3,656 research outputs found
Der avancierte Blick
Die gegenständliche Arbeit befasst sich mit einem Beitrag zur Erforschung des dokumentarischen Films auf theoretischer Basis im Bezug auf Formen und Themen wie sie im dokumentarischen Film zu finden sind. Im zweiten Kapitel werden die wichtigsten Leitfragen bezüglich Formen und Themen, wie sie im dokumentarischen
Film zu finden sind, mit dem Schwerpunkt Essayfilm, ethnographischer Film, Realität und Film, Authentizität und Wirklichkeit, sowie die Rolle der wirklichkeitsgetreuen Wiedergabe, welche der Kamera zugeschrieben wird, zusammengefasst. Im dritten Kapitel werden Techniken, Arbeitsweisen und Ideen, wie sie bei den Filmemachern
Johan van der Keuken und Robert Gardner zu finden sind, beleuchtet. Dabei wird spezielles Augenmerk auf die Filme FOREST OF BLISS und DAS AUGE ÜBER DEM BRUNNEN gelegt.The present work deals with a contribution to the study of the documentary film on a theoretical basis in terms of forms and themes as those found in the documentary film. The second chapter focuses on the essay film, ethnographic film, reality and film, authenticity and reality, and the role of realistic play, which the camera is attributed to. In the third chapter, techniques, methods and ideas as they are
provided with filmmakers Johan van der Keuken and Robert Gardner are discussed. The main focus of attention is given to the films FOREST OF BLISS and EYE ABOVE THE WELL
IRAS 20050+2720: Anatomy of a young stellar cluster
IRAS 20050+2720 is young star forming region at a distance of 700 pc without
apparent high mass stars. We present results of our multiwavelength study of
IRAS 20050+2720 which includes observations by Chandra and Spitzer, and 2MASS
and UBVRI photometry. In total, about 300 YSOs in different evolutionary stages
are found. We characterize the distribution of young stellar objects (YSOs) in
this region using a minimum spanning tree (MST) analysis. We newly identify a
second cluster core, which consists mostly of class II objects, about 10 arcmin
from the center of the cloud. YSOs of earlier evolutionary stages are more
clustered than more evolved objects. The X-ray luminosity function (XLF) of
IRAS 20050+2720 is roughly lognormal, but steeper than the XLF of the more
massive Orion nebula complex. IRAS 20050+2720 shows a lower N_H/A_K ratio
compared with the diffuse ISM.Comment: 15 pages, 12 figures, accepted by A
Spitzer observations of Bow Shocks and Outflows in RCW 38
We report Spitzer observations of five newly identified bow shocks in the
massive star-forming region RCW 38. Four are visible at IRAC wavelengths, the
fifth is visible only at 24 microns. Chandra X-ray emission indicates that
winds from the central O5.5 binary, IRS~2, have caused an outflow to the NE and
SW of the central subcluster. The southern lobe of hot ionised gas is detected
in X-rays; shocked gas and heated dust from the shock-front are detected with
Spitzer at 4.5 and 24 microns. The northern outflow may have initiated the
present generation of star formation, based on the filamentary distribution of
the protostars in the central subcluster. Further, the bow-shock driving star,
YSO 129, is photo-evaporating a pillar of gas and dust. No point sources are
identified within this pillar at near- to mid-IR wavelengths.
We also report on IRAC 3.6 & 5.8 micron observations of the cluster
DBS2003-124, NE of RCW 38, where 33 candidate YSOs are identified. One star
associated with the cluster drives a parsec-scale jet. Two candidate HH objects
associated with the jet are visible at IRAC and MIPS wavelengths. The jet
extends over a distance of ~3 pc. Assuming a velocity of 100 km/s for the jet
material gives an age of about 30,000 years, indicating that the star (and
cluster) are likely to be very young, with a similar or possibly younger age
than RCW 38, and that star formation is ongoing in the extended RCW 38 region.Comment: 27 pages, 6 figures, accepted to Ap
A Combined Spitzer and Chandra Survey of Young Stellar Objects in the Serpens Cloud Core
We present Spitzer and Chandra observations of the nearby (~260 pc) embedded
stellar cluster in the Serpens Cloud Core. We observed, using Spitzer's IRAC
and MIPS instruments, in six wavelength bands from 3 to 70 , to detect
thermal emission from circumstellar disks and protostellar envelopes, and to
classify stars using color-color diagrams and spectral energy distributions
(SEDs). These data are combined with Chandra observations to examine the
effects of circumstellar disks on stellar X-ray properties. Young diskless
stars were also identified from their increased X-ray emission. We have
identified 138 YSOs in Serpens: 22 class 0/I, 16 flat spectrum, 62 class II, 17
transition disk, and 21 class III stars; 60 of which exhibit X-ray emission.
Our primary results are the following: 1.) ten protostars detected previously
in the sub-millimeter are detected at lambda < 24 microns, seven at lambda < 8
microns, 2.) the protostars are more closely grouped than more evolved YSOs
(median separation : ~0.024 pc, and 3.) the luminosity and temperature of the
X-ray emitting plasma around these YSOs does not show any significant
dependence on evolutionary class. We combine the infrared derived values of AK
and X-ray values of NH for 8 class III objects and find that the column density
of hydrogen gas per mag of extinctions is less than half the standard
interstellar value, for AK > 1. This may be the result of grain growth through
coagulation and/or the accretion of volatiles in the Serpens cloud core.Comment: 69 pages, 16 figures, accepted to ApJ. Higher Resolution Figures at:
http://www.cfa.harvard.edu/~ewinston
X-Atlas: An Online Archive of Chandra's Stellar High Energy Transmission Gratings Observations
The high-resolution X-ray spectroscopy made possible by the 1999 deployment
of the Chandra X-ray Observatory has revolutionized our understanding of
stellar X-ray emission. Many puzzles remain, though, particularly regarding the
mechanisms of X-ray emission from OB stars. Although numerous individual stars
have been observed in high-resolution, realizing the full scientific potential
of these observations will necessitate studying the high-resolution Chandra
dataset as a whole. To facilitate the rapid comparison and characterization of
stellar spectra, we have compiled a uniformly processed database of all stars
observed with the Chandra High Energy Transmission Grating (HETG). This
database, known as X-Atlas, is accessible through a web interface with
searching, data retrieval, and interactive plotting capabilities. For each
target, X-Atlas also features predictions of the low-resolution ACIS spectra
convolved from the HETG data for comparison with stellar sources in archival
ACIS images. Preliminary analyses of the hardness ratios, quantiles, and
spectral fits derived from the predicted ACIS spectra reveal systematic
differences between the high-mass and low-mass stars in the atlas and offer
evidence for at least two distinct classes of high-mass stars. A high degree of
X-ray variability is also seen in both high and low-mass stars, including
Capella, long thought to exhibit minimal variability. X-Atlas contains over 130
observations of approximately 25 high-mass stars and 40 low-mass stars and will
be updated as additional stellar HETG observations become public. The atlas has
recently expanded to non-stellar point sources, and Low Energy Transmission
Grating (LETG) observations are currently being added as well
Variability in Proto-Planetary Nebulae: I. Light Curve Studies of 12 Carbon-Rich Objects
We have carried out long-term (14 years) V and R photometric monitoring of 12
carbon-rich proto-planetary nebulae. The light and color curves display
variability in all of them. The light curves are complex and suggest multiple
periods, changing periods, and/or changing amplitudes, which are attributed to
pulsation. A dominant period has been determined for each and found to be in
the range of ~150 d for the coolest (G8) to 35-40 d for the warmest (F3). A
clear, linear inverse relationship has been found in the sample between the
pulsation period and the effective temperature and also an inverse linear
relationship between the amplitude of light variation and the effective
temperature. These are consistent with the expectation for a pulsating post-AGB
star evolving toward higher temperature at constant luminosity. The published
spectral energy distributions and mid-infrared images show these objects to
have cool (200 K), detached dust shells and published models imply that
intensive mass loss ended a few thousand years ago. The detection of periods as
long as 150 d in these requires a revision in the published post-AGB evolution
models that couple the pulsation period to the mass loss rate and that assume
that intensive mass loss ended when the pulsation period had decreased to 100
d. This revision will have the effect of extending the time scale for the early
phases of post-AGB evolution. It appears that real time evolution in the
pulsation periods of individual objects may be detectable on the time scale of
two decades
Real Time Space Weather Support for Chandra X-ray Observatory Operations
NASA launched the Chandra X-ray Observatory in July 1999. Soon after first light in August 1999, however, degradation in the energy resolution and charge transfer efficiency of the Advanced CCD Imaging Spectrometer (ACIS) x-ray detectors was observed. The source of the degradation was quickly identified as radiation damage in the charge-transfer channel of the front-illuminated CCDs, by weakly penetrating ("soft", 100-500 keV) protons as Chandra passed through the Earth s radiation belts and ring currents. As soft protons were not considered a risk to spacecraft health before launch, the only on-board radiation monitoring system is the Electron, Proton, and Helium Instrument (EPHIN) which was included on Chandra with the primary purpose of monitoring energetic solar particle events. Further damage to the ACIS detector has been successfully mitigated through a combination of careful mission planning, autonomous on-board radiation protection, and manual intervention based upon real-time monitoring of the soft-proton environment. The AE-8 and AP-8 trapped radiation models and Chandra Radiation Models are used to schedule science operations in regions of low proton flux. EPHIN has been used as the primary autonomous in-situ radiation trigger; but, it is not sensitive to the soft protons that damage the front-illuminated CCDs. Monitoring of near-real-time space weather data sources provides critical information on the proton environment outside the Earth's magnetosphere due to solar proton events and other phenomena. The operations team uses data from the Geostationary Operational Environmental Satellites (GOES) to provide near-real-time monitoring of the proton environment; however, these data do not give a representative measure of the soft-proton (less than 1 MeV) flux in Chandra s high elliptical orbit. The only source of relevant measurements of sub-MeV protons is the Electron, Proton, and Alpha Monitor (EPAM) aboard the Advanced Composition Explorer (ACE) satellite at L1, with real-time data provided by NOAA's Space Weather Prediction Center. This presentation will discuss radiation mitigation against proton damage, including models and real-time data sources used to protect the ACIS detector system
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