NGC 40
Planetary nebula data from NGC 40 |
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Photo from the Hubble Space Telescope | |
AladinLite | |
Constellation | Cepheus |
Position equinox : J2000.0 |
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Right ascension | 00h 13m 01.0s |
declination | + 72 ° 31 ′ 19 ″ |
Appearance | |
Apparent brightness (visual) | 12.3 mag |
Apparent brightness (B-band) | 10.7 mag |
Angular expansion | 1.23 ′ × 1.23 ′ |
Central star | |
designation | HD 826 |
Apparent brightness | 11.6 mag |
Spectral class | WC |
Physical data | |
Redshift | −0.000068 |
Radial velocity | −20.4 km / s |
distance | 3500 ly |
diameter | 0.6 ly |
Age | 4500 years |
history | |
discovery | Wilhelm Herschel |
Date of discovery | November 25, 1788 |
Catalog names | |
NGC 40 • PK 120 + 9.1 • GC 20 • H IV 58 • h 8 • PN G120.0 + 09.8 |
NGC 40 is a planetary nebula in the constellation Cepheus . The star that has repelled its outer shell has a temperature of 50,000 degrees Celsius and is roughly the size of Earth . This central star has an enormously high density, which is typical for white dwarfs, and thus around 70% solar mass despite its small diameter. The gases surrounding it have a temperature of 10,000 degrees Celsius. NGC 40 is estimated to be around 4,500 years old, with its gas clouds still expanding at about 29 km / s.
Visual observation
NGC 40 can already be seen well in a medium amateur telescope with approx. 8 ". While the bright central star in the eyepiece of a 14-inch device is immediately noticeable, you will be somewhat disappointed about the sheen of the gas cloud around it, because it glows inside you Spectral range to which our eyes are less sensitive: a delicate, colorless and slightly structured "smoke ring" can be seen quite clearly, but not brightly (compared to M57 ).
discovery
The planetary nebula NGC 40 was discovered on November 25, 1788 by the German-British astronomer Friedrich Wilhelm Herschel .