131 research outputs found
High-Cadence, High-Contrast Imaging for Exoplanet Mapping: Observations of the HR 8799 Planets with VLT/SPHERE Satellite Spot-Corrected Relative Photometry
Time-resolved photometry is an important new probe of the physics of
condensate clouds in extrasolar planets and brown dwarfs. Extreme adaptive
optics systems can directly image planets, but precise brightness measurements
are challenging. We present VLT/SPHERE high-contrast, time-resolved broad
H-band near-infrared photometry for four exoplanets in the HR 8799 system,
sampling changes from night to night over five nights with relatively short
integrations. The photospheres of these four planets are often modeled by
patchy clouds and may show large-amplitude rotational brightness modulations.
Our observations provide high-quality images of the system. We present a
detailed performance analysis of different data analysis approaches to
accurately measure the relative brightnesses of the four exoplanets. We explore
the information in satellite spots and demonstrate their use as a proxy for
image quality. While the brightness variations of the satellite spots are
strongly correlated, we also identify a second-order anti-correlation pattern
between the different spots. Our study finds that PCA-based KLIP reduction with
satellite spot-modulated artificial planet-injection based photometry (SMAP)
leads to a significant (~3x) gain in photometric accuracy over standard
aperture-based photometry and reaches 0.1 mag per point accuracy for our
dataset, the signal-to-noise of which is limited by small field rotation.
Relative planet-to-planet photometry can be compared be- tween nights, enabling
observations spanning multiple nights to probe variability. Recent high-quality
relative H-band photometry of the b-c planet pair agree to about 1%.Comment: Astrophysical Journal, in pres
Oral Vitamin D Supplementation does not Impact Cytokine Levels in Uterine Fluid of Women Undergoing Assisted Reproduction Technology (ART)
SPHERE IRDIS and IFS astrometric strategy and calibration
We present the current results of the astrometric characterization of the VLT
planet finder SPHERE over 2 years of on-sky operations. We first describe the
criteria for the selection of the astrometric fields used for calibrating the
science data: binaries, multiple systems, and stellar clusters. The analysis
includes measurements of the pixel scale and the position angle with respect to
the North for both near-infrared subsystems, the camera IRDIS and the integral
field spectrometer IFS, as well as the distortion for the IRDIS camera. The
IRDIS distortion is shown to be dominated by an anamorphism of 0.60+/-0.02%
between the horizontal and vertical directions of the detector, i.e. 6 mas at
1". The anamorphism is produced by the cylindrical mirrors in the common path
structure hence common to all three SPHERE science subsystems (IRDIS, IFS, and
ZIMPOL), except for the relative orientation of their field of view. The
current estimates of the pixel scale and North angle for IRDIS are
12.255+/-0.009 milliarcseconds/pixel for H2 coronagraphic images and
-1.75+/-0.08 deg. Analyses of the IFS data indicate a pixel scale of
7.46+/-0.02 milliarcseconds/pixel and a North angle of -102.18+/-0.13 deg. We
finally discuss plans for providing astrometric calibration to the SPHERE users
outside the instrument consortium.Comment: 12 pages, 6 figures, 3 table
Planetary system architectures with low-mass inner planets: Direct imaging exploration of mature systems beyond 1 au
The discovery of planets orbiting at less than 1 au from their host star and
less massive than Saturn in various exoplanetary systems revolutionized our
theories of planetary formation. The fundamental question is whether these
close-in low-mass planets could have formed in the inner disk interior to 1 au,
or whether they formed further out in the planet-forming disk and migrated
inward. Exploring the role of additional giant planets in these systems may
help us to pinpoint their global formation and evolution. We searched for
additional substellar companions by using direct imaging in systems known to
host close-in small planets. The use of direct imaging complemented by radial
velocity and astrometric detection limits enabled us to explore the giant
planet and brown dwarf demographics around these hosts to investigate the
potential connection between both populations. We carried out a direct imaging
survey with VLT/SPHERE to look for outer giant planets and brown dwarf
companions in 27 systems hosting close-in low-mass planets discovered by radial
velocity. Our sample is composed of very nearby (<20pc) planetary systems,
orbiting G-, K-, and M-type mature (0.5-10Gyr) stellar hosts. We performed
homogeneous direct imaging data reduction and analysis to search for and
characterize point sources, and derived robust statistical detection limits. Of
337 point-source detections, we do not find any new bound companions. We
recovered the emblematic very cool T-type brown dwarf GJ229B. Our typical
sensitivities in direct imaging range from 5 to 30 MJup beyond 2 au. The
non-detection of massive companions is consistent with predictions based on
models of planet formation by core accretion. Our pilot study opens the way to
a multi-technique approach for the exploration of very nearby exoplanetary
systems with future ground-based and space observatories.Comment: 49 pages including 31 pages of appendices and references, 31 figures,
A&A, accepte
Toward the effective surveillance of hypospadias.
Concern about apparent increases in the prevalence of hypospadias--a congenital male reproductive-tract abnormality--in the 1960s to 1980s and the possible connection to increasing exposures to endocrine-disrupting chemicals have underlined the importance of effective surveillance of hypospadias prevalence in the population. We report here the prevalence of hypospadias from 1980 to 1999 in 20 regions of Europe with EUROCAT (European Surveillance of Congenital Anomalies) population-based congenital anomaly registers, 14 of which implemented a guideline to exclude glanular hypospadias. We also report data from the England and Wales National Congenital Anomaly System (NCAS). Our results do not suggest a continuation of rising trends of hypospadias prevalence in Europe. However, a survey of the registers and a special validation study conducted for the years 1994-1996 in nine EUROCAT registers as well as NCAS identified a clear need for a change in the guidelines for registration of hypospadias. We recommend that all hypospadias be included in surveillance, but that information from surgeons be obtained to verify location of the meatus, and whether surgery was performed, in order to interpret trends. Investing resources in repeated special surveys may be more cost-effective than continuous population surveillance. We conclude that it is doubtful whether we have had the systems in place worldwide for the effective surveillance of hypospadias in relation to exposure to potential endocrine-disrupting chemicals
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ESA Voyage 2050 White Paper: Detecting life outside our solar system with a large high-contrast-imaging mission
In this white paper, we recommend the European Space Agency plays a proactive role in developing a global collaborative effort to construct a large high-contrast imaging space telescope, e.g. as currently under study by NASA. Such a mission will be needed to characterize a sizable sample of temperate Earth-like planets in the habitable zones of nearby Sun-like stars and to search for extraterrestrial biological activity. We provide an overview of relevant European expertise, and advocate ESA to start a technology development program towards detecting life outside the Solar system
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 Micron Spectrum of the Planetary-Mass Companion VHS 1256-1257 b
We present the highest fidelity spectrum to date of a planetary-mass object.
VHS 1256 b is a 20 M widely separated (8\arcsec, a =
150 au), young, planetary-mass companion that shares photometric colors and
spectroscopic features with the directly imaged exoplanets HR 8799 c, d, and e.
As an L-to-T transition object, VHS 1256 b exists along the region of the
color-magnitude diagram where substellar atmospheres transition from cloudy to
clear. We observed VHS 1256~b with \textit{JWST}'s NIRSpec IFU and MIRI MRS
modes for coverage from 1 m to 20 m at resolutions of 1,000 -
3,700. Water, methane, carbon monoxide, carbon dioxide, sodium, and potassium
are observed in several portions of the \textit{JWST} spectrum based on
comparisons from template brown dwarf spectra, molecular opacities, and
atmospheric models. The spectral shape of VHS 1256 b is influenced by
disequilibrium chemistry and clouds. We directly detect silicate clouds, the
first such detection reported for a planetary-mass companion.Comment: Accepted ApJL Iterations of spectra reduced by the ERS team are
hosted at this link:
https://github.com/bemiles/JWST_VHS1256b_Reduction/tree/main/reduced_spectr
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems IV: NIRISS Aperture Masking Interferometry Performance and Lessons Learned
We present a performance analysis for the aperture masking interferometry
(AMI) mode on board the James Webb Space Telescope Near Infrared Imager and
Slitless Spectrograph (JWST/NIRISS). Thanks to self-calibrating observables,
AMI accesses inner working angles down to and even within the classical
diffraction limit. The scientific potential of this mode has recently been
demonstrated by the Early Release Science (ERS) 1386 program with a deep search
for close-in companions in the HIP 65426 exoplanetary system. As part of ERS
1386, we use the same dataset to explore the random, static, and calibration
errors of NIRISS AMI observables. We compare the observed noise properties and
achievable contrast to theoretical predictions. We explore possible sources of
calibration errors, and show that differences in charge migration between the
observations of HIP 65426 and point-spread function calibration stars can
account for the achieved contrast curves. Lastly, we use self-calibration tests
to demonstrate that with adequate calibration, NIRISS AMI can reach contrast
levels of mag. These tests lead us to observation planning
recommendations and strongly motivate future studies aimed at producing
sophisticated calibration strategies taking these systematic effects into
account. This will unlock the unprecedented capabilities of JWST/NIRISS AMI,
with sensitivity to significantly colder, lower mass exoplanets than
ground-based setups at orbital separations inaccessible to JWST coronagraphy.Comment: 20 pages, 12 figures, submitted to AAS Journal
The \textit{JWST} Early Release Science Program for Direct Observations of Exoplanetary Systems III: Aperture Masking Interferometric Observations of the star HIP\,65426 at
We present aperture masking interferometry (AMI) observations of the star HIP
65426 at as a part of the \textit{JWST} Direct Imaging Early
Release Science (ERS) program obtained using the Near Infrared Imager and
Slitless Spectrograph (NIRISS) instrument. This mode provides access to very
small inner working angles (even separations slightly below the Michelson limit
of for an interferometer), which are inaccessible with the
classical inner working angles of the \textit{JWST} coronagraphs. When combined
with \textit{JWST}'s unprecedented infrared sensitivity, this mode has the
potential to probe a new portion of parameter space across a wide array of
astronomical observations. Using this mode, we are able to achieve a contrast
of \,mag relative to the host star at a separation
of {\sim}0.07\arcsec but detect no additional companions interior to the
known companion HIP\,65426\,b. Our observations thus rule out companions more
massive than 10{-}12\,\rm{M\textsubscript{Jup}} at separations
from HIP\,65426, a region out of reach of ground or
space-based coronagraphic imaging. These observations confirm that the AMI mode
on \textit{JWST} is sensitive to planetary mass companions orbiting at the
water frost line, even for more distant stars at 100\,pc. This result
will allow the planning and successful execution of future observations to
probe the inner regions of nearby stellar systems, opening essentially
unexplored parameter space.Comment: 15 pages, 9 figures, submitted to ApJ Letter
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