In:
Proceedings of the International Astronomical Union, Cambridge University Press (CUP), Vol. 3, No. S245 ( 2007-07), p. 351-354
Abstract:
A proper motion study of a field of 20′ × 20′ inside Plaut's low extinction window (l,b)=(0 o , −8 o ), has been completed. Relative proper motions and photographic BV photometry have been derived for ~ 21,000 stars reaching to V ~ 20.5 mag, based on the astrometric reduction of 43 photographic plates, spanning over 21 years of epoch difference. Proper motion errors are typically 1 mas yr −1 . Cross-referencing with the 2MASS catalog yielded a sample of ~ 8700 stars, from which predominantly disk and bulge subsamples were selected photometrically from the JH color-magnitude diagram. The two samples exhibited different proper-motion distributions, with the disk displaying the expected reflex solar motion. Galactic rotation was also detected for stars between ~2 and ~3 kpc from us. The bulge sample, represented by red giants, has an intrinsic proper motion dispersion of (σ l , σ b ) = (3.39, 2.91)±(0.11, 0.09) mas yr −1 , which is in good agreement with previous results. A mean distance of $6.37^{+0.87}_{-0.77}$ kpc has been estimated for the bulge sample, based on the observed K magnitude of the horizontal branch red clump. The metallicity [ M / H ] distribution was also obtained for a subsample of 60 bulge giants stars, based on calibrated photometric indices. The observed [ M / H ] shows a peak value at [ M / H ] ~ −0.1 with an extended metal poor tail and around 30% of the stars with supersolar metallicity. No change in proper motion dispersion was observed as a function of [ M / H ]. We are currently in the process of obtaining CCD UBV RI photometry for the entire proper-motion sample of ~ 21,000 stars.
Type of Medium:
Online Resource
ISSN:
1743-9213
,
1743-9221
DOI:
10.1017/S1743921308018097
Language:
English
Publisher:
Cambridge University Press (CUP)
Publication Date:
2007
detail.hit.zdb_id:
2170724-8
SSG:
16,12
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