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Project Progress

During this past year Laws and Gonzalez completed the reduction and initial analysis of all our remaining spectra of planet-hosting stars and proper motion pairs. Laws and Claire developed extensive new software tools to enable processing of large volumes of echelle data and resultant stellar spectra in significantly less time than previously possible. With these tools in hand, we began an ambitious survey program at the Apache Point Observatory to observe several dozen additional stars that are not currently known to harbor planets, but which are under observation by various Doppler-search groups and are furthermore implicated by photometry to be metal-rich.

We reported our initial findings on the non-Fe elemental abundances of stars (and proper motion pairs) hosting giant planets at the Winter Meeting of the American Astronomical Society. We discovered a small but significant trend of increasing elemental abundance with higher condensation temperature that further correlated with decreasing convective envelope mass. We suggested that this is evidence that planet-hosting stars have indeed accreted volatile depleted materials, although not in sufficient quantities to be responsible for the general excess of metals in these stars, which we previously discovered and confirmed. We are currently preparing a full journal article that expands on these findings, as well as a second paper describing our results on the proper motion pairs (with and without planetary companions).

Our paper on the unusual star J37, an A star in the young cluster NGC6633, was published in October, 2003. We determined that no known single process can account for the observed pattern of elemental abundances in J37, and found evidence suggesting that this star has accreted material similar in composition to that of the Earth.