6,915 research outputs found
About the morphology of dwarf spheroidal galaxies and their dark matter content
The morphological properties of the Carina, Sculptor and Fornax dwarfs are
investigated using new wide field data with a total area of 29 square degrees.
The stellar density maps are derived, hinting that Sculptor possesses tidal
tails indicating interaction with the Milky Way. Contrary to previous studies
we cannot find any sign of breaks in the density profiles for the Carina and
Fornax dwarfs. The possible existence of tidal tails in Sculptor and of King
limiting radii in Fornax and Carina are used to derive global M/L ratios,
without using kinematic data. By matching those M/L ratios to kinematically
derived values we are able to constrain the orbital parameters of the three
dwarfs. Fornax cannot have M/L smaller than 3 and must be close to its
perigalacticon now. The other extreme is Sculptor that needs to be on an orbit
with an eccentricity bigger than 0.5 to be able to form tidal tails despite its
kinematic M/L.Comment: 9 pages, 7 figures, accepted by A&
Measurement of thermal conductance of multilayer and other insulation materials Final report
Thermal conductance measurements of multilayer, aluminumized polymeric films for space suit insulation material
Two-body effects in the decay rate of atomic levels
Recoil corrections to the atomic decay rate are considered in the order of
Zm/M . The expressions are treated exactly without any expansion over Z alpha.
The expressions obtained are valid both for muonic atoms (for which they
contribute on the level of a few percent in high Z ions) and for electronic
atoms. Explicit results for Lyman-alpha transitions for low-Z of the order
(Zm/M)(Z alpha)^2 are also presented.Comment: 5 pages, 1 table, email: [email protected]
Stellar Dynamics and the implications on the merger evolution in NGC6240
We report near-infrared integral field spectroscopy of the luminous merging
galaxy NGC 6240. Stellar velocities show that the two K-band peaks separated by
1.6arcsec are the central parts of inclined, rotating disk galaxies with equal
mass bulges. The dynamical masses of the nuclei are much larger than the
stellar mass derived from the K-band light, implying that the progenitor
galaxies were galaxies with massive bulges. The K-band light is dominated by
red supergiants formed in the two nuclei in starbursts, triggered ~2x10^7 years
ago, possibly by the most recent perigalactic approach. Strong feedback effects
of a superwind and supernovae are responsible for a short duration burst
(~5x10^6 years) which is already decaying. The two galaxies form a
prograde-retrograde rotating system and from the stellar velocity field it
seems that one of the two interacting galaxies is subject to a prograde
encounter. Between the stellar nuclei is a prominent peak of molecular gas
(H_2, CO). The stellar velocity dispersion peaks there indicating that the gas
has formed a local, self-gravitating concentration decoupled from the stellar
gravitational potential. NGC 6240 has previously been reported to fit the
paradigm of an elliptical galaxy formed through the merger of two galaxies.
This was based on the near-infrared light distribution which follows a
r^1/4-law. Our data cast strong doubt on this conclusion: the system is by far
not relaxed, rotation plays an important role, as does self-gravitating gas,
and the near-infrared light is dominated by young stars.Comment: 34 pages, 11 figures, using AASTEX 5.0rc3.1, paper submitted to the
Astrophysical Journal, revised versio
The Double Quasar Q2138-431: Lensing by a Dark Galaxy?
We report the discovery of a new gravitational lens candidate Q2138-431AB,
comprising two quasar images at a redshift of 1.641 separated by 4.5 arcsecs.
The spectra of the two images are very similar, and the redshifts agree to
better than 115 km.sec. The two images have magnitudes and
, and in spite of a deep search and image subtraction procedure, no
lensing galaxy has been found with . Modelling of the system
configuration implies that the mass-to-light ratio of any lensing galaxy is
likely to be around , with an absolute lower limit of
for an Einstein-de Sitter universe. We conclude that
the most likely explanation of the observations is gravitational lensing by a
dark galaxy, although it is possible we are seeing a binary quasar.Comment: 17 pages (Latex), 8 postscript figures included, accepted by MNRA
Simultaneous X-ray and Optical Observations of EX Hydrae
The intermediate polar, EX Hydrae, was the object of a large simultaneous
multiwavelength observational campaign during 2000 May - June. Here we present
the Rossi X-ray Timing Explorer photometry and optical photometry and
spectroscopy from ground-based observatories obtained as part of this campaign.
Balmer line radial velocities and Doppler maps provide evidence for an extended
bulge along the outer edge of the accretion disk and some form of
extended/overflowing material originating from the hot spot. In addition, the
optical binary eclipse possesses an extended egress shoulder, an indication
that an additional source (other than the white dwarf) is coming out of
eclipse. We also compare the X-ray and optical results with the results
obtained from the EUV and UV observations from the multiwavelength data set.Comment: to appear in the Astronomical Journal, April 200
Discovery of a binary AGN in the ultraluminous infrared galaxy NGC 6240 using Chandra
Ultraluminous infrared galaxies (ULIRGs) are outstanding due to their huge
luminosity output in the infrared, which is predominantly powered by super
starbursts and/or hidden active galactic nuclei (AGN). NGC 6240 is one of the
nearest ULIRGs and is considered a key representative of its class.
Here, we report the first high-resolution imaging spectroscopy of NGC 6240 in
X-rays. The observation, performed with the ACIS-S detector aboard the Chandra
X-ray observatory, led to the discovery of two hard nuclei, coincident with the
optical-IR nuclei of NGC 6240. The AGN character of both nuclei is revealed by
the detection of absorbed hard, luminous X-ray emission and two strong neutral
Fe_K_alpha lines. In addition, extended X-ray emission components are present,
changing their rich structure in dependence of energy. The close correlation of
the extended emission with the optical Halpha emission of NGC 6240, in
combination with the softness of its spectrum, clearly indicates its relation
to starburst-driven superwind activity.Comment: ApJ Letters in press, 7 colour figures included; preprint and related
papers on NGC 6240 also available at http://www.xray.mpe.mpg.de/~skomossa
On the secondary star of the cataclysmic variable 1RXS J094432.1+035738
We present V and Rc band photometry and optical near-infrared spectroscopy of
the cataclysmic variable 1RXS J094432.1+035738. We detected features of a cool
secondary star, which can be modeled with a red dwarf of spectral type M2 (+0.5
-1.0) V at a distance of 433 +- 100 pc.Comment: Accepted for publication in Astronomy and Astrophysic
Survey of the Federal Circuit\u27s Patent Law Decisions in 2006: A New Chapter in the Ongoing Dialogue with the Supreme Court
In 2006, the Federal Circuit decided only one portion of one patent case en banc, and that was done mainly as a procedural matter (the entire case was not argued to an en banc court) in order to reconcile prior conflicting precedent on the issue of induced patent infringement with the recent Supreme Court decision in Metro-Goldwyn-Mayer Studios, Inc. v. Grokster, Ltd., involving induced copyright infringement. But in light of the Supreme Courtâs much more muscular review of the Federal Circuitâs patent casesâwhich may not even reflect the full extent of the Courtâs interest in the Federal Circuitâs patent decisionsâthe relative paucity of en banc decisions in 2006 is understandable, and in many ways irrelevant to gaining a better understanding of the Federal Circuitâs patent law jurisprudence. In the pages that follow, we will address these and many other developments reflected in the Federal Circuitâs patent jurisprudence of 2006. And, as we did in our article surveying the Federal Circuitâs year 2000 jurisprudence, we again conclude with an addendum that discusses the statistical output of the Federal Circuit and its judges
Survey of the Federal Circuit\u27s Patent Law Decisions in 2006: A New Chapter in the Ongoing Dialogue with the Supreme Court
In 2006, the Federal Circuit decided only one portion of one patent case en banc, and that was done mainly as a procedural matter (the entire case was not argued to an en banc court) in order to reconcile prior conflicting precedent on the issue of induced patent infringement with the recent Supreme Court decision in Metro-Goldwyn-Mayer Studios, Inc. v. Grokster, Ltd., involving induced copyright infringement. But in light of the Supreme Courtâs much more muscular review of the Federal Circuitâs patent casesâwhich may not even reflect the full extent of the Courtâs interest in the Federal Circuitâs patent decisionsâthe relative paucity of en banc decisions in 2006 is understandable, and in many ways irrelevant to gaining a better understanding of the Federal Circuitâs patent law jurisprudence. In the pages that follow, we will address these and many other developments reflected in the Federal Circuitâs patent jurisprudence of 2006. And, as we did in our article surveying the Federal Circuitâs year 2000 jurisprudence, we again conclude with an addendum that discusses the statistical output of the Federal Circuit and its judges
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