STELLA Open Cluster Survey (SOCS): Ein besseres Verständnis der Sternrotation und offener Sternhaufen

• Antragsteller: Dr. Sydney A. Barnes
• Fachliche Zuordnung: Astrophysik und Astronomie
• Förderung: Förderung von 2018 bis 2023
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 398177380

• Erstellungsjahr: 2024

Zusammenfassung der Projektergebnisse

This project was aimed at carefully constructing the rotation period distributions of a series of open clusters to characterize those distributions and to examine their systematics, especially with respect to mass and age. This involves a large amount of precision time-series photometry to construct and analyse light curves of the cool stars in those clusters to derive reliable rotation periods. One of the main goals of the project was to help to further develop the emerging field of gyrochonology, a method whereby the age of a cool star can be derived from its rotation period. There are two main difficulties that attend such a project: 1. It is actually logistically difficult to assemble precise time-series photometry over the long baselines (several weeks to a few months) necessary from the ground, whereas from space the directionality is limited, and 2. The rotational variability of cool stars decreases with stellar age, so that excellent precision is required from ground-based monitoring, and sometimes there is no option but to take recourse to any space-based data that might be available. This project, while nominally a ground-based one, took advantage of both the ground and space options. By constructing a series of rotational distributions for open clusters of different ages, using a heavy dose of ground-based data and specific use of opportune space-based data, this project was able to further develop gyrochronology, a method of deriving ages for cool stars. The biggest surprise that the project had to deal with was the Sars Covid pandemic, which of course caused worldwide disruption. This project was no different, with project-related individuals needing to work at home while juggling family responsibilities. One of the project participants went on maternity leave, leading to the extension of the project. We also had to contend with the inability to travel to Tenerife to conduct the required telescope maintenance at the STELLA observatory, but were able to compensate for this by resorting to use of data from the CTIO observatory. In addition, we were able to add a space-based component that was not originally envisaged. This latter work was particularly useful in extending our project results to ages that were not originally foreseen. Thus, we are pleased to report that the project was very successful, with nine large refereed papers already published, and a couple of follow-on papers still in preparation. The related age derivation method, called gyrochronology, is in routine use now, and is envisioned to be one of the main methods (the others being asteroseismology and stellar activity) for deriving the ages of stars from the PLATO mission. The relevant publications are wellcited, with citations to the project-related publications themselves already in excess of one hundred, and we expect that number to increase substantially in the coming years.

Projektbezogene Publikationen (Auswahl)

• Spectroscopic membership for the populous 300 Myr-old open cluster NGC 3532. Astronomy & Astrophysics, 622, A110.
  Fritzewski, D. J.; Barnes, S. A.; James, D. J.; Geller, A. M.; Meibom, S. & Strassmeier, K. G.
  
• Rotation periods for cool stars in the open cluster Ruprecht 147 (NGC 6774). Astronomy & Astrophysics, 644, A16.
  Gruner, D. & Barnes, S. A.
  
• The rotation period distribution of the rich Pleiades-age southern open cluster NGC 2516. Astronomy & Astrophysics, 641, A51.
  Fritzewski, D. J.; Barnes, S. A.; James, D. J. & Strassmeier, K. G.
  
• A detailed understanding of the rotation-activity relationship using the 300 Myr old open cluster NGC 3532. Astronomy & Astrophysics, 656, A103.
  Fritzewski, D. J.; Barnes, S. A.; James, D. J.; Järvinen, S. P. & Strassmeier, K. G.
  
• Rotation periods for cool stars in the open cluster NGC 3532. Astronomy & Astrophysics, 652, A60.
  Fritzewski, D. J.; Barnes, S. A.; James, D. J. & Strassmeier, K. G.
  
• A rotational age for the open cluster NGC 2281. Astronomy & Astrophysics, 674, A152.
  Fritzewski, D. J.; Barnes, S. A.; Weingrill, J.; Granzer, T.; Cole-Kodikara, E. & Strassmeier, K. G.
  
• New insights into the rotational evolution of near-solar age stars from the open cluster M 67. Astronomy & Astrophysics, 672, A159.
  Gruner, D.; Barnes, S. A. & Weingrill, J.
  
• The rotation period distribution in the young open cluster NGC 6709. Astronomy & Astrophysics, 673, A119.
  Cole-Kodikara, E. M.; Barnes, S. A.; Weingrill, J. & Granzer, T.
  
• Wide binaries demonstrate the consistency of rotational evolution between open cluster and field stars. Astronomy & Astrophysics, 675, A180.
  Gruner, D.; Barnes, S. A. & Janes, K. A.