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Photometric Calibrations after HIPPARCOS or: The Fine Structure of the HR-Diagram Revealed

Published online by Cambridge University Press:  30 March 2016

Michel Grenon
Michel Grenon*
Affiliation:
Geneva Observatory, 1290 Sauverny, Switzerland

Abstract

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The Hipparcos parallaxes allow us to revisit photometric calibrations in terms of Mv and to evaluate the effects of the overall metallicity across the HR-diagram. For evolved stars the spread in mass remains the major and irreducible source of errors in the photometric Mv. If the relative locations of open cluster main-sequences are fully explained by the ∆Mv versus ∆[M/H] relation, the residual scatter in the lower main sequence appears due to additional parameters such as rotation or gravitational settling of the heavy elements. These cannot readily be studied by a purely photometric approach.

Type
II. Joint Discussions
Information
Highlights of Astronomy , Volume 12: Highlights of Astronomy. As presented at the XXIVth General Assembly of the IAU, 2000 , 2002 , pp. 680 - 683
Copyright
Copyright © Astronomical Society of Pacific 2002

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