Shankland, Paul (2007) From Jets to GEMSS*: pan-spectral detection, observation and characterization of the M-Dwarf Exoplanet System Gliese 876 - and beyond. Transit photometry, radial velocity, and millimeter interferometry to constrain and characterize the nearest multiple planet system. PhD thesis, James Cook University.

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Abstract

The results of this thesis put constraints on the physical properties, and dynamics of the exoplanetary system around the 4.69 pc-distant M4 star, Gliese 876. M dwarfs are proving to be what the initial dynamical predictions here have suggested, that they could be statistically viable places to detect terrestrial planets in habitable zones. Gl 876 5 itself harbors three exoplanets: two outer gas-giants with resonating orbits, and a recently discovered ‘Super-Earth’. Differential transit photometry was conducted to put constraints on the inclination of the system, and radial velocity (RV) curves were constructed from high resolution spectroscopic data in order to discern any possible Rossiter-McLaughlin effect. Despite an initial 2003 detection of an optical flux dip, the comprehensive 2004 campaign and RV analyses produced no further transits to 3σ. Following these optical investigations, 3- and 7- mm radiointerferometric synthesis observations were performed using the Very Large Array (VLA) and Australia Telescope Compact Array (ATCA). The radio observations were optimized to detect and resolve any regenerative ~20K dust disk and further characterize its mass, inclination, resonances, and gaps. The ~400 AU primary beams afforded a sensitivity and aperture not found in previous Gl 876 studies.

The observations produced a null result, which put tighter constraints on any disk mass, which placed an upper limit of 0.0006 MEarth ± 0.0001. This lack of dust infers that Jovian planets orbiting in-close sweep dust clear, and infers a small population of dustproducing planetessimals in the system, which is also consistent with its [Fe/H] = -0.5 metallicity. The optical observations constrain the inclination of the Gl 876 system to ~50o rather than its previously thought ~90o inclination, and this result is consistent with the millimeter observations. The masses of planets “b”, “c” and “d” are optically constrained to 2.5 ± 0.MJup, 0.8 ± 0.01 MJup, and 7.5 ± 0.7 MEarth. It was further shown that novel network-distributed, targeted photometric detection schemes can produce rigorously scientific data, and further, that video-rate photometry from the stratosphere was viable.

Item ID:	10347
Item Type:	Thesis (PhD)
Keywords:	pan-spectral detection, M-Dwarf Exoplanet System, Gliese 876, transit photometry, telescopy, observation instruments, radial velocity, observation technologies, GL876, extrasolar astronomy, exoplanets, M dwarfs stars, optical observations, extrasolar planets, red dwarf planets, millimeter interferometry
Date Deposited:	24 Mar 2010 22:27
FoR Codes:	02 PHYSICAL SCIENCES > 0201 Astronomical and Space Sciences > 020102 Astronomical and Space Instrumentation @ 50% 02 PHYSICAL SCIENCES > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems @ 50%
SEO Codes:	97 EXPANDING KNOWLEDGE > 970102 Expanding Knowledge in the Physical Sciences @ 100%
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