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| SN 1993J | |
|---|---|
| Name | SN 1993J |
| Caption | Optical image of the host galaxy Messier 81 with location of the supernova marked |
| Epoch | 1993 |
| Constellation | Ursa Major |
| Host | Messier 81 |
| Ra | 09h 55m 24s |
| Dec | +69° 01′ 13″ |
| Discovery date | 1993-03-28 |
| Discoverer | Fabrizio T. Bianchi; Frederick M. Vrba; William P. Max |
| Magnitude | 10.8 (peak visual) |
| Type | Type IIb |
| Distance | 3.6 Mpc |
| Progenitor | K-type supergiant in a binary with a hot companion |
SN 1993J was a bright, nearby supernova discovered in March 1993 in the spiral galaxy Messier 81 in Ursa Major. It became a benchmark event that connected observations across optical astronomy, radio astronomy, X-ray astronomy, and spectroscopy and influenced models of stripped-envelope explosions studied by teams at institutions such as the Space Telescope Science Institute and observatories including Palomar Observatory and Very Large Array. The event enabled detailed follow-up by instruments aboard Hubble Space Telescope, Chandra X-ray Observatory, and ground facilities, advancing understanding of core-collapse processes associated with massive binary evolution.
The supernova was first reported by amateur and professional observers including Frederick M. Vrba, William P. Max, and others working with facilities such as Kitt Peak National Observatory, Lowell Observatory, and the Harvard-Smithsonian Center for Astrophysics; early identification benefited from pre-explosion images from the Isaac Newton Telescope and archival plates held by Palomar Observatory. Rapid coordination among groups at University of Cambridge, California Institute of Technology, National Radio Astronomy Observatory, and Max Planck Institute for Astronomy produced dense multiwavelength coverage spanning ultraviolet astronomy, optical astronomy, and radio astronomy. Observers at Mauna Kea Observatories and teams using the Hobby–Eberly Telescope contributed late-time imaging, while spectroscopy from European Southern Observatory and Kitt Peak National Observatory traced temporal evolution.
Analysis of pre-explosion images from Hubble Space Telescope and ground-based telescopes identified a likely K-type supergiant progenitor in archival data maintained by Space Telescope Science Institute and analyzed by researchers from University of California, Berkeley and University of Toronto. Subsequent ultraviolet and optical modeling by groups at Princeton University and University of Oxford supported a binary scenario involving mass transfer to a hotter companion, echoing theoretical work by researchers at Max Planck Institute for Astrophysics and University of Chicago. Spectroscopic signatures and post-explosion searches led teams from University of Arizona and Johns Hopkins University to propose a stripped hydrogen envelope consistent with predictions from binary evolution models developed at University of Cambridge and Imperial College London.
Early spectra obtained by observers at Keck Observatory, Lick Observatory, and European Southern Observatory showed prominent hydrogen lines that evolved into helium-dominated features, prompting reclassification efforts by specialists at Harvard-Smithsonian Center for Astrophysics and Carnegie Institution for Science; the event was designated as a transitional Type IIb by classification work tied to researchers at University of California, Santa Cruz and University of Tokyo. High-resolution spectra from Hubble Space Telescope and ground-based echelle spectrographs used by teams at Mount Stromlo Observatory and Royal Greenwich Observatory traced line profiles and velocity evolution, informing radiative-transfer modeling from groups at Max Planck Institute for Astrophysics and University of Barcelona.
Photometry compiled by collaborations involving Space Telescope Science Institute, National Optical Astronomy Observatory, and the Sloan Digital Sky Survey teams revealed a fast initial decline followed by a slower tail, in contrast with classical Type II-P events studied at University of California, Davis and Ohio State University. Observers at Mount Wilson Observatory, Kitt Peak National Observatory, and Calar Alto Observatory contributed color evolution and bolometric light curve reconstruction used by theorists at Massachusetts Institute of Technology and Princeton University to infer ejecta mass and nickel synthesis. Comparative studies with supernovae cataloged by the International Astronomical Union and analyzed by groups at University of Copenhagen and Australian National University placed the photometric behavior in context with stripped-envelope explosions.
Radio monitoring by the National Radio Astronomy Observatory using the Very Large Array and very-long-baseline interferometry by teams at Jodrell Bank Observatory and European VLBI Network detected bright, evolving radio emission, interpreted through shock interaction models developed at Max Planck Institute for Radio Astronomy and University of Groningen. X-ray observations with ROSAT and later Chandra X-ray Observatory by investigators at Harvard-Smithsonian Center for Astrophysics and MIT Kavli Institute revealed thermal and nonthermal components consistent with dense circumstellar material shaped by pre-explosion mass loss studied by researchers at Observatoire de Paris and University of Heidelberg. Multiwavelength campaigns coordinated by institutions such as Space Telescope Science Institute and National Radio Astronomy Observatory constrained wind properties and mass-loss rates predicted by stellar-wind models from University of Wisconsin–Madison and University of Michigan.
Late-time optical, radio, and X-ray monitoring by teams at Hubble Space Telescope, Chandra X-ray Observatory, and the Very Large Array has tracked the fading remnant, with spectroscopic follow-up by astronomers at Max Planck Institute for Astronomy and University of Oxford revealing nebular lines and interaction-driven emission reminiscent of other remnants cataloged by International Astronomical Union. Continued searches for the surviving binary companion conducted by groups at Space Telescope Science Institute and University of California, Berkeley have reported candidate detections that inform population-synthesis models from University of Toronto and Imperial College London. SN 1993J remains a touchstone for studies at institutions including California Institute of Technology, Princeton University, and Max Planck Society into the connection between binary evolution and stripped-envelope core-collapse supernovae.