Massive runaway star HD 254577: the pre-supernova binary companion to the progenitor of the supernova remnant IC 443

TL;DR

The paper tests the binary supernova scenario by identifying a massive runaway star, HD 254577, inside the IC 443 SNR as the pre-SN binary companion to its progenitor and to the neutron star CXOU J61705.3+222127, integrating high-resolution spectroscopy with Gaia DR3 astrometry and isochrone fitting to constrain the progenitor mass to $M_{ZAMS}=31-64$ M⊙ and the runaway to $M_{ZAMS}=28-54$ M⊙. Back-tracing the star’s proper motion yields plausible SN explosion sites and NS transverse velocities of $254-539$ km s$^{-1}$ for an age of $10-20$ kyr at a distance of $1.7$ kpc, consistent with observed SNR asymmetries and ISM absorption features. The findings imply a highly off-centered explosion within IC 443 and suggest a wide pre-SN binary with limited interaction, contributing to understanding NS kicks, SNR morphology, and massive-star evolution in binaries.

Abstract

The secondaries of the massive binary systems can be found as runaway stars after being ejected due to the supernova (SN) of the more massive component. We search for such stars inside the supernova remnants (SNRs), where a recent SN is guaranteed to have happened. In this paper, we present the massive runaway star HD~254577 as the pre-supernova binary companion to the progenitor of the supernova remnant IC~443 and the neutron star (NS) CXOU~J61705.3$+$222127. We performed spectroscopic observations of the runaway star and specified its atmospheric parameters. Together with the precise \textit{Gaia} DR3 astrometry and photometry, we identified the possible birth origin of the runaway star, and by isochrone fitting, we determined the progenitor mass. From the \textit{Gaia} DR3 proper motions, we specified the possible explosion sites and calculated the neutron star (NS) velocity. HD~254577 is a hot and evolved star with an effective temperature of $24000\pm1000$ K (B0.5II) and a surface gravity of $\log({g~\rm[cm/s^2]})=2.75\pm0.25$. It is probably a single star with a peculiar 3-D velocity of $31.3^{+1.2}_{-0.9}$ km~s$^{-1}$, lying at a heliocentric distance of $1701^{+55}_{-54}$ pc. The cometary tail of the NS implies that it is moving away from the same site as the runaway star. From the flight trajectories, we calculated that the NS has typical pulsar velocities such as $254-539$ km~s$^{-1}$ at a distance of $1.7$ kpc for $10-20$ kyr ages. Together with the blue-only shifted interstellar medium lines on its spectrum, HD~254577 must be the pre-supernova binary companion to the progenitor of IC~443. By identifying the pre-supernova companion and the possible parent cluster, we showed that the progenitor zero-age main sequence mass is high: $31-64$ M$_\odot$. We also discuss the expansion dynamics of the SNR due to the highly off-centered explosion site.

Figures (9)

• Figure 1: X-ray (Röntgensatellit (ROSAT) Position Sensitive Proportional Counter (PSPC), 0.1-2.4 keV, in red), and optical (The Space Telescope Science Institute (STScI) 2nd Digitized Sky Survey (DSS2) red image, in green) composite image of IC 443. Left: The geometrical center of the SNR is shown with a black cross and the runaway star search region in 2024MNRAS.531.4212D with a black circle around it. A blue cross indicates the position of HD 254577, while a blue circle indicates that of the NS. The green box is the border of the image on the right. Right: The close-up image of the same. The big green circle represents a region with a radius of 10 pc, hosting a possible stellar group, while the small green circle shows a smaller, more compact group with a 1.5 pc radius. A 100 kyr magnified proper motion vector of HD 254577 is shown with a green arrow.
• Figure 2: Spectrum of HD 254577 with the overlayed model spectra of $T_\mathrm{eff}=23000$, 24000, and 25000 K with a fixed surface gravity of $\log(g~\rm[cm/s^2])=2.75$, a projected rotation velocity of $v \sin i = 150$ km s$^{-1}$ and a single micro-turbulence velocity of $\xi=10$ km s$^{-1}$. Top Left: The wavelength range of $4075-4140$ Å. Si $\textsc{iv}$$\lambda 4089,4116$ lines are prominent temperature indicators. The spectrum shows a consistency with the $T_\mathrm{eff}=24000$ K model at the Si $\textsc{iv}$$\lambda 4116$/ He $\textsc{i}$$\lambda 4121$ ratio. Top Right: The wavelength range of $4540-4660$ Å. The spectrum shows a consistency again with the T$=24000$ K model at the Si $\textsc{iv}$$\lambda 4089$/ Si $\textsc{iii}$$\lambda 4553$ ratio. Bottom Left: The wavelength range of $4670-4725$ Å. The spectrum shows a consistency again with the $T_\mathrm{eff}=24000$ K model at the He $\textsc{ii}$$\lambda 4686$/ He $\textsc{i}$$\lambda 4713$ ratio. Bottom Right: The spectrum of HD 254577 with thew model spectrum of $T_\mathrm{eff}=24000$ K, $\log(g~\mathrm{[cm/s^2]})=2.75$, and $\xi=10$ km s$^{-1}$ overlayed.
• Figure 3: LAMOST Spectrum of the pointing at $\mathrm{\alpha=93.902500^\circ}$$\mathrm{\delta=+22.256944^\circ}$. The prominent emission lines are H$\beta$$\lambda$4861, H$\alpha$$\lambda$6563, and forbidden lines [O iii] $\lambda\lambda$4959/5007, [O i] $\lambda \lambda$6300, [N ii] $\lambda \lambda$6548/6584, and [S ii] $\lambda \lambda$6716/6731.
• Figure 4: Left: FLECHAS spectra of HD254477. Whereas the interstellar medium Na$~\textsc{i}$ lines show no variation between epochs, the Doppler variation of He$~\textsc{i}$$\lambda5876$ line is clear. Right: FLECHAS spectra of HD254577. He$~\textsc{i}$$\lambda5876$ triplet does not show a significant variation as well as the Na$~\textsc{i}$ lines.
• Figure 5: Left:$T_\mathrm{eff}$ vs. $\log(g)$ diagram of the runaway star and OB-type stars within 10 pc from the runaway star. Right: The color-magnitude diagram of the runaway star and the possible cluster members. Isochrones are set for a 1700 pc distance. The bright stars out of the isochrones are the runaway star and HD 254477.