4.7 Article

Star-spots and magnetism: testing the activity paradigm in the Pleiades and M67

期刊

出版社

OXFORD UNIV PRESS
DOI: 10.1093/mnras/stac2706

关键词

stars: activity; stars: fundamental parameters; stars: late-type; stars: magnetic field; stars: rotation; star-spots

资金

  1. Ohio State University College of Arts and Sciences
  2. NASA [80NSSC19K0597]
  3. Alfred P. Sloan Foundation
  4. U.S. Department of Energy Office of Science
  5. Center for High Performance Computing at the University of Utah
  6. Brazilian Participation Group
  7. Carnegie Institution for Science, Carnegie Mellon University
  8. Center for Astrophysics | Harvard Smithsonian
  9. Chilean Participation Group
  10. French Participation Group
  11. Instituto de Astrofisica de Canarias, The Johns Hopkins University
  12. Kavli Institute for the Physics and Mathematics of the Universe (IPMU) / University of Tokyo
  13. Korean Participation Group
  14. Lawrence Berkeley National Laboratory
  15. Leibniz Institut fur Astrophysik Potsdam (AIP)
  16. Max-Planck-Institut fur Astronomie (MPIA Heidelberg)
  17. Max-Planck-Institut fur Astrophysik (MPA Garching)
  18. Max-Planck-Institut fur Extraterrestrische Physik (MPE)
  19. National Astronomical Observatories of China
  20. New Mexico State University
  21. New York University
  22. University of Notre Dame
  23. Observatario Nacional / MCTI
  24. Ohio State University
  25. Pennsylvania State University
  26. Shanghai Astronomical Observatory
  27. United Kingdom Participation Group
  28. Universidad Nacional Autonoma de Mexico
  29. University of Arizona
  30. University of Colorado Boulder
  31. University of Oxford
  32. University of Portsmouth
  33. University of Utah
  34. University of Virginia
  35. University of Washington
  36. University of Wisconsin
  37. Vanderbilt University
  38. Yale University
  39. National Aeronautics and Space Administration
  40. National Science Foundation

向作者/读者索取更多资源

This study measures star-spot filling fractions for 240 stars in the Pleiades and M67 open star clusters using APOGEE high-resolution H-band spectra. A modified spectroscopic pipeline is developed to solve for star-spot filling fraction and star-spot temperature contrast. The results show that this technique can recover real star-spot signals and has an impact on the filling fractions and effective temperatures of active stars.
We measure star-spot filling fractions for 240 stars in the Pleiades and M67 open star clusters using APOGEE high-resolution H-band spectra. For this work, we developed a modified spectroscopic pipeline which solves for star-spot filling fraction and star-spot temperature contrast. We exclude binary stars, finding that the large majority of binaries in these clusters (80 per cent) can be identified from Gaia DR3 and APOGEE criteria - important for field star applications. Our data agree well with independent activity proxies, indicating that this technique recovers real star-spot signals. In the Pleiades, filling fractions saturate at a mean level of 0.248 +/- 0.005 for active stars with a decline at slower rotation; we present fitting functions as a function of Rossby number. In M67, we recover low mean filling fractions of 0.030 +/- 0.008 and 0.003 +/- 0.002 for main sequence GK stars and evolved red giants, respectively, confirming that the technique does not produce spurious spot signals in inactive stars. Star-spots also modify the derived spectroscopic effective temperatures and convective overturn time-scales. Effective temperatures for active stars are offset from inactive ones by -109 +/- 11 K, in agreement with the Pecaut & Mamajek empirical scale. Star-spot filling fractions at the level measured in active stars changes their inferred overturn time-scale, which biases the derived threshold for saturation. Finally, we identify a population of stars statistically discrepant from mean activity-Rossby relations and present evidence that these are genuine departures from a Rossby scaling. Our technique is applicable to the full APOGEE catalogue, with broad applications to stellar, galactic, and exoplanetary astrophysics.

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