Cygnus X-1 is localised and weighed

node

Radio observations in 1971 fixed the position of the X-ray source precisely enough to associate it with the supergiant star HDE 226868. Optical spectroscopy of that star then gave the binary orbit, and the orbit gave a mass function implying an unseen companion too massive to be a neutron star. It was the first object for which the black hole interpretation became the least uncomfortable available, and it remained the standard case for decades.

A node is not a place. Drawing it on a map would assert something about the world that no stored fact supports.

Read in · 1

Approaching a Black HoleSpace

Evidence · 1

Cygnus X-1 contains a 21 solar mass black hole - implications for massive star winds

Timeline

No dated observations are stored for this object. Atlas shows what was observed and when — it does not infer a history.

Connections · 2

Cygnus X-1concerns
Accretion discconcerns

Assembled narrative · 1

An assembled narrative is available for this object.

Observed changes · 0

No public Signals are attached to this object. Signals show what changed and when it was observed — never a direction or a rank.

Actions

Read the assembled narrative Continue in StudioOpen TwinTwin does not start a decision from this kind of object.ShareSaveSaved objects are part of the authenticated projection, which is declared and not yet built.

/atlas?object=EVT_CYGNUS_X1_IDENTIFIED