Preliminary results from the STEPHI2009 campaign on the open cluster NGC 1817

TL;DR

This paper reports preliminary observational results from a multi-site campaign studying the open cluster NGC 1817, focusing on delta Scuti stars and eclipsing binaries to refine stellar models.

Contribution

It presents initial multi-site observational data of NGC 1817, highlighting the potential to constrain stellar models using pulsation frequencies and fundamental parameters.

Findings

Lower initial helium mass fraction likely explains observed pulsations.

Multi-site observations improve duty cycle and data quality.

Preliminary results set the stage for detailed stellar modeling.

Abstract

We present preliminary observational results of the multi-site STEPHI campaign on the cluster NGC 1817. The three observatories involved are San Pedro Martir (Mexico), Xing Long (China) and the Observatorio del Teide (Spain) - giving an ideal combination to maximise the duty cycle. The cluster has 12 known delta Scuti stars and at least two detached eclipsing binary systems. This combination of characteristics is ideal for extracting information about global parameters of the targets, which will in turn impose strict constraints on the stellar models. From an initial comparison with stellar models using the known fundamental parameters, and just the observed pulsation frequencies and measured effective temperatures, it appears that a lower value of initial helium mass fraction will most likely explain the observations of these stars.