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Number of Results: 6 Search : mass function

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:
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. |

core mass function (CMF) karyâ-ye jerm-e maqzé Fr.: fonction de masse des cœurs The mass distribution of → 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). |

dense core mass function karyâ-ye jerm-e maqze-ye cagâl Fr.: fonction de masse des cœurs denses |

initial mass function (IMF) karyâ-ye âqâzin-e jerm Fr.: fonction initiale de masse A mathematical expression describing the relative number of stars found in different
ranges of mass for a cluster of stars at the time of its formation.
It is defined as
M is the mass of a star and N is the number of stars in a
logarithmic mass interval. The value of the slope found by Salpeter (1955) for
→ low-mass
and → intermediate-mass stars in the
→ solar neighborhood is Γ = 1.35.
The IMF can be expressed also in linear mass units:
χ(M) = dN / DM ∝ M.
Note that
^{ -α}χ(M) = (1 / M lm 10) φ(log M), and α = Γ + 1. In this
formalism the Salpeter slope is α = 2.35. There is a third way for
representing the IMF, in which the exponent is x = -α.
The IMF is not a single power law over all masses, from
→ brown dwarfs to → very massive stars
(Kroupa, 2002, Science 295, 82).
Different slopes have been found for different mass segments, as follows:
α = 1.3 for 0.08 ≤ M < 0.5;
α = 2.3 for 0.5 ≤ _{solar}M < 1;
α = 2.3 for 1 ≤ _{solar}M.
The IMF at low masses can be fitted by a
→ _{solar}lognormal distribution
(See Bastian et al., 2010, ARAA 48, 339 and references therein).
See also → canonical IMF. |

mass function karyâ-ye jerm Fr.: fonction de masse 1) The number of a class of objects as a function of their mass.
→ M is the mass of secondary, and _{s}i the
→ angle of inclination of the orbit,
the mass function is given by:
(M. sin_{s}^{3}^{3}i) /
(M._{p} + M_{s})^{2} |

present-day mass function (PDMF) karyâ-ye jerm-e konuni, ~ ~ emruzi Fr.: fonction de masse actuelle The present number of stars on the → |