Giant E2 Research Articles

Isovector giant E2 resonance and overtone of the isovector giant E1 resonance in photonucleon reactions

The effect of the isovector giant quadrupole resonance and an overtone of the isovector giant dipole resonance on the photodisintegration of medium-mass and heavy nuclei in the energy range of 20–40 MeV is studied on the basis of a combined model of photonucleon reactions. Basic features of these resonances are evaluated within a semimicroscopic approach. Their deformation spitting is described on the basis of the model of polarization vibrations of a two-component nuclear liquid.

Nuclear Disks of Gas and Dust in Early‐Type Galaxies and the Hunt for Massive Black Holes:Hubble Space TelescopeObservations of NGC 6251

We discuss Hubble Space Telescope (HST) optical images and spectra of NGC 6251, a giant E2 galaxy and powerful radio source at a distance of 106 Mpc (for H0=70 km s-1 Mpc-1). The galaxy is known to host a very well-defined dust disk; the exceptional resolution of our V and I images allows a detailed study of the disk structure. Furthermore, narrowband images centered on the Hα + [N II] emission lines reveal the presence of ionized gas in the inner 03 of the disk. We used the HST Faint Object Spectrograph with the 009 aperture to study the velocity structure of the disk. Dynamical models were constructed for two extreme (in terms of central concentration) analytical representations of the stellar surface brightness profile, from which the mass density and corresponding rotational velocity are derived assuming a constant mass-to-light ratio (M/L)V~8.5 M☉/L☉. For both representations of the stellar component, the models show that the gas is in Keplerian motion around a central mass ~4-8×108 M☉ and that the contribution of radial flows to the velocity field is negligible.

Distance to the Coma Cluster and a Value for HO Inferred from Globular Clusters in IC 4051

view Abstract Citations (33) References (66) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Distance to the Coma Cluster and a Value for HO Inferred from Globular Clusters in IC 4051 Baum, William A. ; Hammergren, Mark ; Thomsen, Bjarne ; Groth, Edward J. ; Faber, Sandra M. ; Grillmair, Carl J. ; Ajhar, Edward A. Abstract We report HST-WFPC2 observations of the giant E2 galaxy IC 4051 located 14' east of the center of the Coma Cluster. Eight full-orbit exposures were obtained with the F606W filter, and two with the F814W filter. Counts of globular clusters (GCs) in 0.2-mag wide bins were made within the PC1 (f/28) frame, where faint GCs can be distinguished from noise spikes and background objects by PSF fitting. The detection probability was above 86% for F606W<27.6 mag, and it was 40% at F606W=28.1 mag (bin center), which we chose as a working threshold. The latter is equivalent to V≍28.4 mag, which is beyond the peak (turnover) of the globular cluster luminosity function (GCLF). After very small k and reddening corrections, we found the mean rest-frame color index of the IC 4051 GCs to be (V- 1)0=1.06 mag, which implies [Fe/H]=-0.74 and is about average for the GC systems of giant elliptical galaxies. The intrinsic dispersion of color indices is σv-I=0.16 mag. The specific frequency of the GC system in IC 4051 is ∼10, which is an order of magnitude larger than we found in the Coma E0 galaxy NGC 4881. Using a maximum likelihood method, we have compared the observed GCLF of IC 4051 with model GCLFs transported to various strawman Coma Cluster distances, with photometric errors and incompleteness taken into account. For a model based on the GC systems of the Milky Way and M31, the inferred bolometric modulus of IC 4051 is 35.15±0.16 mag. For a model based on the GC system of M87, the apparent V modulus difference (IC 4051 minus M87) is 4.15±0.07 mag, and the inferred bolometric modulus of IC 4051 is 35.07±0.17 mag. These moduli rest on RR Lyrae and Cepheid zero points that may be subject to future adjustments. The difference between the IC 4051 modulus based on the spiral-galaxy GCLF model (Milky Way and M31) and that based on the elliptical-galaxy GCLF model (M87) is only 0.08±0.23 mag, which is not statistically significant. Adopting the mean IC 4051 bolometric modulus, 35.11±0.12 mag, and assuming q0=0.5, we obtain a luminosity distance of 105±6 Mpc (random error). For a cosmological redshift of km/s, the implied Hubble Constant H0 =68±6 km/s per Mpc. Publication: The Astronomical Journal Pub Date: May 1997 DOI: 10.1086/118365 Bibcode: 1997AJ....113.1483B Keywords: COSMOLOGY: OBSERVATIONS; GALAXIES: INDIVIDUAL: IC 4051 full text sources ADS | data products SIMBAD (6) NED (5) MAST (1) ESA (1)

Gamma — decay of giant resonances

The partial widths of the γ-decay of the giant E2 and E4 resonances in 90 Zr and 208 Pub to low-lying states are calculated within the quasiparticle-phonon model. The complex configurations of the wave function can be concluded to be rather important for correct discription of the decay properties of highly excited nuclear states. It is shown that due to the core polarization the decay of the isovector resonances is more intensive compared to the isoscalar ones.

Picture processing analysis of the optical structure of NGC 5128 /Centaurus A/

Results are presented for a detailed study of the peculiar elliptical galaxy NGC 5128 (Cen A), based on computer video analysis of several photographic plates of exceptional quality reduced to the standard UBV system. The picture-processing results and the measured properties of the elliptical and gaseous-disk components of NGC 5128 are examined, along with the distribution, spectral characteristics, and chemical composition of the H II regions in the disk. The data show that NGC 5128 consists of a giant E2 galaxy containing a significant amount of gas and dust situated predominantly in an equatorial disk where vigorous star formation is occurring. Reasons why NGC 5128 is so different from giant ellipticals in clusters are considered.

Sp(6, R) symmetry and α-breakup amplitudes of giant E2 excitations in light nuclei

Shell-model core excitations based on the Sp(6, R) model are compared with those derived from α-cluster models. Overlaps between the first symplectic excitations (essentially giant E2 excitations) and α-cluster states of the same SU(3) symmetry are used to estimate the α-breakup probabilities of giant E2 resonances in 16O, 20Ne, 24Mg and 28Si. Although these probabilities are large, α-cluster and Sp(6, R) core excitations are essentially complementary and may both be needed for a meaningful microscopic description of A = 16–40 nuclei.