12,511 research outputs found
The Mystery of Suffering
Roll 108. Golden Gloves Arena, St. Louis. Image 8 of 18. (19 February, 1954) [PHO 1.108.8]The Boleslaus Lukaszewski (Father Luke) Photographs contain more than 28,000 images of Saint Louis University people, activities, and events between 1951 and 1970. The photographs were taken by Boleslaus Lukaszewski (Father Luke), a Jesuit priest and member of the University's Philosophy Department faculty
Terry Latham, Plaintiff-Appellant, v. Board of Education of the Albuquerque Public Schools, Defendant-Appellee.
Confirmation of Eclipses in KPD 0422+5421, A Binary Containing a White Dwarf and a Subdwarf B Star
We report additional photometric CCD observations of KPD 0422+5421, a binary
with an orbital period of 2.16 hours which contains a subdwarf B star (sdB) and
a white dwarf. There are two main results of this work. First, the light curve
of KPD 0422+5421 contains two distinct periodic signals, the 2.16 hour
ellipsoidal modulation discovered by Koen, Orosz, & Wade (1998) and an
additional modulation at 7.8 hours. This 7.8 hour modulation is clearly not
sinusoidal: the rise time is about 0.25 in phase, whereas the decay time is
0.75 in phase. Its amplitude is roughly half of the amplitude of the
ellipsoidal modulation. Second, after the 7.8 hour modulation is removed, the
light curve folded on the orbital period clearly shows the signature of the
transit of the white dwarf across the face of the sdB star and the signature of
the occultation of the white dwarf by the sdB star. We used the Wilson-Devinney
code to model the light curve to obtain the inclination, the mass ratio, and
the Omega potentials, and a Monte Carlo code to compute confidence limits on
interesting system parameters. We find component masses of M_sdB = 0.36 +/-
0.16 solar masses and M_WD = 0.47 +/- 0.16 solar masses (M_total = 0.86 +/-
0.35 solar masses, 68 per cent confidence limits). If we impose an additional
constraint and require the computed mass and radius of the white dwarf to be
consistent with a theoretical mass-radius relation, we find M_sdB = 0.511
+0.047 -0.050 solar masses and M_WD = 0.526 +0.033 -0.030 solar masses (68 per
cent confidence limits). In this case the total mass of the system is less than
1.4 solar masses at the 99.99 per cent confidence level. We briefly discuss
possible interpretations of the 7.8 hour modulation and the importance of KPD
0422+5421 as a member of a rare class of evolved binaries.Comment: 11 pages, 7 figures, to appear in MNRAS, LaTeX, uses mn.st
The Optical Light Curves of Cygnus X-2 (V1341 Cyg) and the Mass of its Neutron Star
We present U, B and V light curves (taken from the literature) of the low
mass X-ray binary Cygnus X-2. The ``lower envelope'' of the light curves folded
on the orbital period are ellipsoidal. We fit an ellipsoidal model to the lower
envelopes of the B and V light curves to derive inclination constraints. If we
assume the accretion disc is steady-state where its radial temperature profile
goes as T(r) \propto r^{-3/4}, we find an inclination of i = 62.5 +/- 4 deg.
However, the predicted ratio of the disc flux to the total flux in B (the
``disc fraction'') is larger than what is observed (about 0.55 compared to <
0.3). If we use a flatter radial temperature profile of the disc expected for
strongly irradiated discs (T(r) \propto r^{-3/7}), then we find an inclination
of i = 54.6 deg and a disc fraction in B of approximately 0.30. However, in
this case the value of chi^2 is much larger (48.4 with 36 degrees of freedom
compared to 40.9 for the steady-state case). Adopting i = 62.5 +/- 4 deg and
using a previous determination of the mass ratio (q = M_c/M_x = 0.34 +/- 0.04)
and the optical mass function (f(M) = 0.69 +/- 0.03 solar masses), we find that
the mass of the neutron star is M_x = 1.78 +/- 0.23 solar masses and the mass
of the secondary star is M_c = 0.60 +/- 0.13 solar masses. We derive a distance
of d = 7.2 +/- 1.1 kpc, which is significantly smaller than a recent distance
measurement of d = 11.6 +/- 0.3 kpc derived from an observation of a type I
radius-expansion X-ray burst, but consistent with earlier distance estimates.
(abridged)Comment: 12 pages, 9 figures, to appear in MNRAS, LaTeX, uses mn.st
A profile of the Monterey squid fleet in 1992
There were approximately 20 vessels active in the 1992 Monterey Bay squid fishery. The size of the fleet has not changed since the early 1970's when 15 to 20 vessels participated in the fishery.
Since 1977, eleven steel hulled vessels have been added
to the fleet, replacing smaller wooden hulled vessels that were in use during the 1960's. The hold capacity of the new fleet remains about 800 tons, because the new larger vessels replaced small vessels that used lighters (20 - 25 ton capacity non-motorized barges).
Purse seines were legalized in 1989 and have replaced
lamparas which were in use during the 1960'S and 1970's.
Seines used in the squid fishery are small and shallow,
ranging from 120 to 200 fm in length with most less
than 25 fm deep.
Crew size has been reduced nearly 50% by the addition of net reels, power blocks, submersible fish pumps, and vacuum pumps used for unloading at dockside.
In the 1970's flasher type fathometers were used by the fleet and few vessels had navigational aids. Today most
of the fleet have sonar, radar, and loran C. Three vessels carry global positioning systems.
In 1988 squid attracting lights were legalized and the
entire fleet used lights during the 1992 season. (21pp.
A Solar Constant Model for Sun-climate Studies: 1600-2000AD
Discussed here is the solar constant model published recently (Schatten, 1988), but with a modified phasing and amplitude. This model enables the known solar constant variations to be calculated from known active region and quiet region solar parameters. The features which can be modelled are sunspots and faculae, the only two features which mark the photospheric continuum with their unusual contrast behavior. They include both the active region features (sunspots and faculae) and the quiet region features (global faculae). Although the direct influences of sunspots upon the solar constant leads to short term decreases, an opposite, nearly in phase, 11 year variation in the solar constant is modelled, thereby agreeing with the Active Cavity Radiometer Irradiance Monitor (ACRIM) and Earth Radiation Budget (ERB) secular trends observed. This opposite behavior results primarily from global faculae (polar, network, and active region). The main contributors to the global behavior are the network faculae. The model attributes the observed variations in the solar constant entirely to magnetic features in the solar atmosphere. The present model serves purely to model the secular (long term) trend in the solar constant. The model suggests a change of approx. 0.5 W/sq m for the differences between the late twentieth century solar constant and the 17th century solar constant. This supports Eddy's view that this difference could give rise to the glacial increase during the little ice age of the 17th century. Important for present day climate studies, is that it shows the recent peak activity (peaking in 1958) is associated with an atypically high value of the solar constant, with respect to the past few hundred years
KPD 0422+5421: A New Short Period Subdwarf B/White Dwarf Binary
The sdB star KPD 0422+5421 was discovered to be a single-lined spectroscopic
binary with a period of P=0.0901795 +/- (3\times 10^{-7}) days (2 hours, 10
minutes). The U and B light curves display an ellipsoidal modulation with
amplitudes of about 0.02 magnitudes. The sdB star contributes nearly all of the
observed flux. This and the absence of any reflection effect suggest that the
unseen companion star is small (i.e. R_comp ~ 0.01 solar radii) and therefore
degenerate. We modeled the U and B light curves and derived i = 78.05 +/- 0.50
degrees and a mass ratio of q = M_comp/M_sdB = 0.87 +/- 0.15. The sdB star
fills 69% of its Roche lobe. These quantities may be combined with the mass
function of the companion (f(M) = 0.126 +/- 0.028 solar masses) to derive M_sdB
= 0.72 +/- 0.26 solar masses and M_comp = 0.62 +/- 0.18 solar masses. We used
model spectra to derive the effective temperature, surface gravity, and helium
abundance of the sdB star. We found T_eff = 25,000 +/- 1500K, log g = 5.4 +/-
0.1, and [He/H] = -1.0. With a period of 2 hours and 10 minutes, KPD 0422+5421
has one of the shortest known orbital periods of a detached binary. This system
is also one of only a few known binaries which contain a subdwarf B star and a
white dwarf. Thus KPD 0422+5421 represents a relatively unobserved, and
short-lived, stage of binary star evolution.Comment: 9 pages, 8 figures, to appear in MNRAS, LaTeX, uses mn.st
- …