Last modified on January 30, 2020, at 21:08

NGC 2438

NGC 2438
N2438s-crop.jpg
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. 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. 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. Bibcode2018yCat.1345....0G.  arXiv:0708.1752
  3. 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. Bibcode2008ApJ...689..194S.  arXiv:0807.1129
  4. 4.0 4.1 NGC 2348. messier.seds.org (2006-03-18). Retrieved on 2019-11-01.
  5. From direct computation using apparent magnitude of +10.8 and distance of 1,376 light years.
  6. From direct computation of parallax of 2.3687 mas.
  7. Wilson, R. E. (1953). "General catalogue of stellar radial velocities". Carnegie Institute Washington D.C. Publication. Bibcode1953GCRV..C......0W. 
  8. 8.0 8.1 Planetary Nebula NGC 2438. apod.nasa.gov (2011-04-07). Retrieved on 2019-11-01.
  9. 9.0 9.1 9.2 NGC 2438 (= P-K 231+04.2 = "PGC 3517755"). cseligman.com. Retrieved on 2019-11-01.
  10. 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. Bibcode1963PASP...75..370O. 
  11. M46 + NGC 2438. cs.astronomy.com (2016-03-26). Retrieved on 2019-11-01.
  12. George Normandin (2000-03-13). Planetary Nebula NGC 2438 in Puppis. kopernik.org. Retrieved on 2019-11-01.
  13. 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. Bibcode2014A&A...565A..87O.  arXiv:1403.6715