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Session 102 - Pulsating Stars.
Display session, Thursday, January 18
North Banquet Hall, Convention Center

[102.02] The Macho Project LMC Variable Star Inventory: Aperiodic Blue Variables

P. Purdue, C. Alcock, K. Cook (LLNL), R. Allsman (ANUSF), D. Alves (UCD/LLNL), T. Axelrod (MSSSO/LLNL), K. Freeman, B. Peterson, A. Rodgers (MSSSO), A. Becker, C. Stubbs (CfPA/U Washington), D. Bennett (CfPA/LLNL), K. Griest, J. Guern, M. Lehner (CfPA/UCSD), S. Marshall, M. Pratt (CfPA/UCSB), P. Quinn (ESO), W. Sutherland (Oxford), D. Welch (McMaster)

The Macho Project has been monitoring millions of stars in the Large Magellanic Cloud (LMC), the Small Magellanic Cloud, and the bulge of the Milky Way searching for gravitational microlensing. We have analyzed data from about 9 million stars in 11 square degrees of the bar of the LMC over a two-year span. This poster presents a preliminary catalog of aperiodic, variable blue stars. We have defined blue stars as as having (V-R)_macho < 0.3 and 14.0 < V_macho < 18.0 (where these are roughly V and R). From \sim 250,000 such blue stars in the region of observation, about 400 were selected for this catalog. The majority of the catalog was derived from inspection of blue stars' light curves which had been flagged as indicating potential microlensing events, i.e. their light curves triggered a microlens filter and could be moderately well fit by a microlensing curve. Aperiodic blue stars were also selected from stars which had been flagged as variable (but had not been flagged as microlensing candidates).

We have classified these stars by their light curve morphology. For example, some of the light curves are relatively constant with one to a few prominent bumps (bumpers), some are constant with sections of `flickering,' and some have step-like changes. The spatial distribution of the catalog stars will be presented and correlated with known phenomena, such as eruptive variables, star-forming regions, and high energy sources. We are searching for low-level, periodic variablility during quiescence in those stars with relatively long `constant' phases.

Work performed under the auspices of the USDOE at LLNL under contract no. W-7405-ENG-48.

Program listing for Thursday