Type Ib and Ic supernovae

Type Ib and Ic supernovae are core-collapse stellar explosions whose spectra lack hydrogen. Type Ib spectra show helium, while Type Ic spectra lack prominent helium lines.

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Core-collapse supernova: A stellar explosion triggered when the core of a massive star collapses under gravity. Both types arise from core collapse after massive stars lose their outer hydrogen layers.
Supernova classification: The system for grouping supernovae by their spectra and observed properties. Types Ib and Ic are defined chiefly by spectral features, especially hydrogen and helium lines.
SN 1983N: A Type Ib supernova discovered in 1983 in the galaxy M83. Its spectrum helped establish Type Ib as a class distinct from hydrogen-rich supernovae.
Type II supernova: A core-collapse supernova whose spectrum shows hydrogen features. Its hydrogen lines contrast with the defining hydrogen-free spectra of Types Ib and Ic.
Stripped-envelope supernova: A core-collapse supernova whose progenitor has lost much or all of its hydrogen envelope before exploding. This broader class includes Types Ib and Ic, along with Type IIb.
Hydrogen spectral series: The families of discrete wavelengths emitted or absorbed when hydrogen electrons change energy levels. The absence of hydrogen lines is the defining spectral feature shared by Types Ib and Ic.
SN 1994I: A Type Ic supernova discovered in 1994 in the Whirlpool Galaxy, M51. It became a well-studied example of a rapidly evolving Type Ic event.
Type IIb supernova: A core-collapse supernova that initially shows hydrogen lines, which fade as helium features strengthen. It marks an intermediate spectral case between hydrogen-rich Type II and stripped Type Ib events.
Wolf–Rayet star: A hot, luminous evolved star with strong stellar winds and spectra dominated by broad emission lines. Some proposed progenitors are stripped Wolf–Rayet stars, though binary stars can also produce them.
Helium spectral lines: Wavelength-specific emission or absorption features produced by transitions between helium energy levels. Prominent helium lines distinguish Type Ib from Type Ic spectra.