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Galactic Bulge Microlensing Events from the MACHO Collaboration
C. L. Thomas, K. Griest, P. Popowski +21
We present a catalog of 450 high signal-to-noise microlensing events observed by the MACHO collaboration between 1993 and 1999. The events are distributed throughout our fields and…
Microlensing Optical Depth towards the Galactic Bulge Using Clump Giants from the MACHO Survey
P. Popowski, K. Griest, C. L. Thomas +20
Using 7 years of MACHO survey data, we present a new determination of the optical depth to microlensing towards the Galactic bulge. We select the sample of 62 microlensing events (…
The MACHO Project Large Magellanic Cloud Variable Star Inventory. XIII. Fourier Parameters for the First Overtone RR Lyrae Variables and the LMC Distance
C. Alcock, D. R. Alves, T. S. Axelrod +21
Fourier coefficents have been derived for the and light curves of 785 overtone RR Lyrae variables in 16 MACHO fields near the bar of the LMC. The and coef…
The MACHO Project Large Magellanic Cloud variable star inventory. XI. Frequency analysis of the fundamental mode RR Lyrae stars
C. Alcock, D. R. Alves, A. Becker +20
We have frequency analyzed 6391 variables classified earlier as fundamental mode RR Lyrae (RR0) stars in the MACHO database on the Large Magellanic Cloud (LMC). The overwhelming ma…
Recent Microlensing Results from the MACHO Project
P. Popowski, C. A. Nelson, D. P. Bennett +19
We describe a few recent microlensing results from the MACHO Collaboration. The aim of the MACHO Project was the identification and quantitative description of dark and luminous ma…
Variability-Selected Quasars in MACHO Project Magellanic Cloud Fields
M. Geha, C. Alcock, R. A. Allsman +22
We present 47 spectroscopically-confirmed quasars discovered behind the Magellanic Clouds identified via photometric variability in the MACHO database. Thirty-eight quasars lie beh…
MACHO Project Analysis of the Galactic Bulge Microlensing Events with Clump Giants as Sources
P. Popowski, T. Vandehei, K. Griest +19
We present preliminary results of the analysis of 5 years of MACHO data on the Galactic bulge microlensing events with clump giants as sources. This class of events allows one to o…
The MACHO Project LMC Variable Star Inventory: XII. Three Cepheid Variables in Eclipsing Binaries
C. Alcock, R. A. Allsman, D. R. Alves +22
We present a method for solving the lightcurve of an eclipsing binary system which contains a Cepheid variable as one of its components as well as the solutions for three eclipsing…
A Proper Motion Survey for White Dwarfs with the Wide Field Planetary Camera 2
Cailin A. Nelson, Kem H. Cook, Tim S. Axelrod +2
We have performed a search for halo white dwarfs as high proper motion objects in a second epoch WFPC2 image of the Groth-Westphal strip. We identify 24 high proper motion objects…
Gravitational Microlensing Events Due to Stellar Mass Black Holes
D. P. Bennett, A. C. Becker, J. L. Quinn +28
We present an analysis of the longest timescale microlensing events discovered by the MACHO Collaboration during a 7 year survey of the Galactic bulge. We find 6 events that exhibi…
The MACHO Project LMC Variable Star Inventory: X. The R Coronae Borealis Stars
C. Alcock, R. A. Allsman, D. R. Alves +26
We report the discovery of eight new R Coronae Borealis (RCB) stars in the Large Magellanic Cloud (LMC) using the MACHO project photometry database. The discovery of these new star…
Mass-Losing Semiregular Variable Stars in Baade's Windows
C. Alard, J. Blommaert, C. Cesarsky +38
By cross-correlating the results of two recent large-scale surveys, the general properties of a well defined sample of semi-regular variable stars have been determined. ISOGAL mid-…
MACHO 96-LMC-2: Lensing of a Binary Source in the LMC and Constraints on the Lensing Object
C. Alcock, R. A. Allsman, D. R. Alves +21
We present photometry and analysis of the microlensing alert MACHO 96-LMC-2. The ~3% photometry provided by the Global Microlensing Alert Network follow--up effort reveals a period…
A 421 d Activity Cycle in the BeX Recurrent Transient A0538-66 from MACHO monitoring
C. Alcock, R. A. Allsman, D. R. Alves +23
We present a ~ 5-yr optical light curve of the recurrent Be/X-ray transient A0538-66 obtained as a by-product of the MACHO Project. These data reveal both a long-term modulation at…
A Complete Survey of Case A Binary Evolution with Comparison to Observed Algol-Type Systems
Cailin A. Nelson, Peter P. Eggleton
We undertake a comparison of observed Algol-type binaries with a library of computed Case A binary evolution tracks. The library consists of 5500 binary tracks with various values…
The MACHO Project Hubble Space Telescope Follow-Up: Preliminary Results on the Location of the Large Magellanic Cloud Microlensing Source Stars
C. Alcock, R. A. Allsman, D. R. Alves +21
We attempt to determine whether the MACHO microlensing source stars are drawn from the average population of the LMC or from a population behind the LMC by examining the HST color-…
The Rotation Curve of the Large Magellanic Cloud and the Implications for Microlensing
David R. Alves, Cailin A. Nelson
The rotation of the disk of the Large Magellanic Cloud (LMC) is derived from the radial velocities of 422 carbon stars. New aspects of this analysis include the propagation of unce…
Galactic Bulge Microlensing Events with Clump Giants as Sources
P. Popowski, C. Alcock, R. A. Allsman +21
We present preliminary results of the analysis of 5 years of MACHO data on the Galactic bulge microlensing events with clump giants as sources. In particular, we discuss: 1) the se…
The MACHO Project LMC Variable Star Inventory. IX. Frequency Analysis of the First Overtone RR Lyrae Stars and the Indication for Nonradial Pulsations
C. Alcock, R. Allsman, D. R. Alves +26
More than 1300 variables classified provisionally as first overtone RR Lyrae pulsators in the MACHO variable star database of the Large Magellanic Cloud (LMC) have been subjected t…
The MACHO Project: Microlensing Detection Efficiency
The MACHO collaboration, C. Alcock, R. A. Allsman +22
The MACHO project is a search for dark matter in the form of massive compact halo objects (MACHOs). The project has photometrically monitored tens of millions of stars in the Large…
Searching for periodicities in the MACHO light curve of LMC X-2
C. Alcock, R. A. Allsman, D. R. Alves +23
Using the exceptional long-term monitoring capabilities of the MACHO project, we present here the optical history of LMC X-2 for a continuous 6-yr period. These data were used to i…
The MACHO project: Microlensing Optical Depth towards the Galactic Bulge from Difference Image Analysis
C. Alcock, R. A. Allsman, D. R. Alves +21
We present the microlensing optical depth towards the Galactic bulge based on the detection of 99 events found in our Difference Image Analysis (DIA) survey. This analysis encompas…
The MACHO Project 9 Million Star Color-Magnitude Diagram of the Large Magellanic Cloud
C. Alcock, R. A. Allsman, D. R. Alves +23
We present a 9 million star color-magnitude diagram (9M CMD) of the LMC bar. The 9M CMD reveals a complex superposition of different age and metallicity stellar populations, with i…
The MACHO Project: Microlensing Results from 5.7 Years of LMC Observations
The MACHO collaboration, C. Alcock, R. A. Allsman +23
We report on our search for microlensing towards the Large Magellanic Cloud (LMC). Analysis of 5.7 years of photometry on 11.9 million stars in the LMC reveals 13 - 17 microlensing…