Luminosity Functions of Wide Binaries - The Low Luminosity Stars

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Session 46 -- White Dwarfs
Display presentation, Tuesday, 10, 1995, 9:20am - 6:30pm

[46.07] Luminosity Functions of Wide Binaries - The Low Luminosity Stars

J.A.Smith, T.D.Oswalt (Fl. Inst. of Tech.)

For the past several years we have been conducting a comprehensive spectroscopic and photometric study of previously unobserved Luyten and Giclas common proper motion binaries (CPMBs) which contain suspected white dwarfs (WDs). Our initial spectroscopic survey is nearly complete and indicates that $\approx$ 75\% of the more than 500 systems contain WDs as one component and the majority of the companions are M dwarf stars. Two of the remaining primary goals of this study are determination of the WD masses and development of luminosity functions (LFs) for both the degenerate (WD) and non-degenerate components in these systems. \\

We present results of our LF study to date for both degenerate and non-degenerate, halo and disk components and compare these to existing single star LFs. We include a discussion of a new method for determining and correcting the incompleteness in our sample volume. Our data includes a large number of the coolest, therefore oldest WDs known. These cool WDs are crucial to accurately determining the age of the local Galactic Disk. Our sample also includes a large fraction of subdwarf systems which have the potential to place constraints on the age and scale height of the local halo population. \\

We are indebted to W.J. Luyten, who spent decades identifying the CPMBs and to KPNO and CTIO for generous amounts of observing time for this project. The authors also gratefully acknowledge support from NASA Graduate Student Research Program grant NGT-51086 and from NSF grant AST-9016284.

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