Faculty Mentor

Gregory Feiden

Proposal Type

Poster

Start Date

3-11-2018 3:20 PM

End Date

3-11-2018 4:30 PM

Location

Nesbitt 3110

Abstract

Accurate age estimates provide a wealth of information about the mechanisms of different astrophysical phenomenon. However, current methods of applying stellar evolution models to obtain these estimates has proven to be flawed, with models having little consistency. It has been speculated the source of this inconsistency may arise from deviations in stellar properties due to the presence of dark blemishes, starspots, present on young cool stars (Feiden, 2016). Using predictions of expected properties from the flexible starspot model to observed properties of various open clusters, we aim to define what starspot properties bring model predictions into agreement with observed data. The clusters of interest include the Pleiades (~125 Myr), and Praesepe (~700 Myr). Further, we aim to define which properties are required for different mechanisms of starspot formation. These mechanisms explain how a star may react to a starspot depending on where the starspot forms and include; the star inflating to redistribute flux trapped beneath the spot, the star’s photosphere heating to redistribute the trapped flux, and the star merely appearing dimmer and redder given the starspot exists for a short enough time period. Thus far, results have demonstrated the inability of models assuming a heated photosphere to mimic the data. Results for the inflationary models and short timescale models have been difficult to distinguish, with the short timescale models being more consistent with expected temperature contrast values, but the inflationary models generally providing lower surface coverage (Berdyugina, 2005). Our work demonstrates starspots can improve the accuracy of predictions from stellar evolution models. Future efforts to define a mechanism of starspot formation will continue to improve stellar age estimates, and as such, provide a more complete understanding of the planetary formation period

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Nov 3rd, 3:20 PM Nov 3rd, 4:30 PM

4 - A Flexible Model for Investigating the Properties of Starspots: Comparison of Model Predictions to Observed Data

Nesbitt 3110

Accurate age estimates provide a wealth of information about the mechanisms of different astrophysical phenomenon. However, current methods of applying stellar evolution models to obtain these estimates has proven to be flawed, with models having little consistency. It has been speculated the source of this inconsistency may arise from deviations in stellar properties due to the presence of dark blemishes, starspots, present on young cool stars (Feiden, 2016). Using predictions of expected properties from the flexible starspot model to observed properties of various open clusters, we aim to define what starspot properties bring model predictions into agreement with observed data. The clusters of interest include the Pleiades (~125 Myr), and Praesepe (~700 Myr). Further, we aim to define which properties are required for different mechanisms of starspot formation. These mechanisms explain how a star may react to a starspot depending on where the starspot forms and include; the star inflating to redistribute flux trapped beneath the spot, the star’s photosphere heating to redistribute the trapped flux, and the star merely appearing dimmer and redder given the starspot exists for a short enough time period. Thus far, results have demonstrated the inability of models assuming a heated photosphere to mimic the data. Results for the inflationary models and short timescale models have been difficult to distinguish, with the short timescale models being more consistent with expected temperature contrast values, but the inflationary models generally providing lower surface coverage (Berdyugina, 2005). Our work demonstrates starspots can improve the accuracy of predictions from stellar evolution models. Future efforts to define a mechanism of starspot formation will continue to improve stellar age estimates, and as such, provide a more complete understanding of the planetary formation period