Browsing by Author "Rukdee, Surangkhana"

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    Optical design and prototype of a high resolution near IR spectrograph for astronomy.
    (2019) Rukdee, Surangkhana; Vanzi, Leonardo; Pontificia Universidad Católica de Chile. Escuela de Ingeniería
    The search for extraterrestrial planets is an exciting current field of research. One of the most efficient ways to detect exoplanets is through the measurement of the Radial Velocity (RV) detection of Doppler shifts of the host star. Recently, the target of the exoplanet search has moved to cooler and lower mass stars. Although these cool stars are abundant in our galaxy, most of them are too faint to be detected by instruments operating in the visible. Thus, it requires high resolution spectroscopy in the near infrared region. In this work, we will contribute to the field by developing a cost-effective infrared spectrograph which will empower the upcoming generation of telescopes. The Tao Aiuc high Resolution (d) Y band Spectrograph (TARdYS) project is a collaboration between the Center of Astro-Engineering UC-AIUC, Chile and the University of Tokyo, Japan. The instrument is a high resolution near infrared spectrograph for astronomy being developed at the AIUC for installation at the Tokyo Atacama Observatory TAO 6.5 m. telescope. TARdYS is optimized for the precise measurement of radial velocities of cool stars. For this science purpose, the instrument requires high resolution > 60,000 and RV precision of 5 m/s. Moreover, it will also be a powerful tool for the study of astroseismology, star-forming regions, and exoplanet atmosphere. The requirements of the instrument are derived from the science objectives and budget constraint. We select a 1kx1k infrared detector and an R6 echelle disperser. This choice enables high resolution with a small beam diameter. TARdYS can yield a spectral resolution > 60,000 within the spectral coverage from 0.843-1.117 m. We plan to use a cryogenic Dewar in the last part of the objectives to minimize the background radiation reaching the detector. Thus, this will be operated in a semi-cryogenic system as a cost-effective solution. In this work, I created and evaluated the optical design of the two different configurations for a cost-effective high resolution near-infrared spectrograph. This work tests a cost-effective solution with less widely tested spectrograph choices, especially an R6 echelle, and only a semi-cryogenic setup. Optimization with computer-aided simulations yields excellent spectral resolution at the diffraction limit even when taking realistic manufacturing and alignment tolerances into account. I built a prototype of the spectrograph using commercially available components and determined its performance. The measured spectral resolution agrees well with the simulation. With a simple temperature control, I achieved a stability of ±0.1K over several hours. The remaining spectral drift is predominately caused by environmental pressure. Once TARdYS is installed at TAO, it will become available as a exoplanet hunter to the Chilean science community.
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    Precision stellar radial velocity measurements with FIDEOS at the ESO 1-m telescope of La Silla
    (2018) Vanzi, Leonardo; Zapata, Abner; Flores, M.; Brahm Scott, Rafael; Tala Pinto, M.; Rukdee, Surangkhana; Jones Fernández, Matías Ignacio; Ropert, S.; Shen, T.; Ramirez, S.; Suc, V.; Jordán, A.; Espinoza, N.
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    Quantifying the Bayesian Evidence for a Planet in Radial Velocity Data
    (2020) Nelson, B. E.; Ford, E. B.; Buchner, J.; Cloutier, R.; Diaz, R. F.; Faria, J. P.; Hara, N. C.; Rajpaul, V. M.; Rukdee, Surangkhana
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    TARdYS: Design and prototype of an exoplanet hunter for TAO using a R6 Echelle grating
    (2019) Rukdee, Surangkhana; Vanzi, Leonardo; Schwab, C.; Flores Cabrales, Mauricio Fabián; Valenzuela Navarro, Álvaro Enrique Hernán; Pember, J.; Zapata, Abner; Motohara, K.; Yoshii, Y.; Tala Pinto, M.
    One limitation in characterizing exoplanet candidates is the availability of infrared, high-resolution spectrographs. An important factor in the scarcity of high precision IR spectrographs is the high cost of these instruments. We present a new optical design, which leads to a cost-effective solution. Our instrument is a high-resolution (R = 60,000) infrared spectrograph with a R6 Echelle grating and an image slicer. We compare the best possible performance of quasi-Littrow and White Pupil setups, and prefer the latter because it achieves higher image quality. The instrument is proposed for the University of Tokyo Atacama Observatory (TAO) 6.5 m telescope in Chile. The Tao Aiuc high Resolution (d) Y band Spectrograph (TARdYS) covers 0.843-1.117 mu m. To reduce the cost, we squeeze 42 spectral orders onto a 1K detector with a semi-cryogenic solution. We obtain excellent resolution even when taking realistic manufacturing and alignment tolerances as well as thermal variations into account. In this paper, we present early results from the prototype of this spectrograph at ambient temperature.