Superassociations: violent star formation induced by shock–shock collisions

Chernin, A. D.; Efremov, Yu. N.; Voinovich, P. A.

doi:10.1093/mnras/275.2.313

Cited by 36 publications

(19 citation statements)

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“…Another well known mechanism of triggering of star formation is the collision of several expanding supershells. It was reproduced in numerical and analytical models by different authors (e.g., Chernin et al 1995;Ntormousi et al 2011;Kawata et al 2014;Vasiliev & Shchekinov 2017) and observed in a number of nearby galaxies (e.g. Lozinskaya 2002;Egorov et al 2017).…”

Section: Discussionmentioning

confidence: 75%

Star formation complexes in the ‘galaxy-sized’ supergiant shell of the galaxy HolmbergI

Egorov

Lozinskaya

Моисеев

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present the results of observations of the galaxy Holmberg I carried out at the Russian 6-m telescope in the narrow-band imaging, long-slit spectroscopy, and scanning Fabry-Perot interferometer modes. A detailed analysis of gas kinematics, ionization conditions, and metallicity of star-forming regions in the galaxy is presented. The aim of the paper is to analyse the propagation of star formation in the galaxy and to understand the role of the ongoing star formation in the evolution of the central 'galaxy-sized' supergiant H i shell (SGS), where all regions of star formation are observed. We show that star formation in the galaxy occurs in large unified complexes rather than in individual giant H ii regions. Evidence of the triggered star formation is observed both on scales of individual complexes and of the whole galaxy. We identified two supernova-remnant candidates and one late-type WN star and analysed their spectrum and surrounding-gas kinematics. We provide arguments indicating that the SGS in Holmberg I is destructing by the influence of star formation occurring on its rims.

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Section: Discussionmentioning

confidence: 75%

Star formation complexes in the ‘galaxy-sized’ supergiant shell of the galaxy HolmbergI

Egorov

Lozinskaya

Моисеев

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…The mechanism of star formation triggered by the collision of supergiant shells is well known (see Chernin et al 1995); many colliding supergiant shells with star formation have been found in the LMC (see the references in the above paper).…”

Section: What Triggered Star Formation In Ho Ii?mentioning

confidence: 99%

Complexes of triggered star formation in supergiant shell of Holmberg II

Egorov

Lozinskaya

Моисеев

et al. 2016

Mon. Not. R. Astron. Soc.

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We report a detailed analysis of all regions of current star formation in the walls of the supergiant H i shell (SGS) in the galaxy Holmberg II based on observations with a scanning Fabry-Perot interferometer at the 6-m SAO RAS telescope. We compare the structure and kinematics of ionized gas with that of atomic hydrogen and with the stellar population of the SGS. Our deep Hα images and archival images taken by the HST demonstrate that current star formation episodes are larger and more complicated than previously thought: they represent unified star-forming complexes with sizes of several hundred pc rather than 'chains' of separate bright nebulae in the walls of the SGS. The fact that we are dealing with unified complexes is evidenced by identified faint shell-like structures of ionized and neutral gas which connect several distinct bright H ii regions. Formation of such complexes is due to the feedback of stars with very inhomogeneous ambient gas in the walls of the SGS. The arguments supporting an idea about the triggering of star formation in SGS by the H i supershells collision are presented. We also found a faint ionized supershell inside the H i SGS expanding with a velocity of no greater than 10 − 15 km s −1 . Five OB stars located inside the inner supershell are sufficient to account for its radiation, although a possibility of leakage of ionizing photons from bright H ii regions is not ruled out as well.

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“…Strongly growing density variations result eventually in breaking the compressed layer (e.g. Chernin et al 1995), which is clearly seen at a later time as shown in the lower panel. From the hot interior of the bubbles outward, the cold layer gradually cools down and causes the pressure to decrease, thus enhancing destruction of the cold layer.…”

Section: Dynamics Of Merging Bubblesmentioning

confidence: 84%

“…It depends therefore whether SNe explosions inside the bubbles continue or not. In this scenario the layer formed between the collision of two bubbles can be ultimately destroyed (Chernin et al 1995). In this case the overall picture of circulation of molecular clouds and star formation in the Milky Way will differ from that proposed by Inutsuka et al (2015).…”

Section: Introductionmentioning

confidence: 90%

Star formation in shells of colliding multi-SNe bubbles

Vasiliev

Shchekinov

2017

Open Astronomy

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It is believed that when bubbles formed by multiple supernovae explosions interact with one another, they stimulate star formation in overlapping shells. We consider the evolution of a shocked layer formed by the collision of two identical bubbles each of which originated from OB clusters of ∼ 50 members and ∼ 50 pc. The clusters are separated by 200-400 pc. We found that depending on evolutionary status of colliding bubbles the shocked layer can either be destroyed into diffuse lumps, or be fragmented into dense clumps: the former occurs in collisions of young bubbles with continuing supernovae explosions, and the latter occurs in older bubble interactions. We argue that fragmentation efficiency in shells depends on external heating: for a heating rate < ∼ 1.7×10 −24 erg s −1 the number of fragments formed in a collision of two old bubbles reaches several tens at t ∼ 4 Myr, while a heating rate > ∼ 7 × 10 −24 erg s −1 prevents fragmentation. The clumps formed in freely expanding parts of bubbles are gradually destroyed and disappear on t < ∼ 1 Myr, whereas those formed in the overlapping shells survive much longer. Because of this the number of fragments in an isolated bubble begins to decrease after reaching a maximum, while in collision of two old bubbles it fluctuates around 60-70 until longer than t ∼ 5 Myr.

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Superassociations: violent star formation induced by shock–shock collisions

Cited by 36 publications

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Star formation complexes in the ‘galaxy-sized’ supergiant shell of the galaxy HolmbergI

Star formation complexes in the ‘galaxy-sized’ supergiant shell of the galaxy HolmbergI

Complexes of triggered star formation in supergiant shell of Holmberg II

Star formation in shells of colliding multi-SNe bubbles

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