We confirm the difference of chemical abundance between stars with and without exoplanet, as well as present the relation between chemical abundances and the physical properties of exoplanets such as planetary mass and semi-major axis of planetary orbit. We have obtained the spectra of 52 G-type stars with BOES (BOAO Echelle Spectrograph) and carried out the abundance analysis for 12 elements of Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Co, and Ni. We first have found that the [Mn/Fe] ratios of planet-host stars are higher than those of comparisons in the whole metallicity range, and in metal-poor stars of [Fe/H] < -0.4, the abundance difference have been larger than in metal-rich samples, especially for the elements of Mg, Al, Sc, Ti, V, and Co. When examined the relation between planet properties and metallicities of planet-host stars, we have observed that planet-host stars with low-metallicity tend to bear several low-mass planets (< M J ) instead of a massive gas-giant planet.The G-type stars among Planet-Host Stars (PHSs) were gathered from several exoplanet references (Butler et al. 2006; http://exoplanet.eu 2009). Some controversial objects (HD 24040, HD 33636, and HD 137510) are excluded in the list of PHS and regarded as the comparison targets. We have constrained the PHS samples to the G-type stars with δ > −10 • and V < 9.0, in the conditions that can be observable and bright enough to obtain high S/N ratio spectra with 1.8 m telescope at BOAO (Bohyunsan Optical Astronomy Observatory). The comparison stars with no known planets were adopted from The Tycho-2 Spectral Type Catalog (Wright et al. 2003). These comparison stars also have δ > −10 • and V < 9.0 in the solar-neighborhood G-type stars within the distance of 20 pc from the Sun. For this abundance study, we have presented the results of 34 PHSs and 18 comparison stars in the list of G-type stars. Observations and Data ReductionThe observations were carried out with the 1.8 m telescope at BOAO on 2008 and 2009. All spectra were obtained with BOES (BOAO Echelle Spectrograph) using 200 or 300 µm fiber. The observed spectra have a spectral resolution, R ∼ either about 30,000 (using 300µm fiber) or 45,000 (using 200 µm fiber), and S/N ratios of higher than 150 at 6070Å.The wavelength range of the spectra is from 3800Å to 8800Å, covering full optical region.The observational log and basic data of 52 targets are listed in Table 1. In this table, the column 2 to 4 show observation date, exposure time (sec) and signal-to-noise ratio at 6070A. The column 5 shows the radial velocity which was estimated by the difference between
We present the results of high resolution (R≥30,000) optical and near-IR spectroscopic monitoring observations of HBC 722, a recent FU Orionis object that underwent an accretion burst in 2010. We observed HBC 722 in optical/near-IR with the BOES, HET-HRS, and IGRINS spectrographs, at various points in the outburst. We found atomic lines with strongly blueshifted absorption features or P Cygni profiles, both evidence of a wind driven by the accretion. Some lines show a broad double-peaked absorption feature, evidence of disk rotation. However, the wind-driven and disk-driven spectroscopic features are anti-correlated in time; the disk features became strong as the wind features disappeared. This anti-correlation might indicate that the rebuilding of the inner disk was interrupted by the wind pressure during the first two years. The Half-Width at Half-Depth (HWHD) of the double-peaked profiles decreases with wavelength, indicative of the Keplerian rotation; the optical spectra with the disk feature are fitted by a G5 template stellar spectrum convolved with a rotation velocity of 70 km s −1 while the near-IR disk features are fitted by a K5 template stellar spectrum convolved with a rotation velocity of 50 km s −1 . Therefore, the optical and near-IR spectra seem to trace the disk at 39 and 76 R ⊙ , respectively.We fit a power-law temperature distribution in the disk, finding an index of 0.8, comparable to optically thick accretion disk models.
We present a library of high-resolution (R ≡ λ/∆λ ∼ 45,000) and high signal-to-noise ratio (S/N ≥ 200) near-infrared spectra for stars of a wide range of spectral types and luminosity classes. The spectra were obtained with the Immersion GRating INfrared Spectrograph (IGRINS) covering the full range of the H (1.496-1.780 µm) and K (2.080-2.460 µm) atmospheric windows. The targets were primarily selected for being MK standard stars covering a wide range of effective temperatures and surface gravities with metallicities close to the Solar value. Currently, the library includes flux-calibrated and telluric-absorption-corrected spectra of 84 stars, with prospects for expansion to provide denser coverage of the parametric space. Throughout the H and K atmospheric windows, we 2 Park et al.identified spectral lines that are sensitive to T eff or log g and defined corresponding spectral indices.We also provide their equivalent widths. For those indices, we derive empirical relations between the measured equivalent widths and the stellar atmospheric parameters. Therefore, the derived empirical equations can be used to calculate T eff and log g of a star without requiring stellar atmospheric models.
We present a tool for measuring the equivalent width (EW) in high-resolution spectra. The Tool for Automatic Measurement of Equivalent width (TAME)provides the EWs of spectral lines by profile fitting in the automatic or the interactive mode, which can yield a more precise result through the adjustment of the local continuum and fitting parameters. The automatic EW results of TAME have been verified by comparing them with the manual EW measurements by IRAF splot task using the high-resolution spectrum of the Sun, and measuring EWs in the synthetic spectra with different spectral resolutions and S/N ratios. The EWs measured by TAME agree well with manually measured values, with a dispersion of less than 2 mA. By comparing the input EWs for synthetic spectra and EWs measured by TAME, we conclude that it is reliable for measuring the EWs in a spectrum with a spectral resolution, R > 20000 and find that the errors in EWs is less than 1 mA for a S/N ratio > 100.Comment: 27 pages, 10 figures, and 1 tabl
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