8,016 research outputs found
Understanding Legislator Experiences of Family-Friendly Working Practices in Political Institutions
This is a post-peer-review, pre-copy edit version of an article published in Politics and Gender. © 2015, Cambridge University Press
The spin-orbit angle of the transiting hot jupiter CoRoT-1b
We measure the angle between the planetary orbit and the stellar rotation
axis in the transiting planetary system CoRoT-1, with new HIRES/Keck and
FORS/VLT high-accuracy photometry. The data indicate a highly tilted system,
with a projected spin-orbit angle lambda = 77 +- 11 degrees. Systematic
uncertainties in the radial velocity data could cause the actual errors to be
larger by an unknown amount, and this result needs to be confirmed with further
high-accuracy spectroscopic transit measurements.
Spin-orbit alignment has now been measured in a dozen extra-solar planetary
systems, and several show strong misalignment. The first three misaligned
planets were all much more massive than Jupiter and followed eccentric orbits.
CoRoT-1, however, is a jovian-mass close-in planet on a circular orbit. If its
strong misalignment is confirmed, it would break this pattern. The high
occurence of misaligned systems for several types of planets and orbits favours
planet-planet scattering as a mechanism to bring gas giants on very close
orbits.Comment: to appear in in MNRAS letters [5 pages
HATS-1b: The First Transiting Planet Discovered by the HATSouth Survey
We report the discovery of HATS-1b, a transiting extrasolar planet orbiting
the moderately bright V=12.05 G dwarf star GSC 6652-00186, and the first planet
discovered by HATSouth, a global network of autonomous wide-field telescopes.
HATS-1b has a period P~3.4465 d, mass Mp~1.86MJ, and radius Rp~1.30RJ. The host
star has a mass of 0.99Msun, and radius of 1.04Rsun. The discovery light curve
of HATS-1b has near continuous coverage over several multi-day periods,
demonstrating the power of using a global network of telescopes to discover
transiting planets.Comment: Submitted to AJ 10 pages, 5 figures, 6 table
Twenty-One New Light Curves of OGLE-TR-56b: New System Parameters and Limits on Timing Variations
Although OGLE-TR-56b was the second transiting exoplanet discovered, only one
light curve, observed in 2006, has been published besides the discovery data.
We present twenty-one light curves of nineteen different transits observed
between July 2003 and July 2009 with the Magellan Telescopes and Gemini South.
The combined analysis of the new light curves confirms a slightly inflated
planetary radius relative to model predictions, with R_p = 1.378 +/- 0.090 R_J.
However, the values found for the transit duration, semimajor axis, and
inclination values differ significantly from the previous result, likely due to
systematic errors. The new semimajor axis and inclination, a = 0.01942 +/-
0.00015 AU and i = 73.72 +/- 0.18 degrees, are smaller than previously
reported, while the total duration, T_14 = 7931 +/- 38 s, is 18 minutes longer.
The transit midtimes have errors from 23 s to several minutes, and no evidence
is seen for transit midtime or duration variations. Similarly, no change is
seen in the orbital period, implying a nominal stellar tidal decay factor of
Q_* = 10^7, with a three-sigma lower limit of 10^5.7.Comment: 14 pages, 5 figures, accepted to Ap
Selective Principal Component Extraction and Reconstruction: A Novel Method for Ground Based Exoplanet Spectroscopy
Context: Infrared spectroscopy of primary and secondary eclipse events probes
the composition of exoplanet atmospheres and, using space telescopes, has
detected H2O, CH4 and CO2 in three hot Jupiters. However, the available data
from space telescopes has limited spectral resolution and does not cover the
2.4 - 5.2 micron spectral region. While large ground based telescopes have the
potential to obtain molecular-abundance-grade spectra for many exoplanets,
realizing this potential requires retrieving the astrophysical signal in the
presence of large Earth-atmospheric and instrument systematic errors. Aims:
Here we report a wavelet-assisted, selective principal component extraction
method for ground based retrieval of the dayside spectrum of HD 189733b from
data containing systematic errors. Methods: The method uses singular value
decomposition and extracts those critical points of the Rayleigh quotient which
correspond to the planet induced signal. The method does not require prior
knowledge of the planet spectrum or the physical mechanisms causing systematic
errors. Results: The spectrum obtained with our method is in excellent
agreement with space based measurements made with HST and Spitzer (Swain et al.
2009b; Charbonneau et al. 2008) and confirms the recent ground based
measurements (Swain et al. 2010) including the strong 3.3 micron emission.Comment: 4 pages, 3 figures; excepted for publication by A&
Cytogenetic variability in radiation induced mouse leukaemia.
C57BL mice and certain of their hybrids have a high incidence of radiation induced leukaemia. The incidence is greater than 70 % in (C57BL x CBA.T6T6)F1 hybrids aged between 30 and 40 days receiving 4 fractions of 200 rads gamma radiation at 4-day intervals (Ilbery, 1967). The great majority of primary reticular neoplasms arising in irradiated mice show a variation in chromosome number in the range 41 to 45 and distinctive new marker chromosomes are often present (Ford, Hamerton and Mole, 1958). It has been suggested that karyotypic alterations are of primary significance in the onset of neoplasia (Winge, 1930) but more probably there is an association for such changes with tumour progression (Hauschka, 1961). Nevertheless from cytogenetic studies of the thymus in the preleukaemic phase it seems that observable variations in chromosome number and form accompany an early stage of leukaemia induction (Ilbery et al., 1963; Joneja and Stich, 1965). This report is concerned with the cytogenetic results of mice involved in radiation experiments during the last 5 years and who subsequently exhibited macroscopically leukaemia of the thymic type. Thymomas were passaged so that, where for technical reasons examination ofthe primary neoplasm failed, subsequent sampling of the malignant cells could be made in the passage mice. Cytogenetic results of a total of 43 radiation induced leukaemias are recorded of which 26 were sampled from the propositi. A related paper will give the cytogenetic results of mice exposed to the leukaemogenic effects of radiation and in which attempts were made, by the administration of cell supplements, to modify or prevent the onset of leukaemia. MATERIALS AND METHODS Mice of both sexes between 30 and 40 days of age at the time of irradiation were used in the leukaemia induction experiments. The inbred strains employed were C57BL, CBA, DBA and T6T6 all maintained in this laboratory by selective inbreeding during the last 10 years. CBA/H and CBA.T6T6 have been inbred a further 12 and 9 generations respectively in this laboratory since the importation in 1963 of these syngeneic mice from Dr. Mary Lyon of the M.R.C. Radiobiologica
Detection of a transit by the planetary companion of HD 80606
We report the detection of a transit egress by the ~ 3.9-Jupiter-mass planet
HD 80606b, an object in a highly-eccentric orbit (e ~ 0.93) about its parent
star of approximately solar type. The astrophysical reality of the signal of
variability in HD 80606 is confirmed by observation with two independent
telescope systems, and checks against several reference stars in the field.
Differential photometry with respect to the nearby comparison star HD 80607
provides a precise light curve. Modelling of the light curve with a full
eccentric-orbit model indicates a planet/star-radius ratio of 0.1057 +/-
0.0018, corresponding to a planet radius of 1.029 R_J for a solar-radius parent
star; and a precise orbital inclination of 89.285 +/- 0.023 degrees, giving a
total transit duration of 12.1 +/- 0.4 hours. The planet hence joins HD 17156b
in a class of highly eccentric transiting planets, in which HD 80606b has both
the longest period and most eccentric orbit. The recently reported discovery of
a secondary eclipse of HD 80606b by the Spitzer Space Observatory permits a
combined analysis with the mid-time of primary transit in which the orbital
parameters of the system can be tightly constrained. We derive a transit
ephemeris of T_tr = HJD (2454876.344 +/- 0.011) + (111.4277 +/- 0.0032) E.Comment: Accepted for publication in MNRAS Letter
Transiting exoplanets from the CoRoT space mission III. The spectroscopic transit of CoRoT-Exo-2b with SOPHIE and HARPS
We report on the spectroscopic transit of the massive hot-Jupiter
CoRoT-Exo-2b observed with the high-precision spectrographs SOPHIE and HARPS.
By modeling the radial velocity anomaly occurring during the transit due to the
Rossiter-McLaughlin (RM) effect, we determine the sky-projected angle between
the stellar spin and the planetary orbital axis to be close to zero
lambda=7.2+-4.5 deg, and we secure the planetary nature of CoRoT-Exo-2b. We
discuss the influence of the stellar activity on the RM modeling. Spectral
analysis of the parent star from HARPS spectra are presented.Comment: A&A Letters (in press), 5 pages, 2 figure
A multipole-Taylor expansion for the potential of gravitational lens MG J0414+0534
We employ a multipole-Taylor expansion to investigate how tightly the
gravitational potential of the quadruple-image lens MG J0414+0534 is
constrained by recent VLBI observations. These observations revealed that each
of the four images of the background radio source contains four distinct
components, thereby providing more numerous and more precise constraints on the
lens potential than were previously available. We expand the two-dimensional
lens potential using multipoles for the angular coordinate and a modified
Taylor series for the radial coordinate. After discussing the physical
significance of each term, we compute models of MG J0414+0534 using only VLBI
positions as constraints. The best-fit model has both interior and exterior
quadrupole moments as well as exterior m=3 and m=4 multipole moments. The
deflector centroid in the models matches the optical galaxy position, and the
quadrupoles are aligned with the optical isophotes. The radial distribution of
mass could not be well constrained. We discuss the implications of these models
for the deflector mass distribution and for the predicted time delays between
lensed components.Comment: 44 pages, 5 figures, 11 tables, accepted for publication in Ap
Dielectric multilayer waveguides for TE and TM mode matching
We analyse theoretically for the first time to our knowledge the perfect
phase matching of guided TE and TM modes with a multilayer waveguide composed
of linear isotropic dielectric materials. Alongside strict investigation into
dispersion relations for multilayer systems, we give an explicit qualitative
explanation for the phenomenon of mode matching on the basis of the standard
one-dimensional homogenization technique, and discuss the minimum number of
layers and the refractive index profile for the proposed device scheme. Direct
applications of the scheme include polarization-insensitive, intermodal
dispersion-free planar propagation, efficient fibre-to-planar waveguide
coupling and, potentially, mode filtering. As a self-sufficient result, we
present compact analytical expressions for the mode dispersion in a finite,
N-period, three-layer dielectric superlattice.Comment: 13 pages with figure
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