Identification of SH Δv=1\Delta v=1 ro-vibrational lines in R And

We report the identification of SH $\Delta v=1$ ro-vibrational lines in the published high-resolution infrared spectrum of the S-type star, R And. This is the first astronomical detection of this molecule. The lines show inverse P-Cygni profiles, indicating infall motion of the molecular layer due to stellar pulsation. A simple spherical shell model with a constant infall velocity is adopted to determine the condition of the layer. It is found that a single excitation temperature of 2200 K reproduces the observed line intensities satisfactory. SH is located in a layer from 1.0 to ~1.1 stellar radii, which is moving inward with a velocity of 9 km s-1. These results are consistent with the previous measurements of CO $\Delta v=3$ transitions. The estimated molecular abundance SH/H is 1x10^-7, consistent with a thermal equilibrium calculation.Comment: 10 pages, 2 figures. Accepted for publication in ApJ Letter

Carbon stars in the IRTS survey

We have identified 139 cool carbon stars in the near-infrared spectro-photometric survey of the InfraRed Telescope in Space (IRTS) from the conspicuous presence of molecular absorption bands at 1.8, 3.1 and 3.8 microns. Among them 14 are new, bright (K ~ 4.0-7.0), carbon stars. We find a trend relating the 3.1 microns band strength to the K-L' color index, which is known to correlate with mass-loss rate. This could be an effect of a relation between the depth of the 3.1 microns feature and the degree of development of the extended stellar atmosphere where dust starts to form.Comment: accepted by the PASP; December 7, 200

An AKARI Search for Intracluster Dust of Globular Clusters

We report the observations of 12 globular clusters with the AKARI/FIS. Our goal is to search for emission from the cold dust within clusters. We detect diffuse emissions toward NGC 6402 and 2808, but the IRAS 100-micron maps show the presence of strong background radiation. They are likely emitted from the galactic cirrus, while we cannot rule out the possible association of a bump of emission with the cluster in the case of NGC 6402. We also detect 28 point-like sources mainly in the WIDE-S images (90 micron). At least several of them are not associated with the clusters but background galaxies based on some external catalogs. We present the SEDs by combining the near-and-mid infrared data obtained with the IRC if possible. The SEDs suggest that most of the point sources are background galaxies. We find one candidate of the intracluster dust which has no mid-infrared counterpart unlike the other point-like sources, although some features such as its point-like appearance should be explained before we conclude its intracluster origin. For most of the other clusters, we have confirmed the lack of the intracluster dust. We evaluate upper limits of the intracluster dust mass to be between 1.0E-05 and 1.0E-03 solar mass depending on the dust temperature. The lifetime of the intracluster dust inferred from the upper limits is shorter than 5 Myr (T=70K) or 50 Myr (35K). Such short lifetime indicates some mechanism(s) are at work to remove the intracluster dust. We also discuss its impact on the chemical evolution of globular clusters.Comment: Accepted for publication in PASJ AKARI special issue. 14 pages, 11 figure

The time variation in infrared water-vapour bands in Mira variables

The time variation in the water-vapour bands in oxygen-rich Mira variables has been investigated using multi-epoch ISO/SWS spectra of four Mira variables in the 2.5-4.0 micron region. All four stars show H2O bands in absorption around minimum in the visual light curve. At maximum, H2O emission features appear in the ~3.5-4.0 micronm region, while the features at shorter wavelengths remain in absorption. These H2O bands in the 2.5-4.0 micron region originate from the extended atmosphere. The analysis has been carried out with a disk shape, slab geometry model. The observed H2O bands are reproduced by two layers; a `hot' layer with an excitation temperature of 2000 K and a `cool' layer with an excitation temperature of 1000-1400 K. The radii of the `hot' layer (R_hot) are ~1 R_* at visual minimum and 2 R_* at maximum, where R_* is a radius of background source of the model. The time variation of R_hot/R_* from 1 to 2 is attributed to the actual variation in the radius of the H2O layer. A high H2O density shell occurs near the surface of the star around minimum, and moves out with the stellar pulsation. This shell gradually fades away after maximum, and a new high H2O density shell is formed in the inner region again at the next minimum. Due to large optical depth of H2O, the near-infrared variability is dominated by the H2O layer, and the L'-band flux correlates with the area of the H2O shell. The infrared molecular bands trace the structure of the extended atmosphere and impose appreciable effects on near-infrared light curve of Mira variables.Comment: 15 pages, 16 figures, accepted by A&

AKARI Near- to Mid-Infrared Imaging and Spectroscopic Observations of the Small Magellanic Cloud. I. Bright Point Source List

We carried out a near- to mid-infrared imaging and spectroscopic observations of the patchy areas in the Small Magellanic Cloud using the Infrared Camera on board AKARI. Two 100 arcmin2 areas were imaged in 3.2, 4.1, 7, 11, 15, and 24 um and also spectroscopically observed in the wavelength range continuously from 2.5 to 13.4 um. The spectral resolving power (lambda/Delta lambda) is about 20, 50, and 50 at 3.5, 6.6 and 10.6 um, respectively. Other than the two 100 arcmin2 areas, some patchy areas were imaged and/or spectroscopically observed as well. In this paper, we overview the observations and present a list of near- to mid-infrared photometric results, which lists ~ 12,000 near-infrared and ~ 1,800 mid-infrared bright point sources detected in the observed areas. The 10 sigma limits are 16.50, 16.12, 13.28, 11.26, 9.62, and 8.76 in Vega magnitudes at 3.2, 4.1, 7, 11, 15, and 24 um bands, respectively.Comment: 16 pages, 7 figures, accepted for publication in PASJ. Full resolution version is available at http://www-irc.mtk.nao.ac.jp/%7Eyita/smc20100112.pd