oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 7 )

2018 ( 15 )

2017 ( 8 )

2016 ( 4 )

Custom range...

Search Results: 1 - 10 of 1537 matches for " Terry Herter "
All listed articles are free for downloading (OA Articles)
Page 1 /1537
Display every page Item
The Rotation Curves of Galaxies at Intermediate Redshift
Nicole P. Vogt,Terry Herter,Martha P. Haynes,Stephane Courteau
Physics , 1996, DOI: 10.1086/187041
Abstract: We have undertaken a pilot project to measure the rotation velocities of spiral galaxies in the redshift range 0.18 < z < 0.4 using high dispersion long slit spectroscopy obtained with the Palomar 5m telescope. One field galaxy and three cluster objects known to have strong emission lines were observed over wavelength ranges covering the redshifted lines of [OII], CaII K, H beta, and [OIII]. Two of the objects show extended line emission that allows the tracing of the rotation curve in one or more lines. A line width similar to that obtained with single dish telescopes for the 21-cm HI line observed in lower redshift galaxies can be derived from the observed H beta, [OII], and [OIII] emission by measuring a characteristic width from the velocity histogram. These moderately distant galaxies have much stronger emission lines than typical low-redshift spirals but they appear to be kinematically similar. Application of the Tully-Fisher relation suggests that the two galaxies with rotation curves are intrinsically brighter at R-band than nearby galaxies.
A 0.8-2.4 Micron Transmission Spectrum of the Hot Jupiter CoRoT-1b
Everett Schlawin,Ming Zhao,Johanna K. Teske,Terry Herter
Physics , 2014, DOI: 10.1088/0004-637X/783/1/5
Abstract: Hot Jupiters with brightness temperatures > ~2000K can have TiO and VO molecules as gaseous species in their atmospheres. The TiO and VO molecules can potentially induce temperature inversions in hot Jupiter atmospheres and also have an observable signature of large optical to infrared transit depth ratios. Previous transmission spectra of very hot Jupiters have shown a lack of TiO and VO, but only in planets that also appear to lack temperature inversions. We measure the transmission spectrum of CoRoT-1b, a hot Jupiter that was predicted to have a temperature inversion potentially due to significant TiO and VO in its atmosphere. We employ the multi-object spectroscopy (MOS) method using the SpeX and MORIS instruments on the Infrared Telescope Facility (IRTF) and the Gaussian Process method to model red noise. By using a simultaneous reference star on the slit for calibration and a wide slit to minimize slit losses, we achieve transit depth precision of 0.03% to 0.09%, comparable to the atmospheric scale height but detect no statistically significant molecular features. We combine our IRTF data with optical CoRoT transmission measurements to search for differences in the optical and near infrared absorption that would arise from TiO/VO. Our IRTF spectrum and the CoRoT photometry disfavor a TiO/VO-rich spectrum for CoRoT-1b, suggesting that the atmosphere has another absorber that could create a temperature inversion or that the blackbody-like emission from the planet is due to a spectroscopically flat cloud, dust or haze layer that smoothes out molecular features in both CoRoT-1b's emission and transmission spectra. This system represents the faintest planet hosting star (K=12.2) with a measured planetary transmission spectrum.
Dusty Cradles in a Turbulent Nursery: The Sgr A East HII Region Complex at the Galactic Center
Ryan Lau,Terry Herter,Mark Morris,Joe Adams
Physics , 2014, DOI: 10.1088/0004-637X/794/2/108
Abstract: We present imaging at 19, 25, 31, and 37 {\mu}m of the compact HII region complex G-0.02-0.07 located 6 pc in projection from the center of the Galaxy obtained with SOFIA using FORCAST. G-0.02-0.07 contains three compact HII regions (A, B, and C) and one ultra-compact HII region (D). Our observations reveal the presence of two faint, infrared sources located 23'' and 35'' to the east of region C (FIRS 1 and 2) and detect dust emission in two of the three "ridges" of ionized gas west of region A. The 19/37 color temperature and 37 {\mu}m optical depth maps of regions A - C are used to characterize the dust energetics and morphology. Regions A and B exhibit average 19/37 color temperatures of ~105 K, and regions C and D exhibit color temperatures of ~115 K and ~130 K, respectively. Using the DustEM code we model the SEDs of regions A - D and FIRS 1, all of which require populations of very small, transiently heated grains and large, equilibrium-heated grains. We also require the presence of polycyclic aromatic hydrocarbons (PAHs) in regions A - C in order to fit the 3.6, 4.5, 5.8, and 8.0 {\mu}m fluxes observed by Spitzer/IRAC. The location of the heating source for region A is determined by triangulation from distances and temperatures derived from DustEM models fit to SEDs of three different points around the region, and is found to be displaced to the northeast of the center of curvature near the color temperature peak. Based on total luminosity, expected 1.90 {\mu}m fluxes, and proximity to the mid-IR color temperature peaks we identify heating source candidates for regions A, B, and C. However, for region D, the observed fluxes at 1.87 and 1.90 {\mu}m of the previously proposed ionizing star are a factor of ~40 times too bright to be the heating source and hence is likely just a star lying along the line of sight towards region D.
The Luminous Starburst Ring in NGC 7771: Sequential Star Formation?
Denise A. Smith,Terry Herter,Martha P. Haynes,Susan G. Neff
Physics , 1998, DOI: 10.1086/306605
Abstract: Only two of the twenty highly luminous starburst galaxies analyzed by Smith et al. exhibit circumnuclear rings of star formation. These galaxies provide a link between 10^11 L_sun systems and classical, less-luminous ringed systems. We report the discovery of a near-infrared counterpart to the nuclear ring of radio emission in NGC 7771. A displacement between the ~10 radio bright clumps and the ~10 near-infrared bright clumps indicates the presence of multiple generations of star formation. The estimated thermal emission from each radio source is equivalent to that of ~35000 O6 stars. Each near-infrared bright knot contains ~5000 red supergiants, on average. The stellar mass of each knot is estimated to be ~10^7 M_sun. The implied time-averaged star formation rate is \~40 M_sun per yr. Several similarities are found between the properties of this system and other ringed and non-ringed starbursts. Morphological differences between NGC 7771 and the starburst + Seyfert 1 galaxy NGC 7469 suggest that NGC 7771 may not be old enough to fuel an AGN, or may not be capable of fueling an AGN. Alternatively, the differences may be unrelated to the presence or absence of an AGN and may simply reflect the possibility that star formation in rings is episodic.
Old supernova dust factory revealed at the Galactic center
Ryan M. Lau,Terry L. Herter,Mark R. Morris,Zhiyuan Li,Joseph D. Adams
Physics , 2015, DOI: 10.1126/science.aaa2208
Abstract: Dust formation in supernova ejecta is currently the leading candidate to explain the large quantities of dust observed in the distant, early Universe. However, it is unclear whether the ejecta-formed dust can survive the hot interior of the supernova remnant (SNR). We present infrared observations of ~0.02 $M_\odot$ of warm (~100 K) dust seen near the center of the ~10,000 yr-old Sgr A East SNR at the Galactic center. Our findings signify the detection of dust within an older SNR that is expanding into a relatively dense surrounding medium ($n_e$ ~ 100 $\mathrm{cm}^{-3}$) and has survived the passage of the reverse shock. The results suggest that supernovae may indeed be the dominant dust production mechanism in the dense environment of early Universe galaxies.
Nature Versus Nurture: Luminous Blue Variable Nebulae in and near Massive Stellar Clusters at the Galactic Center
Ryan M. Lau,Terry L. Herter,Mark R. Morris,Joseph D. Adams
Physics , 2014, DOI: 10.1088/0004-637X/785/2/120
Abstract: Three Luminous Blue Variables (LBVs) are located in and near the Quintuplet Cluster at the Galactic Center: the Pistol star, G0.120-0.048, and qF362. We present imaging at 19, 25, 31, and 37 {\mu}m of the region containing these three LBVs, obtained with SOFIA using FORCAST. We argue that the Pistol and G0.120-0.048 are identical ``twins" that exhibit contrasting nebulae due to the external influence of their different environments. Our images reveal the asymmetric, compressed shell of hot dust surrounding the Pistol Star and provide the first detection of the thermal emission from the symmetric, hot dust envelope surrounding G0.120-0.048. Dust and gas composing the Pistol nebula are primarily heated and ionized by the nearby Quintuplet Cluster stars. The northern region of the Pistol nebula is decelerated due to the interaction with the high-velocity (2000 km/s) winds from adjacent Wolf-Rayet Carbon (WC) stars. With the DustEM code we determine that the Pistol nebula is composed of a distribution of very small, transiently-heated grains (10-~35 {\AA}) and that it exhibits a gradient of decreasing grain size from the south to the north due to differential sputtering by the winds from the WC stars. Dust in the G0.120-0.048 nebula is primarily heated by the central star; however, the nebular gas is ionized externally by the Arches Cluster. Unlike the Pistol nebula, the G0.120-0.048 nebula is freely expanding into the surrounding medium. Given independent dust and gas mass estimates we find that the Pistol and G0.120-0.048 nebulae exhibit similar gas-to-dust mass ratios of ~310 and ~290, respectively. Both nebulae share identical size scales (~ 0.7 pc) which suggests that they have similar dynamical timescales of ~10^5 yrs, assuming a shell expansion velocity of v_exp 60 km/s.
An Apparent Precessing Helical Outflow from a Massive Evolved Star: Evidence for Binary Interaction
Ryan M. Lau,Matthew J. Hankins,Terry L. Herter,Mark R. Morris,Elisabeth A. C. Mills,Michael E. Ressler
Physics , 2015,
Abstract: Massive, evolved stars play a crucial role in the metal-enrichment, dust budget, and energetics of the interstellar medium; however, the details of their evolution are uncertain because of their rarity and short lifetimes before exploding as supernovae. Discrepancies between theoretical predictions from single-star evolutionary models and observations of massive stars have evoked a shifting paradigm that implicates the importance of binary interaction. We present mid- to far-infrared observations from the Stratospheric Observatory for Infrared Astronomy (SOFIA) of a conical ``helix'' of warm dust ($\sim180$ K) that appears to extend from the Wolf-Rayet star WR102c. Our interpretation of the helix is a precessing, collimated outflow that emerged from WR102c during a previous evolutionary phase as a rapidly rotating luminous blue variable. We attribute the precession of WR102c to gravitational interactions with an unseen compact binary companion whose orbital period can be constrained to $800\,\mathrm{d}
First Science Results From SOFIA/FORCAST: Super-Resolution Imaging of the S140 Cluster at 37\micron
Paul M. Harvey,Joseph D. Adams,Terry L. Herter,George Gull,Justin Schoenwald,Luke D. Keller,James M. De Buizer,William Vacca,William Reach,E. E. Becklin
Physics , 2012, DOI: 10.1088/2041-8205/749/2/L20
Abstract: We present 37\micron\ imaging of the S140 complex of infrared sources centered on IRS1 made with the FORCAST camera on SOFIA. These observations are the longest wavelength imaging to resolve clearly the three main sources seen at shorter wavelengths, IRS 1, 2 and 3, and are nearly at the diffraction limit of the 2.5-m telescope. We also obtained a small number of images at 11 and 31\micron\ that are useful for flux measurement. Our images cover the area of several strong sub-mm sources seen in the area -- SMM 1, 2, and 3 -- that are not coincident with any mid-infrared sources and are not visible in our longer wavelength imaging either. Our new observations confirm previous estimates of the relative dust optical depth and source luminosity for the components in this likely cluster of early B stars. We also investigate the use of super-resolution to go beyond the basic diffraction limit in imaging on SOFIA and find that the van Cittert algorithm, together with the "multi-resolution" technique, provides excellent results.
First Science Observations with SOFIA/FORCAST: 6 TO 37 micron Imaging of Orion BN/KL
James M. De Buizer,Mark R. Morris,E. E. Becklin,Hans Zinnecker,Terry L. Herter,Joseph D. Adams,Ralph Y. Shuping,William D. Vacca
Physics , 2012, DOI: 10.1088/2041-8205/749/2/L23
Abstract: The BN/KL region of the Orion Nebula is the nearest region of high mass star formation in our galaxy. As such, it has been the subject of intense investigation at a variety of wavelengths, which have revealed it to be brightest in the infrared to sub-mm wavelength regime. Using the newly commissioned SOFIA airborne telescope and its 5-40 micron camera FORCAST, images of the entire BN/KL complex have been acquired. The 31.5 and 37.1 micron images represent the highest resolution observations (<=4") ever obtained of this region at these wavelengths. These observations reveal that the BN object is not the dominant brightness source in the complex at wavelengths >31.5 microns, and that this distinction goes instead to the source IRc4. It was determined from these images and derived dust color temperature maps that IRc4 is also likely to be self-luminous. A new source of emission has also been identified at wavelengths >31.5 microns that coincides with the northeastern outflow lobe from the protostellar disk associated with radio source I.
Working to Improve Classroom Climate Using a Ten Point Scale and Focusing on the Development of the Classroom Management Skills of Individual Teachers  [PDF]
Terry Haydn
Creative Education (CE) , 2015, DOI: 10.4236/ce.2015.622241
Abstract: The working atmosphere in the classroom is an important variable in the process of education, with several studies suggesting that classroom climate has a significant impact on student attainment. Recent international studies have suggested that deficits in classroom climate are prevalent in many countries, pointing out that these deficits are more serious and prevalent in some systems compared to others. Attention has also been drawn to the phenomenon of “in-school variation”, with levels of classroom control varying not just between schools, but also, within them. The paper describes the use of a 10 point scale for conceptualising the working atmosphere in the classroom as a continuum between a climate which is ideally conducive to learning (level 10), to a level where learning is severely constrained by the poor behaviour of some pupils (level 1). The scale encourages teachers, student teachers, school managers and school governors to reflect on the factors influencing the working atmosphere in the classroom. In England, there has been a tendency to see school leaders as the key to levels of classroom control (Ofsted, 2014; Wilshaw, 2014). However, this does not explain the phenomenon of “in-school variation” in classroom climate. The research outlined in this paper supports Elliott’s view (Elliott, 2009) that the classroom management skills of individual teachers are one of the key determinants of classroom climate and good pupil behaviour, and therefore more time and effort need to go into developing this dimension of teacher authority. Working with teachers and student teachers, using the 10 point scale to develop their understanding of factors influencing classroom climate offers one way of developing teachers’ skills in this area. Given that deficits in classroom climate and pupil behaviour are not limited to the UK, the scale may be of use and interest to those involved in teaching and teacher education in other countries.
Page 1 /1537
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.