Interactions between AGB stars and a secondary in a close orbit are one possible explanation of why some AGB stars develop into aspherical planetary nebulae. This study uses millimeter observations of the continuum and SiO maser emission in several symbiotic Miras looking for evidence of an interaction between the two stars. New JVLA observations at ~45 mas resolution are analyzed, imaging continuum and SiO masers. Two of the three targets were detected and accurately registered continuum and line images were derived. No clear evidence of an interaction was found between components B and A in Mira. R Aqr has a well known jet arising from the secondary star. The jet may be disturbing the circumstellar envelop of the AGB star or possibly just nearly aligned with it.

W. D. Cotton E. Humphreys M. Wittkowski A. Baudry A. M. S. Richards W. Vlemmings T. Khouri S. Etoka

The luminosity, light curve, post--maximum spectrum, and lack of a progenitor on deep pre-outburst images suggest that SN 2010U was a luminous, fast nova. Its outburst magnitude is consistent with that for a fast nova using the Maximum Magnitude-Rate of Decline relationship for classical novae.

Roberta M. Humphreys Jose L. Prieto Philip Rosenfield L. Andrew Helton Christopher S. Kochanek K. Z. Stanek Rubab Khan Dorota Szczygiel Karen Mogren Robert A. Fesen Dan Milisavljevic Benjamin Williams Jeremiah Murphy Julianne Dalcanton Karoline Gilbert

We present 1.1 mm observations for a sample of 16 powerful radio galaxies at 0.5<z<5.2 and a radio quiet quasar at z=6.3, obtained using the AzTEC bolometer array mounted on the ASTE or the JCMT. This paper more than doubles the number of high-z radio galaxies imaged at millimetre/sub-millimetre wavelengths. We detect probable millimetre-wave counterparts for 11 of the active galaxies. The 6 active galaxies which do not have a probable millimetre counterpart in our images nevertheless have one or more likely associated millimetric source. Thus, we conclude that powerful (radio-loud) active galaxies at high-z are beacons for finding luminous millimetre/sub-millimetre galaxies at high-z. The flux densities of our AzTEC counterparts imply star formation rates ranging from <200 to ~1300 M./yr. In addition, we find that for the radio galaxoes the 1.1 mm flux density is anticorrelated with the largest angular size of the radio source. We also present new Spitzer imaging observations of several active galaxies in our sample. Combining these with archival data, we examine the mid-infrared colours of our sample. We find that radio galaxies for which we have detected a probable 1.1 mm counterpart have mid-infrared colours consistent with dusty starbursts, and are usually bluer than high-z Spitzer-selected active galaxies. In addition, we find arcs of 24 micron sources extending across ~200-500 kpc, apparently associated with three of the radio galaxies.

A. Humphrey M. Zeballos I. Aretxaga D. H. Hughes M. S. Yun R. Cybulski Grant W. Wilson J. Austermann H. Ezawa R. Kawabe K. Kohno T. Perera K. Scott D. Sánchez-Arguelles R. Gutermuth

We investigate the use of 183 GHz H2O masers for characterization of the physical conditions and mass loss process in the circumstellar envelopes of evolved stars. We used APEX SEPIA Band 5 to observe the 183 GHz H2O line towards 2 Red Supergiant and 3 Asymptotic Giant Branch stars. Simultaneously, we observed lines in 28SiO v0, 1, 2 and 3, and for 29SiO v0 and 1. We detected the 183 GHz H2O line towards all the stars with peak flux densities greater than 100 Jy, including a new detection from VY CMa. Towards all 5 targets, the water line had indications of being due to maser emission and had higher peak flux densities than for the SiO lines. The SiO lines appear to originate from both thermal and maser processes. Comparison with simulations and models indicate that 183 GHz maser emission is likely to extend to greater radii in the circumstellar envelopes than SiO maser emission and to similar or greater radii than water masers at 22, 321 and 325 GHz. We speculate that a prominent blue-shifted feature in the W Hya 183 GHz spectrum is amplifying the stellar continuum, and is located at a similar distance from the star as mainline OH maser emission. From a comparison of the individual polarizations, we find that the SiO maser linear polarization fraction of several features exceeds the maximum fraction allowed under standard maser assumptions and requires strong anisotropic pumping of the maser transition and strongly saturated maser emission. The low polarization fraction of the H2O maser however, fits with the expectation for a non-saturated maser. 183 GHz H2O masers can provide strong probes of the mass loss process of evolved stars. Higher angular resolution observations of this line using ALMA Band 5 will enable detailed investigation of the emission location in circumstellar envelopes and can also provide information on magnetic field strength and structure.

E. M. L. Humphreys K. Immer M. D. Gray E. De Beck W. H. T. Vlemmings A. Baudry A. M. S. Richards M. Wittkowski K. Torstensson C. De Breuck P. Moller S. Etoka M. Olberg

An increasing number of non-terminal eruptions are being found in the numerous surveys for optical transients. Very little is known about these giant eruptions, their progenitors and their evolutionary state. A greatly improved census of the likely progenitor class, including the most luminous evolved stars, the Luminous Blue Varaibles (LBVs), and the warm and cool hypergiants is now needed for a complete picture of the final pre-SN stages of very massive stars. We have begun a survey of the evolved and un stable luminous star populations in several nearby resolved galaxies. In this second paper on M31 and M33, we review the spectral characteristics, spectral energy distributions, circumstellar ejecta, and evidence for mass loss for 82 luminous and variable stars.We show that many of these stars have warm circumstellar dust including several of the Fe II emission line stars, but conclude that the confirmed LBVs in M31 and M33 do not. The confirmed LBVs have relatively low wind speeds even in their hot, quiescent or visual minimum state compared to the B-type supergiants and Of/WN stars which they spectroscopically resemble. The nature of the Fe II emis sion line stars and their relation to the LBV state remains uncertain, but some have properties in common with the warm hypergiants and the sgB[e] stars. Several individual stars are discussed in detail. We identify three possible candidate LBVs and three additional post-red supergiant candidates. We suggest that M33-013406.63 (UIT301,B416) is not an LBV/S Dor variable, but is a very luminous late O-type supergiant and one of the most luminous stars or pair of stars in M33.

Roberta M. Humphreys Kerstin Weis Kris Davidson D. J. Bomans Birgitta Burggraf

First principles calculations based on density functional theory are having an incerasing impact on our understanding of molecule-surface interactions. For example, calculations of the multi-dimensional potential energy surface have provided considerable insight into th edynamics of dissociation processes. However, these calculations using a plane-wave basis set are very compute expensive if they are to be fully converged with respect to the plane-wave energy cutoff, k-point sampling, supercell size, slab thickness, etc. Because of this, in this study, we have implemented a mixed-basis set approach which uses pseudo-atomic orbitals and a few low-energy plane waves as the basis set within a density functional, pseudopotential calculation. We show that the method offers a computationally cheap but accurate alternative. The energy barrier for hydrogen dissociation on Cu(111) is calculated as an example.

O. Gulseren D. M. Bird S. E. Humphreys

We have investigated the nonlinear surface impedance and two-tone intermodulation distortion of nine epitaxial YBa2Cu3O7-d films on MgO substrates, using stripline resonators, at frequencies f=2.3-11.2GHz and temperatures T=1.7K-Tc. The power dissipation decreased by up to one order of magnitude as the microwave electric field was increased to about 100V/m for T<20 K, while the reactance Xs showed only a weak increase. The minimum of the losses correlated with a plateau in the intermodulation signal. The same features were observed for a Nb film on MgO. The anomalous response is due to nonlinear dielectric losses in the substrate, which can be described by defect dipole relaxation.

M. A. Hein D. E. Oates P. J. Hirst R. G. Humphreys A. V. Velichko

We analyze five epochs of Spitzer Space Telescope/Infrared Array Camera (IRAC) observations of the nearby spiral galaxy M33. Each epoch covered nearly a square degree at 3.6, 4.5, and 8.0 microns. The point source catalog from the full dataset contains 37,650 stars. The stars have luminosities characteristic of the asymptotic giant branch and can be separated into oxygen-rich and carbon-rich populations by their [3.6] - [4.5] colors. The [3.6] - [8.0] colors indicate that over 80% of the stars detected at 8.0 microns have dust shells. Photometric comparison of epochs using conservative criteria yields a catalog of 2,923 variable stars. These variables are most likely long-period variables amidst an evolved stellar population. At least one-third of the identified carbon stars are variable.

K. B. W. McQuinn Charles E. Woodward S. P. Willner E. F. Polomski R. D. Gehrz Roberta M. Humphreys Jacco Th. van Loon M. L. N. Ashby K. Eicher G. G. Fazio

In Orion BN/KL, proper motions of 7 mm vibrationally-excited SiO masers trace rotation of a nearly edge-on disk and a bipolar wide-angle outflow 10-100 AU from radio Source I, a binary young stellar object (YSO) of ~20 Msun. Here we map ground-state 7 mm SiO emission with the Very Large Array and track proper motions over 9 years. The innermost and strongest emission lies in two extended arcs bracketing Source I. The proper motions trace a northeast-southwest bipolar outflow 100-1000 AU from Source I with a median 3D motion of ~18 km/s. An overlying distribution of 1.3 cm H2O masers betrays similar flow characteristics. Gas dynamics and emission morphology traced by the masers suggest the presence of a magnetocentrifugal disk-wind. Reinforcing evidence lies in the colinearity of the flow, apparent rotation across the flow parallel to the disk rotation, and recollimation that narrows the flow opening angle ~120 AU downstream. The arcs of ground-state SiO emission may mark the transition point to a shocked super-Alfvenic outflow.

L. J. Greenhill C. Goddi C. J. Chandler L. D. Matthews E. M. L. Humphreys

The circumstellar environments of objects on the asymptotic giant branch and beyond are rich in molecular species. Nevertheless, methanol has never been detected in such an object, and is therefore often taken as a clear signpost for a young stellar object. However, we report the first detection of CH3OH in a post-AGB object, HD101584, using ALMA. Its emission, together with emissions from CO, SiO, SO, CS, and H2CO, comes from two extreme velocity spots on either side of the object where a high-velocity outflow appears to interact with the surrounding medium. We have derived molecular abundances, and propose that the detected molecular species are the effect of a post-shock chemistry where circumstellar grains play a role. We further provide evidence that HD101584 was a low-mass, M-type AGB star.

H. Olofsson W. H. T. Vlemmings P. Bergman E. M. L. Humphreys M. Lindqvist. M. Maercker L. Nyman S. Ramstedt D. Tafoya