VBLUW photometry of the association Sco OB1 (containing the open cluster NGC 6231). A discussion on the evolutionary status of the hypergiant zeta 1 Sco (B1 Ia +)

• VBLUW photometry of nearly 190 stars in the very young association Sco OB1, including the cluster NGC 6231, is presented and discussed. Temperature and surface gravity are determined with the aid of theoretical colours. Individual reddenings are also obtained. The distance modulus ( m- M) 0=11.00plusmn0.25 is similar to the value found by Shobbrook (1983). It appears that the reddening is not uniformly distributed across the association (~2degtimes1deg), but that areas of low and high reddening, varying from E( B- V) J=0.35 up to 0.67, can be distinguished. Practically all reddening is caused by dust in the local spiral arm up to a distance of at most 700 pc from the Sun. The Sagittarius-Carina arm where Sco OB1 is situated is practically transparent over a distance of ~0.5 kpc. The kinematical age of ~10 6 yr is in reasonable agreement with the average evolutionary age of ~(3.6plusmn0.6)times10 6 yr of the 12 brightest stars. The evolutionary status of the hypergiant zeta 1 Sco (B1 Ia +) is discussed

Ämnesord

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Nyckelord

Bibliography

Experimental/ interstellar matter

stellar atmospheres

stellar clusters and associations

stellar evolution

stellar photometry

supergiant stars

visible astronomical observations/ stellar photoelectric photometry

Scorpius OB1 association

stellar OB association

star cluster

zeta Scorpii

visible

OB-type stars

association age

effective temperatures

near-UV

AD 1976 to 1977

foreground interstellar reddening

two-colour diagram

colour-magnitude diagram

VBLUW photometry

open cluster

NGC 6231

evolutionary status

hypergiant

B1 Ia

very young association

surface gravity

theoretical colours

distance modulus

E( B- V) J

local spiral arm

Sagittarius-Carina arm

kinematical age

evolutionary age/ A9580J Photographic region astronomical observations A9710C Stellar interiors

evolution

nucleosynthesis

and ages A9710E Stellar atmospheres

radiative transfer

opacity

and line formation A9710R Stellar radiation and spectra A9710V Stellar distances

parallaxes

and space density A9720P Supergiant stars A9820C Associations of stars (OB

T

etc.) A9820E Open clusters A9840B Interstellar matter

Publikations- och innehållstyp

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