Stellar winds, supernovae, and the origin of the H I supershells

Bruhweiler, F. C.; Gull, T. R.; Kafatos, Menas; Sofia, S.

doi:10.1086/183250

Cited by 115 publications

(53 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Here, we propose to put constrains on the H i scale height of M101 based on the properties of the described supershell and the one reported by Kamphuis et al (1991). Bruhweiler et al (1980) have discussed the sizes of galactic H i shells as a function of the neutral hydrogen scale height.…”

Section: Implications For Host Galaxymentioning

confidence: 99%

An Expanding Neutral Hydrogen Supershell Evacuated by Multiple Supernovae in M101

Chakraborti¹,

Ray²

2011

ApJ

View full text Add to dashboard Cite

Several neutral hydrogen (H i) cavities have been detected in the Milky Way and other nearby star-forming galaxies. It has been suggested that at least a fraction of them may be expanding supershells driven by the combined mechanical feedback from multiple supernovae (SNe) occurring in an OB association. Yet most extragalactic H i holes have neither a demonstrated expansion velocity nor an identified OB association inside them. In this work, we report on the discovery of an unbroken expanding H i supershell in the nearby spiral galaxy M101, with a UV-emitting young stellar association inside it. We measure its size (500 pc) and expansion velocity (20 km s −1 ) by identifying both its approaching and receding components in the position-velocity space, using 21 cm emission spectroscopy. This provides us with an ideal system to test the theory of supershells driven by the mechanical feedback from multiple SNe. The UV emission of the cluster inside the supershell is compared with simulated spectral energy distribution of synthetic clusters of the appropriate age (∼15 Myr). The observed UV flux is found to be consistent with an association of the appropriate mass (∼10 5 M ) and age required by the energy budget of the supershell. Properties of this supershell and another previously reported in the same galaxy are used to infer its neutral hydrogen scale height and mean neutral hydrogen density in the disk. The presence of another UV-emitting stellar association in overdense swept-up gas is discussed in the context of propagating star formation.

show abstract

Section: Implications For Host Galaxymentioning

confidence: 99%

An Expanding Neutral Hydrogen Supershell Evacuated by Multiple Supernovae in M101

Chakraborti¹,

Ray²

2011

ApJ

View full text Add to dashboard Cite

show abstract

“…Then, the supernovae occur inside the partially attenuated bubble produced by the winds. The situation has been described in some detail by Bruhweiler et al (1980) and by Dyson (1981); the shock produced by the SN explosion sweeps up the material inside the cavity formed by the stellar winds, and impacts directly on the shell; then the strength of the transmitted shock is reduced by a factor which depends on the contrast in density between the cavity and the newly formed shell. The radiative cooling time within the shell can be very short, and then the momentum conservation is applied as the best approximation to describe the dynamics of the new formed shell.…”

Section: Two Basic Driving Mechanisms: Stellar Winds and Supernova Exmentioning

confidence: 99%

An evolutionary sequence of expanding hydrogen shells in galaxy discs

Relaño¹,

Beckman

Daigle

et al. 2007

A&A

View full text Add to dashboard Cite

Aims. Large HI shells, with diameters of hundreds of pc and expansion velocities of 10−20 km s −1 have been detected in their hundreds in the Milky Way and are well observed features of local gas rich galaxies. These shells could well be predicted as a result of the impact of OB associations on the ISM, but doubt has been cast on this scenario by the apparent absence of OB stars close to the centres of a large fraction of these shells in recent observations of the SMC. Here we present observational evidence within an energetically consistent framework which strongly supports the scenario in which OB associations do produce the giant HI shells.Methods. Using Fabry-Perot scanned Hα emission line mapping of nearby galaxy discs, we have detected, in all the H ii regions where the observations yield sufficient angular resolution and S:N ratio, dominant Hα shells with radii a few tens of pc, expanding at velocities of 50−100 km s −1 , and with gas masses of 10 4 −10 5 M . In previous studies, we found that stellar winds alone can account for the energetics of most of the Hα shells, which form initially before the stars explode as SNe. We have applied a simple dynamically consistent framework in which we can extrapolate the properties of the observed Hα shells to a few 10 7 yr after the formation of the OB stars. The framework includes the dynamical inputs of both winds and SNe on the surrounding ISM. The results give quantitative statistical support to the hypothesis that the Hα emitting shells are generic progenitors of the HI shells. Results. The results are in good agreement with the ranges of masses (∼10 6 M ), velocities (up to ∼20 km s −1 ), and diameters (up to ∼500 pc) of representative HI shells observed in nearby galaxies. The combined effects of stellar winds, acting during the first few 10 6 yr, and SN explosions, "switching on" subsequently, are required to yield the observed parameters.

show abstract

“…Supershells are large-scale shocks with radii larger than a hundred parsecs (Heiles 1979;Tenorio-Tagle & Bodenheimer 1988), commonly formed around clusters of young stars due to their very violent radiative and mechanical feedback (McCray & Snow 1979;Bruhweiler et al 1980;McClure-Griffiths et al 2002). This powerful injection of momentum on large scales makes supershells an important driver of interstellar turbulence (Elmegreen & Scalo 2004;de Avillez & Breitschwerdt 2007;Joung et al 2009) and a possible trigger for the formation of molecular clouds (Ehlerova et al 1997;Dawson et al 2011b;Dawson 2013).…”

Section: Introductionmentioning

confidence: 99%

The role of magnetic fields in the structure and interaction of supershells

Ntormousi

Dawson

Hennebelle

et al. 2017

A&A

View full text Add to dashboard Cite

Context. Large-scale shocks formed by clustered feedback of young OB stars are considered an important source of mechanical energy for the interstellar medium (ISM) and a trigger of molecular cloud formation. Their interaction sites are locations where kinetic energy and magnetic fields are redistributed between ISM phases. Aims. In this work we address two questions, both involving the role of galactic magnetic fields in the dynamics of supershells and their interactions. On the one hand, we study the effect of the magnetic field on the expansion and fragmentation of supershells and, on the other hand, we look for the signatures of supershell collisions on dense structures and on the kinetic and magnetic energy distribution of the ISM. Methods. We performed a series of high-resolution, three-dimensional simulations of colliding supershells. The shocks are created by time-dependent feedback and evolve in a diffuse turbulent environment that is either unmagnetized or has different initial magnetic field configurations. Results. In the hydrodynamical situation, the expansion law of the superbubbles is consistent with the radius-time relation R ∝ t 3/5 that is theoretically predicted for wind-blown bubbles. The supershells fragment over their entire surface into small dense clumps that carry more than half of the total kinetic energy in the volume. However, this is not the case when a magnetic field is introduced, either in the direction of the collision or perpendicular to the collision. In both situations, the shell surfaces are more stable to dynamical instabilities. When the magnetic field opposes the collision, the expansion law of the supershells also becomes significantly flatter than in the hydrodynamical case. Although a two-phase medium arises in all cases, in the magnetohydrodynamical (MHD) simulations the cold phase is limited to lower densities and the cold clumps are located further away from the shocks with respect to the hydrodynamical simulations. Conclusions. For the parameters we explored, self-gravity has no effect on either the superbubble expansion or the shock fragmentation. In contrast, a magnetic field, whether mostly parallel or mostly perpendicular to the collision axis, causes a deceleration of the shocks, deforms them significantly, and largely suppresses the formation of the dense gas on their surface. The result is a multi-phase medium in which the cold clumps are not spatially correlated with the supershells.

show abstract

Stellar winds, supernovae, and the origin of the H I supershells

Cited by 115 publications

References 5 publications

An Expanding Neutral Hydrogen Supershell Evacuated by Multiple Supernovae in M101

An Expanding Neutral Hydrogen Supershell Evacuated by Multiple Supernovae in M101

An evolutionary sequence of expanding hydrogen shells in galaxy discs

The role of magnetic fields in the structure and interaction of supershells

Contact Info

Product

Resources

About