Astronomy:NGC 40
Template:Infobox planetary nebula
NGC 40, also known as the Bow-Tie Nebula or Caldwell 2, is a planetary nebula located around 5280 light years (1619 parsecs) from Earth in the Constellation of Cepheus. The nebula is about one light-year across. It was discovered by William Herschel on November 25, 1788.[1]
The nebula formed due to a dying star ejecting its outer layers of gas leaving behind a small, hot stellar remnant known as a white dwarf. Radiation from the star causes the shed outer layer to heat to about 10,000 degrees Celsius and become visible as a planetary nebula. About 30,000 years from now, scientists theorize that NGC 40 will fade away, leaving only a white dwarf star approximately the size of Earth.[1]
Structure
The main structure of NGC 40 has a barrel-like shape with two moves expanding towards the northern and southern directions. The long axis pointing towards the north-northeast. There are two additional pairs of lobes around the poles, which correspond to additional ejections from the star. There is a cavity located in NGC 40 that is around 6500 years old. The northern and southern lobes were ejected around 4200 years ago.[2]
Central star
The central star of NGC 40 has a Henry Draper Catalogue designation of HD 826. It has a spectral type of [WC8], indicating a spectrum similar to that of a carbon-rich Wolf–Rayet star.[3] The central star has a bolometric luminosity of about 7,000 L☉ and radius of 0.56 R☉.[4]
The star appears to have an effective temperature of about 71,000 K, but the temperature of the source ionizing the nebula is only about 45,000 K. One proposed explanation to this contradiction is that the star was previously cooler, but has experienced a late thermal pulse which re-ignited fusion and caused its temperature to increase.[4]
Gallery
-
-
Image of NGC 40 by Amateur Astronomer -
Optical image from the WIYN telescope
See also
- List of NGC objects
- List of NGC objects (1-1000)
References
- ↑ 1.0 1.1 "Chandra X-Ray Observatory". http://chandra.harvard.edu/photo/2005/n40/.
- ↑ Rodríguez-González, J. B.; Toalá, J. A.; Sabin, L.; Ramos-Larios, G.; Guerrero, M. A.; López, J. A.; Estrada-Dorado, S. (2022). "Adjusting the bow-tie: A morpho-kinematic study of NGC 40". Monthly Notices of the Royal Astronomical Society 515 (2): 1557–1567. doi:10.1093/mnras/stac1761.
- ↑ González-Santamaría, I.; Manteiga, M.; Manchado, A.; Ulla, A.; Dafonte, C.; López Varela, P. (2021). "Planetary nebulae in Gaia EDR3: Central star identification, properties, and binarity". Astronomy & Astrophysics 656: A51. doi:10.1051/0004-6361/202141916. Bibcode: 2021A&A...656A..51G.
- ↑ 4.0 4.1 Toalá, J. A.; Ramos-Larios, G.; Guerrero, M. A.; Todt, H. (2019). "Hidden IR structures in NGC 40: Signpost of an ancient born-again event". Monthly Notices of the Royal Astronomical Society 485 (3): 3360. doi:10.1093/mnras/stz624. Bibcode: 2019MNRAS.485.3360T.
External links
- NGC 40 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
- Kameswara Rao, N.; Sutaria, F.; Murthy, J.; Krishna, S.; Mohan, R.; Ray, A. (2018). "Planetary nebulae with UVIT: Far ultra-violet halo around the Bow Tie nebula (NGC 40)". Astronomy & Astrophysics 609: L1. doi:10.1051/0004-6361/201732188. Bibcode: 2018A&A...609L...1K.
| List |
|
|---|---|
| See also | |
Coordinates: 
00h 13m 01s, +72° 31′ 19″
 |  |
