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: 9 Search : merger
black hole merger
  تشک ِ سیه‌چالها   
tašk-e siyah-câlhâ

Fr.: fusion de trous noirs   

The collision of two → black holes in a → binary black hole system once they come so close that they cannot escape each other's gravity. They will merge in an extremely violent event to become one more massive black hole. The merger would produce tremendous energy and send massive ripples, called → gravitational waves, through the → space-time fabric of the Universe. Such an event (called GW150914) was first detected by the → Laser Interferometer Gravitational-Wave Observatory (LIGO) on September 14, 2015. The initial black hole masses were 36 and 29 Msun which gave a final black hole mass of 62 Msun, with 3 Msun radiated in gravitational waves. The event happened at a distance of 1.3 billion → light-years from Earth (Abbott et al., 2016, Phys. Rev. Lett. 116, 061102). Black hole merger is preceded by → inspiral and followed by → ringdown.

black; → hole; → merger.

dry merger
  تشک ِ بی‌گاز   
tašk-e bigâz

Fr.: fusion sans gaz   

A merger between → gas-poor  → early-type galaxies.

dry; → merger.

major merger
  تشک ِ مهین   
tašk-e mehin

Fr.: fusion majeure   

The → merging of two spiral galaxies with roughly equal masses colliding at appropriate angles. The dynamical friction is so efficient that the galaxies merge after only a few perigalactic passages.

major; → merger.

merger
  ۱) تشکه؛ ۲) تشک   
1) tašké; 2) tašk

Fr.: fusion, coalescence   

1) Any combination of two or more bodies into a single body. In particular, the formation of a galaxy from the collision of two or more separate galaxies.
2) An act or instance of merging.

From → merge + -er (as in waiver).

Tašké; tašk, nouns from taškidan, → merge.

merger process
  فراروند ِ تشک   
farâravand-e tašk

Fr.: processus de fusion   

The process of collision between galaxies which leads to a single galaxy.

merger; → process.

merger tree
  درخت ِ تشک   
deraxt-e tašk

Fr.: arbre de coalescence   

A method used in → numerical simulations for studying the growth and development of galaxies and → dark matter halos. Within the currently accepted ΛCDM cosmology, dark matter halos merge from small → clumps to ever larger structures. This merging history can be traced in simulations and stored in the form of merger trees. Merger trees are necessary because a galaxy may have more than one → progenitor at an early time.

merger; → tree.

minor merger
  تشک ِ کهین   
tašk-e kehin

Fr.: fusion mineure   

The → merging in which one of the galaxies is significantly larger than the other (mass ratios above 10). The larger galaxy will often "swallow" the smaller satellite galaxy. The swallowed galaxy can trigger disk and nuclear star formation or activate a central core with shells that surround the predator.

minor; → merger.

mixed merger
  تشک ِ آمیخته   
tašk-e âmixté

Fr.: fusion mixte   

A merger that takes place when a → gas-poor galaxy collides with a → gas-rich galaxy.

Past-participle of → mix; → merger.

wet merger
  تشک ِ پر گاز   
tašk-e porgâz

Fr.: fusion avec gaz   

A merger between → gas-rich galaxies. Wet mergers may lead to enhanced star formation, trigger → active galactic nuclei, and transform a → disk galaxy into an → elliptical galaxy. The larger the → redshift, the wetter mergers should be.

wet; → merger.