Imaginea Astronomica a Zilei

Descopera cosmosul! In fiecare zi este prezentata o noua imagine sau fotografie a universului nostru fascinant, insotita de o explicatie scurta din partea unui astronom profesionist.

August 24, 1999
See Explanation.  Clicking on the picture will download 
 the highest resolution version available.

A Network of Microlensing Caustics
Credit & Copyright: Joachim Wambsganss (Ap. Inst. Potsdam)

Explicatie: (Edit) A virtual sky map like this would be of interest to astronomers studying gravitational microlensing. In microlensing, the gravity of stars near the line of sight can act to magnify the light of background objects such as distant stars, or quasars. Nowhere is this magnification greater than near a gravitational lensing caustic. In the above computer simulated map, caustics are discernible as the sharp bright curved lines. When a background quasar moves across a microlensing caustic, it can appear dramatically brighter. Many astronomers thought microlensing events practically immeasurable even ten years ago, but within the past five years now hundreds have been found. Precise measurements of microlensing are now providing unique information about the composition and distribution of matter in galaxies and the universe. Some astronomers now predict that future microlensing searches might even isolate planets orbiting distant stars.

Imaginea de maine: Reflections on NGC 6188


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Autori & editori: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
Reprezentanti tehnici NASA: Jay Norris. Specific rights apply.
Un serviciu al: LHEA at NASA/ GSFC
& Michigan Tech. U.