Abstract We present JWST near-infrared (NIR) and mid-infrared (MIR) spectroscopic observations of the nearby normal Type Ia supernova (SN) SN 2021aefx in the nebular phase at +255 days past maximum light. Our Near Infrared Spectrograph (NIRSpec) and Mid Infrared Instrument observations, combined with ground-based optical data from the South African Large Telescope, constitute the first complete optical+NIR+MIR nebular SN Ia spectrum covering 0.3–14μm. This spectrum unveils the previously unobserved 2.5−5μm region, revealing strong nebular iron and stable nickel emission, indicative of high-density burning that can constrain the progenitor mass. The data show a significant improvement in sensitivity and resolution compared to previous Spitzer MIR data. We identify numerous NIR and MIR nebular emission lines from iron-group elements as well as lines from the intermediate-mass element argon. The argon lines extend to higher velocities than the iron-group elements, suggesting stratified ejecta that are a hallmark of delayed-detonation or double-detonation SN Ia models. We present fits to simple geometric line profiles to features beyond 1.2μm and find that most lines are consistent with Gaussian or spherical emission distributions, while the [Ariii] 8.99μm line has a distinctively flat-topped profile indicating a thick spherical shell of emission. Using our line profile fits, we investigate the emissivity structure of SN 2021aefx and measure kinematic properties. Continued observations of SN 2021aefx and other SNe Ia with JWST will be transformative to the study of SN Ia composition, ionization structure, density, and temperature, and will provide important constraints on SN Ia progenitor and explosion models.
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Optical and near-infrared data and modelling of nova V5668 Sgr
ABSTRACT We present Hubble Space Telescope optical images, Keck-OSIRIS near-infrared (NIR) integral field spectroscopy data cubes and Keck-Near InfraRed Camera-2 (NIRC2) NIR images of nova V5668 Sgr from 2016 to 2019. The observations indicate enhanced emission at the polar caps and equatorial torus for low-ionization lines, and enhanced high-ionization emission lines only at the polar caps. The radial velocities are compatible with a homogeneous expansion velocity of v = 590 km s−1 and a system inclination angle of 24°. These values were used to estimate an expansion parallax distance of 1200 ± 400 pc. The NIRC2 data indicate the presence of dust in 2016 and 2017, but no dust emission could be detected in 2019. The observational data were used for assembling 3D photoionization models of the ejecta. The model results indicate that the central source has a temperature of 1.88 × 105 K and a luminosity of 1.6 × 1035 erg s−1 in August of 2017 (2.4 yr post eruption), and that the shell has a mass of 6.3 × 10−5 M⊙. The models also suggest anisotropy of the ionizing flux, possibly by the contribution from a luminous accretion disc.
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- Award ID(s):
- 1751874
- PAR ID:
- 10362616
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 511
- Issue:
- 2
- ISSN:
- 0035-8711
- Page Range / eLocation ID:
- p. 1591-1600
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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