17,903 research outputs found
Twining characters and orbit Lie algebras
We associate to outer automorphisms of generalized Kac-Moody algebras
generalized character-valued indices, the twining characters. A character
formula for twining characters is derived which shows that they coincide with
the ordinary characters of some other generalized Kac-Moody algebra, the
so-called orbit Lie algebra. Some applications to problems in conformal field
theory, algebraic geometry and the theory of sporadic simple groups are
sketched.Comment: 6 pages, LaTeX, Talk given by C. Schweigert at the XXI international
colloquium on group theoretical methods in physics, July 1996, Goslar,
German
High Redshift Candidates and the Nature of Small Galaxies in the Hubble Deep Field
We present results on two related topics: 1. A discussion of high redshift
candidates (z>4.5), and 2. A study of very small galaxies at intermediate
redshifts, both sets being detected in the region of the northern Hubble Deep
Field covered by deep NICMOS observations at 1.6 and 1.1 microns. The high
redshift candidates are just those with redshift z>4.5 as given in the recent
catalog of Thompson, Weymann and Storrie-Lombardi, while the ``small galaxy''
sample is defined to be those objects with isophotal area <= 0.2 squ. arcsec
and with photometric redshifts 1<z<4.5. Of the 19 possible high redshift
candidates listed in the Thompson et al. catalog, 11 have (nominal) photometric
redshifts less than 5.0. Of these, however, only 4 are ``robust'' in the sense
of yielding high redshifts when the fluxes are randomly perturbed with errors
comparable to the estimated measuring error in each wave band. For the 8 other
objects with nominal photometric redshifts greater than 5.0, one (WFPC2 4--473)
has a published spectroscopic redshift. Of the remaining 7, 4 are robust in the
sense indicated above. Two of these form a close pair (NIC 586 and NIC 107).
The redshift of the object having formally the highest redshift, at 6.56
(NIC118 = WFPC2 4--601), is problematic, since F606W and F814W flux are clearly
present, and the nature of this object poses a dilemma. (abridged)Comment: 44 pages, 12 figures, to appear in ApJ v591, July 10, 200
Properties of nonaqueous electrolytes Quarterly report, 20 Sep. - 19 Dec. 1966
Vapor phase chromatographic analysis of dimethyl formamide, and physical properties of electrolytes containing lithium chloride and/or aluminum chlorid
User's Guide for ERB 7 SEFDT. Volume 1: User's Guide. Volume 2: Quality Control Report, Year 1
The Nimbus-7 ERB SEFDT Data User's Guide is presented. The guide consists of four subsections which describe: (1) the scope of the data User's Guide; (2) the background on Nimbus-7 Spacecraft and the ERB experiment; (3) the SEFDT data product and processing scenario; and (4) other related products and documents
A simple single-interval adaptive procedure for estimating thresholds in normal and impaired listeners
Planetary Nebulae with Ultra-Violet Imaging Telescope (UVIT): Far Ultra-violet halo around the Bow Tie nebula (NGC 40)
Context. NGC 40 is a planetary nebula with diffuse X-ray emission, suggesting
an interaction of the high speed wind from WC8 central star (CS) with the
nebula. It shows strong Civ 1550 {\AA} emission that cannot be explained by
thermal processes alone. We present here the first map of this nebula in C IV
emission, using broad band filters on the UVIT.
Aims. To map the hot C IV emitting gas and its correspondence with soft X-ray
(0.3-8 keV) emitting regions, in order to study the shock interaction with the
nebula and the ISM. This also illustrates the potential of UVIT for nebular
studies.
Methods. Morphological study of images of the nebula obtained at an angular
resolution of about 1.3" in four UVIT filter bands that include C IV 1550 {\AA}
and C II] 2326 {\AA} lines and UV continuum. Comparisons with X-ray, optical,
and IR images from literature.
Results. The C II] 2326 {\AA} images show the core of the nebula with two
lobes on either side of CS similar to [N II]. The C IV emission in the core
shows similar morphology and extant as that of diffuse X-ray emission
concentrated in nebular condensations. A surprising UVIT discovery is the
presence of a large faint FUV halo in FUV Filter with {\lambda}eff of 1608
{\AA}. The UV halo is not present in any other UV filter. FUV halo is most
likely due to UV fluorescence emission from the Lyman bands of H2 molecules.
Unlike the optical and IR halo, FUV halo trails predominantly towards
south-east side of the nebular core, opposite to the CS's proper motion
direction.
Conclusions. Morphological similarity of C IV 1550 {\AA} and X-ray emission
in the core suggests that it results mostly from interaction of strong CS wind
with the nebula. The FUV halo in NGC 40 highlights the existence of H2
molecules extensively in the regions even beyond the optical and IR halos.Comment: 4 pages, 5 figures, accepted for publication as a letter in Astronomy
& Astrophysic
Semi-Empirical Bound on the Chlorinr-37 Solar Neutrino Experiment
The Kamiokande measurement of energetic Boron-8 neutrinos from the sun is
used to set a lower bound on the contribution of the same neutrinos to the
signal in the \Chlorine\ experiment. Implications for Beryllium-7 neutrinos are
discussed.Comment: Latex, 6 pages + 1 postscript figure (included). UTAPHY-HEP-
Planetary Nebulae with UVIT II: Revelations from FUV vision of Butterfly Nebula NGC 6302
The high excitation planetary nebula, NGC 6302, has been imaged in two
far-ultraviolet (FUV) filters, F169M (Sapphire; {\lambda}: 1608
{\AA}) and F172M (Silica; {\lambda}: 1717 {\AA}) and two NUV
filters, N219M (B15; {\lambda}: 2196 {\AA}) and N279N (N2;
{\lambda}: 2792 {\AA}) with the Ultra Violet Imaging Telescope
(UVIT). The FUV F169M image shows faint emission lobes that extend to about 5
arcmin on either side of the central source. Faint orthogonal collimated
jet-like structures are present on either side of the FUV lobes through the
central source. These structures are not present in the two NUV filters nor in
the FUV F172M filter. Optical and IR images of NGC 6302 show bright emission
bipolar lobes in the east-west direction with a massive torus of molecular gas
and dust seen as a dark lane in the north-south direction. The FUV lobes are
much more extended and oriented at a position angle of 113{\deg}. They and the
jet-like structures might be remnants of an earlier evolutionary phase, prior
to the dramatic explosive event that triggered the Hubble type bipolar flows
approximately 2200 years ago. The source of the FUV lobe and jet emission is
not known, but is likely due to fluorescent emission from H molecules. The
cause of the difference in orientation of optical and FUV lobes is not clear
and, we speculate, could be related to two binary interactions.Comment: 9 pages, 5 figures, accepted for publication in Astronomy &
Astrophysic
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