Astronomy:Scutum Supershell

From HandWiki
Scutum Supershell
Nebula
Superbubble
File:Frameless
Location of the Scutum Supershell on a map
Observation data: J2000 epoch
Right ascension 18h 42m 00s[1]
Declination−18° 00′ 00″[1]
Distance~11,000 ly
ConstellationScutum and Sagittarius
Physical characteristics
Radius~472 ly
DesignationsGS 018–04+44[1]
See also: Lists of nebulae

Scutum Supershell (also known as Scutum Superbubble) is a giant expanding bubble of hot gas and hydrogen in space. It is located ~11,000 ly away from the earth inside the Scutum-Centaurus Arm of the Milky Way. The superbubble is formed by exploding stars and strong cosmic winds. It was discovered by astronomer Matthew B. Callaway and his colleagues in 1999.[2]

Physical Structure

Scutum supershell is large and has a diameter of approximately 290 pc and extends about 400 pc from the galactic plane, which was derived from a kinematic distance of 3.3 kpc calculated from using D.P. Clemen's formula.[3] Because the superbubble is not cleary distinguishable, a radius of ~29 pc is estimated. Studies indicate that the infrared emission shows the presence of molecular hydrogen in the high column density regions.[4] The infrared emissions 100 μm and 60 μm are the main emission lines in infrared with surface brightness 6.23 MJy sr⁻¹ and 1.64 MJy sr⁻¹ respectively.[2]

Scutum supershell is mostly visible through H I, with the top of the shell appearing to be blown away, leaving a column of neutral hydrogen (H I) and superheated gas pouring directly into the galactic plane at l = 18° and lying between b = -9° and b = -12°, which created a high-latitude cloud that has a distance of ~630 pc from the galactic plane. The high-latitude cloud has an estimated X-ray luminosity of ~1³⁶ ergs s⁻¹. The high-latitude cloud was formed through supernova remnants, H II regions, and OB associations.[5] Two O-type Blue giant stars HD 175754 (O8II(n)((f))p)[6] and HD 175876 (O6.5III(n)(f))[6] most likely formed in this very cloud and were ejected from it, or formed recently at their current distance.[7][2] The Far Ultraviolet Spectroscopic Explorer (FUSE) detected highly ionized absorption lines like O IV, Si IV, and C IV near the blowout spot.[5]

H II regions Sh 2-45 and Sh 2-55 are H II regions that dominate the Hα emissions with the brightest Hα feature located in Sh 2-45 which lies at +20 km s⁻¹. The close proximity of Sh 2-45 causes some confusion regarding membership in the superbubble. Sh 2-55 is most likely in the superbubble, as it has an H I column density of 1.21 x 10²² cm⁻¹ using conversion ratio from Diplas & Savage.[8][9][2]

The galactic worms GW 14.9-1.6 and GW 16.9-3.8 are elongated vertical filamentary structures of neutral hydrogen (H I) that form the walls of the superbubble. GW 16.9-3.8 influences the rightmost edge of the bow-shock Hα emission and overlaps with [S II] line emission and both 60μm and 100μm infrared emission.[10] Simulations show that the outflow and bow-shock are likely formed by many supernovae events.[10] X-ray binary LS 5039 is also speculated as the contributing event from the supernova or hypernova and formation of a magnetar or black hole in the system.[10]

References

  1. ↑ 1.0 1.1 1.2 "NAME Scutum Supershell". https://simbad.cds.unistra.fr/mobile/object.html?object_name=NAME+SCUTUM+SUPERSHELL. 
  2. ↑ 2.0 2.1 2.2 2.3 Callaway, B.; Tufte, L.; Benjamin, A.; Savage, D.; Haffner, L. (April 2000). "Observational Evidence of Supershell Blowout in GS 018-04+44: The Scutum Supershell". The Astrophysical Journal 532 (2): 943–969. doi:10.1086/308601. Bibcode: 2000ApJ...532..943C. https://iopscience.iop.org/article/10.1086/308601/fulltext/. 
  3. ↑ Clemens, D. P. (August 1985). "Massachusetts-Stony Brook Galactic plane CO survey: the galactic disk rotation curve.". The Astrophysical Journal 295 (422–436): 422. doi:10.1086/163386. Bibcode: 1985ApJ...295..422C. https://ui.adsabs.harvard.edu/abs/1985ApJ...295..422C/abstract. 
  4. ↑ Odegard, N.; Reach, T.; Wall, F. (November 1998). "Infrared Excess and Molecular Clouds: A Comparison of New Surveys of Far-Infrared and H I 21 Centimeter Emission at High Galactic Latitudes". The Astrophysical Journal 507 (2): 507–525. doi:10.1086/306357. Bibcode: 1998ApJ...507..507R. https://iopscience.iop.org/article/10.1086/306357. 
  5. ↑ 5.0 5.1 Sterling, N. C.; Savage, B. D.; Richter, P.; Fabian, D.; Sembach, K. R. (November 2001). "FUSE Observations of O VI Overlying the Scutum Supershell". The Astrophysical Journal 567: 954–362. doi:10.1086/338421. https://iopscience.iop.org/article/10.1086/338421/pdf. 
  6. ↑ 6.0 6.1 Sota, A.; Apellániz, J. Maíz; Morrell, N. I.; Barbá, R. H.; Walborn, N. R.; Gamen, R. C.; Arias, J. I.; Alfaro, E. J. (2014-02-25). "The Galactic O-Star Spectroscopic Survey (Gosss). Ii. Bright Southern Stars". The Astrophysical Journal Supplement Series 211 (1): 10. doi:10.1088/0067-0049/211/1/10. ISSN 0067-0049. Bibcode: 2014ApJS..211...10S. https://iopscience.iop.org/article/10.1088/0067-0049/211/1/10. 
  7. ↑ Savage, D.; Sembach, R.; Howk, J. (February 2001). "STIS and GHRS Observations of Warm and Hot Gas Overlying the Scutum Supershell (GS 018-04+44)". The Astrophysical Journal 547 (2): 907–921. doi:10.1086/318411. Bibcode: 2001ApJ...547..907S. https://ui.adsabs.harvard.edu/abs/2001ApJ...547..907S/abstract. 
  8. ↑ Diplas, A.; Savage, B. D. (May 1994). "An IUE Survey of Interstellar H i Lyman-Alpha Absorption. II. Interpretations". The Astrophysical Journal 427: 274. doi:10.1086/174139. Bibcode: 1994ApJ...427..274D. https://ui.adsabs.harvard.edu/abs/1994ApJ...427..274D/abstract. 
  9. ↑ Cardelli, A.; Clayton, C.; Mathis, S. (October 1989). "The Relationship between Infrared, Optical, and Ultraviolet Extinction". The Astrophysical Journal 345: 245. doi:10.1086/167900. Bibcode: 1989ApJ...345..245C. https://ui.adsabs.harvard.edu/abs/1989ApJ...345..245C/abstract. 
  10. ↑ 10.0 10.1 10.2 Alsulami, R.; Einecke, S.; Rowell, G. P.; McGee, P. K.; Filipović, M. D.; Seitenzahl, I. R.; Stupar, M.; Collins, T. et al. (2024-10-21). "Investigating Unusual H$α$ Features towards the Scutum Supershell". Publications of the Astronomical Society of Australia 41. doi:10.1017/pasa.2024.99. Bibcode: 2024PASA...41...98A. 



Retrieved from "https://handwiki.org/wiki/index.php?title=Astronomy:Scutum_Supershell&oldid=4622823"