Observing Supernova 1987A with Near-infrared and Mid-infrared Spectroscopy

Supernova1987A is a type II supernova that was approximately 168,00 light years from Earth. It is the closest supernova observed by scientists since Kepler’s supernova in 1604. Supernova1987A has fascinated scientists for years, because the explosion was thought to have produced a neutron star or black hole (1). Although neither has been detected, scientists studying this supernova have learned valuable information from photoionization models, which indicated that the emission line ratios could reveal velocity shifts that occurred during the explosion, evidence that a neutron star natal kick took place (1).

A recent study published in Science observed the remnants of Supernova1987A (1). The purpose of this study was to learn more about this celestial phenomenon, and to look for emission lines, with the hope that it could reveal whether a compact object, such as a neutron star, formed in the center of the supernova (1). This study was a continuation of previous studies done (2–4).

Supernovas emerge in the presence of a rapid collapse or explosion of a star (5). They are so powerful that they are known to have the ability to create new atomic nuclei (6). Supernovas are widely considered to be one of the original sources of heavy metal elements in the universe (6). Because elements heavier than iron originated from supernova, they are important for the functioning of human life (6). Studying supernova, therefore, can increase our understanding of elements and improve elemental analysis.

Procedure and Observations

The research team in this study observed narrow infrared (IR) emission lines of argon and sulfur from the heart of Supernova1987A (1). These emission lines are unique because of the presence of a distinct blueshift, indicating that there was movement away from the supernova’s rest frame (1). Using photoionization models, the researchers believe that the spectral features observed originated from gas illuminated by a potent source of ionizing photons, potentially a cooling neutron star or a pulsar wind nebula (PWN) (1).

From the velocity shift that the researchers discovered, hints about the neutron star’s formation emerged. For an example, the researchers were about to measure the offset in position to estimate the velocity at 416 ± 206 km/s (1). This figure is indicative that a natal kick, which is defined in the study as a velocity imparted to a neutron star during its formation because of asymmetries in the explosion mechanism, took place (1).

Although the study did not discern the nature of a potential compact object, the presence of high ionization emission lines is important. It suggests that a neutron star might exist at the heart of Supernova1987A (1). Whether it manifests as a young cooling neutron star or within a pulsar wind nebula, the implications of this discovery offer a deeper understanding of the cosmic processes governing stellar evolution and supernova remnants (1).

This study advances the work of astronomers attempting to understand the inner workings of phenomena in the universe, and further research is needed to uncover more information about Supernova1987A and what it can reveal about how the universe works.

Reference

1. Fransson, C.; Barlow, M. J.; Kavanaugh, P. J.; et al. Emission Lines due to Ionizing Radiation from a Compact Object in the Remnant of Supernova 1987A. Science 2024, 383 (6685), 898–903. DOI: 10.1126/science.adj5796
2. Alekseev, E. N.; Alekseeva, L. N.; Volchenko, V. I.; Krivosheina, I. V. Possible Detection of a Neutrino Signal on 23 February 1987 at the Baksan Underground Scintillation Telescope of the Institute of Nuclear Research. JETP Lett. 1987, 45, 589–592.
3. Bionta, R. M.; Blewitt, G.; Bratton, C. B.; et al. Observation of a Neutrino Burst in Coincidence with Supernova 1987A in the Large Magellanic Cloud. Phys. Rev. Lett. 1987, 58, 1494–1496. DOI: 10.1103/PhysRevLett.58.1494
4. Hirata, K.; Kajita, T.; Koshiba, M.; et al. Observation of a Neutrino Burst from the Supernova SN1987A. Phys. Rev. Lett. 1987, 58, 1490–1493.
5. Gilmore, G. The Short Spectacular Life of a Superstar. Science 2004, 304 (5679), 1915–1916. DOI: 10.1126/science.1100370
6. U.S. Department of Energy, DOE Explains…Supernovae. Available at: https://www.energy.gov/science/doe-explainssupernovae#:~:text=Supernovae%20are%20considered%20one%20of,are%20thus%20essential%20to%20life (accessed February 23, 2024).