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[show abstract]
[hide abstract]
ABSTRACT: We present new Spitzer Infrared Spectrograph (IRS) observations of three intermediate polars: V1223 Sgr, EX Hya, and V603 Aql. We detected a strong, fading flare event from V1223 Sgr. During this event, the flux declined by a factor of 13 in 30 minutes. Given the similarity in the slope of its mid-infrared spectrum during this event to that of AE Aqr, we suggest that this event was caused by transient synchrotron emission. Thus, V1223 Sgr becomes the third cataclysmic variable known to be a synchrotron source. We were unable to confirm the mid-infrared excess noted by Harrison et al. (Paper I) for EX Hya, suggesting that this object is either not a synchrotron source, or is slightly variable. Due to a very high background, V603 Aql was not detected in the long-wavelength regions accessible to the IRS. Given the recent detection of SS Cygni at radio wavelengths during outburst, we extract archival Spitzer IRS spectra for this source obtained during two successive maxima. These spectra do not show a strong excess, but without simultaneous data at shorter wavelengths, it is not possible to determine whether there is any contribution to the mid-infrared fluxes from a synchrotron jet.
The Astrophysical Journal. 08/2015; 710:325-331.
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[show abstract]
[hide abstract]
ABSTRACT: Stellar properties are measured for a large set of Kepler Mission exoplanet
candidate host stars. Most of these stars are fainter than 14th magnitude, in
contrast to other spectroscopic follow-up studies. This sample includes many
high-priority Earth-sized candidate planets. A set of model spectra are fitted
to R~3000 optical spectra of 268 stars to improve estimates of Teff, log(g),
and [Fe/H] for the dwarfs in the range 4750K<Teff<7200K. These stellar
properties are used to find new stellar radii and, in turn, new radius
estimates for the candidate planets. The result of improved stellar
characteristics is a more accurate representation of this Kepler exoplanet
sample and identification of promising candidates for more detailed study. This
stellar sample, particularly among stars with Teff>5200K, includes a greater
number of relatively evolved stars with larger radii than assumed by the
mission on the basis of multi-color broadband photometry. About 26% of the
modelled stars require radii to be revised upwards by a factor of 1.35 or
greater, and modelling of 87% of the stars suggest some increase in radius. The
sample presented here also exhibits a change in the incidence of planets larger
than 3-4 Earth radii as a function of metallicity. Once [Fe/H] increases to
>=-0.05, large planets suddenly appear in the sample while smaller planets are
found orbiting stars with a wider range of metallicity. The modelled stellar
spectra, as well as an additional 84 stars of mostly lower effective
temperatures, are made available to the community.
05/2013;
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William J Borucki,
Eric Agol,
Francois Fressin,
Lisa Kaltenegger,
Jason Rowe,
Howard Isaacson,
Debra Fischer,
Natalie Batalha,
Jack J Lissauer,
Geoffrey W Marcy, [......],
Shawn Seader,
Avi Shporer,
Jason H Steffen,
Martin Still,
Peter Tenenbaum,
Susan E Thompson,
Guillermo Torres,
Joseph D Twicken,
William F Welsh,
Joshua N Winn
[show abstract]
[hide abstract]
ABSTRACT: We present the detection of five planets-Kepler-62b, c, d, e, and f-of size 1.31, 0.54, 1.95, 1.61 and 1.41 Earth radii (R⊕), orbiting a K2V star at periods of 5.7, 12.4, 18.2, 122.4, and 267.3 days, respectively. The outermost planets (Kepler-62e and -62f) are super-Earth-size (1.25 < planet radius ≤ 2.0 R⊕) planets in the habitable zone (HZ) of their host star, receiving 1.2 ± 0.2 and 0.41 ± 0.05 times the solar flux at Earth's orbit (S⊙). Theoretical models of Kepler-62e and -62f for a stellar age of ~7 Gyr suggest that both planets could be solid, either with a rocky composition or composed of mostly solid water in their bulk.
Science 04/2013; · 31.20 Impact Factor
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Thomas Barclay,
Christopher J. Burke, Steve B. Howell,
Jason F. Rowe,
Daniel Huber,
Howard Isaacson,
Jon M. Jenkins,
Rea Kolbl,
Geoffrey W. Marcy,
Elisa V. Quintana, [......],
Michael R. Haas,
Roger Hunter,
Jack J. Lissauer,
Fergal Mullally,
Anima Sabale,
Shawn E. Seader,
Jeffrey C. Smith,
Peter Tenenbaum,
AKM Kamal Uddin,
Susan E. Thompson
[show abstract]
[hide abstract]
ABSTRACT: We present the discovery of a super-earth-sized planet in or near the
habitable zone of a sun-like star. The host is Kepler-69, a 13.7 mag G4V-type
star. We detect two periodic sets of transit signals in the three-year flux
time series of Kepler-69, obtained with the Kepler spacecraft. Using the very
high precision Kepler photometry, and follow-up observations, our confidence
that these signals represent planetary transits is >99.1%. The inner planet,
Kepler-69b, has a radius of 2.24+/-0.4 Rearth and orbits the host star every
13.7 days. The outer planet, Kepler-69c, is a super-Earth-size object with a
radius of 1.7+/-0.3 Rearth and an orbital period of 242.5 days. Assuming an
Earth-like Bond albedo, Kepler-69c has an equilibrium temperature of 299 +/- 19
K, which places the planet close to the habitable zone around the host star.
This is the smallest planet found by Kepler to be orbiting in or near habitable
zone of a Sun-like star and represents an important step on the path to finding
the first true Earth analog.
04/2013;
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Lauren M. Weiss,
Geoffrey W. Marcy,
Jason F. Rowe,
Andrew W. Howard,
Howard Isaacson,
Jonathan J. Fortney,
Neil Miller,
Brice-Olivier Demory,
Debra A. Fischer,
Elisabeth R. Adams,
Andrea K. Dupree, Steve B. Howell,
Rea Kolbl,
John Asher Johnson,
Elliott P. Horch,
Mark E. Everett,
Daniel C. Fabrycky,
Sara Seager
[show abstract]
[hide abstract]
ABSTRACT: We measure the mass of a modestly irradiated giant planet, KOI-94d. We wish
to determine whether this planet, which is in a 22-day orbit and receives 2700
times as much incident flux as Jupiter, is as dense as Jupiter or rarefied like
inflated hot Jupiters. KOI-94 also hosts 3 smaller transiting planets, all of
which were detected by the Kepler Mission. With 26 radial velocities of KOI-94
from the W. M. Keck Observatory and a simultaneous fit to the Kepler light
curve, we measure the mass of the giant planet and determine that it is not
inflated. Support for the planetary interpretation of the other three
candidates comes from gravitational interactions through transit timing
variations, the statistical robustness of multi-planet systems against false
positives, and several lines of evidence that no other star resides within the
photometric aperture. The radial velocity analyses of KOI-94b and KOI-94e offer
marginal (>2\sigma) mass detections, whereas the observations of KOI-94c offer
only an upper limit to its mass. Using the KOI-94 system and other planets with
published values for both mass and radius (138 exoplanets total, including 35
with M < 150 Earth masses), we establish two fundamental planes for exoplanets
that relate their mass, incident flux, and radius from a few Earth masses up to
ten Jupiter masses. These equations can be used to predict the radius or mass
of a planet.
03/2013;
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Elisa V. Quintana,
Jason F. Rowe,
Thomas Barclay, Steve B. Howell,
David R. Ciardi,
Brice-Olivier Demory,
Douglas A. Caldwell,
William J. Borucki,
Jessie L. Christiansen,
Jon M. Jenkins,
Todd C. Klaus,
Benjamin J. Fulton,
Robert L. Morris,
Dwight T. Sanderfer,
Avi Shporer,
Jeffrey C. Smith,
Martin Still,
Susan E. Thompson
[show abstract]
[hide abstract]
ABSTRACT: We present high precision photometry of Kepler-41, a giant planet in a 1.86
day orbit around a G6V star that was recently confirmed through radial velocity
measurements. We have developed a new method to confirm giant planets solely
from the photometric light curve, and we apply this method herein to Kepler-41
to establish the validity of this technique. We generate a full phase
photometric model by including the primary and secondary transits, ellipsoidal
variations, Doppler beaming and reflected/emitted light from the planet. Third
light contamination scenarios that can mimic a planetary transit signal are
simulated by injecting a full range of dilution values into the model, and we
re-fit each diluted light curve model to the light curve. The resulting
constraints on the maximum occultation depth and stellar density combined with
stellar evolution models rules out stellar blends and provides a measurement of
the planet's mass, size, and temperature. We expect about two dozen Kepler
giant planets can be confirmed via this method.
03/2013;
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Jack J. Lissauer,
Daniel Jontof-Hutter,
Jason F. Rowe,
Daniel C. Fabrycky,
Eric D. Lopez,
Eric Agol,
Geoffrey W. Marcy,
Katherine M. Deck,
Debra A. Fischer,
Jonathan J. Fortney, Steve B. Howell,
Howard Isaacson,
Jon M. Jenkins,
Rea Kolbl,
Dimitar Sasselov,
Donald R. Short,
William F. Welsh
[show abstract]
[hide abstract]
ABSTRACT: The Kepler-11 planetary system contains six transiting planets ranging in
size from 1.8 to 4.2 times the radius of Earth. Five of these planets orbit in
a tightly-packed configuration with periods between 10 and 47 days. We perform
a dynamical analysis of the system based upon transit timing variations
observed in more than three years of \ik photometric data. Stellar parameters
are derived using a combination of spectral classification and constraints on
the star's density derived from transit profiles together with planetary
eccentricity vectors provided by our dynamical study. Combining masses of the
planets relative to the star from our dynamical study and radii of the planets
relative to the star from transit depths together with deduced stellar
properties yields measurements of the radii of all six planets, masses of the
five inner planets, and an upper bound to the mass of the outermost planet,
whose orbital period is 118 days. We find mass-radius combinations for all six
planets that imply that substantial fractions of their volumes are occupied by
constituents that are less dense than rock. The Kepler-11 system contains the
lowest mass exoplanets for which both mass and radius have been measured.
03/2013;
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Thomas Barclay,
Jason F Rowe,
Jack J Lissauer,
Daniel Huber,
François Fressin, Steve B Howell,
Stephen T Bryson,
William J Chaplin,
Jean-Michel Désert,
Eric D Lopez, [......],
Mikkel N Lund,
Mia Lundkvist,
Travis S Metcalfe,
Andrea Miglio,
Robert L Morris,
Elisa V Quintana,
Dennis Stello,
Jeffrey C Smith,
Martin Still,
Susan E Thompson
[show abstract]
[hide abstract]
ABSTRACT: Since the discovery of the first exoplanets, it has been known that other planetary systems can look quite unlike our own. Until fairly recently, we have been able to probe only the upper range of the planet size distribution, and, since last year, to detect planets that are the size of Earth or somewhat smaller. Hitherto, no planets have been found that are smaller than those we see in the Solar System. Here we report a planet significantly smaller than Mercury. This tiny planet is the innermost of three that orbit the Sun-like host star, which we have designated Kepler-37. Owing to its extremely small size, similar to that of the Moon, and highly irradiated surface, the planet, Kepler-37b, is probably rocky with no atmosphere or water, similar to Mercury.
Nature 02/2013; 494(7438):452-4. · 36.28 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: The NASA {\it Kepler} mission has been in science operation since May 2009
and is providing high precision, high cadence light curves of over 150,000
targets. Prior to launch, nine cataclysmic variables were known to lie within
{\it Kepler's} field of view. We present spectroscopy for seven systems, four
of which were newly discovered since launch. All of the stars presented herein
have been observed by, or are currently being observed by, the {\it Kepler}
space telescope. Three historic systems and one new candidate could not be
detected at their sky position and two candidates are called into question as
to their true identity.
02/2013;
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Ronald L. Gilliland,
Geoffrey W. Marcy,
Jason F. Rowe,
Leslie Rogers,
Guillermo Torres,
Francois Fressin,
Eric D. Lopez,
Lars A. Buchhave,
Joergen Christensen-Dalsgaard,
Jean-Michel Desert, [......],
Mia Lundkvist,
Andrea Miglio,
David Charbonneau,
Eric B. Ford,
Jonathan J. Fortney,
Michael R. Haas,
Andrew W. Howard, Steve B. Howell,
Darin Ragozzine,
Susan E. Thompson
[show abstract]
[hide abstract]
ABSTRACT: NASA's Kepler Mission has revealed two transiting planets orbiting Kepler-68.
Follow-up Doppler measurements have established the mass of the innermost
planet and revealed a third jovian-mass planet orbiting beyond the two
transiting planets. Kepler-68b, in a 5.4 day orbit has mass 8.3 +/- 2.3 Earth,
radius 2.31 +/- 0.07 Earth radii, and a density of 3.32 +/- 0.92 (cgs), giving
Kepler-68b a density intermediate between that of the ice giants and Earth.
Kepler-68c is Earth-sized with a radius of 0.953 Earth and transits on a 9.6
day orbit; validation of Kepler-68c posed unique challenges. Kepler-68d has an
orbital period of 580 +/- 15 days and minimum mass of Msin(i) = 0.947 Jupiter.
Power spectra of the Kepler photometry at 1-minute cadence exhibit a rich and
strong set of asteroseismic pulsation modes enabling detailed analysis of the
stellar interior. Spectroscopy of the star coupled with asteroseismic modeling
of the multiple pulsation modes yield precise measurements of stellar
properties, notably Teff = 5793 +/- 74 K, M = 1.079 +/- 0.051 Msun, R = 1.243
+/- 0.019 Rsun, and density 0.7903 +/- 0.0054 (cgs), all measured with
fractional uncertainties of only a few percent. Models of Kepler-68b suggest it
is likely composed of rock and water, or has a H and He envelope to yield its
density of about 3 (cgs).
02/2013;
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[show abstract]
[hide abstract]
ABSTRACT: We present time-resolved spectroscopic and polarimetric observations of the
AM Her system EU Cnc. EU Cnc is located near the core of the old open cluster
Messier 67; new proper motion measurements indicate that EU Cnc is indeed a
member of the star cluster, this system therefore is useful to constrain the
formation and evolution of magnetic cataclysmic variables. The spectra exhibit
two-component emission features with independent radial velocity variations as
well as time-variable cyclotron emission indicating a magnetic field strength
of 41 MG. The period of the radial velocity and cyclotron hump variations are
consistent with the previously-known photometric period, and the spectroscopic
flux variations are consistent in amplitude with previous photometric amplitude
measurements. The secondary star is also detected in the spectrum. We also
present polarimetric imaging measurements of EU Cnc that show a clear detection
of polarization, and the degree of polarization drops below our detection
threshold at phases when the cyclotron emission features are fading or not
evident. The combined data are all consistent with the interpretation that EU
Cnc is a low-state polar in the cluster Messier 67. The mass function of the
system gives an estimate of the accretor mass of M_WD >= 0.68 M_sun with M_WD ~
0.83 M_sun for an average inclination. We are thus able to place a lower limit
on the progenitor mass of the accreting WD of >= 1.43 M_sun.
01/2013;
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[show abstract]
[hide abstract]
ABSTRACT: We present a study of the relative sizes of planets within the multiple
candidate systems discovered with the $Kepler$ mission. We have compared the
size of each planet to the size of every other planet within a given planetary
system after correcting the sample for detection and geometric biases. We find
that for planet-pairs for which one or both objects is approximately
Neptune-sized or larger, the larger planet is most often the planet with the
longer period. No such size--location correlation is seen for pairs of planets
when both planets are smaller than Neptune. Specifically, if at least one
planet in a planet-pair has a radius of $\gtrsim 3R_\oplus$, $68\pm 6%$ of the
planet pairs have the inner planet smaller than the outer planet, while no
preferred sequential ordering of the planets is observed if both planets in a
pair are smaller than $\lesssim3 R_\oplus$.
12/2012;
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[show abstract]
[hide abstract]
ABSTRACT: The Kepler spacecraft has collected data of high photometric precision and
cadence almost continuously since operations began on 2009 May 2. Primarily
designed to detect planetary transits and asteroseismological signals from
solar-like stars, Kepler has provided high quality data for many areas of
investigation. Unconditioned simple aperture time-series photometry are however
affected by systematic structure. Examples of these systematics are
differential velocity aberration, thermal gradients across the spacecraft, and
pointing variations. While exhibiting some impact on Kepler's primary science,
these systematics can critically handicap potentially ground-breaking
scientific gains in other astrophysical areas, especially over long timescales
greater than 10 days. As the data archive grows to provide light curves for
$10^5$ stars of many years in length, Kepler will only fulfill its broad
potential for stellar astrophysics if these systematics are understood and
mitigated. Post-launch developments in the Kepler archive, data reduction
pipeline and open source data analysis software have occurred to remove or
reduce systematic artifacts. This paper provides a conceptual primer for users
of the Kepler data archive to understand and recognize systematic artifacts
within light curves and some methods for their removal. Specific examples of
artifact mitigation are provided using data available within the archive.
Through the methods defined here, the Kepler community will find a road map to
maximizing the quality and employment of the Kepler legacy archive.
07/2012;
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[show abstract]
[hide abstract]
ABSTRACT: We present the results of an analysis of data covering 1.5 years of the dwarf
nova V447 Lyr. We detect eclipses of the accretion disk by the mass donating
secondary star every 3.74 hrs which is the binary orbital period. V447 Lyr is
therefore the first dwarf nova in the Kepler field to show eclipses. We also
detect five long outbursts and six short outbursts showing V447 Lyr is a U Gem
type dwarf nova. We show that the orbital phase of the mid-eclipse occurs
earlier during outbursts compared to quiescence and that the width of the
eclipse is greater during outburst. This suggests that the bright spot is more
prominent during quiescence and that the disk is larger during outburst than
quiescence. This is consistent with an expansion of the outer disk radius due
to the presence of high viscosity material associated with the outburst,
followed by a contraction in quiescence due to the accretion of low angular
momentum material. We note that the long outbursts appear to be triggered by a
short outburst, which is also observed in the super-outbursts of SU UMa dwarf
novae as observed using Kepler.
07/2012;
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Julian C. van Eyken,
David R. Ciardi,
Kaspar von Braun,
Stephen R. Kane,
Peter Plavchan,
Chad F. Bender,
Timothy M. Brown,
Justin Crepp,
Benjamin J. Fulton,
Andrew W. Howard, [......],
Peter E. Nugent,
Eran O. Ofek,
Dovi Poznanski,
Robert M. Quimby,
Richard Walters,
Carl J. Grillmair,
Russ Laher,
David B. Levitan,
Branimir Sesar,
Jason A. Surace
[show abstract]
[hide abstract]
ABSTRACT: We report observations of a possible young transiting planet orbiting a
previously known weak-lined T-Tauri star in the 7-10Myr-old Orion-OB1a/25-Ori
region. The candidate was found as part of the Palomar Transient Factory (PTF)
Orion project. It has a photometric transit period of 0.448413 \pm 0.000040
days, and appears in both 2009 and 2010 PTF data. Follow-up low-precision
radial velocity observations and adaptive-optics imaging suggest that the star
is not an eclipsing binary, and that it is unlikely that a background source is
blended with the target and mimicking the observed transit. Radial-velocity
observations with the Hobby-Eberly and Keck telescopes yield a radial velocity
that has the same period as the photometric event, but is offset in phase from
the transit center by \approx -0.22 periods. The amplitude (half range) of the
radial velocity variations is 2.4 km/s and is comparable with the expected
radial velocity amplitude that stellar spots could induce. The radial velocity
curve is likely dominated by stellar spot modulation and provides an upper
limit to the projected companion mass of Mp sin iorb \leq 4.8\pm1.2 MJup; when
combined with the orbital inclination, iorb, of the candidate planet from
modeling of the transit lightcurve, we find an upper limit on the mass of the
planetary candidate of Mp \leq 5.5\pm1.4 MJup. This limit implies that the
planet is orbiting close to, if not inside, its Roche limiting orbital radius,
so that it may be undergoing active mass loss and evaporating.
06/2012;
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Susan E. Thompson,
Mark Everett,
Fergal Mullally,
Thomas Barclay, Steve B. Howell,
Martin Still,
Jason Rowe,
Jessie L. Christiansen,
Donald W. Kurtz,
Kelly Hambleton,
Joseph D. Twicken,
Khadeejah A. Ibrahim,
Bruce D. Clarke
[show abstract]
[hide abstract]
ABSTRACT: We have discovered a class of eccentric binary systems within the Kepler data
archive that have dynamic tidal distortions and tidally-induced pulsations.
Each has a uniquely shaped light curve that is characterized by periodic
brightening or variability at time scales of 4-20 days, frequently accompanied
by shorter period oscillations. We can explain the dominant features of the
entire class with orbitally-varying tidal forces that occur in close, eccentric
binary systems. The large variety of light curve shapes arises from viewing
systems at different angles. This hypothesis is supported by spectroscopic
radial velocity measurements for five systems, each showing evidence of being
in an eccentric binary system. Prior to the discovery of these 17 new systems,
only four stars, where KOI-54 is the best example, were known to have evidence
of these dynamic tides and tidally-induced oscillations. We perform preliminary
fits to the light curves and radial velocity data, present the overall
properties of this class and discuss the work required to accurately model
these systems.
03/2012;
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Natalie M. Batalha,
Jason F. Rowe,
Stephen T. Bryson,
Thomas Barclay,
Christopher J. Burke,
Douglas A. Caldwell,
Jessie L. Christiansen,
Fergal Mullally,
Susan E. Thompson,
Timothy M. Brown, [......],
Martin Still,
Martin C. Stumpe,
Jill C. Tarter,
Peter Tenenbaum,
Guillermo Torres,
Joseph D. Twicken,
Kamal Uddin,
Jeffrey Van Cleve,
Lucianne Walkowicz,
William F. Welsh
[show abstract]
[hide abstract]
ABSTRACT: New transiting planet candidates are identified in sixteen months (May 2009 -
September 2010) of data from the Kepler spacecraft. Nearly five thousand
periodic transit-like signals are vetted against astrophysical and instrumental
false positives yielding 1,091 viable new planet candidates, bringing the total
count up to over 2,300. Improved vetting metrics are employed, contributing to
higher catalog reliability. Most notable is the noise-weighted robust averaging
of multi-quarter photo-center offsets derived from difference image analysis
which identifies likely background eclipsing binaries. Twenty-two months of
photometry are used for the purpose of characterizing each of the new
candidates. Ephemerides (transit epoch, T_0, and orbital period, P) are
tabulated as well as the products of light curve modeling: reduced radius
(Rp/R*), reduced semi-major axis (d/R*), and impact parameter (b). The largest
fractional increases are seen for the smallest planet candidates (197% for
candidates smaller than 2Re compared to 52% for candidates larger than 2Re) and
those at longer orbital periods (123% for candidates outside of 50-day orbits
versus 85% for candidates inside of 50-day orbits). The gains are larger than
expected from increasing the observing window from thirteen months (Quarter 1--
Quarter 5) to sixteen months (Quarter 1 -- Quarter 6). This demonstrates the
benefit of continued development of pipeline analysis software. The fraction of
all host stars with multiple candidates has grown from 17% to 20%, and the
paucity of short-period giant planets in multiple systems is still evident. The
progression toward smaller planets at longer orbital periods with each new
catalog release suggests that Earth-size planets in the Habitable Zone are
forthcoming if, indeed, such planets are abundant.
02/2012;
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[show abstract]
[hide abstract]
ABSTRACT: We present the motivations for and methods we used to create a new
ground-based photometric survey of the field targeted by the NASA Kepler
Mission. The survey contains magnitudes for 4414002 sources in one or more of
the UBV filters, including 1862902 sources detected in all three filters. The
typical completeness limit is U~18.7, B~19.3, and V~19.1 magnitudes, but varies
by location. The area covered is 191 square degrees and includes the areas on
and between the 42 Kepler CCDs as well as additional areas around the perimeter
of the Kepler field. The major significance of this survey is our addition of U
to the optical bandpass coverage available in the Kepler Input Catalog, which
was primarily limited to the redder SDSS griz and D51 filters. The U coverage
reveals a sample of the hottest sources in the field, many of which are not
currently targeted by Kepler, but may be objects of astrophysical interest.
02/2012;
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Daniel Huber,
Michael J. Ireland,
Timothy R. Bedding, Steve B. Howell,
Vicente Maestro,
Antoine Mérand,
Peter G. Tuthill,
Timothy R. White,
Christopher D. Farrington,
P. J. Goldfinger,
Harold A. McAlister,
Gail H. Schaefer,
Judit Sturmann,
Laszlo Sturmann,
Theo A. ten Brummelaar,
Nils H. Turner
[show abstract]
[hide abstract]
ABSTRACT: We present long-baseline interferometry of the Kepler exoplanet host star
HD179070 (Kepler-21) using the PAVO beam combiner at the CHARA Array. The
visibility data are consistent with a single star and exclude stellar
companions at separations ~1-1000 mas (~ 0.1-113 AU) and contrasts < 3.5
magnitudes. This result supports the validation of the 1.6 R_{earth} exoplanet
Kepler-21b by Howell et al. (2012) and complements the constraints set by
adaptive optics imaging, speckle interferometry, and radial velocity
observations to rule out false-positives due to stellar companions. We conclude
that long-baseline interferometry has strong potential to validate transiting
extrasolar planets, particularly for future projects aimed at brighter stars
and for host stars where radial velocity follow-up is not available.
02/2012;
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[show abstract]
[hide abstract]
ABSTRACT: We have discovered a dwarf nova (DN) of type SU UMa in Kepler data which is
7.0 arcsec from the G-type exoplanet survey target KIC 4378554. The DN appears
as a background source in the pixel aperture of the foreground G star. We
extracted only the pixels where the DN is present and observed the source to
undergo five outbursts -- one a superoutburst -- over a timespan of 22 months.
The superoutburst was triggered by a normal outburst, a feature that has been
seen in all DNe superoutburst observed by Kepler. Superhumps during the super
outburst had a period of 1.842+/-0.004 h and we see a transition from
disc-dominated superhump signal to a mix of disc and accretion stream impact.
Predictions of the number of DNe present in Kepler data based on previously
published space densities vary from 0.3 to 258. An investigation of the
background pixels targets would lead to firmer constraints on the space density
of DN.
02/2012;
