HD 5980 HD 5980 Fr.: HD 5980 A remarkable → binary star system composed of
→ massive stars that
is associated with NGC 346, the largest → H II region - OB star cluster in the → Small Magellanic Cloud.
HD 5980 is a rather complex system because it consists of at least three stars:
two stars form an → eclipsing binary with a period of
19.266 days, while the third component, an → O star,
is detected by means of a set of absorption lines.
Whether or not the third star is physically bound to the eclipsing binary
remains currently unclear. HD 5980 underwent an
→ LBV-type event in August 1994. Before the LBV eruption,
both components of the eclipsing binary already showed emission lines in their
spectra and were thus classified as → Wolf-Rayet stars.
However, as shown by the analysis of the spectra taken during and after the LBV event, at
least the star that underwent the eruption was not a classical, helium-burning,
Wolf-Rayet object, but rather a WNha star. This means a rather massive star
with substantial amounts of hydrogen present in its outer layers. These WNha
stars have → stellar wind properties that are intermediate
between those of extreme → Of stars and classical
→ WN Wolf-Rayet stars.
See also: → Henry Draper system; → number. |
