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The Distance and Orientation of the Galactic Bulge from Mira Variables: A Preliminary Report

Published online by Cambridge University Press:  25 May 2016

R. M. Catchpole ,
P. A. Whitelock ,
M. W. Feast ,
S.M.G. Hughes ,
C. Alard  and
E. Olivier
R. M. Catchpole
Affiliation:
Royal Observatory Greenwich, Greenwich, London SE10 9NF, UK Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, UK
P. A. Whitelock
Affiliation:
S A Astronomical Observatory, PO Box 9, Observatory, 7935, S Africa
M. W. Feast
Affiliation:
University of Cape Town, Private Bag, Rondebosch, 7700, S Africa
S.M.G. Hughes
Affiliation:
Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, UK
C. Alard
Affiliation:
Observatoire de Paris, 61 Ave. de l'Observatoire, F-75014, Paris
E. Olivier
Affiliation:
University of Western Cape, Private Bag XI7, Bellville, 7535, S Africa S A Astronomical Observatory, PO Box 9, Observatory, 7935, S Africa

Abstract

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Near-infrared, JHKL, observations of 595 Mira variables in two fields on either side of the centre of our Galaxy, confirm that the Bulge is not spherically symmetric about its axis of rotation, but is elongated so that the part to the east of the centre is closer to us. The shape of the Bulge about its axis of rotation is not uniquely defined by these data, but the shape that deviates least from circular symmetry has an axis ratio xo/yo = 1.7, with a major axis at an angle, θ = 58° ± 7, to the plane of the sky, for a galactic centre distance, R0 = 9.4 ± 0.5 kpc. This is based on an assumed scale length in galactic coordinates of bo = 375 pc and lo/bo = 2.0.

Type
Part 2: The Database
Information
Symposium - International Astronomical Union , Volume 192: The Stellar Content of Local Group Galaxies , 1999 , pp. 89 - 94
Copyright
Copyright © Astronomical Society of the Pacific 1999 

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