Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric compositions and luminosities, which are influenced by their formation mechanisms. Using the ...Gemini Planet Imager, we discovered a planet orbiting the ∼20-million-year-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water-vapor absorption. Modeling of the spectra and photometry yields a luminosity (normalized by the luminosity of the Sun) of 1.6 to 4.0 × 10–6 and an effective temperature of 600 to 750 kelvin. For this age and luminosity, "hot-start" formation models indicate a mass twice that of Jupiter. This planet also has a sufficiently low luminosity to be consistent with the "cold-start" core-accretion process that may have formed Jupiter.
Quasars are galaxies hosting accreting supermassive black holes; due to their brightness, they are unique probes of the early universe. To date, only a few quasars have been reported at (<800 Myr ...after the big bang). In this work, we present six additional quasars discovered using the Pan-STARRS1 survey. We use a sample of 15 quasars to perform a homogeneous and comprehensive analysis of this highest-redshift quasar population. We report four main results: (1) the majority of quasars show large blueshifts of the broad C iv λ1549 emission line compared to the systemic redshift of the quasars, with a median value ∼3× higher than a quasar sample at ; (2) we estimate the quasars' black hole masses ( (0.3-5) × 109 M ) via modeling of the Mg ii λ2798 emission line and rest-frame UV continuum and find that quasars at high redshift accrete their material (with ) at a rate comparable to a luminosity-matched sample at lower redshift, albeit with significant scatter (0.4 dex); (3) we recover no evolution of the Fe ii/Mg ii abundance ratio with cosmic time; and (4) we derive near-zone sizes and, together with measurements for quasars from recent work, confirm a shallow evolution of the decreasing quasar near-zone sizes with redshift. Finally, we present new millimeter observations of the C ii 158 m emission line and underlying dust continuum from NOEMA for four quasars and provide new accurate redshifts and C ii/infrared luminosity estimates. The analysis presented here shows the large range of properties of the most distant quasars.
With a combination of adaptive optics imaging and a multi-epoch common proper motion search, we have conducted a large volume-limited (D ≤ 75 pc) multiplicity survey of A-type stars, sensitive to ...companions beyond 30 au. The sample for the Volume-limited A-STar (VAST) survey consists of 435 A-type stars: 363 stars were observed with adaptive optics, 228 stars were searched for wide common proper motion companions and 156 stars were measured with both techniques. The projected separation coverage of the VAST survey extends from 30 to 45 000 au. A total of 137 stellar companions were resolved, including 64 new detections from the VAST survey, and the companion star fraction, projected separation distribution and mass ratio distribution were measured. The separation distribution forms a log-normal distribution similar to the solar-type binary distribution, but with a peak shifted to a significantly wider value of
au. Integrating the fit to the distribution over the 30 to 10 000 au observed range, the companion star fraction for A-type stars is estimated as 33.8 ± 2.6 per cent. The mass ratio distribution of closer (<125 au) binaries is distinct from that of wider systems, with a flat distribution for close systems and a distribution that tends towards smaller mass ratios for wider binaries. Combining this result with previous spectroscopic surveys of A-type stars gives an estimate of the total companion star fraction of 68.9 ± 7.0 per cent. The most complete assessment of higher order multiples was estimated from the 156 star subset of the VAST sample with both adaptive optics and common proper motion measurements, combined with a thorough literature search for companions, yielding a lower limit on the frequency of single, binary, triple, quadruple and quintuple A-type star systems of
,
,
,
and
per cent, respectively.
ABSTRACT Luminous quasars at can be studied in detail with the current generation of telescopes and provide us with unique information on the first gigayear of the universe. Thus far, these studies ...have been statistically limited by the number of quasars known at these redshifts. Such quasars are rare, and therefore, wide-field surveys are required to identify them, and multiwavelength data are required to separate them efficiently from their main contaminants, the far more numerous cool dwarfs. In this paper, we update and extend the selection for the quasars presented in Bañados et al. (2014) using the Pan-STARRS1 (PS1) survey. We present the PS1 distant quasar sample, which currently consists of 124 quasars in the redshift range that satisfy our selection criteria. Of these quasars, 77 have been discovered with PS1, and 63 of them are newly identified in this paper. We present the composite spectra of the PS1 distant quasar sample. This sample spans a factor of ∼20 in luminosity and shows a variety of emission line properties. The number of quasars at presented in this work almost doubles the previously known quasars at these redshifts, marking a transition phase from studies of individual sources to statistical studies of the high-redshift quasar population, which was impossible with earlier, smaller samples.
Studying quasars at the highest redshifts can constrain models of galaxy and black hole formation, and it also probes the intergalactic medium in the early universe. Optical surveys have to date ...discovered more than 60 quasars up to z Asymptotically = to 6.4, a limit set by the use of the z-band and CCD detectors. Only one z gap 6.4 quasar has been discovered, namely the z = 7.08 quasar ULAS J1120+0641, using near-infrared imaging. Here we report the discovery of three new z gap 6.4 quasars in 332 deg super(2) of the Visible and Infrared Survey Telescope for Astronomy Kilo-degree Infrared Galaxy (VIKING) survey, thus extending the number from 1 to 4. The newly discovered quasars have redshifts of z = 6.60, 6.75, and 6.89. The absolute magnitudes are between -26.0 and -25.5, 0.6-1.1 mag fainter than ULAS J1120+0641. Near-infrared spectroscopy revealed the Mg II emission line in all three objects. The quasars are powered by black holes with masses of ~(1-2) x 10 super(9) M sub(middot in circle). In our probed redshift range of 6.44 < z < 7.44 we can set a lower limit on the space density of supermassive black holes of rho(M sub(BH) > 10 super(9) M sub(middot in circle)) > 1.1 x 10 super(-9) Mpc super(-3). The discovery of three quasars in our survey area is consistent with the z = 6 quasar luminosity function when extrapolated to z ~ 7. We do not find evidence for a steeper decline in the space density of quasars with increasing redshift from z = 6 to z = 7.
We present a large-scale, volume-limited companion survey of 245 late-K to mid-M (K7-M6) dwarfs within 15 pc. Infrared adaptive optics (AO) data were analysed from the Very Large Telescope, Subaru ...Telescope, Canada–France–Hawaii Telescope, and MMT Observatory to detect close companions to the sample from ∼ 1 to 100 au, while digitized wide-field archival plates were searched for wide companions from ∼ 100 to 10 000 au. With sensitivity to the bottom of the main sequence over a separation range of 3 to 10 000 au, multiple AO and wide-field epochs allow us to confirm candidates with common proper motions, minimize background contamination, and enable a measurement of comprehensive binary statistics. We detected 65 comoving stellar companions and find a companion star fraction of 23.5 ± 3.2 per cent over the 3 au to 10 000 au separation range. The companion separation distribution is observed to rise to a higher frequency at smaller separations, peaking at closer separations than measured for more massive primaries. The mass ratio distribution across the q = 0.2–1.0 range is flat, similar to that of multiple systems with solar-type primaries. The characterization of binary and multiple star frequency for low-mass field stars can provide crucial comparisons with star-forming environments and hold implications for the frequency and evolutionary histories of their associated discs and planets.
Abstract
We present new near-infrared Gemini Planet Imager (GPI) spectroscopy of HD 206893 B, a substellar companion orbiting within the debris disk of its F5V star. The
J
,
H
,
K1
, and
K2
spectra ...from GPI demonstrate the extraordinarily red colors of the object, confirming it as the reddest substellar object observed to date. The significant flux increase throughout the infrared presents a challenging atmosphere to model with existing grids. Best-fit values vary from 1200 to 1800 K for effective temperature and from 3.0 to 5.0 for log(
g
), depending on which individual wavelength band is fit and which model suite is applied. The extreme redness of the companion can be partially reconciled by invoking a high-altitude layer of submicron dust particles, similar to dereddening approaches applied to the peculiar red field L dwarf population. However, reconciling the HD 206893 B spectra with even those of the reddest low-gravity L dwarf spectra still requires the contribution of additional atmospheric dust, potentially due to the debris disk environment in which the companion resides. Orbit fitting from 4 yr of astrometric monitoring is consistent with a ∼30 yr period, an orbital inclination of 147°, and a semimajor axis of 10 au, well within the estimated disk inner radius of ∼50 au. As one of a very few substellar companions imaged interior to a circumstellar disk, the properties of this system offer important dynamical constraints on companion–disk interaction and provide a benchmark for substellar and planetary atmospheric study.
Abstract
We present
K
-band interferometric observations of the PDS 70 protoplanets along with their host star using VLTI/GRAVITY. We obtained
K
-band spectra and 100
μ
as precision astrometry of ...both PDS 70 b and c in two epochs, as well as spatially resolving the hot inner disk around the star. Rejecting unstable orbits, we found a nonzero eccentricity for PDS 70 b of 0.17 ± 0.06, a near-circular orbit for PDS 70 c, and an orbital configuration that is consistent with the planets migrating into a 2:1 mean motion resonance. Enforcing dynamical stability, we obtained a 95% upper limit on the mass of PDS 70 b of 10
M
Jup
, while the mass of PDS 70 c was unconstrained. The GRAVITY
K
-band spectra rules out pure blackbody models for the photospheres of both planets. Instead, the models with the most support from the data are planetary atmospheres that are dusty, but the nature of the dust is unclear. Any circumplanetary dust around these planets is not well constrained by the planets’ 1–5
μ
m spectral energy distributions (SEDs) and requires longer wavelength data to probe with SED analysis. However with VLTI/GRAVITY, we made the first observations of a circumplanetary environment with sub-astronomical-unit spatial resolution, placing an upper limit of 0.3 au on the size of a bright disk around PDS 70 b.
In some 5% of patients with facioscapulohumeral muscular dystrophy (FSHD), no D4Z4 repeat contraction on chromosome 4q35 is observed. Such patients, termed patients with FSHD2, show loss of DNA ...methylation and heterochromatin markers at the D4Z4 repeat that are similar to patients with D4Z4 contractions (FSHD1). This commonality suggests that a change in D4Z4 chromatin structure unifies FSHD1 and FSHD2. The aim of our study was to critically evaluate the clinical features in patients with FSHD2 in order to establish whether these patients are phenotypically identical to FSHD1 and to establish the effects of the (epi-) genotype on the phenotype.
This cross-sectional study studied 33 patients with FSHD2 from 27 families, the largest cohort described to date. All patients were clinically assessed using a standardized clinical evaluation form. Genotype analysis was performed by pulsed field gel electrophoresis and PCR; D4Z4 methylation was studied by methylation-sensitive Southern blot analysis.
FSHD2 is identical to FSHD1 in its clinical presentation. Notable differences include a higher incidence (67%) of sporadic cases and the absence of gender differences in disease severity in FSHD2. Overall, average disease severity in FSHD2 was similar to that reported in FSHD1 and was not influenced by D4Z4 repeat size. In FSHD2, a small effect of the degree of hypomethylation on disease severity was observed.
Clinically, patients with FSHD2 are indistinguishable from patients with FSHD1. The present data suggest that FSHD1 and FSHD2 are the result of the same pathophysiologic process.
Planck intermediate results Aghanim, N; Ashdown, M; Aumont, J ...
Astronomy and astrophysics (Berlin),
12/2016, Volume:
596
Journal Article
Peer reviewed
Open access
This paper describes the identification, modelling, and removal of previously unexplained systematic effects in the polarization data of the Planck High Frequency Instrument (HFI) on large angular ...scales, including new mapmaking and calibration procedures, new and more complete end-to-end simulations, and a set of robust internal consistency checks on the resulting maps. These maps, at 100, 143, 217, and 353GHz, are early versions of those that will be released in final form later in 2016. The improvements allow us to determine the cosmic reionization optical depth tau using, for the first time, the low-multipole EE data from HFI, reducing significantly the central value and uncertainty, and hence the upper limit. Two different likelihood procedures are used to constrain tau from two estimators of the CMB E- and B-mode angular power spectra at 100 and 143GHz, after debiasing the spectra from a small remaining systematic contamination. These all give fully consistent results. A further consistency test is performed using cross-correlations derived from the Low Frequency Instrument maps of the Planck 2015 data release and the new HFI data. For this purpose, end-to-end analyses of systematic effects from the two instruments are used to demonstrate the near independence of their dominant systematic error residuals. The tightest result comes from the HFI-based tau posterior distribution using the maximum likelihood power spectrum estimator from EE data only, giving a value 0.055 + or - 0.009. In a companion paper these results are discussed in the context of the best-fit PlanckLambdaCDM cosmological model and recent models of reionization.