5,297 research outputs found
A Large Mass of H_2 in the Brightest Cluster Galaxy in Zwicky 3146
We present the Spitzer/IRS mid-infrared spectrum of the infrared-luminous (L_(IR) = 4 × 10^(11) L_☉) brightest cluster galaxy (BCG) in the X-ray-luminous cluster Zwicky 3146 (Z3146; z = 0.29). The spectrum shows strong aromatic emission features, indicating that the dominant source of the infrared luminosity is star formation. The most striking feature of the spectrum, however, is the exceptionally strong molecular hydrogen (H_2) emission lines, which seem to be shock-excited. The line luminosities and inferred warm H_2 gas mass (~10^(10) M_☉) are 6 times larger than those of NGC 6240, the most H_2-luminous galaxy at z ≲ 0.05. Together with the large amount of cold H_2 detected previously (~10^(11) M_☉), this indicates that the Z3146 BCG contains disproportionately large amounts of both warm and cold H_2 gas for its infrared luminosity, which may be related to the intracluster gas cooling process in the cluster core
Pinpointing the Position of the Post-AGB Star at the Core of RAFGL 2688 using Polarimetric Imaging with NICMOS
We have used infrared polarimetric imaging with NICMOS to determine precisely
the position of the star that illuminates (and presumably generated) the
bipolar, pre-planetary reflection nebula RAFGL 2688 (the Egg Nebula). The
polarimetric data pinpoint the illuminating star, which is not detected
directly at wavelengths less than or equal to 2 microns, at a position well
within the dark lane that bisects the nebula, 0.55" (about 550 AU) southwest of
the infrared peak which was previously detected at the southern tip of the
northern polar lobe. The inferred position of the central star corresponds to
the geometric center of the tips of the four principle lobes of near-infrared
H2 emission; identifying the central star at this position also reveals the
strong point symmetric structure of the nebula, as seen both in the intensity
and polarization structure of the polar lobes. The polarimetric and imaging
data indicate that the infrared peak directly detected in the NICMOS images is
a self-luminous source and, therefore, is most likely a distant binary
companion to the illuminating star. Although present theory predicts that
bipolar structure in pre-planetary and planetary nebulae is a consequence of
binary star evolution, the separation between the components of the RAFGL 2688
binary system, as deduced from these observations, is much too large for the
presence of the infrared companion to have influenced the structure of the
RAFGL 2688 nebula.Comment: 15 pages, 6 figures, to appear in The Astrophysical Journa
A Large Mass of H2 in the Brightest Cluster Galaxy in Zwicky 3146
We present the Spitzer/IRS mid-infrared spectrum of the infrared-luminous
(L_{IR}=4e11 L_sun) brightest cluster galaxy (BCG) in the X-ray-luminous
cluster Z3146 (z=0.29). The spectrum shows strong aromatic emission features,
indicating that the dominant source of the infrared luminosity is star
formation. The most striking feature of the spectrum, however, is the
exceptionally strong molecular hydrogen (H2) emission lines, which seem to be
shock-excited. The line luminosities and inferred warm H2 gas mass (~1e10
M_sun) are 6 times larger than those of NGC 6240, the most H2-luminous galaxy
at z <~ 0.1. Together with the large amount of cold H2 detected previously
(~1e11 M_sun), this indicates that the Z3146 BCG contains disproportionately
large amounts of both warm and cold H2 gas for its infrared luminosity, which
may be related to the intracluster gas cooling process in the cluster core.Comment: 13 pages, 3 figures, 1 table; Accepted for publication in ApJ
Dust in the wind: Crystalline silicates, corundum and periclase in PG 2112+059
We have determined the mineralogical composition of dust in the Broad
Absorption Line (BAL) quasar PG 2112+059 using mid-infrared spectroscopy
obtained with the Spitzer Space Telescope. From spectral fitting of the solid
state features, we find evidence for Mg-rich amorphous silicates with olivine
stoichiometry, as well as the first detection of corundum (Al_2O_3) and
periclase (MgO) in quasars. This mixed composition provides the first direct
evidence for a clumpy density structure of the grain forming region. The
silicates in total encompass 56.5% of the identified dust mass, while corundum
takes up 38 wt.%. Depending on the choice of continuum, a range of mass
fractions is observed for periclase ranging from 2.7% in the most conservative
case to 9% in a less constrained continuum. In addition, we identify a feature
at 11.2 micron as the crystalline silicate forsterite, with only a minor
contribution from polycyclic aromatic hydrocarbons. The 5% crystalline silicate
fraction requires high temperatures such as those found in the immediate quasar
environment in order to counteract rapid destruction from cosmic rays.Comment: 2 figure
Analytical and experimental study of stratification and liquid-ullage coupling, 1 June 1964 - 31 May 1965
Closed-form solution for stratification of subcooled fluids in containers subjected to heating, and for liquid-ullage vapor couplin
Selection for muscling in swine and its effect on carcass traits
Line differences in weight, litter size at different ages, and in age, loin eye area, and backfat thickness of pigs (adjusted to 200 pounds live weight) were not significant. Sex differences in weight and backfat thickness were significant. Dam groups of progeny differed significantly (P\u3c.0l) in-weights at birth and at 14 and 28 days old and in age, loin eye area, and backfat thickness adjusted to 220 pounds live weight. Hams produced by barrows in the select line were significantly (P\u3c.0l) darker and firmer than those from barrows in the control line.; Swine Day, Manhattan, KS, November 14, 197
Muscling selection in swine and its effect on carcass traits
Pigs farrowed in May, 1972, were the first born in the select and control lines. Performances of animals in the two lines were essentially the same. However, ham firmness and color differed significantly (P\u3c0.0l) between lines, with those in the select line firmer and darker than those from the control line.; Swine Day, Manhattan, KS, November, 197
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