C. Tegkelidis | Searcharxiv

arXiv2026

Exploring the central region of SNR 0540-69.3 with JWST I: 3D morphology

The young supernova remnant SNR 0540-69.3 in the Large Magellanic Cloud offers a detailed view of an energetic pulsar-wind nebula interacting with the surrounding ejecta. We present infrared observations of the central region of SNR 0540-69.3 obtained with the JWST NIRSpec and MRS integral field units. From the observations we reconstruct the 3D morphology of the strongest emission lines in the inner ejecta ($\lesssim$ 1000 km/s), which reveals the distribution of H I, He I, [Ne II], [Ne III], [S III], [S IV], [Fe II], and [Ni II]. The 3D morphology of most lines is dominated by two highly fragmented lobes of approximately similar size. Based on the assumption that the lobes are symmetric around the pulsar, we infer a pulsar kick velocity of ~300 km/s away from the observer. There are differences in the 3D morphologies of individual emission lines due to a combination of varying physical conditions and abundances. The detection of H I 1.8756 $\mu$m in the inner ejecta confirms the classification of the SN as a Type II and shows that hydrogen was mixed down to low velocities of < 400 km/s in the explosion. We compare the results to the Crab nebula and conclude that asymmetries originating in the explosion most likely play a major role in shaping the PWNe.

astro-ph.HE↗

arXiv2025

The position of SN 1987A

The accurate positional measurement of Supernova (SN) 1987A is important for determining the kick velocity of its compact object and the velocities of the ejecta and various shock components. In this work, we perform absolute astrometry to determine the position of SN 1987A. We used multi-epoch Hubble Space Telescope imaging to model the early ejecta and the equatorial ring (ER). We combined our measurements and obtained the celestial coordinates in the International Celestial Reference System (ICRS) by registering the observations onto Gaia Data Release 3. The final average position of the different measurements is ${\alpha = 5^{\mathrm{h}}~ 35^{\rm{m}}~ 27^{\rm{s}}.9884(30)}$, ${\delta = -69^{\circ}~ 16'~ 11''.1134(136)}$ (ICRS J2016). The early ejecta position is located 14 mas south and 16 mas east of the ER center, with the offset being significant at 96% confidence. The offset may be due to instrument and/or filter-dependent systematics and registration uncertainties, though an intrinsic explosion offset relative to the ER remains possible. Image registration with proper motion corrections yields similar astrometry and a source proper motion of ${\mu_{\rm east} (\equiv \rm{PM_{\alpha }*}) = 1.60 \pm 0.15 ~\rm{mas ~ yr^{-1}}}$ and ${\mu_{\rm{north}} (\equiv \rm{PM_{\delta}}) = 0.44 \pm 0.09~\rm{mas ~ yr^{-1}}}$, in agreement with the typical local motion of the Large Magellanic Cloud. The absolute positional uncertainty of 21 mas adds a systematic uncertainty to the sky-plane kick velocity of ${123}~(t/40~\rm{yr})^{-1}~\rm{km~s}^{-1}$, where $t$ is the time since the explosion. Comparing the location of the compact source observed with JWST to our updated position implies a sky-plane kick of ${399\pm148~\mathrm{km~s^{-1}}}$ and a 3D kick of ${472\pm126~\mathrm{km~s^{-1}}}$, which is consistent with previous estimates.

astro-ph.HE↗