Key Clinical Message
We present a patient with Phelan‐McDermid syndrome, a rare neurodevelopmental disorder caused by a 22q13 deletion, with the previously undescribed finding of progressive dilation ...of the great arteries. While congenital heart defects have been identified in patients previously, dilation of the great arteries has not been described to our knowledge.
We present a patient with Phelan‐McDermid syndrome, a rare neurodevelopmental disorder caused by a 22q13 deletion, with the previously undescribed finding of progressive dilation of the great arteries. While congenital heart defects have been identified in patients previously, dilation of the great arteries has not been described to our knowledge.
ABSTRACT
Pristine_183.6849 + 04.8619 (P1836849) is an extremely metal-poor (Fe/H = −3.3 ± 0.1) star on a prograde orbit confined to the Galactic disc. Such stars are rare and may have their origins ...in protogalactic fragments that formed the early Milky Way, in low-mass satellites accreted later, or forming in situ in the Galactic plane. Here, we present a chemo-dynamical analysis of the spectral features between 3700−11 000 Å from a high-resolution spectrum taken during Science Verification of the new Gemini High-resolution Optical SpecTrograph. Spectral features for many chemical elements are analysed (Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Fe, Ni), and valuable upper limits are determined for others (C, Na, Sr, Ba). This main sequence star exhibits several rare chemical signatures, including (i) extremely low metallicity for a star in the Galactic disc, (ii) very low abundances of the light α-elements (Na, Mg, Si) compared to other metal-poor stars, and (iii) unusually large abundances of Cr and Mn, where Cr, Mn/FeNLTE > +0.5. A comparison to theoretical yields from supernova models suggests that two low-mass Population III objects (one 10 M⊙ supernova and one 17 M⊙ hypernova) can reproduce the abundance pattern well (reduced χ2 < 1). When this star is compared to other extremely metal-poor stars on quasi-circular, prograde planar orbits, differences in both chemistry and kinematics imply there is little evidence for a common origin. The unique chemistry of P1836849 is discussed in terms of the earliest stages in the formation of the Milky Way.
Abstract
We present the first exoplanet atmospheric detection made as part of the SPIRou Legacy Survey, a Large Observing Program of 300 nights exploiting the capabilities of SPIRou, the new ...near-infrared high-resolution (
R
∼ 70,000) spectropolarimeter installed on the Canada–France–Hawaii Telescope (3.6 m). We observed two transits of HD 189733b, an extensively studied hot Jupiter that is known to show prominent water vapor absorption in its transmission spectrum. When combining the two transits, we successfully detect the planet’s water vapor absorption at 5.9
σ
using a cross-correlation
t-
test, or with a ΔBIC > 10 using a log-likelihood calculation. Using a Bayesian retrieval framework assuming parameterized temperature–pressure (T-P) profile atmospheric models, we constrain the planet atmospheric parameters, in the region probed by our transmission spectrum, to the following values:
log
10
VMR
H
2
O
=
−
4.4
−
0.4
+
0.4
, and
P
cloud
≳ 0.2 bar (gray clouds), both of which are consistent with previous studies of this planet. Our retrieved water volume-mixing ratio is slightly subsolar; although, combining it with the previously retrieved super-solar CO abundances from other studies would imply a super-solar C/O ratio. We furthermore measure a net blueshift of the planet signal of
−
4.62
−
0.44
+
0.46
km s
−1
, which is somewhat larger than many previous measurements and unlikely to result solely from winds in the planet's atmosphere, although it could possibly be explained by a transit signal dominated by the trailing limb of the planet. This large blueshift is observed in all of the different detection/retrieval methods that were performed and in each of the two transits independently.
Over five thousand exoplanets have been discovered, but relatively little is known about their atmospheric properties and compositions. Characterizing exoplanet atmospheres is the most promising ...avenue through which we can learn more about exoplanets themselves, and analyzing high-resolution spectra through Doppler cross-correlation is currently one of the best methods by which this can be accomplished. In this thesis, I use state-of-the-art ground-based spectrographs in the optical and near-infrared wavelength regimes to detect, characterize, and understand the atmospheres of exoplanets. My focus is on super-Earths and hot Jupiters, for which there are no Solar System analogues and which remain poorly understood. I begin by characterizing the atmospheres of two warm, sub-Saturn mass exoplanets with high-resolution optical spectroscopy, pushing current observational techniques to lower masses and temperatures and exploring the effects of clouds on high-resolution optical spectra. I then investigate the atmospheric composition of a hot super-Earth with high-resolution near-infrared spectroscopy, providing stringent constraints on its chemical composition and presenting the first atmospheric characterization of an exoplanet from a new near-infrared spectrograph. I also investigate the efficacy of telluric removal methods across a broad, near-infrared wavelength range. Lastly, I turn my attention to the atmosphere of a highly irradiated ultra-hot Jupiter with high-resolution optical spectroscopy, resulting in a new detection of ionized calcium indicative of atmospheric outflows and/or a hotter-than-expected temperature. I then carry out a detailed search for atomic and molecular species in this planet's atmosphere, shedding light on its chemical composition and setting the stage for a multi-year optical survey of exoplanet atmospheres at high spectral resolution. These works expand our knowledge and understanding of exoplanet atmospheres, and shed light on the enigmatic populations of super-Earths and hot Jupiters. They also introduce novel techniques across a range of new instruments and surveys, paving the way for future studies in the field and opening the doors to an era of comparative exoplanetology.
Exoplanet atmosphere studies are often enriched by synergies with brown dwarf analogs. However, many key molecules commonly seen in brown dwarfs have yet to be confirmed in exoplanet atmospheres. An ...important example is chromium hydride (CrH), which is often used to probe atmospheric temperatures and classify brown dwarfs into spectral types. Recently, tentative evidence for CrH was reported in the low-resolution transmission spectrum of the hot Jupiter WASP-31b. Here, we present high spectral resolution observations of WASP-31b's transmission spectrum from GRACES/Gemini North and UVES/VLT. We detect CrH at 5.6\(\sigma\) confidence, representing the first metal hydride detection in an exoplanet atmosphere at high spectral resolution. Our findings constitute a critical step in understanding the role of metal hydrides in exoplanet atmospheres.
Over a hundred rocky planets orbiting Sun-like stars in very short orbital periods (<1 day) have been discovered by the Kepler mission. These planets, known as ultra-short-period (USP) planets, are ...unlikely to have attained their orbits in situ. Instead, they must have migrated in. Here we propose that these planets reach their current orbits by high-eccentricity migration. In a scaled-down version of the dynamics that may have been experienced by their high mass analog, the hot Jupiters, these planets reach high eccentricities via chaotic secular interactions with their companion planets and then undergo orbital circularization due to dissipation of tides raised on the planet. This proposal is motivated by the following observations: planetary systems observed by Kepler often contain several super-Earths with non-negligible eccentricities and inclinations, and possibly extending beyond AU distances; while only a small fraction of USP planets have known transiting companions, and none closely spaced, we argue that most of them should have companions at periods of ~10-50 days. The outer sibling planets, through secular chaos, can remove angular momentum from the inner most planet, originally at periods of ~5-10 days. When the latter reaches an eccentricity higher than 0.8, it is tidally captured by the central star and becomes an USP planet. This scenario naturally explains the observation that most USP planets have significantly more distant transiting companions compared to their counterparts at slightly longer periods (1-3 days), a feature un-accounted for in other proposed scenarios. Our model also predicts that USP planets should have: (i) spin-orbit angles, and inclinations relative to outer planets, in the range of ~10-50 degrees; (ii) several outer planetary companions extending to beyond AU distances, both of which may be tested by TESS and its follow-up observations.
We have used systematic, sustained visual observations from the AAVSO International Database, and the AAVSO time-series analysis package VSTAR to study the unexplained "long secondary periods" (LSPs) ...in 27 pulsating red giants. In our sample, the LSPs range from 479 to 2967 days, and are on average 8.1 +/- 1.3 times the pulsation period. There is no evidence for more than one LSP in each star. In stars with both the fundamental and first overtone radial period present, the LSP is more often about 10 times the latter. The visual amplitudes of the LSPs are typically 0.1 magnitude and do not correlate with the LSP. The phase curves tend to be sinusoidal, but at least two are sawtooth. The LSPs are stable, within their errors, over the timespan of our data, which is typically 25,000 days. The amplitudes, however, vary by up to a factor of two or more on a timescale of roughly 20-30 LSPs. There is no obvious difference between the behavior of the carbon (C) stars and the normal oxygen (M) stars. Previous multicolor photoelectric observations showed that the LSP color variations are similar to those of the pulsation period, and of the LSPs in the Magellanic Clouds, and not like those of eclipsing stars. We note that the LSPs are similar to the estimated rotation periods of the stars, though the latter have large uncertainties. This suggests that the LSP phenomenon may be a form of modulated rotational variability.
We present high-resolution transmission spectroscopy of WASP-76b with GRACES/Gemini North obtained as part of the ExoGemS survey. With a broad spectral range of 400-1050 nm and a relatively high ...resolution of ~66,000, these observations are particularly well-suited to searching for atomic and molecular atmospheric species via the Doppler cross-correlation technique. We recover absorption features due to neutral iron (Fe I), sodium (Na I), and ionized calcium (Ca II) at high significance (>5\(\sigma\)), and investigate possible atmospheric temperatures and wind speeds. We also report tentative (>3\(\sigma\)) detections of Li I, K I, Cr I, and V I in the atmosphere of WASP-76b. Finally, we report non-detections of a number of other species, some of which have previously been detected with other instruments. Through model injection/recovery tests, we demonstrate that many of these species are not expected to be detected in our observations. These results allow us to place GRACES and the ExoGemS survey in context with other high-resolution optical spectrographs.
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