NGC 2438
| NGC 2438 | |
|---|---|
| |
| Observational Data | |
| Designation | NGC 2348 P-K 231+04.2 PGC 3517755 |
| Right ascension | 07h 41m 50.5198s[1][2] |
| Declination | -14° 44′ 07.4842″[1][2] |
| Constellation | Puppis |
| Type of object | Planetary nebula |
| Dimensions | 1.17° × 1.17°[1][3] |
| Magnitude | Apparent Mag: +10.8[4] Absolute Mag: +2.67[5] |
| Astrometry | |
| Distance from Earth | 1,376 ly[6] |
| Radial velocity | 77.0 ± 5 km/s[1][7] |
| Proper motion | RA: -6.027 mas/yr[1][2] Dec: 2.456 mas/yr[1][2] |
| Parallax | 2.3687 ± 0.2227 mas[1][2] |
NGC 2438 (P-K 231+04.2, PGC 3517755) is a planetary nebula in the constellation of Puppis.[8] The nebula was first observed march 19, 1786 by William Herschel, who designated it as H IV.39.[9] The nebula appears superimposed over the open star cluster Messier 46 but it is thought this is simply a coincidence and the two are separate objects. This is due to the difference in the speeds of the two objects as well as more recently a difference in distance estimates.[10] The nebula is also designated "PGC 3517755" even through this type of designation is normally reserved for galaxies.[9] To emphasize it is not actually a galaxy, quotation marks are usually used when referring to the nebula with this designation.
Like many planetary nebulae, there is a star at the nebula's centre. It has a magnitude of +17.7 and exhibits a continuous spectrum.[4][11] The star, a white dwarf, is one of the hottest stars ever observed with an estimated surface temperature of 75,000 K.[12] This central star is surrounded by a bright ring of diameter 1 light year and a much fainter halo of ionized gas with a diameter of 4.5 light years.[8][9] The fainter enveloping halo has a surface brightness around 1,000 dimmer than the inner region.[13]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 NGC 2438. Simbad Astronomical Database. simbad.u-strasbg.fr. Retrieved on 2019-11-01.
- ↑ 2.0 2.1 2.2 2.3 2.4 Gaia Collaboration (2018). "VizieR Online Data Catalog: Gaia DR2". VizieR Online Data Catalog I/345: I/345. Bibcode: 2018yCat.1345....0G. arXiv:0708.1752
- ↑ Stanghellini, L.; Shaw, R. A.; Villaver, E. (2008). "The Magellanic Cloud Calibration of the Galactic Planetary Nebula Distance Scale". The Astrophysical Journal 689 (1): 194-202. doi:10.1086/592395. Bibcode: 2008ApJ...689..194S. arXiv:0807.1129
- ↑ 4.0 4.1 NGC 2348. messier.seds.org (2006-03-18). Retrieved on 2019-11-01.
- ↑ From direct computation using apparent magnitude of +10.8 and distance of 1,376 light years.
- ↑ From direct computation of parallax of 2.3687 mas.
- ↑ Wilson, R. E. (1953). "General catalogue of stellar radial velocities". Carnegie Institute Washington D.C. Publication. Bibcode: 1953GCRV..C......0W.
- ↑ 8.0 8.1 Planetary Nebula NGC 2438. apod.nasa.gov (2011-04-07). Retrieved on 2019-11-01.
- ↑ 9.0 9.1 9.2 NGC 2438 (= P-K 231+04.2 = "PGC 3517755"). cseligman.com. Retrieved on 2019-11-01.
- ↑ O'Dell, C. R. (1963). "On the Association of NGC 2437 and NGC 2438". Publications of the Astronomical Society of the Pacific 75 (455): 370-372. doi:10.1086/127970. Bibcode: 1963PASP...75..370O.
- ↑ M46 + NGC 2438. cs.astronomy.com (2016-03-26). Retrieved on 2019-11-01.
- ↑ George Normandin (2000-03-13). Planetary Nebula NGC 2438 in Puppis. kopernik.org. Retrieved on 2019-11-01.
- ↑ Oettl, S.; Kimeswenger, S.; Zijlstra, A. A. (2014). "The ionization structure of multiple shell planetary nebulae: I. NGC 2438". Astronomy & Astrophysics 565 (id.A87, 13). doi:10.1051/0004-6361/201323205. Bibcode: 2014A&A...565A..87O. arXiv:1403.6715
