60 research outputs found
Lack of observational evidence for quantum structure of space-time at Plank scales
It has been noted (Lieu & Hillmann, 2002) that the cumulative affect of
Planck-scale phenomenology, or the structure of space-time at extremely small
scales, can be lead to the loss of phase of radiation emitted at large
distances from the observer. We elaborate on such an approach and demonstrate
that such an effect would lead to an apparent blurring of distant
point-sources. Evidence of the diffraction pattern from the HST observations of
SN 1994D and the unresolved appearance of a Hubble Deep Field galaxy at z=5.34
lead us to put stringent limits on the effects of Planck-scale phenomenology.Comment: 12 pages, 3 figures, accepter for ApJ
Pasteurization of cream for buttermaking
In some European countries the pasteurization of cream for buttermaking is extensively practiced. Butter manufacturers in the United States have long recognized that this is a desirable procedure and they have written numerous letters to the experiment stations seeking information regarding it. In many cases it has been more or less difficult to answer these inquiries because of the comparatively small amount of experimental work which has been done along this line.
The purpose of the experiments herein reported was to determine the value of pasteurization to those engaged in the manufacture of butter. In this connection the effect of pasteurization on the flavor of the butter, on the keeping quality, on the body, on the chemical composition, and on the mechanical losses was considered and an effort was made to determine the relative merits of the various methods of pasteurization
Some Observations on the Effect of Iodine Administration upon Sheep
On account of the occasional incidence of goitre and death of lambs produced on the experiment station farm, an experiment on the administration of potassium iodide to the pregnant ewes was carried on in 1917-18. Three lots of four on the same ration were fed from 2 to 15 grains potassium iodide daily. Results on the prevention of goitre in the young were not conclusive, but the passage of the iodine into the milk of the ewes was demonstrated, and pronounced unfavorable results from too large a dose of iodine were obtained, especially in the lots receiving the larger allowances. These unfavorable effects were not particularly in the vigor of the new-born and the lack of resistance to disease
Near-Infrared Adaptive Optics Spectroscopy of Binary Brown Dwarf HD 130948B and C
We present near-infrared spectroscopy of low-mass companions in a nearby
triple system HD 130948 (Gliese 564, HR 5534). Adaptive optics on the Subaru
Telescope allowed spectroscopy of the individual components of the 0".13 binary
system. Based on a direct comparison with a series of template spectra, we
determined the spectral types of HD 130948B and C to be L4 +- 1. If we take the
young age of the primary star into account (0.3-0.8 Gyr), HD 130948B and C most
likely are a binary brown dwarf system.Comment: 6 pages, 3 figures, accepted for publication in ApJ Letter
Diffraction-limited 3 μm spectroscopy of IRAS 04296+3429 and IRAS 05341+0852: Spatial extent of hydrocarbon dust emission and dust evolutionary sequence
We present 3 μm spectroscopy of the carbon-rich protoplanetary nebulae IRAS 04296+3429 and IRAS 05341+0852, conducted with the adaptive optics system at the Subaru Telescope. We utilize the nearly diffraction-limited spectroscopy to probe the spatial extent of the hydrocarbon dust emitting zone. We find a hydrocarbon emission core extending up to 100-160 mas from the center of IRAS 04296+3429, corresponding to a physical diameter of 400-640 AU, assuming a distance of 4 kpc. However, we find that IRAS 05341+0852 is not spatially resolved with this instrumentation. The physical extent of these protoplanetary nebulae, along with the reanalyzed data of IRAS 22272+5435 published previously, suggests a correlation between the physical extent of the hydrocarbon dust emission and the spectral evolution of the aliphatic to aromatic features in these post-AGB stars. These measurements represent the first direct test of the proposed chemical synthesis route of carbonaceous dust in the circumstellar environment of evolved stars. © 2007, The American Astronomical Society, Ail rights reserved.published_or_final_versio
First Detection of NaI D lines in High-Redshift Damped Lyman-alpha Systems
A Near-infrared (1.18-1.35 micron) high-resolution spectrum of the
gravitationally-lensed QSO APM 08279+5255 was obtained with the IRCS mounted on
the Subaru Telescope using the AO system. We detected strong NaI D 5891,5897
doublet absorption in high-redshift DLAs at z=1.062 and 1.181, confirming the
presence of NaI, which was first reported for the rest-frame UV NaI
3303.3,3303.9 doublet by Petitjean et al. This is the first detection of NaI D
absorption in a high-redshift (z>1) DLA. In addition, we detected a new NaI
component in the z=1.062 DLA and four new components in the z=1.181 DLA. Using
an empirical relationship between NaI and HI column density, we found that all
"components" have large HI column density, so that each component is classified
as DLA absorption. We also detected strong NaI D absorption associated with a
MgII system at z=1.173. Because no other metal absorption lines were detected
in this system at the velocity of the NaI absorption in previously reported
optical spectra (observed 3.6 years ago), we interpret this NaI absorption
cloud probably appeared in the line of sight toward the QSO after the optical
observation. This newly found cloud is likely to be a DLA based upon its large
estimated HI column density. We found that the N(NaI)/N(CaII) ratios in these
DLAs are systematically smaller than those observed in the Galaxy; they are
more consistent with the ratios seen in the Large Magellanic Cloud. This is
consistent with dust depletion generally being smaller in lower metallicity
environments. However, all five clouds of the z=1.181 system have a high
N(NaI)/N(CaII) ratio, which is characteristic of cold dense gas. We tentatively
suggest that the host galaxy of this system may be the most significant
contributor to the gravitational-lens toward APM 08279+5255.Comment: 22 pages, 6 Postscript figures, 3 tables, ApJ in press (Vol.643, 2
June 2006
LBT/ARGOS adaptive optics observations of z lensed galaxies
Gravitationally lensed systems allow a detailed view of galaxies at high
redshift. High spatial- and spectral-resolution measurements of arc-like
structures can offer unique constraints on the physical and dynamical
properties of high-z systems. We present near-infrared spectra centred on the
gravitational arcs of six known z ~ 2 lensed star-forming galaxies of stellar
masses of 10^9-10^11 Msun and star formation rate (SFR) in the range between 10
and 400 Msun/yr. Ground layer adaptive optics (AO)-assisted observations are
obtained at the Large Binocular Telescope (LBT) with the LUCI spectrographs
during the commissioning of the ARGOS facility. We used MOS masks with curved
slits to follow the extended arched structures and study the diagnostic
emission lines. Combining spatially resolved kinematic properties across the
arc-like morphologies, emission line diagnostics and archival information, we
distinguish between merging and rotationally supported systems, and reveal the
possible presence of ejected gas. For galaxies that have evidence for outflows,
we derive outflow energetics and mass-loading factors compatible with those
observed for stellar winds in local and high-z galaxies. We also use flux ratio
diagnostics to derive gas-phase metallicities. The low signal-to-noise ratio in
the faint H and nitrogen lines allows us to derive an upper limit of ~
0.15 dex for the spatial variations in metallicity along the slit for the
lensed galaxy J1038. Analysed near-infrared spectra presented here represent
the first scientific demonstration of performing AO-assisted multi-object
spectroscopy with narrow curved-shape slits. The increased angular and spectral
resolution, combined with the binocular operation mode with the 8.4-m-wide eyes
of LBT, will allow the characterisation of kinematic and chemical properties of
a large sample of galaxies at high-z in the near future.Comment: 18 pages, 13 figures, accepted for publication in A&
Spatially Resolved 3 um Spectroscopy of IRAS 22272+5435: Formation and Evolution of Aliphatic Hydrocarbon Dust in Proto-Planetary Nebula
We present medium-resolution 3 um spectroscopy of the carbon-rich
proto-planetary nebula IRAS 22272+5435. Spectroscopy with the Subaru Telescope
adaptive optics system revealed a spatial variation of hydrocarbon molecules
and dust surrounding the star. The ro-vibrational bands of acetylene (C2H2) and
hydrogen cyanide (HCN) at 3.0 um are evident in the central star spectra. The
molecules are concentrated in the compact region near the center. The 3.3 and
3.4 um emission of aromatic and aliphatic hydrocarbons is detected at 600--1300
AU from the central star. The separation of spatial distribution between gas
and dust suggests that the small hydrocarbon molecules are indeed the source of
solid material, and that the gas leftover from the grain formation is being
observed near the central star. The intensity of aliphatic hydrocarbon emission
relative to the aromatic hydrocarbon emission decreases with distance from the
central star. The spectral variation is well matched to that of a laboratory
analog thermally annealed with different temperatures. We suggest that either
the thermal process after the formation of a grain or the variation in the
temperature in the dust-forming region over time determines the chemical
composition of the hydrocarbon dust around the proto-planetary nebula.Comment: 14 pages, 7 figures, Accepted for publication in the Astrophyical
Journa
- …