Abstract
HR 8799 hosts four directly imaged giant planets, but none has a mass measured from first principles. We present the first dynamical mass measurement in this planetary system, finding that ...the innermost planet HR 8799 e has a mass of
9.6
−
1.8
+
1.9
M
Jup
. This mass results from combining the well-characterized orbits of all four planets with a new astrometric acceleration detection (5
σ
) from the Gaia EDR3 version of the Hipparcos-Gaia Catalog of Accelerations. We find with 95% confidence that HR 8799 e is below 13
M
Jup
, the deuterium-fusing mass limit. We derive a hot-start cooling age of
42
−
16
+
24
Myr for HR 8799 e that agrees well with its hypothesized membership in the Columba association but is also consistent with an alternative suggested membership in the
β
Pictoris moving group. We exclude the presence of any additional ≳5 −
M
Jup
planets interior to HR 8799 e with semimajor axes between ≈3–16 au. We provide proper motion anomalies and a matrix equation to solve for the mass of any of the planets of HR 8799 using only mass ratios between the planets.
Abstract
We present an open-source Python package, Orbits from Radial Velocity, Absolute, and/or Relative Astrometry (
orvara
), to fit Keplerian orbits to any combination of radial velocity, ...relative astrometry, and absolute astrometry data from the Hipparcos-Gaia Catalog of Accelerations. By combining these three data types, one can measure precise masses and sometimes orbital parameters even when the observations cover a small fraction of an orbit. The computational performance of
orvara
is achieved with an eccentric anomaly solver 5–10 times faster than commonly used approaches and low-level memory management to avoid Python overheads and by analytically marginalizing out parallax, barycenter proper motion, and instrument-specific radial velocity zero-points. Through its integration with the Hipparcos and Gaia intermediate astrometry package
htof
,
orvara
can properly account for the epoch astrometry measurements of Hipparcos and the measurement times and scan angles of individual Gaia epochs. We configure
orvara
with modifiable
.ini
configuration files tailored to any specific stellar or planetary system. We demonstrate
orvara
with a case study application to a recently discovered white dwarf/main-sequence system, HD 159062. By adding absolute astrometry to literature radial velocity and relative astrometry data, our comprehensive Markov Chain Monte Carlo analysis improves the precision of HD 159062B’s mass by more than an order of magnitude to
0.6083
−
0.0073
+
0.0083
M
☉
. We also derive a low eccentricity and large semimajor axis, establishing HD 159062AB as a system that did not experience Roche lobe overflow.
Abstract
Radial-velocity (RV) surveys have discovered hundreds of exoplanetary systems but suffer from a fundamental degeneracy between planet mass
M
p
and orbital inclination
i
. In this paper, we ...resolve this degeneracy by combining RVs with complementary absolute astrometry taken from the Gaia EDR3 version of the cross calibrated Hipparcos–Gaia Catalog of Accelerations (HGCA). We use the Markov Chain Monte Carlo orbit code
orvara
to simultaneously fit literature RVs and absolute astrometry from the HGCA. We constrain the orbits, masses, and inclinations of nine single and massive RV companions orbiting nearby G and K stars. We confirm the planetary nature of six companions: HD 29021 b (
4.47
−
0.65
+
0.67
M
Jup
), HD 81040 b (
7.24
−
0.37
+
1.0
M
Jup
), HD 87883 b (
6.31
−
0.32
+
0.31
M
Jup
), HD 98649 b (
9.7
−
1.9
+
2.3
M
Jup
), HD 106252 b (
10.00
−
0.73
+
0.78
M
Jup
), and HD 171238 b (
8.8
−
1.3
+
3.6
M
Jup
). We place one companion, HD 196067 b (
12.5
−
1.8
+
2.5
M
Jup
) on the planet–brown dwarf boundary and two companions in the low-mass brown dwarf regime: HD 106515 Ab (
18.9
−
1.4
+
1.5
M
Jup
), and HD 221420 b (
20.6
−
1.6
+
2.0
M
Jup
). The brown dwarf HD 221420 b, with a semimajor axis of
9.99
−
0.70
+
0.74
au, a period of
27.7
−
2.5
+
3.0
yr, and an eccentricity of
0.162
−
0.030
+
0.035
represents a promising target for high-contrast imaging. The RV orbits of HD 87883 b, HD 98649 b, HD 171238 b, and HD 196067 b are not fully constrained yet because of insufficient RV data. We find two possible inclinations for each of these orbits due to difficulty in separating prograde from retrograde orbits, but we expect this will change decisively with future Gaia data releases.
We present the direct imaging discovery of a substellar companion to the nearby Sun-like star, HD 33632 Aa, at a projected separation of ∼20 au, obtained with SCExAO/CHARIS integral field ...spectroscopy complemented by Keck/NIRC2 thermal infrared imaging. The companion, HD 33632 Ab, induces a 10.5σ astrometric acceleration on the star as detected with the Gaia and Hipparcos satellites. SCExAO/CHARIS JHK (1.1–2.4 μm) spectra and Keck/NIRC2 L(sub p) (3.78 μm) photometry are best matched by a field L/T transition object: an older, higher-gravity, and less dusty counterpart to HR 8799 cde. Combining our astrometry with Gaia/Hipparcos data and archival Lick Observatory radial velocities, we measure a dynamical mass of 46.4 ± 8 MJ and an eccentricity of e < 0.46 at 95% confidence. HD 33632 Ab’s mass and mass ratio (4.0% ± 0.7%) are comparable to the low-mass brown dwarf GJ 758 B and intermediate between the more massive brown dwarf HD 19467 B and the (near-)planet-mass companions to HR 2562 and GJ 504. Using Gaia to select for direct imaging observations with the newest extreme adaptive optics systems can reveal substellar or even planet-mass companions on solar system–like scales at an increased frequency compared to blind surveys
Abstract Objective To develop and validate a computable phenotype algorithm for identifying patient populations with sickle cell disease. Methods In this retrospective study we used electronic health ...record data from the Children's Hospital of Wisconsin to develop a computable phenotype algorithm for sickle cell disease. The algorithm was on the basis of the International Classification of Diseases, Ninth Revision codes, number of visits, and hospital admissions for sickle cell disease. Using Informatics for Integrating Biology and the Bedside queries, the algorithm was refined in an iterative process. The final algorithm was verified using manual medical records review and by comparison with a gold standard set of confirmed sickle cell cases. The algorithm was then validated at Froedtert Hospital, a neighboring health system for adults. Results From the Children's Hospital of Wisconsin, our computable phenotype algorithm identified patients with confirmed sickle cell disease with a positive predictive value of 99.4% and a sensitivity of 99.4%. Additionally, using data from Froedtert, the computable phenotype algorithm identified patients with confirmed sickle cell disease with a positive predictive value of 95.8% and a sensitivity of 98.3%. Conclusions The computable phenotype algorithm developed in this study had a high sensitivity and positive predictive value when identifying patients with sickle cell disease in the electronic health records of the Children's Hospital of Wisconsin and Froedtert, a neighboring health system for adults. Our algorithm allows us to harness data provided by the electronic health record to rapidly and accurately identify patient with sickle cell disease and is a rich resource for future clinical trials.
The Pr3+-doped solid solutions from (Ba,Ca)(Ti,Zr)O3 (BCTZO) system were successfully synthesized using an efficient and low-energy consuming route—the Pechini method combined with the sintering at ...relatively low temperature (1450 °C). The obtained materials were characterized by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The dielectric properties were systematically studied. The Pr3+-doped BCTZO diphasic material generates intense and broad red photoluminescence (PL) emission at room temperature. The optical properties were significantly improved with the Ti4+ substitution by Zr4+ ions. As a result, the Pr3+-doped (Ba,Ca)(Ti,Zr)O3 ceramics is a promising candidate for environmentally friendly, multifunctional material by combining good dielectric and photoluminescent properties with prognosis for the manifestation of strong photoluminescent and mechanoluminescent effects.
The Tycho - Gaia astrometric solution Michalik, Daniel; Lindegren, Lennart; Hobbs, David
Astronomy and astrophysics (Berlin),
2/2015, Letnik:
574
Journal Article
Recenzirano
Context. The first release of astrometric data from Gaia will contain the mean stellar positions and magnitudes from the first year of observations, and proper motions from the combination of Gaia ...data with Hipparcos prior information (HTPM). Aims. We study the potential of using the positions from the Tycho-2 Catalogue as additional information for a joint solution with early Gaia data. We call this the Tycho-Gaia astrometric solution (TGAS). Methods. We adapt Gaia's Astrometric Global Iterative Solution (AGIS) to incorporate Tycho information, and use simulated Gaia observations to demonstrate the feasibility of TGAS and to estimate its performance. Results. Using six to twelve months of Gaia data, TGAS could deliver positions, parallaxes, and annual proper motions for the 2.5 million Tycho-2 stars, with sub-milliarcsecond accuracy. TGAS overcomes some of the limitations of the HTPM project and allows its execution half a year earlier. Furthermore, if the parallaxes from Hipparcos are not incorporated in the solution, they can be used as a consistency check of the TGAS/HTPM results.
Context. The first release of astrometric data from Gala will contain the mean stellar positions and magnitudes from the first year of observations, and proper motions from the combination of Gala ...data with HIPPARCOS prior information (HTPM). Aims. We study the potential of using the positions from the Tycho-2 Catalogue as additional information for a joint solution with early Gala data. We call this the Tycho -Gain astrometric solution (TGAS). Methods. We adapt Gala's Astrornetric Global Iterative Solution (AGIS) to incorporate Tycho information, and use simulated Gala observations to demonstrate the feasibility of TGAS and to estimate its performance. Results. Using six to twelve months of Gala data, TGAS could deliver positions, parallaxes, and annual proper motions for the 2.5 million Tycho -2 stars, with sub-milliarcsecond accuracy. TGAS overcomes some of the limitations of the FITPM project and allows its execution half a year earlier. Furthermore, if the parallaxes from HIPPARCOS are not incorporated in the solution, they can be used as a consistency check of the TOAS/IITPM results.
The present paper describes the effect of various Si–N substitution degree on the crystal structure and optical properties of yellow YAG:Ce phosphor commonly used with combination of InGaN in white ...LEDs. It has been found that the course of silicon/nitrogen YAG:Ce garnet doping as well as formation of the liquid phase and its chemical composition controlled formation of the side phase besides YAG:Ce. Substitution of Al–O for Si–N chemical bonds according to the general formula Y2.94Ce0.06Al(5−x)SixO(12−x)Nx was confirmed by changes of the unit cell parameter and formation of the Si–N bonds as detected by FT-IR studies. Formation of the nitrogen ligand in cerium arrangement resulted in a red shift in emission spectrum of trivalent cerium if nominal x value was in the range of 0.2–0.3. Above x=0.3 only decrease of emission intensity was observed because of the secondary phase precipitation but further solution of Si–N in YAG:Ce crystal lattice cannot be excluded.
Vestibular schwannomas (commonly referred to by the misnomer acoustic neuroma) are benign, slow-growing tumours arising from the Schwann cells on the sheath of the vestibulocochlear nerve. Vestibular ...schwannomas are the third most common benign intracranial tumour after meningioma and pituitary adenoma and are the most common tumour of the cerebellopontine angle. Vestibular schwannomas can present and grow in unpredictable ways. There is a lack of high-level evidence on appropriate management, and as such, this can vary significantly between centres. With the ease of access to sensitive neurological imaging, vestibular schwannomas are identified in more patients, at more advanced ages, and at smaller sizes, with a shift in the management towards a more conservative approach over previous decades. This article summarises the epidemiology, aetiology, clinical features, investigation, management and prognosis of vestibular schwannoma.
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