1,835 research outputs found
Line-of-Sight Reddening Predictions: Zero Points, Accuracies, the Interstellar Medium, and the Stellar Populations of Elliptical Galaxies
Revised (B-V)_0-Mg_2 data for 402 elliptical galaxies are given to test
reddening predictions which can also tell us both what the intrinsic errors are
in this relationship among gE galaxy stellar populations, as well as details of
nearby structure in the interstellar medium (ISM) of our Galaxy and of the
intrinsic errors in reddening predictions. Using least-squares fits, the
explicit 1-sigma errors in the Burstein-Heiles (BH) and the Schlegel et al.
(IR) predicted reddenings are calculated, as well as the 1-sigma observational
error in the (B-V)_0-Mg_2 for gE galaxies. It is found that, in directions with
E(B-V)<0.100 mag (where most of these galaxies lie), 1-sigma errors in the IR
reddening predictions are 0.006 to 0.009 in E(B-V) mag, those for BH reddening
prediction are 0.011 mag, and the 1-sigma agreement between the two reddening
predictions is 0.007 mag. IR predictions have an accuracy of 0.010-0.011 mag in
directions with E(B-V)>= 0.100 mag, significantly better than those of the BH
predictions (0.024-0.025). Gas-to-dust variations that vary by a factor of 3,
both high and low, exist along many lines-of-sight in our Galaxy. The approx
0.02 higher reddening zero point in E(B-V) previously determined by Schlegel et
al. is confirmed, primarily at the Galactic poles. Despite this, both methods
also predict many directions with E(B-V)<0.015 mag. Independent evidence of
reddening at the North Galactic pole is reviewed, with the conclusion that
there still exists directions at the NGP that have E(B-V)<<0.01. Two lines of
evidence suggest that IR reddenings are overpredicted in directions with high
gas-to-dust ratios. As high gas-to-dust directions in the ISM also include the
Galactic poles, this overprediction is the likely cause of the E(B-V) = 0.02
mag larger IR reddening zero point.Comment: 5 figure
Marked hydrophobicity of the NH2-terminal extra piece of immunoglobulin light-chain precursors: possible physiological functions of the extra piece.
M Dwarfs from Hubble Space Telescope Star Counts. IV
We study a sample of about 1400 disk M dwarfs that are found in 148 fields
observed with the Wide Field Camera 2 (WFC2) on the Hubble Space Telescope and
162 fields observed with pre-repair Planetary Camera 1 (PC1), of which 95 of
the WFC2 fields are newly analyzed. The method of maximum likelihood is applied
to derive the luminosity function and the Galactic disk parameters. At first,
we use a local color-magnitude relation and a locally determined
mass-luminosity relation in our analysis. The results are consistent with those
of previous work but with considerably reduced statistical errors. These small
statistical errors motivate us to investigate the systematic uncertainties.
Considering the metallicity gradient above the Galactic plane, we introduce a
modified color-magnitude relation that is a function of Galactic height. The
resultant M dwarf luminosity function has a shape similar to that derived using
the local color-magnitude relation but with a higher peak value. The peak
occurs at and the luminosity function drops sharply toward . We then apply a height-dependent mass-luminosity function
interpolated from theoretical models with different metallicities to calculate
the mass function. Unlike the mass function obtained using local relations,
which has a power-law index , the one derived from the
height-dependent relations tends to be flat (). The resultant
local surface density of disk M dwarfs (12.2 +/- 1.6 M_sun pc^{-2}) is somewhat
smaller than the one obtained using local relations (14.3 +/- 1.3 M_sun
pc^{-2}). Our measurement favors a short disk scale length, H = 2.75 +/- 0.16
(statistical) +/- 0.25 (systematic) kpc.Comment: 20 pages, 10 ps figures, accepted for publication in Ap
Nitrogen Overabundance: Globular Cluster and Halo Formation
Halo globular clusters pose four succinct issues that must be solved in any
scenario of their formation: single-age, single metallicity stellar
populations; a lower limit ([Fe/H] ~ -2.3) to their average metallicity;
comprising only 1% of the stellar halo mass, and being among the oldest stars
in our Galaxy. New spectra are presented of Galactic stars and integrated
spectra of Galactic globular clusters which extend to 3250 angstroms. These
spectra show show that the most metal-poor and among the best-studied Galactic
globular clusters show strong NH3360 absorption, even though their spectral
energy distributions in the near-UV are dominated by blue horizontal branch,
AF-type stars. These strong NH features must be coming from the main sequence
stars in these clusters. These new data are combined with existing data on the
wide range of carbon and nitrogen abundance in very metal-poor ([Fe/H] < -3.5)
halo giant and dwarf stars, together with recent models of zero-metal star
formation, to make a strawman scenario for globular cluster formation that can
reproduce three of the above four issues, and well as related two of the three
issues pertaining to nitrogen overabundance. This strawman proposal makes
observational and theoretical predictions that are testable, needing specific
help from the modelers to understand all of the elemental constraints on
globular cluster and halo formation.Comment: to be published in ApJL, 2 figures, one tabl
Amino acid-sequence variability at the N-terminal extra piece of mouse immunoglobulin light-chain precursors of the same and different subgroups
Resonant Enhancement of Inelastic Light Scattering in the Fractional Quantum Hall Regime at
Strong resonant enhancements of inelastic light scattering from the long
wavelength inter-Landau level magnetoplasmon and the intra-Landau level spin
wave excitations are seen for the fractional quantum Hall state at .
The energies of the sharp peaks (FWHM ) in the profiles of
resonant enhancement of inelastic light scattering intensities coincide with
the energies of photoluminescence bands assigned to negatively charged exciton
recombination. To interpret the observed enhancement profiles, we propose
three-step light scattering mechanisms in which the intermediate resonant
transitions are to states with charged excitonic excitations.Comment: 5 pages, 5 figure
Supernova 1996L: evidence of a strong wind episode before the explosion
Observations of the type II SN 1996L reveal the presence of a slowly
expanding (V~700$ km/s) shell at ~ 10^(16) cm from the exploding star. Narrow
emission features are visible in the early spectra superposed on the normal SN
spectrum. Within about two months these features develop narrow symmetric
P-Cygni profiles. About 100 days after the explosion the light curve suddenly
flattens, the spectral lines broaden and the Halpha flux becomes larger than
what is expected from a purely radioactive model. These events are interpreted
as signatures of the onset of the interaction between the fast moving ejecta
and a slowly moving outer shell of matter ejected before the SN explosion. At
about 300 days the narrow lines disappear and the flux drops until the SN fades
away, suggesting that the interaction phase is over and that the shell has been
swept away. Simple calculations show that the superwind episode started 9 yr
before the SN explosion and lasted 6 yr, with an average dM/dt=10^(-3)
M_solar/yr. Even at very late epochs (up to day 335) the typical forbidden
lines of [OI], CaII], [FeII] remain undetected or very weak. Spectra after day
270 show relatively strong emission lines of HeI. These lines are narrower than
other emission lines coming from the SN ejecta, but broader than those from the
CSM. These high excitation lines are probably the result of non-thermal
excitation and ionization caused by the deposition of the gamma-rays emitted in
the decay of radioactive material mixed in the He layer.Comment: 8 pages, 6 figures, Latex, To appear in M.N.R.A.
Follow-up for breast cancer - the patients' view
Background: International and national guidelines (S3 guideline) for the surveillance of post-treatment breast cancer patients recommend a clinical follow-up including routine history and physical examination and regular mammograms. The practice of a clinical follow-up has been often discussed, but has been proven not to be inferior when compared to an intensified follow-up in randomized trials. Patients and Methods: The present manuscript reports the patients' view on the basis of a survey including 2000 patients with a history of breast cancer. Results: A total of 452 patients (22.6%) answered the questionnaire. The median age was 62 years (range 23-85 years). More than 80% of the patients were disease-free at the time of the survey. The need for surveillance was affirmed by the majority of patients (>95%), and one third stated that there was a need for more technical efforts during follow-up. In contrast to the follow-up guidelines, the results of the present survey indicated that most of the regularly scheduled follow-up visits were expanded using extensive laboratory and imaging procedures. Conclusion: This survey shows that the majority of physicians obviously do not accept the present follow-up guidelines. A new surveillance study investigating the efficacy of an intensified surveillance based on the improved possibilities of modern diagnostics and endocrine, immunotherapeutic, chemotherapeutic and interventional treatment options is warranted
The Velocity Function of Galaxies
We present a galaxy circular velocity function, Psi(log v), derived from
existing luminosity functions and luminosity-velocity relations. Such a
velocity function is desirable for several reasons. First, it enables an
objective comparison of luminosity functions obtained in different bands and
for different galaxy morphologies, with a statistical correction for dust
extinction. In addition, the velocity function simplifies comparison of
observations with predictions from high-resolution cosmological N-body
simulations.
We derive velocity functions from five different data sets and find rough
agreement among them, but about a factor of 2 variation in amplitude. These
velocity functions are then compared with N-body simulations of a LCDM model
(corrected for baryonic infall) in order to demonstrate both the utility and
current limitations of this approach. The number density of dark matter halos
and the slope of the velocity function near v_*, the circular velocity
corresponding to an ~L_* spiral galaxy, are found to be comparable to that of
observed galaxies. The primary sources of uncertainty in construction of
Psi(log v) from observations and N-body simulations are discussed and
explanations are suggected to account for these discrepancies.Comment: Latex. 28 pages, 4 figures. Accepted by Ap
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