1,800 research outputs found

    The Radio Emission from the Ultra-Luminous Far-Infrared Galaxy NGC 6240

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    We present new radio observations of the ``prototypical'' ultra-luminous far- infrared galaxy NGC~6240, obtained using the VLA at 20~cm in `B' configuration and at 3.6~cm in `A' configuration. These data, along with those from four previous VLA observations, are used to perform a comprehensive study of the radio emission from NGC~6240. Approximately 70\% (~3 x 1023^{23} W~Hz−1^{-1}) of the total radio power at 20 cm originates from the nuclear region ( <~ 1.5 kpc), of which half is emitted by two unresolved (R< 36pc)coresandhalfbyadiffusecomponent.Theradiospectrumofthenuclearemissionisrelativelyflat(R <~ 36 pc) cores and half by a diffuse component. The radio spectrum of the nuclear emission is relatively flat (\alpha= 0.6; =~ 0.6; S_{\nu} \propto \nu^{-\alpha}). The supernova rate required to power the diffuse component is consistent with that predicted by the stellar evolution models of Rieke \etal (1985). If the radio emission from the two compact cores is powered by supernova remnants, then either the remnants overlap and form hot bubbles in the cores, or they are very young ( <~ 100 yr). Nearly all of the other 30\% of the total radio power comes from an ``arm-like'' region extending westward from the nuclear region. The western arm emission has a steep spectrum (\alpha= 1.0),suggestiveofagingeffectsfromsynchrotronorinverse−Comptonlosses,andisnotcorrelatedwithstarlight;wesuggestthatitissynchrotronemissionfromashellofmaterialdrivenbyagalacticsuperwind.Inverse−Comptonscatteringoffar−infraredphotonsintheradiosourcesisexpectedtoproduceanX−rayfluxof 2−6x10 =~ 1.0), suggestive of aging effects from synchrotron or inverse-Compton losses, and is not correlated with starlight; we suggest that it is synchrotron emission from a shell of material driven by a galactic superwind. Inverse-Compton scattering of far-infrared photons in the radio sources is expected to produce an X-ray flux of ~2-6 x 10^{-14}$ erg/s/cm2 in the 2-10 keV band. No significant radio emission is detected from or near the possible ultra-massive ``dark core'' hypothesized by Bland-Hawthorn, Wilson \& Tully (1991).Comment: 36 pages (text and tables) as an uuencoded compressed postscript file (figures available upon request), accepted for the ApJ (20 Nov issue), STScI preprint no. ?? -- May 199

    NASA micromin computer Monthly progress letter, Jan. 1967

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    Microminiature circuit development for flight control computer

    Adolescent Dating Violence Prevention and Intervention in a Community Setting: Perspectives of Young Adults and Professionals

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    Adolescent dating violence (ADV) is a significant community problem. In this study, we examine the perspectives of two groups (young adults who experienced ADV as teens and professionals who work with teens) on ADV prevention/intervention in a community context. We interviewed 88 young adults and 20 professionals. Our research team used Thorne’s (2008) interpretive description methods to determine participants’ perspectives on community views on ADV, community ADV prevention/intervention programs, and ideal ADV prevention/intervention strategies. Participants perceived most communities as being blind to ADV. They perceived prevention programs as unavailable, inappropriate, or impersonal. Young adults indicated that professionals should use a gradual approach with teens experiencing ADV. Participants suggested that ideal prevention programs should include personal development and education. Helping professionals can use these findings to develop effective community-based ADV prevention/intervention program

    Enigma of ultraluminous X-ray sources may be resolved by 3D-spectroscopy (MPFS data)

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    The ultraluminous X-ray sources (ULXs) were isolated in external galaxies for the last 5 years. Their X-ray luminosities exceed 100-10000 times those of brightest Milky Way black hole binaries and they are extremely variable. There are two models for the ULXs, the best black hole candidates. 1. They are supercritical accretion disks around a stellar mass black hole like that in SS433, observed close to the disk axes. 2. They are Intermediate Mass Black Holes (of 100-10000 solar masses). Critical observations which may throw light upon the ULXs nature come from observations of nebulae around the ULXs. We present results of 3D-spectroscopy of nebulae around several ULXs located in galaxies at 3-6 Mpc distances. We found that the nebulae to be powered by their central black holes. The nebulae are shocked and dynamically perturbed probably by jets. The nebulae are compared with SS433 nebula (W50).Comment: Proceedings of the ESO and Euro3D Workshop "Science Perspectives for 3D Spectroscopy", Garching (Germany), October 10-14, 2005. M. Kissler-Patig, M.M. Roth and J.R. Walsh (eds.
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