NGC 7538

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Emission nebula
NGC 7538

Far infrared image of the emission nebula NGC 7538 with the help of the Herschel space telescope

Far infrared image of the emission nebula NGC 7538 with the help of the Herschel space telescope
AladinLite
Constellation Cepheus
Position
equinox :  J2000.0 , epoch : J2000.0
Right ascension 23 h 13 m 45.7 s
declination + 61 ° 28 ′ 21 ″
Appearance

Angular expansion 8/7 
Ionizing source
designation IRS1, IRS6 
Type O7V star 
Physical data

Affiliation Milky Way ,
Perseus Arm ,
Cassiopeia OB2 Association 
distance  9100 ly
(2800 pc )
Dimensions 400,000 M ☉
history

discovery William Herschel
Date of discovery November 3, 1787
Catalog names
 NGC  7538 •  GC  4907 •  Sh2 -158, LBN 542, H II-706

NGC 7538 is an emission nebula in the constellation Kepheus , which was discovered in 1787 by the astronomer William Herschel using his 18.7-inch reflecting telescope and later listed by Johan Dreyer in his New General Catalog .

The nebula is about 9,100  light years away, located on the Perseus arm of the Milky Way, and is directly linked to the great Cassiopeia OB2 association. Like the OB2 association, it is an H-II area , i.e. a molecular cloud consisting mainly of hydrogen , which is stimulated to shine by the stars that have formed in it. The total mass of NGC 7538 is approximately 400,000 solar masses .

In the emission nebula there are different phases of star formation . It is most advanced in the north-western sector of the nebula. Two infrared surveys of the area in the 1970s show 11 bright sources, labeled IRS1 through IRS11. IRS1, IRS2 and IRS3 form a small group of stars of the spectral classes  O and B at the southeastern edge of the nebula, of which IRS1, located in a small H-II area measuring 180  AU, is the brightest with 10 4  L ☉ ; spectra of OH-Maser , water, formaldehyde , ammonia and methanol can be detected in its vicinity . A diffuse H-II area around IRS4-6 is predominantly illuminated by IRS6, an O7V star . IRS7, IRS8 and probably also IRS10 are stars in the foreground or background that do not belong to the nebula. IRS9 is a protostar in a similar environment to IRS1 and is only an arc minute away from it. IRS11 has an OH maser spectrum and is another protostar. Together with IRS9, it is one of the newest objects of the nebula. Another very young protostar, designated NGC7538 S, stands out due to one of the largest accretion disks found so far , which with 14,000 AU measures about 300 times the solar system . More sensitive IR examinations of the nebula show thousands of infrared sources and point to star clusters that have formed and are in the process of being formed with an age of up to 4 billion years, but also less than 1 billion years, which are concentrated in the areas mentioned.

literature

Individual evidence

  1. ^ Simbad Query Result .
  2. ↑ a b c S. Kraus, Y. Balega, M. Elitzur, K.-H. Hofmann, Th. Preibisch, A. Rosen, D. Schertl, G. Weigelt, ET Young: Outflows from the high-mass protostars NGC 7538 IRS1 / 2 observed with bispectrum speckle interferometry. Signatures of flow precession . In: Astronomy and Astrophysics . 455, No. 2, 2006, pp. 521-537. bibcode : 2006A & A ... 455..521K . doi : 10.1051 / 0004-6361: 20065068 .
  3. ↑ a b C. Fallscheer et al: Herschel Reveals Massive Cold Clumps in NGC 7538 . In: The Astrophysical Journal . 773, 2013, p. 102. arxiv : 1307.0022 . bibcode : 2013ApJ ... 773..102F . doi : 10.1088 / 0004-637X / 773/2/102 .
  4. ^ A b Z. Balog, SJ Kenyon, EA Lada, M. Barsony, J. Vinkó, A. Gáspar: A Near-Infrared (JHK) Survey of the Vicinity of the H II Region NGC 7538: Evidence for a Young Embedded Cluster . In: The Astronomical Journal . 128, No. 6, 2004, pp. 2942-2953. arxiv : astro-ph / 0409115 . bibcode : 2004AJ .... 128.2942B . doi : 10.1086 / 425548 .
  5. ^ Mark McCaughrean, John Rayner, Hans Zinnecker: Near-infrared imaging of embedded young clusters . In: Società Astronomica Italiana, Memorie . 62, No. 4, 1991, ISSN  0037-8720 , pp. 715-723. bibcode : 1991MmSAI..62..715M .
  6. ↑ a b c C. G. Wynn-Williams, EE Becklin, G. Neugebauer: Infrared studies of H II regions and OH sources . In: Astrophysical Journal . 187, 1974, pp. 473-485. bibcode : 1974ApJ ... 187..473W . doi : 10.1086 / 152656 .
  7. ↑ a b c M. W. Werner, EE Becklin, I. Gatley, K. Matthews, G. Neugebauer, CG Wynn-Williams: An infrared study of the NGC 7538 region . In: Monthly Notices of the Royal Astronomical Society . 1979. bibcode : 1979MNRAS.188..463W . doi : 10.1093 / mnras / 188.3.463 .
  8. ↑ K. Akabane, N. Kuno: Dust content in compact HII regions (NGC 7538-IRS1, IRS2, and IRS3) . In: Astronomy and Astrophysics . 431, 2005, pp. 183-195. bibcode : 2005A & A ... 431..183A . doi : 10.1051 / 0004-6361: 200400116 .
  9. ↑ DK Ojha, M. Tamura, Y. Nakajima, M. Fukagawa, K. Sugitani, C. Nagashima, T. Nagayama, T. Nagata, S. Sato, S. Vig, SK Ghosh, AJ Pickles, M. Momose, K. Ogura: A Near-Infrared Study of the NGC 7538 Star-forming Region . In: The Astrophysical Journal . 616, No. 2, 2004, pp. 1042-1057. arxiv : astro-ph / 0408219 . bibcode : 2004ApJ ... 616.1042O . doi : 10.1086 / 425068 .
  10. ^ A b John C. Barentine, John H. Lacy: A Comparative Astrochemical Study Of The High-Mass Protostellar Objects NGC 7538 IRS 9 and IRS 1 . In: The Astrophysical Journal . 2012. arxiv : 1208.2036 . bibcode : 2012ApJ ... 757..111B . doi : 10.1088 / 0004-637X / 757/2/111 .
  11. ↑ Göran Sandell, Melvyn Wright: A detailed study of the accretion disk surrounding the high-mass protostar NGC 7538 S . In: The Astrophysical Journal . 2010. arxiv : 1004.0643 . bibcode : 2010ApJ ... 715..919S . doi : 10.1088 / 0004-637X / 715/2/919 .
  12. ↑ KK Mallick, DK Ojha, M. Tamura, AK Pandey, S. Dib, SK Ghosh, K. Sunada, I. Zinchenko, L. Pirogov, M. Tsujimoto: NGC 7538: multiwavelength study of stellar cluster regions associated with IRS 1 -3 and IRS 9 sources . In: Monthly Notices of the Royal Astronomical Society . 2014. arxiv : 1407.1987 . bibcode : 2014MNRAS.443.3218M . doi : 10.1093 / mnras / stu1396 .