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64 - T. Velusamy , W. D. Langer , 2013
To study the role of protosellar jets and outflows in the time evolution of the parent cores and the protostars, the astronomical community needs a large enough data base of infrared images of protostars at the highest spatial resolution possible, to reveal the details of their morphology. Spitzer provides unprecedented sensitivity in the infrared to study both the jet and outflow features, however its spatial resolution is limited by its 0.85m mirror. Here we use a high resolution deconvolution algorithm, HiRes, to improve the visualization of spatial morphology by enhancing resolution (to sub-arcsecond levels in the IRAC bands) and removing the contaminating sidelobes from bright sources in a sample of 89 protostellar objects. These reprocessed images are useful to detect: (i) wide angle outflow seen in scattered light; (ii) morphological details of H2 emission in jets and bow shocks; and (iii) compact features in MIPS 24 micron images as protostar/ disk and atomic/ionic line emissions associated with the jets. The HiRes fits image data of such a large homogeneous sample presented here will be useful to the community in studying these protostellar objects. To illustrate the utility of this HiRes sample, we show how the opening angle of the wide angle outflows in 31 sources, all observed in the HiRes processed Spitzer images, correlates with age. Our data suggest a power law fit to opening angle versus age with an exponent of ~0.32 and 0.02, respectively for ages less than 8000 yr and greater than 8000 yr.
HIFI GOT C+ Galactic plane [CII] spectral survey has detected strong emission at the spiral arm tangencies. We use the unique viewing geometry of the Scutum-Crux (S-C) tangency near i = 30degs to detect the warm ionized medium (WIM) component traced by [CII] and to study the effects of spiral density waves on Interstellar Medium (ISM) gas. We compare [CII] velocity features with ancillary HI, 12CO and 13CO data near tangent velocities at each longitude to separate the cold neutral medium and the warm neutral + ionized components in the S-C tangency, then we identify [CII] emission at the highest velocities without any contribution from 12CO clouds, as WIM. We present the GOT C+ results for the S-C tangency. We interpret the diffuse and extended excess [CII] emission at and above the tangent velocities as arising in the electron-dominated warm ionized gas in the WIM. We derive an electron density in the range of 0.2 - 0.9 cm^-3 at each longitude, a factor of several higher than the average value from Halpha and pulsar dispersion. We interpret the excess [CII] in S-C tangency as shock compression of the WIM induced by the spiral density waves.
In some protostellar objects both wide angle outflows and collimated jets are seen, while in others only one is observed. Spitzer provides unprecedented sensitivity in the infrared to study both the jet and outflow features. Here, we use HiRes deconv olution to improve the visualization of spatial morphology by enhancing resolution (to sub-arcsecond levels in the IRAC bands) and removing the contaminating sidelobes from bright sources. We apply this approach to study the jet and outflow features in Cep E a young, energetic Class 0 protostar. In the reprocessed images we detect: (i) wide angle outflow seen in scattered light; (ii) morphological details on at least 29 jet driven bow shocks and jet heads or knots; (iii) three compact features in 24 micron continuum image as atomic/ionic line emission coincident with the jet heads; and, (iv) a flattened 35 arcsec size protostellar envelope seen against the interstellar background PAH emission as an absorption band across the protostar at 8 micron. By separating the protostellar photospheric scattered emission in the wide angle cavity from the jet emission we show that we can study directly the scattered light spectrum. We present the H2 emission line spectra, as observed in all IRAC bands, for 29 knots in the jets and bowshocks and use them in the IRAC color -- color space as a diagnostic of the thermal gas in the shocks driven by the jets. The data presented here will enable detailed modeling of the individual shocks retracing the history of the episodic jet activity and the associated accretion on to the protostar. The Spitzer data analysis presented here shows the richness of its archive as a resource to study the jet/outflow features in H2 and scattered light in a large homogeneous sample.
190 - T. velusamy , R. Peng , D. Li 2008
To study the evolution of high mass cores, we have searched for evidence of collapse motions in a large sample of starless cores in the Orion molecular cloud. We used the Caltech Submillimeter Observatory telescope to obtain spectra of the optically thin (H13CO+) and optically thick (HCO+) high density tracer molecules in 27 cores with masses $>$ 1 Ms. The red- and blue-asymmetries seen in the line profiles of the optically thick line with respect to the optically thin line indicate that 2/3 of these cores are not static. We detect evidence for infall (inward motions) in 9 cores and outward motions for 10 cores, suggesting a dichotomy in the kinematic state of the non-static cores in this sample. Our results provide an important observational constraint on the fraction of collapsing (inward motions) versus non-collapsing (re-expanding) cores for comparison with model simulations.
We present new details of the structure and morphology of the jets and outflows in HH46/47 as seen in Spitzer infrared images from IRAC and MIPS, reprocessed using the ``HiRes deconvolution technique. HiRes improves the visualization of spatial morph ology by enhancing resolution (to sub-arcsec levels in IRAC bands) and removing the contaminating side lobes from bright sources. In addition to sharper views of previously reported bow shocks, we have detected: (i) the sharply-delineated cavity walls of the wide-angle biconical outflow, seen in scattered light on both sides of the protostar, (ii) several very narrow jet features at distances 400 AU to 0.1 pc from the star, and, (iii) compact emissions at MIPS 24 micron coincident with the jet heads, tracing the hottest atomic/ionic gas in the bow shocks.
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