1,072 research outputs found
Internationalization and Financial Federalism: The United States and Germany at the Crossroads?
In this article, the authors examine some effects of economic internationalization on state structures, especially in regard to the distribution of power and authority within federalist systems. Using an institutional rational choice model, they analyze changes in financial regulation and market structures in Germany and the United States. The focus is on the financial realm because of its high degree of internationalization and because, in both countries, financial markets and regulation have historically exhibited federalist traits. The findings indicate that internationalization has led to significant convergence in financial market structures and regulation across the two countries and that in each case this convergence has been accompanied by centralization of financial regulatory authority. Although both the German type of cooperative federalism and the U.S. model of competitive federalism proved to be vulnerable to the growing international pressures, the two countries took different paths of change that reflected differences in domestic institutions. Thus, the authors conclude that convergence is, and will likely remain, of a limited nature
CoRoT 101186644: A transiting low-mass dense M-dwarf on an eccentric 20.7-day period orbit around a late F-star
We present the study of the CoRoT transiting planet candidate 101186644, also
named LRc01_E1_4780. Analysis of the CoRoT lightcurve and the HARPS
spectroscopic follow-up observations of this faint (m_V = 16) candidate
revealed an eclipsing binary composed of a late F-type primary (T_eff = 6090
+/- 200 K) and a low-mass, dense late M-dwarf secondary on an eccentric (e =
0.4) orbit with a period of ~20.7 days. The M-dwarf has a mass of 0.096 +/-
0.011 M_Sun, and a radius of 0.104 +0.026/-0.006 R_Sun, which possibly makes it
the smallest and densest late M-dwarf reported so far. Unlike the claim that
theoretical models predict radii that are 5%-15% smaller than measured for
low-mass stars, this one seems to have a radius that is consistent and might
even be below the radius predicted by theoretical models.Comment: Accepted for publication in Astronomy & Astrophysics, 8 pages, 10
figure
Ground-based photometry of space-based transit detections: Photometric follow-up of the CoRoT mission
The motivation, techniques and performance of the ground-based photometric
follow-up of transit detections by the CoRoT space mission are presented. Its
principal raison d'\^{e}tre arises from the much higher spatial resolution of
common ground-based telescopes in comparison to CoRoT's cameras. This allows
the identification of many transit candidates as arising from eclipsing
binaries that are contaminating CoRoT's lightcurves, even in low-amplitude
transit events that cannot be detected with ground-based obervations. For the
ground observations, 'on'-'off' photometry is now largely employed, in which
only a short timeseries during a transit and a section outside a transit is
observed and compared photometrically. CoRoT planet candidates' transits are
being observed by a dedicated team with access to telescopes with sizes ranging
from 0.2 to 2 m. As an example, the process that led to the rejection of
contaminating eclipsing binaries near the host star of the Super-Earth planet
CoRoT-7b is shown. Experiences and techniques from this work may also be useful
for other transit-detection experiments, when the discovery instrument obtains
data with a relatively low angular resolution.Comment: Accepted for the A&A special issue on CoRo
Radio Continuum and Star Formation in CO-rich Early Type Galaxies
In this paper we present new high resolution VLA 1.4 GHz radio continuum
observations of five FIR bright CO-rich early-type galaxies and two dwarf
early-type galaxies. The position on the radio-FIR correlation combined with
striking agreements in morphology between high resolution CO and radio maps
show that the radio continuum is associated with star formation in at least
four of the eight galaxies. The average star formation rate for the sample
galaxies detected in radio is approximately 2 solar masses per year. There is
no evidence of a luminous AGN in any of our sample galaxies. We estimate Toomre
Q values and find that the gas disks may well be gravitationally unstable,
consistent with the above evidence for star formation activity. The radio
continuum emission thus corroborates other recent suggestions that star
formation in early type galaxies may not be uncommon.Comment: 21 pages, 7 figures, to be published in the Astronomical Journa
High angular resolution imaging and infrared spectroscopy of CoRoT candidates
Studies of transiting extrasolar planets are of key importance for
understanding the nature of planets outside our solar system because their
masses, diameters, and bulk densities can be measured. An important part of
transit-search programmes is the removal of false-positives. The critical
question is how many of the candidates that passed all previous tests are false
positives. For our study we selected 25 CoRoT candidates that have already been
screened against false-positives using detailed analysis of the light curves
and seeing-limited imaging, which has transits that are between 0.7 and 0.05%
deep. We observed 20 candidates with the adaptive optics imager NaCo and 18
with the high-resolution infrared spectrograph CRIRES. We found previously
unknown stars within 2 arcsec of the targets in seven of the candidates. All of
these are too faint and too close to the targets to have been previously
detected with seeing-limited telescopes in the optical. Our study thus leads to
the surprising results that if we remove all candidates excluded by the
sophisticated analysis of the light-curve, as well as carrying out deep imaging
with seeing-limited telescopes, still 28-35% of the remaining candidates are
found to possess companions that are bright enough to be false-positives. Given
that the companion-candidates cluster around the targets and that the J-K
colours are consistent with physical companions, we conclude that the
companion-candidates are more likely to be physical companions rather than
unrelated field stars.Comment: 12 pages, 12 figures, A&A in pres
The HARPS search for southern extra-solar planets XXXII. Only 4 planets in the Gl~581 system
The Gl 581 planetary system has generated wide interest, because its 4
planets include both the lowest mass planet known around a main sequence star
other than the Sun and the first super-Earth planet in the habitable zone of
its star. A recent paper announced the possible discovery of two additional
super-Earth planets in that system, one of which would be in the middle of the
habitable zone of Gl 581. The statistical significance of those two discoveries
has, however, been questioned. We have obtained 121 new radial velocity
measurements of Gl 581 with the HARPS spectrograph on the ESO 3.6 m telescope,
and analyse those together with our previous 119 measurements of that star to
examine these potential additional planets. We find that neither is likely to
exist with their proposed parameters. We also obtained photometric observations
with the 2.5 m Isaac Newton Telescope during a potential transit of the inner
planet, Gl 581e, which had a 5% geometric transit probability. Those
observations exclude transits for planet densities under 4 times the Earth
density within -0.2 sigma to +2.7 sigma of the predicted transit center.Comment: Submitted to Astronomy & Astrophysic
Revisiting the transits of CoRoT-7b at a lower activity level
CoRoT-7b, the first super-Earth with measured radius discovered, has opened
the new field of rocky exoplanets characterisation. To better understand this
interesting system, new observations were taken with the CoRoT satellite.
During this run 90 new transits were obtained in the imagette mode. These were
analysed together with the previous 151 transits obtained in the discovery run
and HARPS radial velocity observations to derive accurate system parameters. A
difference is found in the posterior probability distribution of the transit
parameters between the previous CoRoT run (LRa01) and the new run (LRa06). We
propose this is due to an extra noise component in the previous CoRoT run
suspected to be transit spot occultation events. These lead to the mean transit
shape becoming V-shaped. We show that the extra noise component is dominant at
low stellar flux levels and reject these transits in the final analysis. We
obtained a planetary radius, , in agreement
with previous estimates. Combining the planetary radius with the new mass
estimates results in a planetary density of
which is consistent with a rocky composition. The CoRoT-7 system remains an
excellent test bed for the effects of activity in the derivation of planetary
parameters in the shallow transit regime.Comment: 13 pages, 13 figures, accepted to A&
Kepler423b: a half-Jupiter mass planet transiting a very old solar-like star
We report the spectroscopic confirmation of the Kepler object of interest
KOI-183.01 (Kepler-423b), a half-Jupiter mass planet transiting an old
solar-like star every 2.7 days. Our analysis is the first to combine the full
Kepler photometry (quarters 1-17) with high-precision radial velocity
measurements taken with the FIES spectrograph at the Nordic Optical Telescope.
We simultaneously modelled the photometric and spectroscopic data-sets using
Bayesian approach coupled with Markov chain Monte Carlo sampling. We found that
the Kepler pre-search data conditioned (PDC) light curve of KOI-183 exhibits
quarter-to-quarter systematic variations of the transit depth, with a
peak-to-peak amplitude of about 4.3 % and seasonal trends reoccurring every
four quarters. We attributed these systematics to an incorrect assessment of
the quarterly variation of the crowding metric. The host star KOI-183 is a G4
dwarf with M_\rm{Sun},
R_\rm{Sun}, K, dex, and with
an age of Gyr. The planet KOI-183b has a mass of
M and a radius of
R, yielding a planetary bulk
density of g/cm. The radius of KOI-183b
is consistent with both theoretical models for irradiated coreless giant
planets and expectations based on empirical laws. The inclination of the
stellar spin axis suggests that the system is aligned along the line of sight.
We detected a tentative secondary eclipse of the planet at a 2-
confidence level ( ppm) and found that the
orbit might have a small non-zero eccentricity of .
With a Bond albedo of , KOI-183b is one of the
gas-giant planets with the lowest albedo known so far.Comment: 13 pages, 13 figures, 5 tables. Accepted for publication in A&A.
Planet designation changed from KOI-183b to Kepler-423
Detection of Neptune-size planetary candidates with CoRoT data. Comparison with the planet occurrence rate derived from Kepler
[Abridged] Context. The CoRoT space mission has been searching for transiting
planets since the end of December 2006. Aims. We aim to investigate the
capability of CoRoT to detect small-size transiting planets in short-period
orbits, and to compare the number of CoRoT planets with 2 \leq R_p \leq 4
Rearth with the occurrence rate of small-size planets provided by the
distribution of Kepler planetary candidates (Howard et al. 2012). Methods. We
performed a test that simulates transits of super-Earths and Neptunes in real
CoRoT light curves and searches for them blindly by using the LAM transit
detection pipeline. Results. The CoRoT detection rate of planets with radius
between 2 and 4 Rearth and orbital period P \leq 20 days is 59% (31%) around
stars brighter than r'=14.0 (15.5). By properly taking the CoRoT detection rate
for Neptune-size planets and the transit probability into account, we found
that according to the Kepler planet occurrence rate, CoRoT should have
discovered 12 \pm 2 Neptunes orbiting G and K dwarfs with P \leq 17 days in six
observational runs. This estimate must be compared with the validated Neptune
CoRoT-24b and five CoRoT planetary candidates in the considered range of
planetary radii. We thus found a disagreement with expectations from Kepler at
3 \sigma or 5 \sigma, assuming a blend fraction of 0% (six Neptunes) and 100%
(one Neptune) for these candidates. Conclusions. This underabundance of CoRoT
Neptunes with respect to Kepler may be due to several reasons. Regardless of
the origin of the disagreement, which needs to be investigated in more detail,
the noticeable deficiency of CoRoT Neptunes at short orbital periods seems to
indirectly support the general trend found in Kepler data, i.e. that the
frequency of small-size planets increases with increasing orbital periods and
decreasing planet radii.Comment: 10 pages, 7 figures. Accepted for publication in A&
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