[45.07] The Distance to the Pleiades from HST/FGS Measurements

AAS 204th Meeting, June 2004
Session 45 The Galaxy and The Magellanic Clouds
Poster, Tuesday, June 1, 2004, 10:00am-7:00pm, Ballroom

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[45.07] The Distance to the Pleiades from HST/FGS Measurements

D. R. Soderblom (STScI), G. F. Benedict (McDonald Obs.), E. Nelan (STScI), B. E. McArthur, W. Spiesman, I. Ramirez (McDonald Obs.), B. F. Jones (Lick Obs.), M. Pinsonneault (OSU), G. Torres, D. W. Latham (CfA), O. Franz, L. Wasserman (Lowell Obs.)

We have used FGS1r on HST to measure the trigonometric parallaxes of three cool dwarfs in the Pleiades open cluster. We have obtained spectra of the reference stars used in order to place these parallaxes on an absolute basis. Our net result is a parallax for the Pleiades of 7.43±.17 milliarcsec, corresponding to a distance of 135± pc, in excellent agreement with traditional estimates of the Pleiades distance from main sequence fitting. Our trigonometric determination also agrees with the recent dynamical determination of Pan et al. (2004, Nature, 427, 326). Thus two different techniques independently show that the Hipparcos determination for the Pleiades is in error.

Support for this work was provided through grant GO-08335 from the Space Telescope Science Institute, operated for NASA by AURA.

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