Very massive runaway stars from three-body encounters

Gvaramadze, V. V.; Gualandris, Alessia

doi:10.1111/j.1365-2966.2010.17446.x

Cited by 71 publications

(76 citation statements)

References 75 publications

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“…1 of Ueta et al (2008). A curved tail has already been observed for the massive O9.5 supergiant α Camelopardalis (S. Mandel 4 ) and likely for the O6 I(n)f runaway star λ Cep (Gvaramadze & Gualandris 2011). Although these are much hotter stars with faster stellar winds, the physical mechanism responsible for producing a curved tail is the same.…”

Section: The Shape Of the Bow Shockmentioning

confidence: 96%

3D simulations of Betelgeuse’s bow shock

Mohamed

Mackey²,

Langer³

2012

A&A

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Betelgeuse, the bright, cool red supergiant in Orion, is moving supersonically relative to the local interstellar medium. The star emits a powerful stellar wind that collides with this medium, forming a cometary structure, a bow shock, pointing in the direction of motion. We present the first 3D hydrodynamic simulations of the formation and evolution of Betelgeuse's bow shock. The models include realistic low-temperature cooling and cover a range of plausible interstellar medium densities of 0.3-1.9 cm −3 and stellar velocities of 28-73 km s −1 . We show that the flow dynamics and morphology of the bow shock differ substantially because of the growth of Rayleigh-Taylor or Kelvin-Helmholtz instabilities. The former dominate the models with slow stellar velocities resulting in a clumpy bow shock substructure, whereas the latter produce a smoother, more layered substructure in the fast models. If the mass in the bow shock shell is low, as seems to be implied by the AKARI luminosities (∼3 × 10 −3 M ), then Betelgeuse's bow shock is very young and is unlikely to have reached a steady state. The circular nature of the bow shock shell is consistent with this conclusion. Thus, our results suggest that Betelgeuse only entered the red supergiant phase recently.

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Section: The Shape Of the Bow Shockmentioning

confidence: 96%

3D simulations of Betelgeuse’s bow shock

Mohamed

Mackey²,

Langer³

2012

A&A

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“…To conclude, we note that searches for bow shocks with the next generation of space infrared telescopes along with future high-precision proper motion measurements for massive field stars with the space astrometry mission Gaia will allow us to solve the problem of whether the massive stars form solely in the clustered mode and subsequently leave their parent clusters because of the gravitational interaction with other massive stars (Poveda et al 1967;Leonard & Duncan 1990; see also Kroupa 1998;Pflamm-Altenburg & Kroupa 2006;Gvaramadze et al 2009b;Gvaramadze & Gualandris 2010), or whether they can also form in situ (in the field and/or in low-mass clusters; e.g. Oey et al 2004;Parker & Goodwin 2007).…”

Section: Discussionmentioning

confidence: 99%

Massive runaway stars in the Small Magellanic Cloud

Gvaramadze

Kroupa

Pflamm-Altenburg

2010

A&A

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Using archival Spitzer Space Telescope data, we identified for the first time a dozen runaway OB stars in the Small Magellanic Cloud (SMC) through the detection of their bow shocks. The geometry of detected bow shocks allows us to infer the direction of motion of the associated stars and to determine their possible parent clusters and associations. One of the identified runaway stars, AzV 471, was already known as a high-velocity star on the basis of its high peculiar radial velocity, which is offset by 40 km s −1 from the local systemic velocity. We discuss implications of our findings for the problem of the origin of field OB stars. Several of the bow shockproducing stars are found in the confines of associations, suggesting that these may be "alien" stars contributing to the age spread observed for some young stellar systems. We also report the discovery of a kidney-shaped nebula attached to the early WN-type star SMC-WR3 (AzV 60a). We interpreted this nebula as an interstellar structure created owing to the interaction between the stellar wind and the ambient interstellar medium.

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“…Gvaramadze 2007;Gvaramadze et al 2009a;Gvaramadze & Gualandris 2011). One can, therefore, expect to find some of the runaways via detection of their associated bow shocks -the natural attributes of supersonically moving stars (Baranov et al 1971;Weaver et al 1977).…”

Section: Search For Bow Shocksmentioning

confidence: 99%

Search for OB stars running away from young star clusters

Gvaramadze

Kniazev

Kroupa

et al. 2011

A&A

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Dynamical few-body encounters in the dense cores of young massive star clusters are responsible for the loss of a significant fraction of their massive stellar content. Some of the escaping (runaway) stars move through the ambient medium supersonically and can be revealed via detection of their bow shocks (visible in the infrared, optical or radio). In this paper, which is the second of a series of papers devoted to the search for OB stars running away from young ( < ∼ several Myr) Galactic clusters and OB associations, we present the results of the search for bow shocks around the star-forming region NGC 6357. Using the archival data of the Midcourse Space Experiment (MSX) satellite and the Spitzer Space Telescope, and the preliminary data release of the Wide-Field Infrared Survey Explorer (WISE), we discovered seven bow shocks, whose geometry is consistent with the possibility that they are generated by stars expelled from the young (∼1-2 Myr) star clusters, Pismis 24 and AH03 J1725-34.4, associated with NGC 6357. Two of the seven bow shocks are driven by the already known OB stars, HD 319881 and [N78] 34. Follow-up spectroscopy of three other bow-shockproducing stars showed that they are massive (O-type) stars as well, while the 2MASS photometry of the remaining two stars suggests that they could be B0 V stars, provided that both are located at the same distance as NGC 6357. Detection of numerous massive stars ejected from the very young clusters is consistent with the theoretical expectation that star clusters can effectively lose massive stars at the very beginning of their dynamical evolution (long before the second mechanism for production of runaway stars, based on a supernova explosion in a massive tight binary system, begins to operate) and lends strong support to the idea that probably all field OB stars have been dynamically ejected from their birth clusters. A by-product of our search for bow shocks around NGC 6357 is the detection of three circular shells typical of luminous blue variable and late WN-type Wolf-Rayet stars.

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Very massive runaway stars from three-body encounters

Cited by 71 publications

References 75 publications

3D simulations of Betelgeuse’s bow shock

3D simulations of Betelgeuse’s bow shock

Massive runaway stars in the Small Magellanic Cloud

Search for OB stars running away from young star clusters

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