Depletion of CCS in a Candidate Warm-Carbon-Chain-Chemistry Source L483

We have carried out an observation of the CCS ($J_{N}$=2$_{1}-$1$_{0}$) line with the Very Large Array in its D-configuration toward a protostellar core L483 (IRAS~18140$-$0440). This is a candidate source of the newly found carbon-chain rich environment called "Warm-Carbon-Chain-Chemistry (WCCC)", according to the previous observations of carbon-chain molecules. The CCS distribution in L483 is found to consist of two clumps aligned in the northwest-southeast direction, well tracing the CCS ridge observed with the single-dish radio telescope. The most remarkable feature is that CCS is depleted at the core center. Such a CCS distribution with the central hole is consistent with those of previously observed prestellar and protostellar cores, but it is rather unexpected for L483. This is because the distribution of CS, which is usually similar to that of CCS, is centrally peaked. Our results imply that the CCS ($J_{N}$=2$_{1}-$1$_{0}$) line would selectively trace the outer cold envelope in the chemically less evolved phase that is seriously resolved out with the interferometric observation. Thus, it is most likely that the high abundance of CCS in L483 relative to the other WCCC sources is not due to the activity of the protostar, although it would be related to its younger chemical evolutionary stage, or a short timescale of the prestellar phase.Comment: 10 pages, 3 figures, accepted for publication in ApJ Part

Survival of shrines from the 2011 Great Tsunami

A massive earthquake with a magnitude of 9.0 occurred on March 11, 2011, and a powerful tsunami devastated a large area along Japan???s eastern coastline. We investigated the tsunami damage using satellite images and aerial photographs, and visited damaged sites including 27 shrines near the coast in 2011 and 2012. It was found that all but two of these shrines survived the tsunami, even though the tsunami height differed from place to place. As a memorial to people who lost their lives in previous tsunamis, shrines were built on safe places where people can evacuate. Many of these shrines were undamaged because their elevation was higher than the tsunami height, and the lives of people who evacuated to the shrines were saved

TOWARD UNDERSTANDING CHEMICAL EVOLUTION ALONG PROTOPLANETARY DISK FORMATION

Star and planet formation is one of the most fundamental structure-formation processes in the Universe. Physical processes of star and planet formation have widely been investigated as one of the major targets of observational astronomy and astrophysics during the last few decades. Meanwhile, star and planet formation is inevitably accompanied with the evolution of interstellar matter. Increasing observational sensitivity allows us to identify about 200 interstellar molecules so far. This indicates high chemical complexity of interstellar clouds and star-forming regions despite their extreme physical condition of low temperature (10-100 K) and low density (10$^{2}$-10$^{7}$ cm$^{-3}$). Such chemical complexity would ultimately be related to an origin of a huge variety of substances in the Solar System. Thus, both physical and chemical approaches are indispensable to bridge star/planet formation studies and the Solar System science. In the last two decades, it is clearly demonstrated that envelopes and disks around solar-type protostars have significant chemical diversity: some sources harbor various saturated-"complex"-organic molecules (COMs) such as HCOOCH$_{3}$ and (CH$_{3}$)$_{2}$O, whereas some others harbor unsaturated species instead. The chemical diversity would originate from different duration time of the starless core phase of each protostar. In fact, sources showing intermediate-type of chemistry have also been found. On the other hand, the most interesting issue to be studied is how the chemical diversity in the protostellar envelopes/disks is brought into the later stages toward protoplanetary disks. Fortunately, such studies are now feasible with high sensitivity and angular-resolution capabilities of ALMA (Atacama Large Millimeter/Submillimeter Array). During its 7 year/cycle operation, spectacular images are being obtained after another by ALMA. These results have newly reminded us of a lack of sufficient information on molecular properties, such as accurate rest frequencies of molecular lines, desorption mechanism of molecules, isotopic fractionations of molecules, and so on. Modern importance of molecular science in relation to astronomy will be discussed by introducing recent observations with ALMA