Milky Way MACHO detected

From: Damien Broderick (
Date: Fri Dec 07 2001 - 20:09:27 MST

By fusing microlensing light data, high-resolution images and
 spectroscopy, researchers can finally view a complete picture
 of a MACHO (Massive Compact Halo Object) by measuring
 its mass, distance and velocity. This demonstrates that
 precision brightness measurements and extensive follow-up
 will allow astronomers to characterize a significant fraction of
 the Milky Way's dark matter. The work is presented in the
 Dec. 6 issue of Nature.

 The team of scientists used the NASA/ESA Hubble Space
 Telescope and the Europeans Southern Observatory's Very
 Large Telescope to take images and make spectra of a
 MACHO microlens --which turned out to be a red star in the
 Milky Way.

 The observation makes it possible to determine the mass of the
 MACHO and its distance from the Earth. In this case, the
 MACHO is a small star with a mass between 5 percent and 10
 percent of the mass of the sun at a distance of 600 light-years.
 This makes the MACHO a dwarf star and a faint member of
 the disk population of stars in the Milky Way.

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