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Spitzer 2007 Conference Abstracts

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Spitzer 2007 Conference Abstracts SPITZER 2007 CONFERENCE ABSTRACTS Abramson, Anne Yale University Spitzer Observations of ISM Stripping in NGC 4330 We present Spitzer IRAC and MIPS observations of the Virgo cluster spiral galaxy NGC 4330, which is currently undergoing ICM-ISM stripping. This galaxy was observed as part of the Virgo Spitzer Survey. HI and optical observations of this galaxy have provided ample evidence that the ISM is actively being pushed out of the stellar disk. Nearly 50% of its HI emission is extraplanar to one side of the major axis, with 10% of the total emission coming from a tail which extends well outside of the edge of the stellar disk. H-alpha observations reveal that star formation is confined to the inner regions of the stellar disk where enough gas remains to fuel it. Spitzer IRAC and MIPS data provide a detailed picture of the effects of ram pressure stripping on the galaxy's ISM. No IR emission at any wavelength is detected in the HI tail, indicating that there is not sufficient star formation or stellar continuum heating to excite dust grains in the stripped gas. 8 micron data show that PAH emission is confined to the inner parts of the galactic disk, indicating that the stripped gas has a very low ratio of FIR to HI emission. A comparison between 24 micron and H-alpha, both of which trace star formation, shows that H-alpha emission is comparatively strong only at the edges of the star-forming disk, where the dust that normally obscures H-alpha emission has been stripped away. These observations have greatly enhanced our understanding of the stripping process and fate of the stripped gas in this galaxy. Alexov, Anastasia Caltech - IPAC/IRSA Spitzer Data Access through the NASA/IPAC Infrared Science Archive (IRSA) In August 2007, in collaboration with the Spitzer Science Center, IRSA released an interface to the Spitzer Space Telescope post-BCD products. The interface is accessible at http://irsa.ipac.caltech.edu/applications/Spitzer/Spitzer/ and offers coverage maps for all three instruments and their modes. The interface supports queries by position/target, by instrument and/or by program parameters. It returns spatial coverage and footprint maps, previews of data and metadata, and single file or bulk data download options. IRSA has also curated and served Spitzer Legacy Enhanced Products and Ancillary data since 2003. Currently, it serves data from eight Legacy projects, and will serve data sets from all the Legacy teams (currently numbering 26). Allamandola, Louis J NASA Ames Research Center The NASA Ames PAH IR Spectroscopic Database Authors: C. Bauschlicher, Jr.1, J. Cami2,4, D.M. Hudgins3, A.L. Mattioda1, E. Peeters2,4, A. Ricca1,4, and L. J. Allamandola1 The unprecedented sensitivity and mid-IR spectroscopic capabilities of the Spitzer Space Telescope show that the mid-IR emission features, formerly known as the unidentified infrared bands, are unique and powerful diagnostics of physical and chemical conditions throughout the Universe. These features are now generally attributed to the vibrational emission from Polycyclic Aromatic Hydrocarbons (PAHs), the molecular component of the interstellar carbon-rich dust population. This major breakthrough in understanding was made possible by combining observations with extensive theoretical and experimental studies which showed PAH spectra can reproduce the observed pattern of band positions, relative intensities, and variations. The Ames PAH IR spectral database created over the last 15 years represents an important part of the foundation for our understanding of this abundant and widespread material. This paper presents an overview of the database and some applications. THE EXPERIMENTAL PAH SPECTRAL DATABASE- Driven by the astrophysical problem the IR spectroscopic properties of over 200 charged and neutral, cold, individual aromatic compounds have been measured. THE COMPUTATIONAL PAH SPECTRAL DATABASE- It is not possible to obtain samples of all possible PAHs of interest for experimental study. This includes molecules for which the ion is a stable closed shell species while the neutral is a reactive open-shell radical. Such species could be formed easily in the ISM and be quite common, yet they are very difficult to form in the lab. Even for the neutrals, not all large PAHs of potential interest have been synthesized, nor is it straightforward to measure the complete mid-IR spectrum of ionized PAHs. Modern electronic structure theory offers a way to obtain accurate spectra of astrophysically important species that could not be obtained in any other way. There are about 600 spectra in the theoretical PAH spectral database. This includes the spectra of very large PAHs (C40 to C132), comparable to the size of the PAHs thought to dominate the interstellar emission spectrum, and many PAH variants. Together, these data show that PAH spectra can reproduce the pattern of band positions, intensities, and variations of the observed interstellar IR emission in detail. While a number of these spectra have been published, and the spectra of 21 small neutral PAHs and 16 PAH cations are listed on the Ames database website (http://www.astrochem.org), the vast majority of the spectra in the database are not readily accessible to the public. It is our intention to make these data publicly available in a unified format over the next year. 1- NASA Ames Research Center, Moffett Field, CA. 94035-1000 2- Physics Department, U. Western Ontario, 3- NASA Headquarters 4- SETI Institute Andersen, Morten Spitzer Science Center, Caltech PAH Features in Supernova Remnants Shocks from supernova are responsible for destruction of interstellar dust and possibly for the creation of poly aromatic hydrocarbons (PAHs, Jones et al 1996) However, the rate and effectiveness of the creation of PAHs in supernova shocks are largely unknown quantities. Only with the sensitivity and spatial resolution with SPITZER has it been possible to obtain high quality spectra of Galactic supernova remnants to examine if PAHs are indeed created in the shock. We have undertaken a spectroscopic survey of the known supernovae in the Galaxy that were detected in the GLIMPSE survey. We present here new results on the presence of PAH in a subset of the supernovae, including RCW103 and G311.5-0.3, based on low resolution SPITZER IRS spectroscopy. The ratio of the ratio of the 11.3 micron feature (due to C-H bending) to the 15-20 micron PAH plateau (due to C-C-C bending) is investigated. We discuss the evolution of the PAH features across the supernova shell and use our spectra of a control field to disentangle the Galactic PAH features with those intrinsic to the supernova remnants. We further combine the IRS spectra with MIPS spectral observations to constrain the relative abundance of large and Small grains to the amount of PAH detected. Andersson, B-G FUSE/JHU, SOFIA/USRA Observational Evidence for Radiative Grain Alignment in the ISM We have used multi-band optical polarimetry towards six nearby interstellar clouds, supported by NIR and FIR photometry, to show that the wavelength of maximum polarization shows a universal, linear dependence on the visual extinction, indicating a radiatively driven grain alignment mechanism. We show that the observed polarization is also sensitive to environmental factors, such as hot stars nearby to the dust and, the characteristics of the embedded star formation in the clouds. These dependencies are consistent with, and might have been expected from, radiative grain alignment. We recover the dependence on the total-to-selective extinction seen in earlier studies, but only in the form or a zero level offset varying from cloud to cloud. Having established the first order dependence of the polarization curve on extinction will allow more detailed work to be pursued on the second order alignment and disalignment mechanisms. Andersson, B-G FUSE/JHU, SOFIA/USRA Observational Evidence for Radiative Grain Alignment in the ISM We have used multi-band optical polarimetry towards six nearby interstellar clouds, supported by NIR and FIR photometry, to show that the wavelength of maximum polarization shows a universal, linear dependence on the visual extinction, indicating a radiatively driven grain alignment mechanism. We show that the observed polarization is also sensitive to environmental factors, such as hot stars nearby to the dust and, the characteristics of the embedded star formation in the clouds. These dependencies are consistent with, and might have been expected from, radiative grain alignment. We recover the dependence on the total-to-selective extinction seen in earlier studies, but only in the form or a zero level offset varying from cloud to cloud. Having established the first order dependence of the polarization curve on extinction will allow more detailed work to be pursued on the second order alignment and disalignment mechanisms. Appleton, Philip NHSC-Caltech IRS Spectroscopy and Imaging of Collisional Ring Galaxies We present spectroscopy of a sample of collisional ring galaxies observed with the IRS, IRAC and MIPS. The IRS observations, taken with both the low and hi-res are aimed at investigating the physical conditions in the nuclei and rings in these near head-on collisional systems. The observations will be used, in conjunction with other optical and near-IR imaging and spectroscopy to investigate these generally low-metallicity systems. Armus, Lee Spitzer Science Center Mapping the Wind from M82 with the IRS As one of the nearest starburst galaxies, M82 is often used as a prototype when studying distant, star-forming galaxies. Besides hosting a burst of star formation, M82 is also driving an outflowing (super) wind along its minor axis. Superwinds have been identified in many other starburst galaxies over a large range in luminosities, but the wind in M82 is the closest, brightest example of this phenomenon. Here we present results from the first large-scale, mid-infrared spectral maps of the M82 wind taken with the IRS on Spitzer.
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