Cepheids
Pulsating Stars Under the Spanish Sun
15/09/11 18:00
I just returned from a conference in Granada Spain on Stellar Pulsation, I took some pictures that you can see here. The conference was very interesting, discussing almost all aspects of pulsating variable stars, the city was amazing, with clear skies and 30 degree heat and no, absolutely no humidity. The only problem was getting there.
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Naples and the Distance to Everything
20/05/11 18:19
After I returned to Germany from China, I turned right back around and hopped on a plane to Naples for a conference on the Cosmic Distance Scale. The goal of this conference was to understand how well astronomers can measure the distances to far away stellar objects and galaxies and use this information to measure the rate of expansion of the universe, denoted by Hubble’s Constant H0. By more precisely measuring the expansion, it is hoped that we can better understand the structure of the universe, and the physics of the universe such as dark energy. Read More...
Stellar Astrophysics in Lijiang
16/05/11 19:44
I returned a week ago from a couple of conferences, one in Lijiang, China, and one in Naples, Italy. I’ll write about the latter conference in a later post. The conference in Lijiang was titled The 9th Pacific Rim Conference on Stellar Astrophysics and featured a number of presentations and posters on various aspects of stellar astronomy from star formation to Cepheids to black holes. Read More...
The Cepheid mass discrepancy and pulsation-driven mass loss
08/04/11 08:04
Just had a letter accepted for publication in Astronomy & Astrophysics titled “The Cepheid mass discrepancy and pulsation-driven mass loss” co-authored with Dr. Matteo Cantiello and Prof. Norbert Langer from the Argelander Institute for Astronomy. The abstract is
Context. A longstanding challenge for understanding classical Cepheids is the Cepheid mass discrepancy, where theoretical mass estimates using stellar evolution and stellar pulsation calculations have been found to differ by approximately 10 - 20%. Aims. We study the role of pulsation-driven mass loss during the Cepheid stage of evolution as a possible solution to this mass discrepancy.
Methods. We computed stellar evolution models with a Cepheid mass-loss prescription and various amounts of convective core overshooting. The contribution of mass loss towards the mass discrepancy is determined using these models, Results. Pulsation-driven mass loss is found to trap Cepheid evolution on the instability strip, allowing them to lose about 5 − 10% of their total mass when moderate convective core overshooting, an amount consistent with observations of other stars, is included in the stellar models.
Conclusions. We find that the combination of moderate convective core overshooting and pulsation-driven mass loss can solve the Cepheid mass discrepancy.
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Context. A longstanding challenge for understanding classical Cepheids is the Cepheid mass discrepancy, where theoretical mass estimates using stellar evolution and stellar pulsation calculations have been found to differ by approximately 10 - 20%. Aims. We study the role of pulsation-driven mass loss during the Cepheid stage of evolution as a possible solution to this mass discrepancy.
Methods. We computed stellar evolution models with a Cepheid mass-loss prescription and various amounts of convective core overshooting. The contribution of mass loss towards the mass discrepancy is determined using these models, Results. Pulsation-driven mass loss is found to trap Cepheid evolution on the instability strip, allowing them to lose about 5 − 10% of their total mass when moderate convective core overshooting, an amount consistent with observations of other stars, is included in the stellar models.
Conclusions. We find that the combination of moderate convective core overshooting and pulsation-driven mass loss can solve the Cepheid mass discrepancy.
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