The Bow Tie Nebula, NGC 40, is a planetary nebula in Cepheus, a barrel-shaped shell around a hot, carbon-rich central star of the Wolf–Rayet type.
At a glance
| type | nebula |
|---|---|
| distance from the Sun | 5,790 light-years (1.77 kpc) |
| its light left it | 5,790 years ago |
| size in the piece | about 0.79 light-years acrossmodel |
Read off the piece’s own catalogue, the same values it draws with. Model marks a property of the piece’s galaxy model rather than a measurement.
About Bow Tie Nebula
NGC 40 is a planetary nebula in the far northern constellation Cepheus, discovered by William Herschel. It is the expelled envelope of a dying star, and its shape is a hollow barrel of gas with brighter caps at either end, which in telescopes gives it the look of a bow tie.
What makes it unusual is its central star. Instead of the hydrogen-rich surface of most stellar cores, it shows a strong, fast wind rich in carbon, with the broad emission lines of a Wolf–Rayet star, though at a far lower mass than the true Wolf–Rayet stars. Such stars appear to have lost their remaining hydrogen in a late burst of helium burning, and NGC 40 is one of the brighter examples.
What you see in the piece
In the piece it is a small cloud of glowing gas above the plane of the disc in the direction of Cepheus; from the Sun it is only a point.
Questions
What is special about the Bow Tie Nebula’s central star?
It is hydrogen-poor and carbon-rich, with a strong wind like that of a Wolf–Rayet star, a rare type among the cores of planetary nebulae.
How far away is the Bow Tie Nebula?
The Bow Tie Nebula is 5,790 light-years (1.77 kpc) from the Sun.