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The Orion OB1 association. 1: Stellar contentWalfraven photometry of established and probable members of the Orion OB1 association is presented. Effective temperature, surface gravity, luminosity and mass are derived for all stars, using atmosphere model by Kurucz (1979). Absolute magnitudes are calculated using the Straizys and Kuriliene (1981) tables. Distance moduli and visual extinctions are determined. A comparison of the visual extinctions to IRAS 100 micrometers data shows that the near edge of the Orion A and B clouds lies at a distance of approximately 320 pc, while the far edge is at approximately 500 pc. A method for deriving the ages of the subgroups by comparing theoretical isochrones to the observations in the log g, log T(sub eff) plane is presented. The derived ages suggest, contrary to earlier studies, that subgroup 1b is younger than 1c, which can possibly be explained by past geometries of the system of stars and gas. The initial mass function for Orion OB1 is derived with the aid of the Kolmogorov-Smirnoff test. Through extensive simulations, we show that it is very difficult to derive accurately the Initial Mass Function (IMF) from the available data. To within somewhat weak limits the IMF is found to be of the form xi(log M) = AM(exp -1.7 +/- 0.2) for all subgroups. The energy output of the subgroups in the form of stellar winds and supernovae is calculated and compared to the observed size and expansion velocity of the Orion-Eridanus bubble. It is shown that the energy output of the association can account for the morphology and kinematics of the interstellar medium (ISM).
Document ID
19950058624
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Brown, A. G. A.
(Sterrewacht Leiden Leiden, Netherlands)
De Geus, E. J.
(Caltech, Pasadena, CA United States)
De Zeeuw, P. T.
(Sterrewacht Leiden Leiden, Netherlands)
Date Acquired
August 16, 2013
Publication Date
September 1, 1994
Publication Information
Publication: Astronomy and Astrophysics
Volume: 289
Issue: 1
ISSN: 0004-6361
Subject Category
Astronomy
Accession Number
95A90223
Funding Number(s)
CONTRACT_GRANT: NAG5-1736
CONTRACT_GRANT: NSF AST-89-18912
Distribution Limits
Public
Copyright
Other

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