Fabrication of superconducting magnesium diboride thin films by electron beam annealing

Xiangdong Kong, Qian Dai, Li Han, Qingrong Feng, Zhaoshun Gao, Yanwei Ma, Mingzhang Chu, Hong Xue, Jianguo Li, Furen Wang, Yibing Zhang
2011 Superconductors Science and Technology  
We construct high signal-to-noise "template" spectra by co-adding hundreds of spectra of nearby dwarfs spanning K7 to M4, taken with Keck/HIRES as part of the California Planet Search. We identify several spectral regions in the visible (370-800 nm) that are sensitive to the stellar luminosity and metallicity. We use these regions to develop a spectral calibration method to measure the mass, metallicity, and distance of low-mass stars, without the requirement of geometric parallaxes. Testing
more » ... allaxes. Testing our method on a sample of nearby M dwarfs, we show that we can reproduce stellar masses to about 8%-10%, metallicity to ∼0.15 dex, and distance to 11%. We were able to make use of HIRES spectra obtained as part of the radial velocity monitoring of the star KOI-314 to derive a new mass estimate of 0.57 ± 0.05 M , a radius of 0.54 ± 0.05 R , a metallicity, [Fe/H], of −0.28 ± 0.10, and a distance of 66.5 ± 7.3 pc. Using HARPS archival data and combining our spectral method with constraints from transit observations, we are also able to derive the stellar properties of GJ 3470, a transiting planet hosting M dwarf. We estimate a mass of 0.53 ± 0.05 M , a radius of 0.50 ± 0.05 R , a metallicity, [Fe/H], of 0.12 ± 0.12, and a distance of 29.9± 3.7 3.4 pc.
doi:10.1088/0953-2048/24/10/105013 fatcat:uvn4fn2cazf23ankkohcco37i4