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Results from the Optical Gravitational Lensing Experiment (OGLE)

Published online by Cambridge University Press:  25 May 2016

B. Paczyński ,
K. Z. Stanek ,
A. Udalski ,
M. Szymański ,
J. Kałużny ,
M. Kubiak ,
M. Mateo ,
W. Krzemiński  and
G. W. Preston
B. Paczyński
Affiliation:
Princeton University Observatory Princeton, NJ 08544-1001
K. Z. Stanek
Affiliation:
Princeton University Observatory Princeton, NJ 08544-1001
A. Udalski
Affiliation:
Warsaw University Observatory Al. Ujazdowskie 4, 00-478 Warszawa, Poland
M. Szymański
Affiliation:
Warsaw University Observatory Al. Ujazdowskie 4, 00-478 Warszawa, Poland
J. Kałużny
Affiliation:
Warsaw University Observatory Al. Ujazdowskie 4, 00-478 Warszawa, Poland
M. Kubiak
Affiliation:
Warsaw University Observatory Al. Ujazdowskie 4, 00-478 Warszawa, Poland
M. Mateo
Affiliation:
Department of Astronomy, University of Michigan 821 Dennison Bldg., Ann Arbor, MI 48109-1090
W. Krzemiński
Affiliation:
Carnegie Observatories, Las Campanas Observatory Casilla 601, La Serena, Chile
G. W. Preston
Affiliation:
Carnegie Observatories, Institution of Washington 813 Santa Barbara Street, Pasadena, CA 91101

Abstract

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The analysis of the first three years of the OGLE data revealed 12 microlensing events of the Galactic bulge stars, with the characteristic time scales in the range 8.6 < t 0 < 80 days, where t 0 = RE/V. A complete sample of nine events gave the optical depth to gravitational microlensing larger than (3.3 ± 1.2) × 10–6, in excess of current theoretical estimates, indicating a much higher efficiency for microlensing by either bulge or disk lenses. The lenses are likely to be ordinary stars in the Galactic bar, which has its long axis elongated towards us. At this time we have no evidence that the OGLE events are related to dark matter. The OGLE color magnitude diagrams reveal the presence of the Galactic bar and a low density inner disk region ∼ 4 kpc in radius. A catalogue of a few thousand variable stars is in preparation.

Type
Chapter 2: Is the Milky Way a Barred Spiral Galaxy?
Information
Symposium - International Astronomical Union , Volume 169: Unsolved Problems of the Milky Way , 1996 , pp. 93 - 102
Copyright
Copyright © Kluwer 1996 

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