Spatially-Resolved Spectra of the "Teacup" AGN: Tracing the History of a Dying Quasar

The Sloan Digital Sky Survey (SDSS) Galaxy Zoo project has revealed a number of spectacular galaxies possessing Extended Emission-Line Regions (EELRs), the most famous being Hanny's Voorwerp galaxy. We present another EELR object discovered in the SDSS endeavor: the Teacup Active Galactic Nucleus (AGN), nicknamed for its EELR, which has a handle like structure protruding 15 kpc into the northeast quadrant of the galaxy. We analyze physical conditions of this galaxy with long-slit ground based spectroscopy from Lowell, Lick, and KPNO observatories. With the Lowell 1.8m Perkin's telescope we took multiple observations at different offset positions, allowing us to recover spatially resolved spectra across the galaxy. Line diagnostics indicate the ionized gas is photoionized primarily by the AGN. Additionally we are able to derive the hydrogen density from the [S II] 6716/6731 ratio. We generated two-component photoionization models for each spatially resolved Lowell spectrum. These models allow us to calculate the AGN bolometric luminosity seen by the gas at different radii from the nuclear center of the Teacup. Our results show a drop in bolometric luminosity by more than two orders of magnitude from the EELR to the nucleus, suggesting that the AGN has decreased in luminosity by this amount in a continuous fashion over 46,000 years, supporting the case for a dying AGN in this galaxy independent of any IR based evidence. We demonstrate that spatially resolved photoionization modeling could be applied to EELRs to investigate long time scale variability.Comment: 38 pages, 11 figures, accepted for publication in the Astrophysical Journa

Probability Density Function of Longitudinal Velocity Increment in Homogeneous Turbulence

Two conditional averages for the longitudinal velocity increment u_r of the simulated turbulence are calculated: h(u_r) is the average of the increment of the longitudinal Laplacian velocity field with u_r fixed, while g(u_r) is the corresponding one of the square of the difference of the gradient of the velocity field. Based on the physical argument, we suggest the formulae for h and g, which are quite satisfactorily fitted to the 512^3 DNS data. The predicted PDF is characterized as (1) the Gaussian distribution for the small amplitudes, (2) the exponential distribution for the large ones, and (3) a prefactor before the exponential function for the intermediate ones.Comment: 4 pages, 4 figures, using RevTeX3.

Improving Language Acquisition Through Better Task Design

departmental bulletin pape

Chandra HETGS Multi-Phase Spectroscopy of the Young Magnetic O Star theta^1 Orionis C

We report on four Chandra grating observations of the oblique magnetic rotator theta^1 Ori C (O5.5 V) covering a wide range of viewing angles with respect to the star's 1060 G dipole magnetic field. We employ line-width and centroid analyses to study the dynamics of the X-ray emitting plasma in the circumstellar environment, as well as line-ratio diagnostics to constrain the spatial location, and global spectral modeling to constrain the temperature distribution and abundances of the very hot plasma. We investigate these diagnostics as a function of viewing angle and analyze them in conjunction with new MHD simulations of the magnetically channeled wind shock mechanism on theta^1 Ori C. This model fits all the data surprisingly well, predicting the temperature, luminosity, and occultation of the X-ray emitting plasma with rotation phase.Comment: 52 pages, 14 figures (1 color), 6 tables. To appear in the Astrophysical Journal, 1 August 2005, v628, issue 2. New version corrects e-mail address, figure and table formatting problem

First HARPSpol discoveries of magnetic fields in massive stars

In the framework of the Magnetism in Massive Stars (MiMeS) project, a HARPSpol Large Program at the 3.6m-ESO telescope has recently started to collect high-resolution spectropolarimetric data of a large number of Southern massive OB stars in the field of the Galaxy and in many young clusters and associations. In this Letter, we report on the first discoveries of magnetic fields in two massive stars with HARPSpol - HD 130807 and HD 122451, and confirm the presence of a magnetic field at the surface of HD 105382 that was previously observed with a low spectral resolution device. The longitudinal magnetic field measurements are strongly varying for HD 130807 from $\sim$-100 G to $\sim$700 G. Those of HD 122451 and HD 105382 are less variable with values ranging from $\sim$-40 to -80 G, and from $\sim$-300 to -600 G, respectively. The discovery and confirmation of three new magnetic massive stars, including at least two He-weak stars, is an important contribution to one of the MiMeS objectives: the understanding of origin of magnetic fields in massive stars and their impacts on stellar structure and evolution.Comment: 4 pages, 2 figures, accepted for publication in A&A Lette

Alien Registration- Gagne, Marie D. (Portland, Cumberland County)

https://digitalmaine.com/alien_docs/23994/thumbnail.jp

Self-efficacy and allocation of effort during reading among older and younger adults

Recent research in social cognition suggests one\u27s self-efficacy beliefs regarding one\u27s cognitive abilities can influence the effort expended on cognitive tasks (Bandura, 1989; 1997; Cavanaugh & Greene, 1990; Dunlosky & Hertzog, 1998), which may affect performance. This project was conducted to examine the relationship between age, self-efficacy beliefs, text difficulty, resource allocation to text comprehension processes, and memory for text. 82 younger adults and 74 older adults completed the Metamemory in Adulthood Questionnaire (MIA; Dixon, Hultsch & Hertzog, 1988), Reading Self-Efficacy Questionnaire (RSEQ), and Media Consumption Habits Questionnaire. Using the on-line word-by-word moving window method, participants read 24 two-sentence passages for immediate recall after reading either comparatively easier or more difficult texts. Younger adults reported higher Memory Self-Efficacy (MSE) and higher Reading Self-Efficacy Strength (RSE) than older adults; there were no age differences in RSE Level. Groups were split into high reading self-efficacy (HRSE) and low reading self-efficacy (LRSE) based on RSEQ scores. Analyses of reading times indicated that HRSE individuals allocated more time to processing target texts after reading difficult texts than LRSE individuals, suggesting that SE may influence effort and persistence following difficulty. HRSE individuals recalled more of the text than LRSE individuals overall. A marginal interaction of Self-Efficacy and Age was found; older adults with HRSE recalled more from the text than older adults with LRSE, whereas there were no differences in performance among younger adults. RSE was also more strongly related to recall performance among the old than among the young. HRSE individuals recalled more from target texts following difficult texts than those with LRSE. While HRSE individuals overpredicted recall performance, LRSE individuals were relatively accurate. Regression analyses indicate that working memory span, verbal ability, age, and reading self-efficacy make independent contributions to recall performance. The data also suggest that reading self-efficacy, as measured by the domain-specific RSEQ, may be a better predictor of memory for text than memory self-efficacy, as measured by the domain-general MIA. Collectively, the data support Bandura\u27s (1997) self-efficacy theory in that self-efficacy beliefs influence both effort to reading and performance. Limitations and avenues for future research are discussed