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第1417回 天文学教室談話会

日時

2015年6月22日(月) 15:00

場所

合同C棟N507

講演者

Stevanus K. Nugroho(東北大学天文学専攻)

題目

High Contrast and High Dispersion Spectroscopy for Characterization of Directly Imaged Exoplanet: Simulated Analysis with Subaru IRCS+AO188 Spectra

要旨


In this work, using data taken by IRCS+AO188 (R~20,000) in K band for Upsilon And we simulate high contrast and high dispersion spectroscopy observation for directly imaged exoplanet. The exoplanet spectrum was produced using the data from HITRAN and VMR parameter for CO and H2O were taken from the best fit model of Snellen et al. 2014 for Beta Pic b and adjust it to represent the resolution of IRCS in echelle mode. The data were reduced following the standard procedure for IRCS. The spectrum were found to be suffered from centroid wiggling and PSF shape variation along the wavelength. The centroid wiggling along the wavelength was corrected by creating interpolated sub pixel and remapping the image according to the certain reference centroid coordinate. The Doppler shifted (30 km/s) exoplanet spectrum were injected after the centroid wiggling correction. In order to subtract the stellar profile along the slit, the PSF had to be modelled and convolved with the broadening function produced by deconvolve the broadened spectrum using SVD technique each frame and each line position along the slit. The residual frames then were combined, weighting the frames considering the mean PSF size (total time exposure ~1.8 h). We focus on the CO lines in aperture 5 and aperture 6 (2.29-2.45 micron) to do the cross correlation (CC) in each line of the combined residual frame along the slit by varying the radial velocity of the template from -150 km/s to 150 km/s. We marginally detect the signal from the combined CO lines. We are still doing research to improve the CC signal. This technique can be used as a good companion to characterise the directly imaged exoplanets that will be found by TESS, WFIRST, JWST, TMT or any other extra large telescope class since those facility observing time will be much more strict.

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【The Colloquium Committee in 2015】
Kenji Toma (toma<at>astr.tohoku.ac.jp)
Yurina Mizuno
Kohei Miyazawa
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