|Right ascension||05h 27m 28.2037s|
|Declination||-12° 41′ 50.265″|
|Type of object||Planetary nebula|
|Dimensions||14" × 10"|
|Magnitude||Apparent Mag: +13.0|
|Distance from Earth||3,590 ly|
|Radial velocity||62.0±0.9 km/s|
|Proper motion|| RA: -1.20 mas/yr|
Dec.: 2.50 mas/yr
The Spirograph nebula is a planetary nebula in the constellation of Lepus. Its name derives from its intricate patterns which lend it a resemblance to those produced by the geometrical drawing tool of the same name. These patterns are poorly understood.
Properties and Structure
The nebula's distance from Earth is, like most planetary nebulae, rather uncertain. Many estimates are at 2,000 light years with newer estimates suggesting a greater distance closer to 3,600 light years. This means the nebula's apparent size of 14×10 arcseconds corresponds to a physical diameter of 0.2-0.3 light years. The nebula is receding from Earth at 62.0±0.9 km/s. the nebula is also expanding, albeit slowly compared to other planetary nebulae at around 12 km/s The nebula has been discovered to possess a shell-like structure, with three rings and two larger and detached haloes. These are very nearly concentric (slightly off centre) and have been observed in similar nebulae.
A white dwarf star is situated in the centre of the nebula and has a temperature of 35,000 kelvin. The star is an irregular variable star, meaning its luminosity varies in an unpredictable fashion over time. These changes that can occur over several hours and strong stellar winds generated by these changes may be the cause for the intricate filament like structure seen in the nebula. Interestingly, the star is cool compared to most white dwarfs meaning the gas, mainly helium, is 75% ionized. Helium-3 ions have also been detected in the nebula. The nebula has a low metallicity (low amount of elements heavier than helium) but does have a surprisingly high amount of carbon.
- IC 418 from the SIMBAD Astronomical Database
- Guzmán, L., Loinard, L., Gómez, Y. and Morisset, C. (2009). Expansion Parallax Of The Planetary Nebula IC 418. The Astronomical Journal, 138(1), pp.46-49. arXiv:0905.0021
- Spirograph nebula (IC 418) from esa.int
- IC 418: The Spirograph Nebula from apod.nasa.gov
- The Spirograph Nebula, a bright planetary nebula in Lepus from annesastronomynews.com
- Ramos-Larios, G., Vázquez, R., Guerrero, M., Olguín, L., Marquez-Lugo, R. and Bravo-Alfaro, H. (2012). Discovery of multiple shells around the planetary nebula IC 418. Monthly Notices of the Royal Astronomical Society, 423(4), pp.3753-3760. arXiv:1204.5816
- Guzman-Ramirez, L., Rizzo, J., Zijlstra, A., García-Miró, C., Morisset, C. and Gray, M. (2016). First detection of 3He+in the planetary nebula IC 418. Monthly Notices of the Royal Astronomical Society: Letters, 460(1), pp.L35-L39. arXiv:1604.02679
- Hyung, S., Aller, L. and Feibelman, W. (1994). The spectrum of the planetary nebula IC 418. Publications of the Astronomical Society of the Pacific, 106, p.745. Online