900 research outputs found
Detection of gravity modes in the massive binary V380 Cyg from Kepler spacebased photometry and high-resolution spectroscopy
We report the discovery of low-amplitude gravity-mode oscillations in the
massive binary star V380 Cyg, from 180 d of Kepler custom-aperture space
photometry and 5 months of high-resolution high signal-to-noise spectroscopy.
The new data are of unprecedented quality and allowed to improve the orbital
and fundamental parameters for this binary. The orbital solution was subtracted
from the photometric data and led to the detection of periodic intrinsic
variability with frequencies of which some are multiples of the orbital
frequency and others are not. Spectral disentangling allowed the detection of
line-profile variability in the primary. With our discovery of intrinsic
variability interpreted as gravity mode oscillations, V380 Cyg becomes an
important laboratory for future seismic tuning of the near-core physics in
massive B-type stars.Comment: 5 pages, 4 figures, 2 tables. Accepted for publication in MNRAS
Letter
WASP-43b: The closest-orbiting hot Jupiter
We report the discovery of WASP-43b, a hot Jupiter transiting a K7V star
every 0.81 d. At 0.6-Msun the host star has the lowest mass of any star hosting
a hot Jupiter. It also shows a 15.6-d rotation period. The planet has a mass of
1.8 Mjup, a radius of 0.9 Rjup, and with a semi-major axis of only 0.014 AU has
the smallest orbital distance of any known hot Jupiter. The discovery of such a
planet around a K7V star shows that planets with apparently short remaining
lifetimes owing to tidal decay of the orbit are also found around stars with
deep convection zones.Comment: 4 page
Searching For Transiting Circumbinary Planets in CoRoT and Ground-Based Data Using CB-BLS
Aims. We search for transiting circumbinary (CB) planets around eclipsing
binaries (EBs).
Methods. CB-BLS is a recently-introduced algorithm for the detection of
transiting CB planets around EBs.We describe progress in search sensitivity,
generality and capability of CB-BLS, and detection tests of CB-BLS on simulated
data. We also describe an analytical approach for the determination of CB-BLS
detection limits, and a method for the correct detrending of
intrinsically-variable stars.
Results. We present some blind-tests with simulated planets injected to real
CoRoT data. The presented upgrades to CB-BLS allowed it to detect all the blind
tests successfully, and these detections were in line with the detection limits
analysis. We also correctly detrend bright eclipsing binaries from observations
by the TrES planet search, and present some of the first results of applying
CB-BLS to multiple real light curves from a wide-field survey.
Conclusions. CB-BLS is now mature enough for its application to real data,
and the presented processing scheme will serve as the template for our future
applications of CB-BLS to data from wide-field surveys such as CoRoT. Being
able to put constraints even on non-detection will help to determine the
correct frequency of CB planets, contributing to the understanding of planet
formation in general. Still, searching for transiting CB planets is still a
learning experience, similarly to the state of transiting planets around single
stars only a few years ago. The recent rapid progress in this front, coupled
with the exquisite quality of space-based photometry, allows to realistically
expect that if transiting CB planets exist - then they will soon be found.Comment: A&A accepted. Presented at the 1st CoRoT symposium. Note table 3 is
too wide in this version, but omitted data is of minor significance. 10
pages, 10 figures, 3 table
Thermal emission from WASP-24b at 3.6 and 4.5 {\mu}m
Aims. We observe occultations of WASP-24b to measure brightness temperatures
and to determine whether or not its atmosphere exhibits a thermal inversion
(stratosphere). Methods. We observed occultations of WASP-24b at 3.6 and 4.5
{\mu}m using the Spitzer Space Telescope. It has been suggested that there is a
correlation between stellar activity and the presence of inversions, so we
analysed existing HARPS spectra in order to calculate log R'HK for WASP-24 and
thus determine whether or not the star is chromospherically active. We also
observed a transit of WASP-24b in the Str\"{o}mgren u and y bands, with the
CAHA 2.2-m telescope. Results. We measure occultation depths of 0.159 \pm 0.013
per cent at 3.6 {\mu}m and 0.202 \pm 0.018 per cent at 4.5 {\mu}m. The
corresponding planetary brightness temperatures are 1974 \pm 71 K and 1944 \pm
85 K respectively. Atmosphere models with and without a thermal inversion fit
the data equally well; we are unable to constrain the presence of an inversion
without additional occultation measurements in the near-IR. We find log R'HK =
-4.98 \pm 0.12, indicating that WASP-24 is not a chromospherically active star.
Our global analysis of new and previously-published data has refined the system
parameters, and we find no evidence that the orbit of WASP-24b is non-circular.
Conclusions. These results emphasise the importance of complementing Spitzer
measurements with observations at shorter wavelengths to gain a full
understanding of hot Jupiter atmospheres.Comment: 7 pages, 4 figures, 3 tables. Accepted for publication in A&
Spectroscopically resolving the Algol triple system
Algol (β Persei) is the prototypical semidetached eclipsing binary and a hierarchical triple system. From 2006 to 2010 we obtained 121 high-resolution and high signal-to-noise ratio échelle spectra of this object. Spectral disentangling yields the individual spectra of all three stars, and greatly improved elements both the inner and outer orbits. We find masses of M_A = 3.39 ± 0.06 M⊙, M_B = 0.770 ± 0.009 M⊙ and M_C = 1.58 ± 0.09 M⊙. The disentangled spectra also give the light ratios between the components in the B and V bands. Atmospheric parameters for the three stars are determined, including detailed elemental abundances for Algol A and Algol C. We find the following effective temperatures: T_A = 12 550 ± 120 K, T_B = 4900 ± 300 K and T_C = 7550 ± 250 K. The projected rotational velocities are v_A sin i_A = 50.8 ± 0.8 km/s, v_B sin i_B = 62 ± 2 km/s and v_C sin i_C = 12.4 ± 0.6 km/s. This is the first measurement of the rotational velocity for Algol B, and confirms that it is synchronous with the orbital motion. The abundance patterns of components A and C are identical to within the measurement errors, and are basically solar. They can be summarized as mean metal abundances: [M/H]_A = −0.03 ± 0.08 and [M/H]_C = 0.04 ± 0.09. A carbon deficiency is confirmed for Algol A, with tentative indications for a slight overabundance of nitrogen. The ratio of their abundances is (C/N)_A = 2.0 ± 0.4, half of the solar value of (C/N)⊙ = 4.0 ± 0.7. The new results derived in this study, including detailed abundances and metallicities, will enable tight constraints on theoretical evolutionary models for this complex system
WASP-157b, a Transiting Hot Jupiter Observed with K2
We announce the discovery of the transiting hot Jupiter WASP-157b in a 3.95-d
orbit around a V = 12.9 G2 main-sequence star. This moderately inflated planet
has a Saturn-like density with a mass of M and a
radius of R. We do not detect any rotational or
phase-curve modulations, nor the secondary eclipse, with conservative
semi-amplitude upper limits of 250 and 20 ppm, respectively.Comment: 6 pages, 5 figures and 4 tables. Accepted for publication in PAS
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