Handbuch der Physik / Encyclopedia of Physics
1 primary work • 26 total works
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External Properties of Atomic Nuclei / Aussere Eigenschaften der Atomkerne
by S. Flugge
Published 2 January 1958
39 2 2 Here B = hJ8:!t Ib and A = hJ8:!t Ia where Ia and Ib are the moments of inertia parallel and perpendicular respectively to the symmetry axis. ~ V I(J + 1) is 2n the total angular momentum of the molecule and K ~ its projection on the 2n symmetry axis. If the molecule possesses a permanent electric dipole moment it can absorb a quantum of microwave energy hv and make a transition to a higher rotational' state governed by the selection rules L1 I = + 1, L1 K = O. The pure rotational absorption frequency is then given by v=2BI (1. 2) where I is the angular momentum quantum number for the upper state of the transition. If an isotopic substitution is made for an atom lying along the sym- metry axis of the molecule, thus changing its moment of inertia and hence its B value, the rotational absorption frequency will shift. The program of mass determination from microwave spectra is to correlate this frequency shift with the change in mass of the substituted isotope. These shifts can range from a few Mc to several thousands of Mc for a change of one mass unit, being larger generally for the lighter atoms.
Typical isotopic shifts in the middle mass region (A =60 to 130) are 100 Mc per mass unit. As mentioned above, frequency shifts in the 24000 Mc region can be measured to at least an accuracy of 0.
Typical isotopic shifts in the middle mass region (A =60 to 130) are 100 Mc per mass unit. As mentioned above, frequency shifts in the 24000 Mc region can be measured to at least an accuracy of 0.
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Astrophysik I: Sternoberflachen-Doppelsterne / Astrophysics I: Stellar-Surfaces-Binaries
by S. Flugge
Published 2 January 1958
Sect. 13. 203 and the geometric elements for the large orbit are re-computed. From the analysis it cannot be decided whether the third body is close to the visual primary or secondary component; this can only be decided by measuring the orbital motion on an astrometric background of other stars (Chap. IV). In accurate long-term problems the perspective change in the apparent orbit due to motion of the center of mass in the line of sight, must be taken into account. In the future this feature of orbital analysis will undoubtedly become more and more important. An example of the required reduction is the orbital analysis of the 61 Cygni system by A. FLETCHER!. 1890 90 1960 0 Fig. 11. Relative orbit of the visual binary Kruger 60. * visual observations. 0 photographic observations. IV. Analysis of orbit referred to external reference system. 13. Introduction. In the preceding Chap. III we dealt with the analysis of the relative orbit of the two components of a binary star. We now extend the analysis to the measurements and orbits of the individual components referred to a system of, presumably distant, reference stars.
Both micrometer measure- ments and, particularly, meridian circle positions have been successfully employed in the past; the current observing technique is primarily long-focus photographic astrometry. The problems studied include those of mass-ratio and parallax, and of perturbations. Long-focus technique and analysis are in the first place suitable for the so-called resolved binaries, whose components are clearly separated.
Both micrometer measure- ments and, particularly, meridian circle positions have been successfully employed in the past; the current observing technique is primarily long-focus photographic astrometry. The problems studied include those of mass-ratio and parallax, and of perturbations. Long-focus technique and analysis are in the first place suitable for the so-called resolved binaries, whose components are clearly separated.
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