Gravitation: Caught by the lens

Gravitational microlensing occurs when light from a background star is amplified by an object between us and the star. This week sees publication of the first detection of a microlensing event caused by an object in a globular cluster. Unlike all other microlensing events observed so far towards the Galactic bulge and the Magellanic Clouds, the locations of the lens and source are known, making it possible to determine the mass of the lensing object with some accuracy. The body is of just over a tenth the mass of the Sun. And the existence of six further possible microlensing events of a similar type points to the intriguing possibility of a population of planetary mass objects in globular clusters.

Gravitational microlensing by low-mass objects in the globular cluster M22
KAILASH C. SAHU, STEFANO CASERTANO, MARIO LIVIO, RONALD L. GILLILAND, NINO PANAGIA, MICHAEL D. ALBROW & MIKE POTTER
Nature 411, 1022-1024 (28 June 2001)
| First Paragraph | Full Text | PDF (148 K) |

Astronomy: Planetary candidates
BOHDAN PACZYNSKI
The tentative discovery of planets roaming freely through interstellar space has far-reaching implications. If confirmed, it would imply that there are more planets on the loose than there are around stars.
Nature 411, 1002-1003 (28 June 2001)
| Full Text | PDF (75 K) |

28 June 2001 table of contents