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dc.contributor.authorZhao, J.K.
dc.contributor.authorOswalt, Terry D.
dc.contributor.authorLu, Q.H.
dc.contributor.authorLuo, A.L.
dc.contributor.authorZhang, L.Y.
dc.contributor.authorZhao, G.
dc.date.accessioned2013-10-08T17:39:18Z
dc.date.available2013-10-08T17:39:18Z
dc.date.issued2013-05
dc.identifier.citationZhao, J. K., Oswalt, T. D., Zhao, G., Lu, Q. H., Luo, A. L., & Zhang, L. Y. (2013). Tracers of Chromospheric Structure. I. Ca II H&K Emission Distribution of 13,000 F, G, and K Stars in SDSS DR7 Spectroscopic Sample. The Astronomical Journal, 145(5), 140.en_US
dc.identifier.urihttp://hdl.handle.net/11141/75
dc.description.abstractWe present chromospheric activity index SHK measurements for over 13,000 F, G, and K disk stars with high signal-to-noise ratio (>60) spectra in the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) spectroscopic sample. A parameter δS is defined as the difference between SHK and a “zero” emission line fitted by several of the most inactive stars. The SHK indices of subgiant stars tend to be much lower than dwarfs, which provide a way to distinguish dwarfs and giants with relatively low-resolution spectra. Cooler stars are generally more active and display a larger scatter than hotter stars. Stars associated with the thick disk are in general less active than those of the thin disk. The fraction of K dwarfs that are active drops with vertical distance from the Galactic plane. Metallicity affects SHK measurements differently among F, G, and K dwarfs in this sample. Using the open clusters NGC 2420, M67, and NGC 6791 as calibrations, ages of most field stars in this SDSS sample range from 3 to 8 Gyr.en_US
dc.language.isoen_USen_US
dc.rightsThis published article is available in accordance with the publisher's policy. It may be subject to U.S. copyright lawen_US
dc.rights.urihttp://aas.org/publications/aas-copyright-policyen_US
dc.titleTracers of chromospheric structure.I. Ca ii H&K emission distribution of 13,000 F, G, and K stars in SDSS DR7 spectroscopic sampleen_US
dc.typeArticleen_US
dc.identifier.doi10.1088/0004-6256/145/5/140


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