Yamato-86789: A heated CM-like carbonaceous chondrite

We have studied the mineralogy and petrology of the Yamato (Y)-86789 meteorite and concluded that this meteorite is a new member of heated carbonaceous chondrites with CI-CM affinities. Y-86789 contains 14vol% of translucent chondrules which mainly consist of fibrous phyllosilicate-like materials. The high abundance of the phyllosilicate-like minerals in chondrules suggests severe aqueous alteration. Major parts of the matrix are also composed of the phyllosilicate-like materials. The phyllosilicate-like materials have compositions of a mixture of serpentine and saponite. However, the phyllosilicate-like materials show consistently high analytical totals; thus, they are dehydrated. X-ray diffraction measurements of the phyllosilicate-like materials reveal that they are mainly composed of olivine. Diffractions from serpentine and saponite are absent from the X-ray powder patterns. These results suggest that Y-86789 has experienced heating and the phyllosilicate minerals which were once present in Y-86789 were dehydrated to from anhydrous materials such as olivine. Y-86789 has textural, mineralogical, and compositional characteristics similar to those of Y-86720,which is one of the three unusual Antarctic carbonaceous chondrites with CI-CM affinities that show evidence of dehydration. Chondrules are completely replaced by the phyllosilicate-like materials and are surrounded by fine-grained rims. Some chondrules contain Ca-carbonates. There is an abundance of troilite in the matrix, but magnetite and PCP, which are common in CM chondrites, are absent. Some large troilite grains have a euhedral lath-like morphology. The bulk chemical composition of Y-86789 is also similar to that of Y-86720. On the basis of these similarities, we propose that Y-86789 and Y-86720 are paired meteorites

The Complete Infrared View of Active Galactic Nuclei from the 70-month Swift/BAT Catalog

We systematically investigate the near- (NIR) to far-infrared (FIR) photometric properties of a nearly complete sample of local active galactic nuclei (AGN) detected in the Swift/Burst Alert Telescope (BAT) all-sky ultra hard X-ray (14-195 keV) survey. Out of 606 non-blazar AGN in the Swift/BAT 70-month catalog at high galactic latitude of $|b|>10^{\circ}$, we obtain IR photometric data of 604 objects by cross-matching the AGN positions with catalogs from the WISE, AKARI, IRAS, and Herschel infrared observatories. We find a good correlation between the ultra-hard X-ray and mid-IR (MIR) luminosities over five orders of magnitude ($41 < \log (L_{14-195}/{\rm erg}~{\rm s}^{-1})< 46$). Informed by previous measures of the intrinsic spectral energy distribution of AGN, we find FIR pure-AGN candidates whose FIR emission is thought to be AGN-dominated with low starformation activity. We demonstrate that the dust covering factor decreases with the bolometric AGN luminosity, confirming the luminosity-dependent unified scheme. We also show that the completeness of the WISE color-color cut in selecting Swift/BAT AGN increases strongly with 14-195 keV luminosity.Comment: 24 pages, 11 figures, accepted for publication in ApJ. The full list of Table 1 is available at http://www.kusastro.kyoto-u.ac.jp/~ichikawa/table1_MRT.tx

Slow and Fast Transitions in the Rising Phase of Outbursts from NS-LMXB transients, AqlX-1 and 4U1608-52

We analyzed the initial rising behaviors of X-ray outbursts from two transient low-mass X-ray binaries (LMXBs) containing a neutron-star (NS), Aql X-1 and 4U 1608-52, which are continuously being monitored by MAXI/GSC in 2--20 keV, RXTE/ASM in 2--10 keV, and Swift/BAT in 15--50 keV. We found that the observed ten outbursts are classified into two types by the patterns of the relative intensity evolutions in the two energy bands below/above 15 keV. One type behaves as the 15--50 keV intensity achieves the maximum during the initial hard-state period and drops greatly at the hard-to-soft state transition. On the other hand, the other type does as both the 2--15 keV and the 15--50 keV intensities achieve the maximums after the transition. The former have the longer initial hard-state ($\gtrsim$ 9 d) than the latter's (\ltsim5 d). Therefore, we named them as slow-type (S-type) and fast-type (F-type), respectively. These two types also show the differences in the luminosity at the hard-to-soft state transition as well as in the average luminosity before the outburst started, where the S-type are higher than the F-type in the both. These results suggest that the X-ray radiation during the pre-outburst period, which heats up the accretion disk and delays the disk transition (i.e., from a geometrically thick disk to a thin one), would determine whether the following outburst becomes S-type or F-type. The luminosity when the hard-to-soft state transition occurs is higher than $\sim 8 \times10^{36}$ erg s$^{-1}$ in the S-type, which corresponds to 4% of the Eddington luminosity for a 1.4 \Mo NS.Comment: 14 pages, 10 figures; Publications of the Astronomical Society of Japan, 201