An astrometric study of the nucleus of the ζ Persei Association.

Abstract

view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An astrometric study of the nucleus of the ζ Persei Association. Frederick, Laurence W. Abstract Seventeen early epoch plates and fifty-eight recent epoch plates, all taken with the Sproul refractor, were used to make a proper motion study of the nucleus of the ~ Persei Association. The plate material was divided into six groups, each group having an interval of about thirty- five years between the early and recent plates. The reductions were made for each group, using seven reference stars and the method of least squares. The annual proper motions obtained have an average probable error in x and y combined of ~o'.'ooo5. The errors in the plate constants are investigated. The proper motions were referred to the FK3 system by means of o Persei. Corrections are given for precession, galactic rotation and secular parallax. General conclusions reached earlier by Blaauw concerning this cluster are confirmed. An attempt was made to assign group membership on the basis of the proper motions and other data that were available. There are at most eleven stars that might belong to the cluster. Using these eleven stars, the internal annual motion was found to lie between 0 "0000 and ~o'.'ooo6. The present diameter of the cluster, 400", agrees with a value +0'.'0003 for the internal motion. The internal motions obtained are compatible with the age of the association as given by Blaauw. It is shown that o Persei is not a member of the nucleus and perhaps is not even a member of the association. The effect of temperature on the scale of the Sproul telescope was investigated, but proved to be negligible. The probable error for one plate was found to be ~ "0324, which is of the expected order of magnitude. Sproul Observatory, Swarthmore College, Swarthmore, Pa. Publication: The Astronomical Journal Pub Date: October 1954 DOI: 10.1086/107027 Bibcode: 1954AJ.....59..321F full text sources ADS |