The Ages Of The Old Open Clusters Ngc 188 Ngc 6791 Melotte 66 And Ngc 2204 Microform

Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721653164
Total Pages : 28 pages
Book Rating : 4.6/5 (531 download)

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Download or read book Membership and Coronal Activity in the Ngc 2232 and Cr 140 Open Clusters written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-21 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Making use of eight archival ROSAT HRI images in the regions of the NGC 2232 and Cr 140, this project's primary focus is to identify X-ray sources and to extract net source counts for these sources in these two open clusters. These X-ray data would be combined with ground-based photometry and spectroscopy in order to identify G, K, and early-M type cluster members. Such membership data are important because, at present, no members later than spectral type approx. F5 are currently known for either cluster. With ages estimated to be approx. 25 Myr and at distances of just approx. 350 pc, the combined late-type membership of the NGC 2232 and Cr 140 clusters would yield an almost unique sample of solar-type stars in the post-T Tauri/pre-main sequence phase of evolution. These stars could be used to assess the level and dispersion of coronal activity levels, as a part of a probe of the importance of magnetic braking and the level of magnetic dynamo activity, for solar-type stars just before they reach the zero-age main sequence. Oliversen, Ronald J. (Technical Monitor) and Patten, Brian M. Goddard Space Flight Center