Submitting Campus

Daytona Beach

Department

Physical Sciences

Document Type

Article

Publication/Presentation Date

4-10-2013

Abstract/Description

We 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 S 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 NGC6791 as calibrations, ages of most field stars in this SDSS sample range from 3-8 Gyr.

Publication Title

The Astrophysical journal

DOI

https://doi.org/10.1088/0004-6256/145/5/140

Publisher

The Institute of Physics

Grant or Award Name

NSF grant AST-0807919, NSFC grants 11078019, 11233004, 10978010, 10973021

Additional Information

Dr. Oswalt was not affiliated with Embry-Riddle Aeronautical University at the time this paper was published.

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