Separated before birth: pulsars B2020+28 and B2021+51 as the remnants of runaway stars

Gvaramadze, V. V.

doi:10.1051/0004-6361:20077693

Cited by 15 publications

(30 citation statements)

References 40 publications

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“…Hobbs et al 2005), and thereby could contribute to the origin of peculiar velocities of these objects (cf. Gvaramadze 2006b, 2007; Gvaramadze et al 2008; Gvaramadze & Bomans 2008b).…”

Section: Discussionmentioning

confidence: 99%

Very massive runaway stars from three-body encounters

Gvaramadze¹,

Gualandris²

2010

Monthly Notices of the Royal Astronomical Society

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Very massive stars preferentially reside in the cores of their parent clusters and form binary or multiple systems. We study the role of tight very massive binaries in the origin of the field population of very massive stars. We performed numerical simulations of dynamical encounters between single (massive) stars and a very massive binary with parameters similar to those of the most massive known Galactic binaries, WR 20a and NGC 3603-A1. We found that these three-body encounters could be responsible for the origin of high peculiar velocities ($\geq$ 70 km/s) observed for some very massive ($\geq$ 60-70 Msun) runaway stars in the Milky Way and the Large Magellanic Cloud (e.g., $\lambda$ Cep, BD+43 3654, Sk-67 22, BI 237, 30 Dor 016), which can hardly be explained within the framework of the binary-supernova scenario. The production of high-velocity massive stars via three-body encounters is accompanied by the recoil of the binary in the opposite direction to the ejected star. We show that the relative position of the very massive binary R145 and the runaway early B-type star Sk-69 206 on the sky is consistent with the possibility that both objects were ejected from the central cluster, R136, of the star-forming region 30 Doradus via the same dynamical event -- a three-body encounter.Comment: 10 pages, 12 figures, accepted to MNRA

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“…Hobbs et al 2005), and thereby could contribute to the origin of peculiar velocities of these objects (cf. Gvaramadze 2006b, 2007; Gvaramadze et al 2008; Gvaramadze & Bomans 2008b).…”

Section: Discussionmentioning

confidence: 99%

Very massive runaway stars from three-body encounters

Gvaramadze¹,

Gualandris²

2010

Monthly Notices of the Royal Astronomical Society

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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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“…Still, the existence of a population of extremely high-velocity neutron stars can be explained without exploiting the idea of asymmetric supernova explosion -they simply could be the remnants of massive hypervelocity runaway stars (Gvaramadze 2007(Gvaramadze , 2009Gvaramadze et al , 2009. Assuming that the neutron star in 4U 1907+09 attained a kick velocity of 200−400 km s −1 at birth (typical of radio pulsars; e.g.…”

Section: Asymmetric Supernova Explosionmentioning

confidence: 99%

4U 1907+09: an HMXB running away from the Galactic plane

Gvaramadze

Röser

Scholz

et al. 2011

A&A

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We report the discovery of a bow shock around the high-mass X-ray binary (HMXB) 4U 1907+09 using the Spitzer Space Telescope 24 μm data (after Vela X-1 the second example of bow shocks associated with HMXBs). The detection of the bow shock implies that 4U 1907+09 is moving through space with a high (supersonic) peculiar velocity. To confirm the runaway nature of 4U 1907+09, we measured its proper motion, which for an adopted distance to the system of 4 kpc corresponds to a peculiar transverse velocity of 160 ± 115 km s −1 , meaning that 4U 1907+09 is indeed a runaway system. This also supports the general belief that most HMXBs possess high space velocities. The direction of motion of 4U 1907+09 inferred from the proper motion measurement is consistent with the orientation of the symmetry axis of the bow shock, and shows that the HMXB is running away from the Galactic plane. We also present the Spitzer images of the bow shock around Vela X-1 (a system similar to 4U 1907+09) and compare it with the bow shock generated by 4U 1907+09.

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Separated before birth: pulsars B2020+28 and B2021+51 as the remnants of runaway stars

Cited by 15 publications

References 40 publications

Very massive runaway stars from three-body encounters

Very massive runaway stars from three-body encounters

Search for OB stars running away from young star clusters

4U 1907+09: an HMXB running away from the Galactic plane

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