17,444 research outputs found
Infrared Astronomy
Several observational programs in infrared astronomy are described and significant findings are briefly discussed. The near infrared work concentrates largely on the use of the 5 m Hale telescope in spectroscopic and photometric studies of extragalactic sources. Observations of the P alpha line profile in a low redshift quasar, X-ray bursters, reflection nebula, and cataclysmic variables are included. Millimeter continuum observations of dust emission from quasars and galactic molecular clouds are also discussed. Finally, improvements to instrumentation are reported
Near Infrared Observations of a Redshift 5.34 Galaxy: Further Evidence for Dust Absorption in the Early Universe
Imaging at 1.25 and 2.20 microns has been obtained of the field containing
the galaxy (RD1) found at redshift 5.34 by Dey et al.(1998). This galaxy has
been detected at 1.25 microns, while the lower redshift (z=4.02) galaxy also
found in the same field by Dey et al. was detected at both 1.25 and 2.20
microns. Comparison to stellar population synthesis models indicates that if
RD1 is a young ( 0.5 mag)
is indicated. Combined with observations of other high redshift systems, these
data show that dust is likely to be an important component of young galaxies
even at redshifts of z > 5. The extinction-corrected monochromatic luminosity
of RD1 at 1500 angstroms is then a factor of about three larger than L(1500)*
as determined by Dickinson (1998) for z ~ 3 starburst galaxies. The implied
star formation rate in RD1, corrected for extinction, is ~ 50-100 solar masses
per year.Comment: plain LaTex with 1 postscript figure. ApJ Letters, accepte
Near Infrared Observations of a Redshift 4.92 Galaxy: Evidence for Significant Dust Absorption
Near-infrared imaging and spectroscopy have been obtained of the
gravitationally lensed galaxy at z=4.92 discovered in HST images by Franx et
al. (1997). Images at 1.2, 1.6 and 2.2 microns show the same arc morphology as
the HST images. The spectrum with resolution \lambda / \Delta\lambda ~ 70 shows
no emission lines with equivalent width stronger than 100 A in the rest frame
wavelength range 0.34 to 0.40 microns. In particular, [OII]3727 A and
[NeIII]3869 A are not seen. The energy distribution is quite blue, as expected
for a young stellar population with the observed Ly alpha flux. The spectral
energy distribution can be fit satisfactorily for such a young stellar
population when absorption by dust is included. The models imply a reddening
0.1 mag < E(B-V) < 0.4 mag. The stellar mass of the lensed galaxy lies in the
range of 2 to 16 x 10^9 Msun. This is significantly higher than estimates based
on the HST data alone. Our data imply that absorption by dust is important to
redshifts of ~5.Comment: LaTeX with ApJ journal format, 2 postscript figures, ApJL, accepte
Infrared properties of serendipitous X-ray quasars
Near infrared measurements were obtained of 30 quasars originally found serendipitously as X-ray sources in fields of other objects. The observations show that the infrared characteristics of these quasars do not differ significantly from those of quasars selected by other criteria. Because this X-ray selected sample is subject to different selection biases than previous radio and optical surveys, this conclusion is useful in validating previous inferences regarding the infrared colors of 'typical' quasars
Magnetic Field Structure around Low-Mass Class 0 Protostars: B335, L1527 and IC348-SMM2
We report new 350 micron polarization observations of the thermal dust
emission from the cores surrounding the low-mass, Class 0 YSOs L1527,
IC348-SMM2 and B335. We have inferred magnetic field directions from these
observations, and have used them together with results in the literature to
determine whether magnetically regulated core-collapse and star-formation
models are consistent with the observations. These models predict a pseudo-disk
with its symmetry axis aligned with the core magnetic field. The models also
predict a magnetic field pinch structure on a scale less than or comparable to
the infall radii for these sources. In addition, if the core magnetic field
aligns (or nearly aligns) the core rotation axis with the magnetic field before
core collapse, then the models predict the alignment (or near alignment) of the
overall pinch field structure with the bipolar outflows in these sources. We
show that if one includes the distorting effects of bipolar outflows on
magnetic fields, then in general the observational results for L1527 and
IC348-SMM2 are consistent with these magnetically regulated models. We can say
the same for B335 only if we assume the distorting effects of the bipolar
outflow on the magnetic fields within the B335 core are much greater than for
L1527 and IC348-SMM2. We show that the energy densities of the outflows in all
three sources are large enough to distort the magnetic fields predicted by
magnetically regulated models.Comment: Accepted for publication in The Astrophysical Journa
Cognitive characteristics of older Japanese drivers
<p>Abstract</p> <p>Background</p> <p>Some causes of accidents among older drivers are: not paying attention to traffic signals; missing stop lines; and having to deal with and misjudging emergency situations. These causes of accidents reveal problems with attention and cognition. Such incidents are also related to driver perception and stress-coping mechanisms. It is important to examine the relation of stress reactions to attention and cognition as a factor influencing the causes of accidents commonly involving older drivers.</p> <p>Finding</p> <p>Subjects were 10 young drivers (23.3 ± 3.33 years) and 25 older drivers divided into two groups (older1 [60 to 65 years] and older2 [> 65 years]). This study revealed the correlation within driver stress inventory and driver coping questionnaires parameters was observed only in older drivers. They also needed a longer response time for Trail Making Test A and B. The factors affected the attention and cognition of older drivers by age but not driving experience itself, and coping parameters such as emotion focus, reappraisal, and avoidance were not included as stress inventory parameters. Being prone to fatigue was less for younger drivers than older drivers. Because they have shorter distances, shorter drive times, and no need for expressways, older drivers also had a significantly lower risk of thrill-seeking behaviour and more patience.</p> <p>Conclusion</p> <p>The intervention addressing their attention skills, aggressive feelings, and emotion focus should be considered. The technological improvements in cars will make older drivers feel safer and make driving easier which might lower the attention paid to the road, and regular driving training might be needed to assess and enhance their safety.</p
Mass and orbit constraints of the gamma-ray binary LS 5039
We present the results of space-based photometric and ground-based
spectroscopic observing campaigns on the gamma-ray binary LS 5039. The new
orbital and physical parameters of the system are similar to former results,
except we found a lower eccentricity. Our MOST-data show that any broad-band
optical photometric variability at the orbital period is below the 2 mmag
level. Light curve simulations support the lower value of eccentricity and
imply that the mass of the compact object is higher than 1.8 solar masses.Comment: 2 pages, 1 figure (with 2 panels); to be published in the
Proceedings: From Interacting Binaries to Exoplanets: Essential Modeling
Tools, IAU Symposium 282 (18-22 July, 2011, Tatranska Lomnica, Slovakia
The 1.5-2.5 µm spectrum of Pluto
New spectrophotometric observations of Pluto from 1.5-2.5 µm with a resolution of λ/λ ~0.05 are reported. The new observations confirm the presence of methane frost on the
surface of Pluto
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