havâtud, tude-ye havâ (#)
Fr.: masse d'air
A measure of the path length traversed by starlight through Earth's atmosphere before it reaches the detector; it is taken relative to the length at the zenith.
1) To collect into a mass or pile; → accumulate.
Anbâštan, anbârdan "to fill, to replete," from Mid.Pers. hambāridan "to fill;" from Proto-Iranian *ham-par-, from prefix ham-, → com-, + par- "to fill;" cf. Av. par- "to fill," parav-, pauru-, pouru- "full, much, many;" O.Pers. paru- "much, many;" Mid.Pers. purr "full;" Mod.Pers. por "full, much, very;" PIE base *pelu- "full," from *pel- "to be full;" cf. Skt. puru- "much, abundant;" Gk. polus "many," plethos "great number, multitude;" O.E. full.
atomic mass number (A-number)
adad-e jerm-e atomi (#)
Fr.: nombre de masse atomique
The total number of protons and neutrons in the nucleus of an atom. For example, Oxygen-16 has a mass number of sixteen, because it has eight protons and eight neutrons.
atomic mass unit (amu)
yekâ-ye jerm-e atomi (#)
Fr.: unité de masse atomique
A unit of mass used for atoms and molecules, equal to 1/12 of the mass of an atom of carbon-12 (including orbital electrons). It is equal to 1.660 33 × 10-24 g.
binary supermassive black hole
siyah-câl-e abar-porjerm-e dorin
Fr.: trou noir supermassif double
A → dual supermassive black hole whose components are separated by a few parsecs.
Fr.: masse de Bonnor-Ebert
The largest gravitationally stable mass of the → Bonnor-Ebert sphere.
After W.B. Bonnor (1956) and R. Ebert (1955); → mass.
center of mass
Fr.: centre de masse
Fr.: masse caractéristique
A typical or most likely mass for the formation of an astronomical object. In current star formation models, it is of order of a few tenths of a → solar mass.
cluster mass function (CMF)
karyâ-ye jerm-e xušé
Fr.: fonction de masse d'amas
An empirical power-law relation representing the number of clusters as a function of their mass. It is defined as: N(M)dM ∝ M -αdM, where the exponent α has an estimated value of about 2 and dM is the mass interval. It is believed that this is a universal law applying to a variety of objects including globular clusters, massive young clusters, and H II regions.
compact massive galaxy (CMG)
kahkešân-e porjerm-e hampak
Fr.: galaxie massive compacte
A galaxy with a stellar mass of M ≥ 1011Msun and an → effective radius of Re ≤ 1.5 kpc. Many studies have shown that massive galaxies with low → star formation rates were remarkably compact at a → redshift of z≥ 2. At fixed stellar mass of Mstars ≅ 1011Msun, quiescent galaxies are a factor of ~ 4 smaller at z = 2 than at z = 0. As the stellar mass of the galaxies also evolves, the inferred size growth of individual galaxies is even larger. It is unlikely that all massive galaxies in the present-day Universe had a compact progenitor. However, the vast majority of CMGs that are observed at z = 2 ended up in the center of a much larger galaxy today. Their size growth after z = 2 is probably dominated by minor → mergers. Such mergers are expected because other mechanisms cannot easily produce the observed scaling between size growth and mass growth (P. G. van Dokkum1 et al., 2015, ApJ 813, 23).
conservation of mass
Fr.: conservation de masse
A → principle of → classical physics whereby → matter can be neither created nor destroyed. Matter can, however, be → converted into → energy, as predicated by the theory of → special relativity. Also called → conservation of matter.
conservation of mass and energy
pâyeš-e jerm o kâruž
Fr.: conservation de masse et d'énergie
core mass function (CMF)
karyâ-ye jerm-e maqzé
Fr.: fonction de masse des cœurs
The mass distribution of → pre-stellar cores in → star-forming regions. The CMF is usually represented by dN/dM = Mα, where dM is the mass interval, dN the number of cores in that interval, and α takes different values in different mass ranges. In the case of → low-mass stars, it is found that the CMF resembles the → Salpeter function, although deriving the masses and radii of pre-stellar cores is not straightforward. The observational similarity between the CMF and the → initial mass function (IMF) was first put forth by Motte et al. (1988, A&A, 336, 150), and since then many other samples of dense cores have been presented in this context. For example, Nutter & Ward-Thompson (2007, MNRAS 374, 1413), using SCUBA archive data of the Orion star-forming regions, showed that the CMF can be fitted to a three-part → power law consistent with the form of the stellar IMF. Recent results, obtained using observations by the → Herschel Satellite, confirm the similarity between the CMF and IMF with better statistics (Könyves et al. 2010, A&A, 518, L106; André et al. 2010, A&A, 518, L102). Moreover, these works show that the CMF has a → lognormal distribution (i.e. dN/dlog M follows a → Gaussian form against log M), as is the case for the IMF at low masses (below about 1 solar mass).
coronal mass ejection (CME)
ešâneš-e jerm az hurtâj
Fr.: éjection de masse coronale
A huge eruption of material from regions of the solar corona in which the magnetic field is closed, but which suffer an extremely energetic disruption. Over the course of several hours up to 10,000 billion kg of this material is ejected into → interplanetary space with a a speed of as high as 3000 km/s. CMEs are most spectacularly observed by a white light coronagraph located outside Earth's atmosphere. Such observations from Skylab in the early 1970's were the first to reveal this phenomenon. CME's disrupt the flow of the → solar wind and can produce intense electromagnetic disturbances that can severely damage satellites and disrupt power grids on Earth. When these ejections reach the Earth, they give rise to → geomagnetic storms. The frequency varies with the → solar cycle; during solar minimum they come at a rate of about one per week, and during maximum there is an average of about two or three per day. See also → interplanetary coronal mass ejections (ICME).
critical Bonnor-Ebert mass
jerm-e paržani-ye Bonnor-Ebert
Fr.: masse critique de Bonnor-Ebert
The upper value of mass that a → Bonnor-Ebert sphere must have in order that → hydrodynamic equilibrium be maintained. This → critical mass is given by: Mcrit = 1.18 (a4/G3/2)Pext-1/2, where a = (kT/m)1/2 is the isothermal → sound speed inside the sphere, G is the → gravitational constant, and Pext the pressure of the external medium (see, e.g., F. H. Shu, 1977, ApJ 214, 488).
Fr.: masse critique
Of a fissile material (235U or 239Pu), the minimum mass needed for a sustained nuclear chain reaction, as in an atomic bomb.
dense core mass function
karyâ-ye jerm-e maqze-ye cagâl
Fr.: fonction de masse des cœurs denses
dual supermassive black hole
siyah-câl-e abar-porjerm-e dogâné
Fr.: trou noir supermassif double
The outcome of a → merger process between two galaxies, each with its own central → supermassive black hole (SMBH), resulting in a remnant galaxy hosting two SMBHs. Simulations of → galaxy mergers show there should be lots of dual → active galactic nuclei (AGN) visible at less than 10 kpc separations. As of 2015 more than 100 known dual supermassive black holes have been found. See also → binary supermassive black hole.
Fr.: masse dynamique
The mass of an object derived indirectly from theoretical formulae based on the laws governing the behavior of a → dynamical system.
jerm-e zamin (#)
Fr.: masse de la Terre