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We have conducted B-, g-, V-, and R-band imaging in a 45 × 40 field containing part of the high Galactic latitude translucent cloud MBM32, and correlated the intensity of diffuse optical light S ν (λ) with that of 100 μm emission S ν (100 μm). A χ 2 minimum analysis is applied to fit a linear function to the measured correlation and derive the slope parameter b(λ) = ΔS ν (λ)/ΔS ν (100 μm) of the best-fit linear function. Compiling a sample by combining our b(λ) and published ones, we show that the b(λ) strength varies from cloud to cloud by a factor of four. Finding that b(λ) decreases as S ν (100 μm) increases in the sample, we suggest that a nonlinear correlation including a quadratic term of S ν (100 μm) 2 should be fitted to the measured correlation. The variation of optical depth, which is A V = 0.16-2.0 in the sample, can change b(λ) by a factor of 2-3. There would be some contribution to the large b(λ) variation from the forward-scattering characteristic of dust grains which is coupled to the non-isotropic interstellar radiation field (ISRF). Models of the scattering of diffuse Galactic light (DGL) underestimate the b(λ) values by a factor of two. This could be reconciled by deficiency in UV photons in the ISRF or by a moderate increase in dust albedo. Our b(λ) spectrum favors a contribution from extended red emission (ERE) to the diffuse optical light; b(λ) rises from B to V faster than the models, seems to peak around 6000 Å and decreases toward long wavelengths. Such a characteristic is expected from the models in which the DGL is combined with ERE.

We present an analysis of the blank sky spectra observed with the Faint Object Spectrograph on board the Hubble Space Telescope. We study the diffuse sky emission from ultraviolet to optical wavelengths, which is composed of the zodiacal light (ZL), diffuse Galactic light (DGL), and residual emission. The observations were performed toward 54 fields distributed widely over the sky, with the spectral coverage from 0.2 to 0.7µm. In order to avoid contaminating light from the earthshine, we use the data collected only in orbital nighttime. The observed intensity is decomposed into the ZL, DGL, and residual emission, in eight photometric bands spanning our spectral coverage. We found that the derived ZL reflectance spectrum is flat in the optical, which indicates major contribution of C-type asteroids to the interplanetary dust (IPD). In addition, the ZL reflectance spectrum has an absorption feature at ∼ 0.3µm. The shape of the DGL spectrum is consistent with those found in earlier measurements and model predictions. While the residual emission contains a contribution from the extragalactic background light, we found that the spectral shape of the residual looks similar to the ZL spectrum. Moreover, its optical intensity is much higher than that measured from beyond the IPD cloud by Pioneer10/11, and also than that of the integrated galaxy light. These findings may indicate the presence of an isotropic ZL component, which is missed in the conventional ZL models.

We investigate Fe II emission in the broad-line region (BLR) of active galactic nuclei by analysing the Fe II(UV), Fe II(λ4570) and Mg II emission lines in 884 quasars in the Sloan Digital Sky Survey Quasar catalogue in a redshift range of 0.727 < z < 0.804. Fe II(λ4570)/Fe II(UV) is used to infer the column density of Fe II-emitting clouds and explore the excitation mechanism of Fe II emission lines. As suggested before in various works, the classical photoionization models fail to account for Fe II(λ4570)/Fe II(UV) by a factor of 10, which may suggest anisotropy of UV Fe II emission, or an alternative mechanism like shocks. The column density distribution derived from Fe II(λ4570)/Fe II(UV) indicates that radiation pressure plays an important role in BLR gas dynamics. We find a positive correlation between Fe II(λ4570)/Fe II(UV) and the Eddington ratio. We also find that the ionizing photon fraction must be much smaller than that previously suggested unless Fe II-emitting clouds are super-Eddington. Finally, we propose a physical interpretation of a striking set of correlations between various emission-line properties, known as 'Eigenvector 1'.

We present the detailed optical to far-infrared observations of SST J1604+4304, an ULIRG at z = 1.135. Analyzing the stellar absorption lines, namely, the CaII H & K and Balmer H lines in the optical spectrum, we derive the upper limits of an age for the stellar population. Given this constraint, the minimum χ 2 method is used to fit the stellar population models to the observed SED from 0.44 to 5.8µm. We find the following properties. The stellar population has an age 40 -200 Myr with a metallicity 2.5 Z ⊙ . The starlight is reddened by E(B − V ) = 0.8. The reddening is caused by the foreground dust screen, indicating that dust is depleted in the starburst site and the starburst site is surrounded by a dust shell. The infrared (8-1000µm) luminosity is L ir = 1.78 ± 0.63 × 10 12 L ⊙ . This is two times greater than that expected from the observed starlight, suggesting either that 1/2 of the starburst site is completely obscured at UV-optical wavelengths, or that 1/2 of L ir comes from AGN emission. The inferred dust mass is 2.0±1.0×10 8 M ⊙ . This is sufficient to form a shell surrounding the galaxy with an optical depth E(B −V ) = 0.8. From our best stellar population modelan instantaneous starburst with an age 40 Myr, we infer the rate of 19 supernovae(SNe) per year. Simply analytical models imply that 2.5 Z ⊙ in stars was reached when the gas mass reduced to 30% of the galaxy mass. The gas metallcity is 4.8Z ⊙ at this point. The gas-to-dust mass ratio is then 120 ± 73. The inferred dust production rate is 0.24 ± 0.12M ⊙ per SN. If 1/2 of L ir comes from AGN emission, the rate is 0.48 ± 0.24M ⊙ per SN. We discuss the evolutionary link of SST J1604+4304 to other galaxy populations in terms of the stellar masses and the galactic winds, including optically selected low-luminosity Lyman α-emitters and submillimeter selected highluminosity galaxies.