Study of the Bipolar Nebula IRAS 19312+1950. I. Mapping Observations

IRAS 19312+1950 is an SiO maser source that exhibits a prominent bipolar nebulosity. Mapping observations of this object were made in the CO J=1--0, 13CO J=1--0, C18O J=1--0, CS J=2--1, and HCN J=1--0 lines and in the 150 GHz continuum band. Near-infrared imaging observations were also made in the J, H, and K-bands. The line profiles of the 12CO and HCN spectra consist of a weak broad component with a line width of about 50 km/s and a strong narrow component of the width of about 3 km/s. The profiles of the 13CO, C18O, and CS lines have only the narrow component. Both of the components have an intensity peak at the IRAS position. The narrow component was clearly resolved with a 15'' telescope beam. The spectral energy distribution of this object exhibits a doubly peaked profile between 1 and 25 micron. The 150 GHz continuum flux density was found to be 0.07 Jy, which is consistent with the flux density predicted by the expanding envelope model with a mass loss rate of ~10^{-4} M_sun/y at a distance of 2.5 kpc. We argue that the broad component originates from the expanding envelope of this object, and that the hot dust cloud, which is the source of the narrow component, is also physically associated with this object. Though the present observations do not preclude the possibility of a young stellar object, we argue that it is less plausible. We conclude that IRAS 19312+1950 is an AGB/post-AGB star that is evolved from a massive progenitor.Comment: 13 pages, 6 figures (jpg), high resolution figures available as no598 in http://www.nro.nao.ac.jp/library/report/list.html. PASJ, 56 No. 1 in pres

Search for lepton flavor violation via the intense high-energy muon beam

A deep inerastic scattering process \mutau is discussed to study lepton flavor violation between muons and tau leptons. In supersymmetric models, the Higgs boson mediated diagrams could be important for this reaction. We find that at a muon energy ($E_{\mu}$) higher than 50 GeV, the predicted cross section significantly increases due to the contribution from sea $b$-quarks. The number of produced tau leptons can be $\mathcal{O}(10^4)$ at $E_{\mu}$= 300 GeV from $10^{20}$ muons, whereas $\mathcal{O}(10^2)$ events are given at $E_{\mu}= 50$ GeV.Comment: Contribution to the 6th International Workshop on Neutrino Factories & Superbeams(NuFact04), Jul. 26-Aug. 1, 2004, Osaka Univerisity, Osaka, Japan, talk given by S.K., to appear in the Proceedings, 3 pages, 4 figure

The mapping class group and the Meyer function for plane curves

For each d>=2, the mapping class group for plane curves of degree d will be defined and it is proved that there exists uniquely the Meyer function on this group. In the case of d=4, using our Meyer function, we can define the local signature for 4-dimensional fiber spaces whose general fibers are non-hyperelliptic compact Riemann surfaces of genus 3. Some computations of our local signature will be given.Comment: 24 pages, typo adde