An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 3 Search : microlensing
microlensing
  ریز‌لنزش   
riz-lenzeš

Fr.: effet de microlentille   

A type of → gravitational lens, where the foreground → lensing object is of low mass, and the multiple images produced are too close together on the sky to be observed as separate images. Gravitational microlensing occurs when a foreground star happens to lie very close to our line of sight to a more distant background star. The foreground star acts as a lens, splitting the light from the background source star into two or more images, which are typically unresolved. However, these images of the source are magnified, by an amount that depends on the angular separation between the lens and source. If with the passage of time the lens moves across the Earth-source, the amount of brightening changes. Typically the source will appear to brighten, reach a maximum and then fade symmetrically back to normal over the course of a few weeks or months; this is called a → microlensing event. If the foreground star happens to host a planet with projected separation near the paths of these images, the planet will also act as a lens, further perturbing the images and resulting in a characteristic, short-lived signature of the planet. Microlensing is used in the search for → dark matter in the → Milky Way galaxy and its nearest neighbours, as well as for → extrasolar planets (e.g. B. S. Gaudi, 2010, arXiv:1002.0332).

micro-; → lensing.

microlensing degeneracy
  واگنی ِ ریز‌لنزش   
vâgeni-ye riz-lenzeš

Fr.: dégénérescence des paramètres de l'effet de microlentille   

Determining the three various parameters of a microlensing event (the lens-source relative parallax and proper motion, and the mass of the lens) from only one physical parameter (the event time scale). Currently the microlensing degeneracy affects the vast majority of events and makes any individual event impossible to interpret with certainty.

microlensing; → degeneracy.

microlensing event
  رویداد ِ ریزلنزش   
ruydâd-e rizlenzeš

Fr.: événement de microlentille   

The effect arising whenever a source star and lens star pass each other at an angular separation involving the → Einstein radius (RE) of the lens. The time-scale for such an event is defined as tE = RE/v, where v is the magnitude of the relative transverse velocity between source and lens projected onto the lens plane.

microlensing; → event.