Since the start of the Wide-angle Search for Planets (WASP) program, more than 160 transiting exoplanets have been discovered in the WASP data. In the past, possible transit-like events identified by ...the WASP pipeline have been vetted by human inspection to eliminate false alarms and obvious false positives. The goal of this paper is to assess the effectiveness of machine learning as a fast, automated, and reliable means of performing the same functions on ground-based wide-field transit-survey data without human intervention. To this end, we have created training and test data sets made up of stellar light curves showing a variety of signal types including planetary transits, eclipsing binaries, variable stars, and non-periodic signals. We use a combination of machine-learning methods including Random Forest Classifiers (RFCs) and convolutional neural networks (CNNs) to distinguish between the different types of signals. The final algorithms correctly identify planets in the test data ∼90 per cent of the time, although each method on its own has a significant fraction of false positives. We find that in practice, a combination of different methods offers the best approach to identifying the most promising exoplanet transit candidates in data from WASP, and by extension similar transit surveys.
The Green Bank Telescope (GBT) H II Region Discovery Survey has doubled the number of known H II regions in the Galactic zone 343? <= l <= 67? with | b | <= 1?. We detected 603 discrete hydrogen ...radio recombination line (RRL) components at 9 GHz (3 cm) from 448 targets. Our targets were selected based on spatially coincident mid-infrared and 20 cm radio continuum emission. Such sources are almost invariably H II regions; we detected hydrogen RRL emission from 95% of our target sample. The sensitivity of the GBT and the power of its spectrometer together made this survey possible. Here, we provide a catalog of the measured properties of the RRL and continuum emission from the survey nebulae. The derived survey completeness limit, 180 mJy at 9 GHz, is sufficient to detect all H II regions ionized by single O-stars to a distance of 12 kpc. These recently discovered nebulae share the same distribution on the sky as does the previously known census of Galactic H II regions. On average, however, the new nebulae have fainter continuum fluxes, smaller continuum angular sizes, fainter RRL intensities, and smaller RRL line widths. Though small in angular size, many of our new nebulae show little spatial correlation with tracers associated with extremely young H II regions, implying that our sample spans a range of evolutionary states. We discovered 34 first quadrant negative-velocity H II regions, which lie at extreme distances from the Sun and appear to be part of the Outer Arm. We found RRL emission from 208 Spitzer GLIMPSE 8.0 Delta *mm 'bubble' sources, 65 of which have been cataloged previously. It thus appears that nearly all GLIMPSE bubbles are H II regions and that ~50% of all Galactic H II regions have a bubble morphology at 8.0 Delta *mm.
Summary
In a phase 2 open‐label study of the novel proteasome inhibitor bortezomib, 54 patients with multiple myeloma who had relapsed after or were refractory to frontline therapy were randomized to ...receive intravenous 1·0 or 1·3 mg/m2 bortezomib twice weekly for 2 weeks, every 3 weeks for a maximum of eight cycles. Dexamethasone was permitted in patients with progressive or stable disease after two or four cycles respectively. Responses were determined using modified European Group for Blood and Marrow Transplantation criteria. The complete response (CR) + partial response (PR) rate for bortezomib alone was 30% 90% confidence interval (CI), 15·7–47·1 and 38% (90% CI, 22·6–56·4) in the 1·0 mg/m2 (8 of 27 patients) and 1·3 mg/m2 (10 of 26 patients) groups respectively. The CR + PR rate for patients who received bortezomib alone or in combination with dexamethasone was 37% and 50% for the 1·0 and 1·3 mg/m2 cohorts respectively. The most common grade 3 adverse events were thrombocytopenia (24%), neutropenia (17%), lymphopenia (11%) and peripheral neuropathy (9%). Grade 4 events were observed in 9% (five of 54 patients). Bortezomib alone or in combination with dexamethasone demonstrated therapeutic activity in patients with multiple myeloma who relapsed after frontline therapy.
The 'hot Jupiters' that abound in lists of known extrasolar planets are thought to have formed far from their host stars, but migrate inwards through interactions with the proto-planetary disk from ...which they were born, or by an alternative mechanism such as planet-planet scattering. The hot Jupiters closest to their parent stars, at orbital distances of only ∼0.02 astronomical units, have strong tidal interactions, and systems such as OGLE-TR-56 have been suggested as tests of tidal dissipation theory. Here we report the discovery of planet WASP-18b with an orbital period of 0.94 days and a mass of ten Jupiter masses (10 MJup), resulting in a tidal interaction an order of magnitude stronger than that of planet OGLE-TR-56b. Under the assumption that the tidal-dissipation parameter Q of the host star is of the order of 106, as measured for Solar System bodies and binary stars and as often applied to extrasolar planets, WASP-18b will be spiralling inwards on a timescale less than a thousandth that of the lifetime of its host star. Therefore either WASP-18 is in a rare, exceptionally short-lived state, or the tidal dissipation in this system (and possibly other hot-Jupiter systems) must be much weaker than in the Solar System.
Kinematic Distances: A Monte Carlo Method Wenger, Trey V.; Balser, Dana S.; Anderson, L. D. ...
The Astrophysical journal,
03/2018, Volume:
856, Issue:
1
Journal Article
Peer reviewed
Open access
Distances to high-mass star-forming regions (HMSFRs) in the Milky Way are a crucial constraint on the structure of the Galaxy. Only kinematic distances are available for a majority of the HMSFRs in ...the Milky Way. Here, we compare the kinematic and parallax distances of 75 Galactic HMSFRs to assess the accuracy of kinematic distances. We derive the kinematic distances using three different methods: the traditional method using the Brand & Blitz rotation curve (Method A), the traditional method using the Reid et al. rotation curve and updated solar motion parameters (Method B), and a Monte Carlo technique (Method C). Methods B and C produce kinematic distances closest to the parallax distances, with median differences of 13% (0.43 ) and 17% (0.42 ), respectively. Except in the vicinity of the tangent point, the kinematic distance uncertainties derived by Method C are smaller than those of Methods A and B. In a large region of the Galaxy, the Method C kinematic distances constrain both the distances and the Galactocentric positions of HMSFRs more accurately than parallax distances. Beyond the tangent point along = 30°, for example, the Method C kinematic distance uncertainties reach a minimum of 10% of the parallax distance uncertainty at a distance of 14 . We develop a prescription for deriving and applying the Method C kinematic distances and distance uncertainties. The code to generate the Method C kinematic distances is publicly available and may be utilized through an online tool.
We present the discovery of three new transiting hot Jupiters by the WASP-South project, WASP-161 b, WASP-163 b, and WASP-170 b. Follow-up radial velocities obtained with the Euler/CORALIE ...spectrograph and transit light curves obtained with the TRAPPIST-North, TRAPPIST-South, SPECULOOS-South, NITES, and Euler telescopes have enabled us to determine the masses and radii for these transiting exoplanets. WASP-161 b completes an orbit around its V = 11.1 F6V-type host star in 5.406 days, and has a mass Mp = 2.5 0.2MJup and radius Rp = 1.14 0.06 RJup. WASP-163 b orbits around its host star (spectral type G8V and the magnitude V = 12.5) every 1.609 days, and has a mass of MP = 1.9 0.2 MJup and a radius of Rp = 1.2 0.1 RJup. WASP-170 b has a mass of 1.7 0.2 MJup and a radius of 1.14 0.09 RJup and is on a 2.344 day orbit around a G1V-type star of magnitude V = 12.8. Given their irradiations (∼109 erg s−1 cm−2) and masses, the three new planets' sizes are in good agreement with classical models of irradiated giant planets.
Aims. To constrain models of high-mass star formation, the Herschel-HOBYS key program aims at discovering massive dense cores (MDCs) able to host the high-mass analogs of low-mass prestellar cores, ...which have been searched for over the past decade. We here focus on NGC 6334, one of the best-studied HOBYS molecular cloud complexes. Methods. We used Herschel/PACS and SPIRE 70−500 μm images of the NGC 6334 complex complemented with (sub)millimeter and mid-infrared data. We built a complete procedure to extract ~0.1 pc dense cores with the getsources software, which simultaneously measures their far-infrared to millimeter fluxes. We carefully estimated the temperatures and masses of these dense cores from their spectral energy distributions (SEDs). We also identified the densest pc-scale cloud structures of NGC 6334, one 2 pc × 1 pc ridge and two 0.8 pc × 0.8 pc hubs, with volume-averaged densities of ~105 cm-3. Results. A cross-correlation with high-mass star formation signposts suggests a mass threshold of 75 M⊙ for MDCs in NGC 6334. MDCs have temperatures of 9.5−40 K, masses of 75−1000 M⊙, and densities of 1 × 105−7 × 107 cm-3. Their mid-infrared emission is used to separate 6 IR-bright and 10 IR-quiet protostellar MDCs while their 70 μm emission strength, with respect to fitted SEDs, helps identify 16 starless MDC candidates. The ability of the latter to host high-mass prestellar cores is investigated here and remains questionable. An increase in mass and density from the starless to the IR-quiet and IR-bright phases suggests that the protostars and MDCs simultaneously grow in mass. The statistical lifetimes of the high-mass prestellar and protostellar core phases, estimated to be 1−7 × 104 yr and at most 3 × 105 yr respectively, suggest a dynamical scenario of high-mass star formation. Conclusions. The present study provides good mass estimates for a statistically significant sample, covering the earliest phases of high-mass star formation. High-mass prestellar cores may not exist in NGC 6334, favoring a scenario presented here, which simultaneously forms clouds, ridges, MDCs, and high-mass protostars.
The metallicity structure of the Milky Way disk stems from the chemodynamical evolutionary history of the Galaxy. We use the National Radio Astronomy Observatory Karl G. Jansky Very Large Array to ...observe ∼8-10 GHz hydrogen radio recombination line and radio-continuum emission toward 82 Galactic H ii regions. We use these data to derive the electron temperatures and metallicities for these nebulae. Since collisionally excited lines from metals (e.g., oxygen, nitrogen) are the dominant cooling mechanism in H ii regions, the nebular metallicity can be inferred from the electron temperature. Including previous single-dish studies, there are now 167 nebulae with radio-determined electron temperature and either parallax or kinematic distance determinations. The interferometric electron temperatures are systematically 10% larger than those found in previous single-dish studies, likely due to incorrect data analysis strategies, optical depth effects, and/or the observation of different gas by the interferometer. By combining the interferometer and single-dish samples, we find an oxygen abundance gradient across the Milky Way disk with a slope of −0.052 0.004 dex kpc−1. We also find significant azimuthal structure in the metallicity distribution. The slope of the oxygen gradient varies by a factor of ∼2 when Galactocentric azimuths near ∼30° are compared with those near ∼100°. This azimuthal structure is consistent with simulations of Galactic chemodynamical evolution influenced by spiral arms.
We resolve the kinematic distance ambiguity for 266 inner Galaxy H II regions out of a sample of 291 using existing H I and 13CO sky surveys. Our sample contains all H II regions with measured radio ...recombination line emission over the extent of the 13CO Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey (18° < l < 55° and |b| < 1) and contains ultra compact (UC), compact, and diffuse H II regions. We use two methods for resolving the distance ambiguity for each H II region: H I emission/absorption (H I E/A) and H I self-absorption (H I SA). We find that the H I E/A and H I SA methods can resolve the distance ambiguity for 72% and 87% of our sample, respectively. When projected onto the Galactic plane, this large sample appears to reveal aspects of Galactic structure, with spiral arm-like features at Galactocentric radii of 4.5 and 6 kpc, and a lack of H II regions within 3.5 kpc of the Galactic center. Our H II regions are approximately in the ratio of 2 to 1 for far versus near distances. The ratio of far-to-near distances for UC H II regions is 2.2 to 1. Compact H II regions are preferentially at the near distance; their ratio of far-to-near distances is 1.6 to 1. Diffuse H II regions are preferentially at the far distance; their ratio of far-to-near distances is 3.8 to 1. This implies that the distinction between UC and compact H II regions is largely due to distance, and that the large angular size of diffuse H II regions is not solely due to proximity to the Sun.
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