The O Associations in the Solar Neighborhood

Blaauw, Adriaan

doi:10.1146/annurev.aa.02.090164.001241

Cited by 587 publications

(486 citation statements)

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“…The 26 A1 production from the Sco-Cen association as a whole is under study: ages of stellar subgroups lend themselves to separatable features on the sky, detailed HI maps help to clarify how those may relate to low-significance structures of the 1.8 MeV image (Blaauw 1964, deGeus 1992.…”

Section: Gamma-ray Resultsmentioning

confidence: 99%

²⁶ Al Radioactivity in the Galaxy

Diehl¹,

Oberlack²,

Knödlseder³

et al. 1997

International Astronomical Union Colloquium

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Abstract. 26 A1 radioactivity is believed to originate predominantly from massive stars, ejected into interstellar medium in wind phases and/or supernova events. With its million-year decay time, penetrating 7-rays from 26 A1 decay measure the massive-star history averaged over a time scale of ~million years, thus extending times cales accessible otherwise. The COMPTEL 1.809 MeV all-sky data from 5 years of observations show irregularities and features at intermediate latitudes, which may have a more local origin (~ 1 kpc). We find that the large scale emission can be characterized by a Galactic scale height of ~ 130 pc, and a Galactocentric scale radius of ~ 5 kpc, with features from spiral structure. Catalogues from massive-star related objects do not significantly improve the description of COMPTEL data above this. Emission associated with nearby structures such as the Gould Belt, Loop I, or stellar aggregates, is indicated, yet cannot be clearly detected. Combined with our imaging results, this suggests that 26 A1 yields from massive star ensembles depend on specifics of those stars and their history. Further 26 A17-ray studies are underway to help mapping of the massive star history in the solar vicinity.

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Section: Gamma-ray Resultsmentioning

confidence: 99%

²⁶ Al Radioactivity in the Galaxy

Diehl¹,

Oberlack²,

Knödlseder³

et al. 1997

International Astronomical Union Colloquium

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“…In Binns et al (2005) we stated that this gives sufficient time between events for the 59 Ni, which is synthesized in the SN explosions, to decay before its daughter product, 59 Co, is accelerated to cosmic ray energies. However, Prantzos (2005) MY (Blaauw, 1964). Some of the larger associations are composed of two or more subgroups, with the stars in each subgroup forming at about the same time, but with the subgroups themselves having differing ages.…”

Section: Discussionmentioning

confidence: 99%

OB Associations, Wolf–Rayet Stars, and the Origin of Galactic Cosmic Rays

Binns

Wiedenbeck

Arnould³

et al. 2007

The Composition of Matter

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Abstract. We have measured the isotopic abundances of neon and a number of other species in the galactic cosmic rays (GCRs) using the Cosmic Ray Isotope Spectrometer (CRIS) aboard the ACE spacecraft. Our data are compared to recent results from two-component (Wolf-Rayet material plus solar-like mixtures) Wolf-Rayet (WR) models. The three largest deviations of galactic cosmic ray isotope ratios from solar-system ratios predicted by these models, 12 C/ 16 O, 22 Ne/ 20 Ne, and 58 Fe/ 56 Fe, are very close to those observed. All of the isotopic ratios that we have measured are consistent with a GCR source consisting of ~20% of WR material mixed with ~80% material with solar-system composition. Since WR stars are evolutionary products of OB stars, and most OB stars exist in OB associations that form superbubbles, the good agreement of our data with WR models suggests that OB associations within superbubbles are the likely source of at least a substantial fraction of GCRs. In previous work it has been shown that the primary 59 Ni (which decays only by electron-capture) in GCRs has decayed, indicating a time interval between nucleosynthesis and acceleration of >10 5 yr. It has been suggested that in the OB association environment, ejecta from supernovae might be accelerated by the high velocity WR winds on a time scale that is short compared to the half-life of 59 Ni. Thus the 59 Ni might not have time to decay and this would cast doubt upon the OB association origin of cosmic rays. In this paper we suggest a scenario that should allow much of the 59 Ni to decay in the OB association environment and conclude that the hypothesis of the OB association origin of cosmic rays appears to be viable.

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“…Particularly, the formation of an OB association -a co-eval group of stars, a significant number of which are of spectral type B or earlier -can dominate the energy balance of, and control the subsequent evolution of, the local ISM. The model of sequential star formation grew out of observations of 'chains' of OB associations, in which the member associations are separated from one another by distances ∼ 10 − 40 pc, and in which there is an age gradient, with the oldest OB association at one end of the chain, and the youngest at the other (Blaauw 1964). Elmegreen & Lada (1977) proposed a mechanism of sequential star formation, in which a young group of high-mass stars inject mechanical energy, momentum and material into the local ISM through outflows, stellar winds and, after a time delay of a few Myr, supernovae.…”

Section: Sequential Star Formationmentioning

confidence: 99%

Submillimetre Studies of Prestellar and Starless Cores in the Ophiuchus, Taurus and Cepheus Molecular Clouds

Pattle¹

2017

Springer Theses

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The O Associations in the Solar Neighborhood

Cited by 587 publications

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²⁶ Al Radioactivity in the Galaxy

²⁶ Al Radioactivity in the Galaxy

OB Associations, Wolf–Rayet Stars, and the Origin of Galactic Cosmic Rays

Submillimetre Studies of Prestellar and Starless Cores in the Ophiuchus, Taurus and Cepheus Molecular Clouds

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The O Associations in the Solar Neighborhood

Cited by 587 publications

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26 Al Radioactivity in the Galaxy

26 Al Radioactivity in the Galaxy

OB Associations, Wolf–Rayet Stars, and the Origin of Galactic Cosmic Rays

Submillimetre Studies of Prestellar and Starless Cores in the Ophiuchus, Taurus and Cepheus Molecular Clouds

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Product

Resources

About

²⁶ Al Radioactivity in the Galaxy

²⁶ Al Radioactivity in the Galaxy