10 research outputs found
Search for Rayleigh scattering in the atmosphere of GJ1214b
We investigate the atmosphere of GJ1214b, a transiting super-Earth planet
with a low mean density, by measuring its transit depth as a function of
wavelength in the blue optical portion of the spectrum. It is thought that this
planet is either a mini-Neptune, consisting of a rocky core with a thick,
hydrogen-rich atmosphere, or a planet with a composition dominated by water.
Most observations favor a water-dominated atmosphere with a small scale-height,
however, some observations indicate that GJ1214b could have an extended
atmosphere with a cloud layer muting the molecular features. In an atmosphere
with a large scale-height, Rayleigh scattering at blue wavelengths is likely to
cause a measurable increase in the apparent size of the planet towards the
blue. We observed the transit of GJ1214b in the B-band with the FOcal Reducing
Spectrograph (FORS) at the Very Large Telescope (VLT) and in the g-band with
both ACAM on the William Hershel Telescope (WHT) and the Wide Field Camera
(WFC) at the Isaac Newton Telescope (INT). We find a planet-to-star radius
ratio in the B-band of 0.1162+/-0.0017, and in the g-band 0.1180+/-0.0009 and
0.1174+/-0.0017 for the WHT & INT observations respectively. These optical data
do not show significant deviations from previous measurements at longer
wavelengths. In fact, a flat transmission spectrum across all wavelengths best
describes the combined observations. When atmospheric models are considered a
small scale-height water-dominated model fits the data best.Comment: Accepted for publication in Ap
Applying a temporal systematics model to vector Apodizing Phase Plate coronagraphic data: TRAP4vAPP
The vector Apodizing Phase Plate (vAPP) is a pupil plane coronagraph that
suppresses starlight by forming a dark hole in its point spread function (PSF).
The unconventional and non-axisymmetrical PSF arising from the phase
modification applied by this coronagraph presents a special challenge to
post-processing techniques. We aim to implement a recently developed
post-processing algorithm, temporal reference analysis of planets (TRAP) on
vAPP coronagraphic data. The property of TRAP that uses non-local training
pixels, combined with the unconventional PSF of vAPP, allows for more
flexibility than previous spatial algorithms in selecting reference pixels to
model systematic noise. Datasets from two types of vAPPs are analysed: a double
grating-vAPP (dgvAPP360) that produces a single symmetric PSF and a
grating-vAPP (gvAPP180) that produces two D-shaped PSFs. We explore how to
choose reference pixels to build temporal systematic noise models in TRAP for
them. We then compare the performance of TRAP with previously implemented
algorithms that produced the best signal-to-noise ratio (S/N) in companion
detections in these datasets. We find that the systematic noise between the two
D-shaped PSFs is not as temporally associated as expected. Conversely, there is
still a significant number of systematic noise sources that are shared by the
dark hole and the bright side in the same PSF. We should choose reference
pixels from the same PSF when reducing the dgvAPP360 dataset or the gvAPP180
dataset with TRAP. In these datasets, TRAP achieves results consistent with
previous best detections, with an improved S/N for the gvAPP180 dataset.Comment: 15 pages, 10 figures, accepted to A&
Improved companion mass limits for Sirius A with thermal infrared coronagraphy using a vector-apodizing phase plate and time-domain starlight-subtraction techniques
We use observations with the infrared-optimized MagAO system and Clio camera
in 3.9 m light to place stringent mass constraints on possible undetected
companions to Sirius A. We suppress the light from Sirius A by imaging it
through a grating vector-apodizing phase plate coronagraph with 180-degree dark
region (gvAPP-180). To remove residual starlight in post-processing, we apply a
time-domain principal-components-analysis-based algorithm we call PCA-Temporal
(PCAT), which uses eigen-time-series rather than eigen-images to subtract
starlight. By casting the problem in terms of eigen-time-series, we reduce the
computational cost of post-processing the data, enabling the use of the fully
sampled dataset for improved contrast at small separations. We also discuss the
impact of retaining fine temporal sampling of the data on final contrast
limits. We achieve post-processed contrast limits of to
outside of 0.75 arcsec which correspond to planet masses
of 2.6 to 8.0 . These are combined with values from the recent literature
of high-contrast imaging observations of Sirius to synthesize an overall
completeness fraction as a function of mass and separation. After synthesizing
these recent studies and our results, the final completeness analysis rules out
99% of planets from 2.5-7 AU.Comment: 19 pages, 22 figures, accepted to A
ON-SKY PERFORMANCE ANALYSIS OF THE VECTOR APODIZING PHASE PLATE CORONAGRAPH ON MagAO/Clio2
We report on the performance of a vector apodizing phase plate coronagraph that operates over a wavelength range of 2-5 mu m. and is installed in MagAO/Clio2 at the 6.5 m Magellan Clay telescope at Las Campanas Observatory, Chile. The coronagraph manipulates the phase in the pupil to produce three beams yielding two coronagraphic point-spread functions (PSFs) and one faint leakage PSF. The phase pattern is imposed through the inherently achromatic geometric phase, enabled by liquid crystal technology and polarization techniques. The coronagraphic optic is manufactured using a direct-write technique for precise control of the liquid crystal pattern. and multitwist retarders for achromatization. By integrating a linear phase ramp to the coronagraphic phase pattern, two separated coronagraphic PSFs are created with a single pupil-plane optic, which makes it robust and easy to install in existing telescopes. The two coronagraphic PSFs contain a 180 degrees dark hole on each side of a star, and these complementary copies of the star are used to correct the seeing halo close to the star. To characterize the coronagraph, we collected a data set of a bright (m(L) = 0-1) nearby star with similar to 1.5 hr of observing time. By rotating and optimally scaling one PSF. and subtracting it from the other PSF, we see a contrast improvement by 1.46 magnitudes at 3.5 lambda/D. With regular angular differential imaging at 3.9 mu m, the MagAO vector apodizing phase plate coronagraph delivers a 5 sigma Delta mag contrast of 8.3 (= 10(-3.3)) at 2 lambda/D and 12.2 (= 10(-4.8)) at 3.5 lambda/D.Netherlands Organization for Scientific Research (NWO); European Research Council [678194]; NASA Exoplanets Research Program (XRP) [NNX16AD44G]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
ON-SKY PERFORMANCE ANALYSIS OF THE VECTOR APODIZING PHASE PLATE CORONAGRAPH ON MagAO/Clio2
We report on the performance of a vector apodizing phase plate coronagraph
that operates over a wavelength range of m and is installed in
MagAO/Clio2 at the 6.5 m Magellan Clay telescope at Las Campanas Observatory,
Chile. The coronagraph manipulates the phase in the pupil to produce three
beams yielding two coronagraphic point-spread functions (PSFs) and one faint
leakage PSF. The phase pattern is imposed through the inherently achromatic
geometric phase, enabled by liquid crystal technology and polarization
techniques. The coronagraphic optic is manufactured using a direct-write
technique for precise control of the liquid crystal pattern, and multitwist
retarders for achromatization. By integrating a linear phase ramp to the
coronagraphic phase pattern, two separated coronagraphic PSFs are created with
a single pupil-plane optic, which makes it robust and easy to install in
existing telescopes. The two coronagraphic PSFs contain a 180 dark hole
on each side of a star, and these complementary copies of the star are used to
correct the seeing halo close to the star. To characterize the coronagraph, we
collected a dataset of a bright () nearby star with 1.5 hr of
observing time. By rotating and optimally scaling one PSF and subtracting it
from the other PSF, we see a contrast improvement by 1.46 magnitudes at . With regular angular differential imaging at 3.9 m, the MagAO
vector apodizing phase plate coronagraph delivers a mag
contrast of 8.3 () at 2 and 12.2 () at .Comment: Published in ApJ. 8 figures, 1 table. Received 2016 June 17; revised
2016 November 3; accepted 2016 November 28; published 2017 January 1
The Influence of the ‘Trier Social Stress Test’ on Free Throw Performance in Basketball: An Interdisciplinary Study
International audienceThe aim of the present study was to explore the relationship between stress and sport performance in a controlled setting. The experimental protocol used to induce stress in a basketball free throw was the Trier Social Stress Test (TSST) and its control condition (Placebo -TSST). Participants (n = 19), novice basketball players but trained sportspersons, were exposed to two counterbalanced conditions in a crossover design. They were equipped with sensors to measure movement execution, while salivary cortisol and psychological state were also measured. The task consisted of two sequences of 40 free throws, one before either the TSST or Placebo-TSST and one after. Physiological and psychological measures evidenced that the TSST induced significant stress responses, whereas the Placebo-TSST did not. Shooting performance remained stable after the TSST but decreased after the Placebo -TSST. We found no effect of the TSST or Placebo-TSST on movement execution. A multivariate model of free throw performance demonstrated that timing, smoothness and explosiveness of the movements are more relevant to account for beginner's behavior than stress-related physiological and psychological states. We conclude that the TSST is a suitable protocol to induce stress responses in sport context, even though the effects on begin-ners' free throw performance and execution are small and complex
TOI-1431b/MASCARA-5b: A Highly Irradiated Ultra-Hot Jupiter Orbiting One of the Hottest & Brightest Known Exoplanet Host Stars
Accepted for publication in the Astronomical Journal. 39 pages, 18 figures, and 4 tablesWe present the discovery of a highly irradiated and moderately inflated ultra-hot Jupiter, TOI-1431b/MASCARA-5b (HD 201033b), first detected by NASA's Transiting Exoplanet Survey Satellite mission (TESS) and the Multi-site All-Sky CAmeRA (MASCARA). The signal was established to be of planetary origin through radial velocity measurements obtained using SONG, SOPHIE, FIES, NRES, and EXPRES, which show a reflex motion of m s. A joint analysis of the TESS and ground-based photometry and radial velocity measurements reveals that TOI-1431b has a mass of ( M), an inflated radius of ( R), and an orbital period of d. Analysis of the spectral energy distribution of the host star reveals that the planet orbits a bright ( mag) and young ( Gyr) Am type star with , resulting in a highly irradiated planet with an incident flux of 10 erg s cm () and an equilibrium temperature of K. TESS photometry also reveals a secondary eclipse with a depth of ppm as well as the full phase curve of the planet's thermal emission in the red-optical. This has allowed us to measure the dayside and nightside temperature of its atmosphere as K and K, the second hottest measured nightside temperature. The planet's low day/night temperature contrast (420 K) suggests very efficient heat transport between the dayside and nightside hemispheres
TOI-1431b/MASCARA-5b: A Highly Irradiated Ultrahot Jupiter Orbiting One of the Hottest and Brightest Known Exoplanet Host Stars
We present the discovery of a highly irradiated and moderately inflated ultrahot Jupiter, TOI-1431b/MASCARA-5 b (HD 201033b), first detected by NASA's Transiting Exoplanet Survey Satellite mission (TESS) and the Multi-site All-Sky Camera (MASCARA). The signal was established to be of planetary origin through radial velocity measurements obtained using SONG, SOPHIE, FIES, NRES, and EXPRES, which show a reflex motion of K = 294.1 1.1 m s-1. A joint analysis of the TESS and ground-based photometry and radial velocity measurements reveals that TOI-1431b has a mass of M p = 3.12 0.18 M J (990 60 M ⊕), an inflated radius of R p = 1.49 0.05 R J (16.7 0.6 R ⊕), and an orbital period of P = 2.650237 0.000003 days. Analysis of the spectral energy distribution of the host star reveals that the planet orbits a bright (V = 8.049 mag) and young ({0.29-0.19+0.32 Gyr) Am type star with R eff=7690-250+400 K, resulting in a highly irradiated planet with an incident flux of F =7.24-0.64+0.68 × 109 erg s-1 cm-2 (5300-470+500 S) and an equilibrium temperature of T eq = 2370 70 K. TESS photometry also reveals a secondary eclipse with a depth of 127-5+4 ppm as well as the full phase curve of the planet's thermal emission in the red-optical. This has allowed us to measure the dayside and nightside temperature of its atmosphere as T day = 3004 64 K and T night = 2583 63 K, the second hottest measured nightside temperature. The planet's low day/night temperature contrast (∼420 K) suggests very efficient heat transport between the dayside and nightside hemispheres. Given the host star brightness and estimated secondary eclipse depth of ∼1000 ppm in the K band, the secondary eclipse is potentially detectable at near-IR wavelengths with ground-based facilities, and the planet is ideal for intensive atmospheric characterization through transmission and emission spectroscopy from space missions such as the James Webb Space Telescope and the Atmospheric Remote-sensing Infrared Exoplanet Large-survey