Kinematic Determination of the Luminosity Function in the Solar Neighbourhood

Vicente, B.; Garzón, F.; Cabrera-Lavers, A.
Bibliographical reference

Stellar Clusters & Associations: A RIA Workshop on Gaia. Proceedings. Granada, Spain, May 23 - 27, 2011. Edited by: Alfaro Navarro, E. J.; Gallego Calvente, A. T.; Zapatero Osorio, M. R., pp.393-394

Advertised on:
2011
Number of authors
3
IAC number of authors
3
Citations
0
Refereed citations
0
Description
The luminosity function is not only crucial to know stellar density distribution in space, and thus to know the structure of the Galaxy, but it allows the determination of the stellar mass function using the mass-luminosity relationship. The luminosity function and mass function are fundamental to the understanding of star formation and the evolution of the Milky Way. It is customary to assume that the luminosity function in the solar neighbourhood, which can be obtained directly from precise star counts, well represents that of the Galactic disk, if not over the whole Galaxy and external galaxies of similar morphological type. Under this assumption, we simply need to calculate in the solar vicinity and then move it to the disk area of interest. In this regard, the larger the sample used for the determination the more reliable the extrapolation to galactic studies. We have determined the luminosity function in the solar neighbourhood up to 200 pc considering the proper motions as distance estimators. We used the parameter "reduced proper motion" (Luyten [1938]) for calibration of the apparent magnitudes to absolute ones. This calibration must be done with kinematically similar populations, i.e., they share the same velocity distribution. So, prior to calculating the luminosity determination we used the SKY model (Wainscoat et al. [1992]) to separate stars with different kinematic evolution in our catalogue. As our kinematical database, we used the CdC-SF Catalogue (Vicente et al. [2010]), which has proper motion precision similar to that of Hipparcos but up to much fainter magnitudes (V = 15). Such a rich data allow getting the luminosity function for distances greater than those identified so far by extending existing results. Having stars at greater distances implies that we can get information covering the bright field of the luminosity function. Also, a larger sample with smaller proper motions produces a luminosity function that is more adapted to the real Galaxy model thanks to a smaller correction factor.