Larsson, J;
Fransson, C;
Kavanagh, PJ;
Sargent, B;
Barlow, MJ;
Matsuura, M;
Gall, C;
... Temim, T; + view all
(2025)
The Compact Object and Innermost Ejecta of SN 1987A.
The Astrophysical Journal
, 991
(2)
, Article 130. 10.3847/1538-4357/adf741.
Preview |
PDF
Larsson_2025_ApJ_991_130.pdf - Published Version Download (4MB) | Preview |
Abstract
The first JWST observations of SN 1987A provided clear evidence that a compact object is ionizing the innermost ejecta. Here, we analyze a second epoch of JWST NIRSpec and MIRI/Medium-Resolution Spectrometer observations to better characterize the properties of this region, aided by a higher spectral resolving power for the new NIRSpec data. We confirm the presence of the previously identified narrow lines from the central region, i.e., ([Ar vi] 4.5292 μm, [Ar ii] 6.9853 μm, [S iv] 10.5105 μm, and [S iii] 18.7130 μm), and also identify similar components in [Ca v] 4.1585 μm, [Cl ii] 14.3678 μm, and possibly [Fe ii] 1.6440 μm. These lines are blueshifted by ∼−250 km s<sup>−1</sup>, while the emission region is spatially unresolved and located southeast of the center. The offset and blueshift could imply a kick velocity of 510 ± 55 km s<sup>−1</sup> for the neutron star. We also identify [Ca iv] 3.2068 μm near the center, but it is displaced to the north and has a redshift of ∼700 km s<sup>−1</sup>. We find that scattering by dust in the ejecta with a typical grain size ∼0.3 μm can explain the [Ca iv] properties and the absence of other narrow lines at shorter wavelengths, while dust absorption is important at λ ≳ 8 μm. Photoionization models for a pulsar wind nebula and a cooling neutron star are both compatible with the observations, with the exception of the [Fe ii] feature. The two models primarily differ at short wavelengths, where new lines are expected to emerge over time as the optical depth of dust in the expanding ejecta decreases.
| Type: | Article |
|---|---|
| Title: | The Compact Object and Innermost Ejecta of SN 1987A |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/1538-4357/adf741 |
| Publisher version: | https://doi.org/10.3847/1538-4357/adf741 |
| Language: | English |
| Additional information: | Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10217155 |
Archive Staff Only
 |
View Item |
