About The Event

“How old is that star?”

That is one of the most difficult questions to answer in galactic astrophysics. We have ways of determining the ages of ensembles of stars (groups and clusters), but critical astrophysical questions can only be addressed if we can estimate the ages of individual stars in the field.

Stellar ages lie at the heart of astrophysics, and stellar evolution is all about time and how stars change with time. We want to know time-scales for physical processes such as angular momentum loss, nucleosynthetic processing, changes in magnetic fields, and the like, or we wish to compare objects or groups of objects at different stages in their lives. Stellar and galactic evolution cannot be understood without some knowledge of ages.

If we could pin ages on individual stars we could determine the star formation history of the Galaxy and its principal components, and we could understand the physics of low-mass stars much better. The well-studied spin-down of stars like the Sun and the concomitant decline of observed activity indices makes it possible to estimate rough ages for individual stars, but the scarcity and remoteness of older clusters makes calibrating and testing the activity–age relation problematic.

Ages of Resolved Populations

The discovery and study of multiple populations of stars in clusters and other resolved objects in recent years has been a major accomplishment of HST and has led to changing views on how clusters form and evolve. In some cases there is evidence for multiple ages, in others for differences in composition. A full and complete understanding of the nature and ages of groups of stars is vital to stellar astrophysics.

A Call to Convene

Now is an appropriate time to examine the problem of stellar ages in detail. It is time to bring together astronomers from the around the world to discuss the current state of the problem of estimating ages of individual stars and of populations, where the advances are now being made, and what the near future offers.

Join us in Baltimore this October to join us in an unusual symposium that will examine the problem of stellar ages from all angles! We are planning a program that will bring together diverse interests and talents, and we have scheduled it for the best time of year to be in Maryland.

For information, please contact David R. Soderblom (iau258@stsci.edu).