A superbubble is a region of interstellar space filled with hot gas, having a lower density compared to the environment and reaching several hundred light-years across. Unlike stellar wind bubbles created by single stars , superbubbles form around OB associations located inside molecular clouds . The stellar wind from OB stars and the energy from supernova explosions heat the substance of superbubbles to temperatures of the order of 10 6 K. [1] Older superbubbles having a denser dusty outer shell and a more sparse and cooler inner space are also called supershells . The solar system is located near the center of the old superbubble, known as the Local Bubble , whose boundaries can be determined by a sudden increase in dust extinction at distances of more than several hundred light years.
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The most massive (from 8 to 100 solar masses ) and hot ( spectral class O or B) stars, as a rule, are located in groups called OB associations. All these stars emit a powerful stellar wind, whose total energy during the life of a star is estimated at 10 50 erg (10 43 J ) and is comparable to the energy released during a supernova burst. [2]
The stellar wind can form a bubble of matter around each star several tens of light years in diameter. Inside the OB association, the stars are close enough to each other to combine these bubbles into one large superbubble. Moreover, many of the OB stars at the end of their lives turn into supernovae , whose blast waves accelerate the gas even more, the expansion rate of which can ultimately reach several hundred km / s. The stars in the OB associations are not gravitationally coupled, but their lifetime (of the order of several million years) and the speed of motion relative to each other (about 20 km / s) are small, so most supernova explosions occur inside the bubble formed. [1] [3] These explosions never form visible supernova remnants; instead, they dissipate their energy in the form of shock waves. As a result, both the stellar wind and the flares of stars lead to the expansion of the superbubble into the surrounding space.
Over time, interstellar gas scattered by a stellar wind cools down, forming a dense shell around a less dense region. Such shells were first detected by the emission of the HI line of neutral hydrogen [4] , which led to the formulation of the theory of the formation of superbubbles. Subsequently, these structures were observed in the X-ray range (emitted by the red-hot substance of the inner region), visible rays (from the ionized shell) and the infrared range (from the dust shell). X-ray and visible radiation are typically detected for younger superbubbles, while older and larger formations are detected along the HI line and may even be the result of combining several superbubbles; such objects are sometimes called supershells .
Sufficiently large superbubbles can “escape” beyond the boundaries of the galactic disk, transferring their energy to the surrounding halo or even to intergalactic space. [5] [6]
Super Bubble Examples
- Local bubble
- Gama Nebula [1]
- Super Bubble Swan [1]
- Bubble of Orion - Eridan [1]
- Ophiuchus Super Bubble [7]
- Shield Super Shell [8] [9]
- Henize 44 in the Large Magellanic Cloud [10]
- Henize 70 - ibid. [11]
- Milky Way Anticenter Super Shell [12]
Notes
- ↑ 1 2 3 4 5 Tomisaka K., Habe A., Ikeuchi S. Sequential explosions of supernovae in an OB association and formation of a superbubble (Eng.) // Astrophysics and Space Science . - Springer , 1981. - Vol. 78 , no. 2 . - P. 273-285 . - DOI : 10.1007 / BF00648941 . - .
- ↑ Castor J., McCray R., Weaver R. Interstellar Bubbles (Eng.) // The Astrophysical Journal . - IOP Publishing 1975. - Vol. 200 . - P. L107 — L110 . - DOI : 10.1086 / 181908 . - .
- ↑ McCray R., Kafatos M. Supershells and Propagating Star Formation // The Astrophysical Journal . - IOP Publishing 1987. - Vol. 317 . - P. 190—196 . - DOI : 10.1086 / 165267 . - .
- ↑ Heiles CE HI shells and supershells // The Astrophysical Journal . - IOP Publishing . Heiles, C. {{{title}}} (unopened) . - 1979.- T. 229 . - S. 533-544 . - DOI : 10.1086 / 156986 . - .
- ↑ Tomisaka K., Ikeuchi S. Evolution of superbubble driven by sequential supernova explosions in a plane-stratified gas distribution // Publications of Astronomical Society of Japan. - 1986. - T. 38 , No. 5 . - S. 697-715 . - ISSN 0004-6264 . - .
- ↑ Mac Low M.-M., McCray R. Superbubbles in Disk Galaxies (Eng.) // The Astrophysical Journal . - IOP Publishing 1988. - Vol. 324 . - P. 776-785 . - DOI : 10.1086 / 165936 . - .
- ↑ Pidopryhora Y., Lockman FJ, Shields JC The Ophiuchus Superbubble: A Gigantic Eruption from the Inner Disk of the Milky Way (Eng.) // The Astrophysical Journal . - IOP Publishing 2007. - Vol. 656 . - P. 928–942 . - DOI : 10.1086 / 510521 . - . - arXiv : astro-ph / 0610894 .
- ↑ Savage BD, Sembach KR, and Howk JC STIS and GHRS Observations of Warm and Hot Gas Overlying the Scutum Supershell (GS 018? 04 + 44 ) // The Astrophysical Journal . - IOP Publishing , 2001. - Vol. 547 . - P. 907-921 . - DOI : 10.1086 / 318411 .
- ↑ Callaway MB Observational Evidence of Supershell Blowout in GS 018-04 + 44: The Scutum Supershell (Eng.) // The Astrophysical Journal . - IOP Publishing . - Vol. 532 , no. 2 . - P. 943-969 . - .
- ↑ Nakajima H. et al. Exploring High Energy Activities in the Superbubble N44 With XMM-NEWTON . The X-Ray Universe Symposium . European Space Agency (September 26, 2005). Date of treatment January 13, 2013. Archived January 28, 2013.
- ↑ Nemiroff R., Bonnell J. Henitz 70: Superbubble in the Large Magellanic Cloud . Astronomy Picture of the Day . Astronet / NASA (November 30, 1999). - Per. Kozyreva A. V. .. Date of treatment January 10, 2013. Archived on January 28, 2013.
- ↑ Tamanaha CM The Anticenter Shell and the Anticenter Chain // The Astrophysical Journal . - IOP Publishing , 1997 .-- T. 109 . - S. 139-175 . - DOI : 10.1086 / 312975 .
Literature
- Tenorio-Tagle G., Bodenheimer P. Large-scale expanding superstructures in galaxies (Eng.) // Annual Review of Astronomy and Astrophysics . - Annual Reviews , 1988. - Vol. 26 . - P. 145-197 . - .