Fr.: écart de masse
1) For → massive stars and → supergiants,
the difference between the → spectroscopic mass and the
→ evolutionary mass. Early studies found that the spectroscopic
mass was systematically less than the evolutionary mass by as much as a factor of 2 for
supergiants. Improvements in the stellar atmosphere models (taking into account
→ line blanketing) have decreased or eliminated the size of the
discrepancy for Galactic stars. There is still a mass discrepancy for the hottest
→ O stars in the → Magellanic Clouds
(See, e.g. Massey et al. 2009, ApJ 692, 618).
Fr.: énergie de masse
The energy (E) associated with a mass (m), as specified by the → mass-energy equivalence E = mc2, where c is the → speed of light. For a moving body the total energy of the particle is expressed by: E2 = m2c4 + p2c2, where m is → rest mass and p → momentum.
Fr.: extinction en masse
An event in the history of life on Earth in which large numbers of species (sometimes more than 90% of some species) vanish in a relatively short period of time. In spite of controversy, it is generally recognized that there have been at least six major mass extinctions. These occurred in the late Cambrian (500 million years ago), in the late Ordovician (440 million years ago), in the late Devonian (365 million years ago), at the end of the Permian (245 million years ago), in the late Triassic (208 million years ago), and at the end of the Cretaceous (65 million years ago).
Fr.: écoulement de masse
The mass of a fluid that passes a specified unit area in a unit amount of time.
Fr.: formule de masse
Fr.: fraction de masse
The fractional amount (by mass) of a given element or nuclide in a given composition.
Fr.: fonction de masse
1) The number of a class of objects as a function of their mass.
→ initial mass function (IMF);
→ present-day mass function (PDMF).
Fr.: perte de masse
The outpouring of particles and gas from a star, occurring at varying rates and by a variety of processes throughout a star's lifetime. → Bipolar flows are believed to be due to mass loss by forming → protostars, while → massive stars lose their mass through powerful → stellar winds.
mass loss rate
nerx-e dastraft-e jerm
Fr.: taux de perte de masse
The rate with which the → mass loss process takes place, usually expressed in → solar mass per year. → radiation-driven mass loss. The mass loss rate and the → terminal velocity are anti-correlated, since the → wind momentum is constant, → bi-stability jump.
adad-e jermi (#)
Fr.: nombre de masse
The total number of → protons and → neutrons in the → atomic nucleus (symbol A). The mass number is written either after the → chemical element name or as a superscript to the left of an element's symbol. For example, the most common isotope of oxygen is oxygen-16, or 16O, which has 8 protons and 8 neutrons.
Fr.: écoulement de masse
The flowing out of mass through various processes from an object, for example in a star forming region or in a close binary.
Fr.: ségrégation de masse
A consequence of the → dynamical relaxation process in a gravitationally → bound system, such as a → star cluster or a → globular cluster, where massive and low-mass members occupy different volumes. Massive members sink toward the center, while less massive members tend to move farther away from the center.
The portion of the isotope shift which results from the difference between the nuclear masses of different isotopes.
Fr.: spectrométrie de masse
An analytical technique for identification of chemical structures, determination of mixtures, and quantitative elemental analysis, in which ions are separated according to the mass/charge ratio and detected by a suitable detector.
binâb-e jerm (#)
Fr.: spectre de masse
A spectrum of charged particles, arranged in order of mass or mass-to-charge ratios. → mass spectrometry.
Fr.: transfert de masse
The process in which the evolved member of a close binary system passes gaseous material to its companion star.
tarâbord-e jerm (#)
Fr.: transport de masse
In fluid mechanics, the motion of a given amount of material carried by a fluid from one point to another.
Fr.: équivalence masse-énergie
The principle of interconversion of mass and energy, described by the → mass-energy relation.
Fr.: relation masse-énergie
The famous equation proposed by Einstein as a consequence of his special theory of relativity describing the equivalence of mass and energy: E = mc2, where E is energy, m is the equivalent amount of mass, and c is the velocity of light.
Fr.: rapport masse-luminosité
The ratio of the mass of a system, expressed in solar masses, to its visual luminosity, expressed in solar luminosities. The Milky Way Galaxy has a mass-luminosity ratio in its inner regions of about 10, whereas a rich cluster of galaxies such as the Coma Cluster has a mass-luminosity ratio of about 200, indicating the presence of a considerable amount of dark matter.