4 research outputs found
Precise Stellar Radial Velocities of an M Dwarf with a Michelson Interferometer and a Medium-resolution Near-infrared Spectrograph
Precise near-infrared radial velocimetry enables efficient detection and
transit verification of low-mass extrasolar planets orbiting M dwarf hosts,
which are faint for visible-wavelength radial velocity surveys. The TripleSpec
Exoplanet Discovery Instrument, or TEDI, is the combination of a variable-delay
Michelson interferometer and a medium-resolution (R=2700) near-infrared
spectrograph on the Palomar 200" Hale Telescope. We used TEDI to monitor GJ
699, a nearby mid-M dwarf, over 11 nights spread across 3 months. Analysis of
106 independent observations reveals a root-mean-square precision of less than
37 m/s for 5 minutes of integration time. This performance is within a factor
of 2 of our expected photon-limited precision. We further decompose the
residuals into a 33 m/s white noise component, and a 15 m/s systematic noise
component, which we identify as likely due to contamination by telluric
absorption lines. With further development this technique holds promise for
broad implementation on medium-resolution near-infrared spectrographs to search
for low-mass exoplanets orbiting M dwarfs, and to verify low-mass transit
candidates.Comment: 55 pages and 13 figures in aastex format. Accepted by PAS
Recommended from our members
β-delayed neutron studies of 137−138I and 144−145Cs performed with trapped ions
The β-delayed neutron (βn) emission decay mode, prevalent in a vast number of neutron- rich nuclei, influences abundances calculated in the r-process nucleosynthesis models, affects nuclear reactor safety analysis calculations, and can illuminate aspects of nuclear structure. This thesis describes a newly developed recoil ion detection technique that was applied for high-precision βn branching ratio and neutron energy measurements of 137−138I and 144−145Cs. The recoil ion measurement approach avoids difficulties associated with direct neutron detec- tion by instead detecting the daughter ion recoiling from neutron emission. The radioactive ions of interest are held in near-rest with the use of an ion trap, from which they leave the trap upon β or βn decay. The detector array surrounding the trap measures the time-of- flight of the recoil ion, as well as several associated decay products. Measuring the recoil ion’s time-of-flight determines the recoil energy, from which the emitted neutron’s energy can be deduced. Detecting other decay products gives rise to three different methods of measuring the βn branching ratio, which helps expose systematic effects. The technique builds upon a previous proof-of-principle experiment, and was expanded for the present measurements to include twice as many improved detectors, an upgraded ion trap, and a stronger source. This thesis also examines various backgrounds and detailed detector characterizations. The experimental campaign presented here serves to probe the limits of applying the recoil ion technique to explore further into the neutron-rich region