âhazeš; anjoman (#)
1) The act of associating, → associate;
the state of being associated.
Association, noun from → associate.
Âhazeš, verbal noun of → âhazidan→ associate. Anjoman, for the meaning 3, from Mid.Pers. anjaman, from Av. han-jamana, from han- "together" + jamana, from gam- "to come;" cf. Skt. samgamana "gathering together."
Fr.: membre d'une association
A celestial body making part of an astronomical association.
Cygnus OB association
âhazeš-e OB Mâkiyân
Fr.: association OB Cygne
One of nine → OB associations located in the Cygnus → constellation. The central association, → Cygnus OB2, is the most famous and the youngest of the Cygnus region. (L. Mahy et al. 2013, astro-ph/1301.0500 and references therein).
Fr.: association OB
A loosely bound grouping of O and B stars that typically stretches up to several hundred → light-years and may contain between a dozen and several hundred → O stars and → B stars. The members of an OB association are young and of roughly the same age. OB associations dissipate in a few tens of millions of years.
O and B, from spectral types; → association.
âhazeš-e Šekârgar, ~ Orion
Fr.: association d'Orion
Orion OB1 Association
âhazeš-e OB1 Šekârgar, ~ ~ Oryon
Fr.: Association Orion OB1
An → OB association consisting of several
dozen → hot stars
of → spectral types O and B
(→ O star, → B star).
The Orion OB1 association consists of several subgroups, first
divided by Blaauw (1964) into four subgroups. The subgroups differ
in age and gas and dust content:
Fr.: association R
A → stellar association containing a number of → reflection nebulae. The stars are of low or intermediate mass and young, less than a million years old. They are still surrounded by patches of dust that reflect and absorb light from the interstellar cloud in which they formed. This type of association was first suggested by Sidney van den Bergh (1966, AJ 71, 900).
Fr.: association Scorpius-Centaurus
The nearest → OB association to the Sun. It contains several hundred stars, mostly → B stars which concentrate in the three subgroups: Upper Scorpius, Upper Centaurus Lupus, and Lower Centaurus Crux. Upper Scorpius is the youngest subgroup, Upper Centaurus Lupus the oldest subgroup of the association. Isochrone fitting to the Hertzsprung-Russell diagram indicates that the star formation occurred some 5-20 Myr ago. Based on data from the → Hipparcos catalog, it turns out that the Sco-Cen association lies at a distance of 118-145 → parsecs, with the exact value depending on the subgroup of the association. The Sco-Cen association is probably a member of the → Gould Belt (Preibisch & Mamajek, 2008, astro-ph/0809.0407).
Fr.: association stellaire
1) A large, loose grouping of 10 to 1000 stars that are of similar spectral type and
share a common origin. The members move together
through space, but have become gravitationally → unbound.
Stellar associations are primarily identified by their common
movement vectors and ages.
→ OB association;
→ T association;
→ R association.
The concept of stellar association was first introduced by Viktor A. Ambartsumian (1908-1996), Armenian astrophysicist (1947, Stellar Evolution and Astrophysics, Armenian Acad. of Sci.; German translation, Abhandl. Sowjetischen Astron. Ser. 1. 33, 1951). → stellar; → association.
Fr.: association T
T, letter of alphabet; → association.
TW Hydrae association
âhazeš-e TW Hudrâ
Fr.: Association TW Hydrae
A young (≤ 100 million years) association of stars (abbreviated TWA) with at least 27 members, from → intermediate mass stars to planetary mass objects. Five of them, including → TW Hydrae, display signatures of → T Tauri stars. TWA is the first moving group of young nearby (≤ 100 → paesecs) stars to be identified.