Observations using the NASA Infrared Telescope Facility: Exoplanets Candidates
Missouri State University
Joshua W. Kern
Abstract
On August 26, 2015, observations were taken using the NASA Infrared Telescope Facility on Mauna Kea in Hawaii. Although weather was somewhat ideal, the dome shutters were not working properly allowing for only airmasses below ~1.1 to be accessible. Because of this, we were only able to observe one exoplanet candidate, GJ725A, as well as a standard star, AlfCrB. Darks and flats were also taken to correct for errors in the data caused by instrumentation.
Introduction
The purpose of this experiment is to detect exoplanets around M dwarf stars. Gravitational interactions between the host star and an exoplanet cause the system to orbit its center of mass, in effect, causing the star to (in some cases) move toward or away from our line of view. This movement or wobble of the star causes the light to be blue or red shifted, and is seen most notably in the spectra of the star. By taking spectra of the star at different times of the orbital period of the exoplanet, we can measure the shift in the wavelength emitted by the star allowing us to calculate its radial velocity which we use to constrain the mass and orbital period of the exoplanet. Over the course of this experiment, we will (hopefully) confirm the exoplanets around thirteen M dwarf stars using this radial velocity method.
Procedures
First, sign into CSHELL and the gas cell laptop, turn on the heater and move the gas cell in front of the light beam. Ask the telescope operator to put the slit into its default position and to focus the telescope (if necessary). Set the wavelength to 2.3124 micrometers. Observations should be taken of our standard A star with the gas cell in place in order to set the wavelength to a get the deepest gas cell lines and to acquire the signal to noise ratio spectra for calibration. A flat should be taken after observing the standard A star. Science targets are now available to be observed remembering that after each object is observed a flat should be take. At the end of the night, take a few darks and remove the gas cell from the beam.
Results and Discussion
The weather on August 26, 2015 was sparsely cloudy and the humidity was hovering around %90 at the beginning of the evening. As the night progressed, the humidity level lowered to where observations could be made safely. However, in the process of opening up for observations, the dome shutters malfunctioned and wouldn't open completely restricting our view to only airmasses below ~1.1. However, a standard star and three science targets were accessible. After observing AlfCrB through the 0.5 arcsecond slit with an integration time of 30 seconds per cycle for ten cycles we obtained a SNR = ~71/exp and set the wavelength to 2.3125. We then took flats and moved onto GJ725A. After two bad observing attempts, we obtained good data with an integration time of 240 seconds for 12 cycles. The SNR for GJ725A during those cycles was ~69/exp and the airmass was 1.357. However, it was at this time that the telescope operator informed us that the dome was going to be maintained and further observations that evening were not possible. The remaining flats and darks were taken after observations had concluded.
Conclusions
The observations made on August 26, 2015 were difficult and few. Due to the varying humidity levels at the beginning of the evening and the malfunctioning of the dome shutters, we were only able to observe one science target; GJ725A. However, the data obtained for this target should be a useful part of the entire data set that will be collected through September 16th.
