Tracers of chromospheric structure. I. CaII H&\&K emission distribution of 13000 F, G and K stars in SDSS DR7 spectroscopic sample

We present chromospheric activity index $S\rm_{HK}$ 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 $\delta$S is defined as the difference between $S\rm_{HK}$ and a `zero' emission line fitted by several of the most inactive stars. The $S\rm_{HK}$ 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 $S\rm_{HK}$ 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.Comment: 9 pages, 11 figures, AJ, 2013, 145, 14

Maximizing groundnut production

The cu1tivated groundnut (Arachis hypogaea L.) probably originated in Bolivia or Argentina at the base of the Andes (Krapovickas 1968). Groundnut belongs to the family Fabaceae of the tribe aeschynomene..

Genetics and Breeding of Groundnut

The objective of a crop breeding program is to create variability and select the desirable genotype (s) for cultivation or for breeding purposes. Groundnut, being a highly self-pollinated crop, requires special attention in emasculation, crossing, and selection as these processes require special skills and may be time consuming. Genetic studies assist the breeder in understanding the inheritance mechanism and enhance the efficiency of a breeding program. Considerable progress has been made in genetics and plant breeding of groundnut during the last three decades (see reviews Wynne and Gregory 1981; Wynne and Coffelt 1982; Norden et al. 1982; Reddy 1988; and Wynne and Halward 1 9 8 9 ) . An attempt has been made to compile the recorded experiences of groundnut breeders and geneticists. Questions are provided to assist in self evaluation of selected skills by the, readers

70 DA White Dwarfs Identified in Lamost Pilot Survey

We present a spectroscopically identified catalog of 70 DA white dwarfs (WDs) from the LAMOST pilot survey. Thirty-five are found to be new identifications after cross-correlation with the Eisenstein et al. and Villanova catalogs. The effective temperature and gravity of these WDs are estimated by Balmer lines fitting. Most of them are hot WDs. The cooling times and masses of these WDs are estimated by interpolation in theoretical evolution tracks. The peak of the mass distribution is found to be ∼0.6M, which is consistent with prior work in the literature. The distances of these WDs are estimated using the method of synthetic spectral distances. All of these WDs are found to be in the Galactic disk from our analysis of space motions. Our sample supports the expectation that WDs with high mass are concentrated near the plane of the Galactic disk