We use the microlensing variability observed for nine gravitationally lensed quasars to show that the accretion disk size at 2500Å is related to the black hole mass by log(R2500/cm) = (15.6± 0.2) + (0.54± 0.28) log(MBH/10M⊙). This scaling is consistent with the expectation from thin disk theory (R ∝ M BH), but it implies that black holes radiate with relatively low efficiency, log(η) = −1.29 ± ...

We report on ASCA observations of the low mass X-ray binaries GX 354-0 and KS 1731-260. The spectrum of GX 354-0 is best described as a power-law or a Comptonized spectrum with τ ∼ 5 and kT∼ 8 keV and a residual at ∼ 6.5 keV. The residual may be a disk reflection or a Compton broadened Gaussian line from the hot inner ADAF-like coronal region. The absorption column density to the source is 2.9 ...

Absorption lines of interstellar molecular hydrogen in the far ultraviolet (FUV) have been observed in the spectrum of the O9.5 halo star HD 93521, located some 1500 pc from the Galactic plane. During the second ORFEUS-SPAS mission a spectrum with the Echelle spectrometer has been recorded with a total integration time of 1740 s. The resolution achieved was about λ/∆λ ≥ 10.000 with a signal-to-...

The Red Sea Alcyonarian Heteroxeniafuscescens (Ehrb.) consists of a pinkish brown fleshy syndete up to 5 cm. in length, firmly attached to a stone or dead coral, from which grows a mass of autozooids with columns 2-4 cm. long and 2-3 mm. in diameter (Fig. 1). The first physiological observations on a xenid were made by Keller (1883) on a brown species from Suez that he considered to be H. fusce...

Three recent surveys of 21-cm line emission in the Galactic plane, combining single dish and interferometer observations to achieve resolution of 1 to 2, ∼ 1 km s, and good brightness sensitivity, have provided some 650 absorption spectra with corresponding emission spectra for study of the distribution of warm and cool phase HI in the interstellar medium. These emission-absorption spectrum pai...

Probing the gas and dust in proto-planetary disks is central for understanding the process of planet formation. In disks surrounding solar type protostars, the bulk of the disk mass resides in the outer midplane, which is cold (≤20 K), dense (≥ 107 cm−3) and depleted of CO. Observing the disk midplane has proved, therefore, to be a formidable challenge. Ceccarelli et al. (2004) detected H2D emi...

Emphasis and interest in carbon (C) and nitrogen (N) storage (sequestration) in soils has greatly increased in the last few years, especially C with its’ potential to help alleviate or offset some of the negative effects of the increase in greenhouse gases in the atmosphere. Several questions still exist with regard to what management practices optimize C storage in the soil profile. A long-ter...

The assumption that black hole accretion disks possess an untorqued inner boundary, the so-called zero torque boundary condition, has been employed by models of black hole disks for many years. However, recent theoretical and observational work suggests that magnetic forces may appreciably torque the inner disk. This raises the question of the effect that a time-changing magnetic torque may hav...

Progenitor models for the "luminous" subclass of Fast Blue Optical Transients (LFBOTs; prototype: AT2018cow) are challenged to simultaneously explain all their observed properties: fast optical rise times < days; peak luminosities >1e44 erg/s; low yields <0.1 Msun 56Ni; aspherical ejecta with a wide velocity range (<3000 km/s > 0.1-0.5 c increasing polar latitude); presence hydrogen-depleted-bu...

The non-detection of a point source in SN 1987A imposes an upper limit for the optical luminosity of L opt < ∼ 2 L ⊙. This limits the size of a possible fallback disk around the stellar remnant. Assuming a steady-state thin disk with blackbody emission requires a disk smaller than 100 000 km if the accretion rate is at 30% of the Eddington rate [6]. We have performed detailed non-LTE radiation ...