the stellar ejecta. The environment of SN1987A has significant star formation, which has been studied using HST imaging during parallel HST imaging spectroscopic observations of SN 1987A. This star formation will be studied using parallel fields when SN 1987A is the prime target

SN1987A is in the continuous viewing zone We can observe changes in SN1987A over a wide temporal base-line.

What will JWST do for us? We are going to observe the ring and ejecta of SN1987A at two epochs using: MIRI imaging: F560W, F1000W, F1800W & F2550W MRS IFU and NIRSpec IFU imaging spectroscopy Plus parallel observations with the MRS & MIRI simultaneous imaging (when possible). Total observing time (inc. overheads): 9 hours We want to understand how massive stars age and explode, how their ejecta form dust and molecules and how the blast wave from their violent explosion affects their surroundings. JWST MIRI imaging, MRS spectroscopy and NIRSpec IFU spectroscopy will provide key emission line diagnostics and dust feature and continuum measurements of SN 1987A. The central stellar ejecta of SN 1987A is surrounded by a ring of progenitor gas and dust that is being shocked by the blast wave of the explosion. A large quantity (0.4-0.7 M) of dust in the stellar ejecta has an unknown composition and our MIRI observations may provide the first constraints through the imaging and MRS spectroscopy. Both the MRS and NIRSpec IFU spectroscopy will measure key shocked line diagnostics that will constrain the shock physics as well as the elemental abundances in both the ring and the stellar ejecta. The environment of SN1987A has significant star formation, which has been studied using HST imaging during parallel HST imaging spectroscopic observations of SN 1987A. This star formation will be studied using parallel fields when SN 1987A is the prime target

MIRI Imaging

Goal 1: Study the interaction of the blast wave with the equatorial ring. Map the dust temperature distribution. Obtain light curves at different wavelengths. Determine whether dust grains are destroyed. Goal 2: Search for mid-IR emission from the dust ejecta. Goal 3: Look for a remnant neutron star.

High S/N MIRI imaging at F560W, F1000W, F1800W & F2550W MIRI imager has 0.11”x0.11” pixels -> better spatial resolution than MRS spaxels. Caution: The ring is very bright, but any dust emission from the ejecta is faint. Need to use a subarray & many dithers to avoid saturation.

MIRI imaging at F560W, F1000W, F1800W & F2550W Spitzer IRS spectra of the equatorial ring

MIRI MRS spectroscopy

Goal 1: What is the composition of the dust in the stellar ejecta. Goal 2: Constrain elemental abundances, temperature and densities in both the ring and the stellar ejecta. Goal 3: How does the dust and molecules change as they undergoes processing due to the blast wave. Are there unknown dust and molecular components in the equatorial ring? Goal 4: Understand the physics behind the shock.

What is the composition of the dust in the ejecta of SN1987A? Matsuura et al. 2015

What is the composition of the dust in the ejecta of SN1987A? Sensitivity of the MRS Matsuura et al. 2015

What is the composition of the dust in the ejecta of SN1987A? Determining the dust composition of the ejecta is going to be a challenge! Sensitivity of the MRS Matsuura et al. 2015

Is a hot dust component also present in the equatorial ring of SN 1987A ? IRS spectra Dust model Amorphous silicates Hot Carbon dust Dwek et al. 2010

NIRSpec IFU spectroscopy

Velocity components in the UVES/VLT spectrum Un-shocked ring V~10 km/s Shocked ring V ~ 300–700 km/s SN ejecta (inner core) V~2000–3000km/s Reverse shock V~ 11,000 km/s Migotto et al. in prep.

Most interesting lines: He I 2.058 μm & H2 2.12 & 2.43 μm Many low & high ionization lines seen with Spitzer. Offer very useful diagnostics of the shocked ring & the explosion mechanism. Most interesting lines: He I 2.058 μm & H2 2.12 & 2.43 μm Possibly use lines to obtain 3D structure of SN1987a. NB: Molecular hydrogen is excited by UV or non thermal electrons. Dust or line emission outside the ring - excited by X-rays. Gives information about the mixing and clumping of the ejecta complementary to the SINFONI 1.644 [SiI]+[Fe II] lines and the ALMA CO & SiO lines. Caution: Mind the gap! Avoid high resolution (R = 2700) gratings as coverage gaps where key lines are. Use the medium resolution IFU instead.

Parallel Observations

When MIRI imager is prime When MRS is prime MIRI simultaneous imaging in the 5.6, 7.7 and 25 micron filters to measure the dust emission from young stellar objects & the surrounding interstellar medium. When MIRI imager is prime The MRS will provide critical background measurements of both the telescope emission & the ISM background. This is essential to reducing systematic issues with the MRS measurement of SN1987A.

Science goals Study the interaction of the blast wave with the equatorial ring. Determine the nature of the ring’s hot dust component. Search for mid-IR emission from the 0.5 Msun of ejecta dust that was discovered at far-IR wavelengths by Herschel. Study the evolution of the dust and molecules in the ejecta. Look for a remnant neutron star. Study the environment adjacent to SN1987A which has significant star formation (30 Dor!) using parallel fields.